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000
FXUS63 KLOT 042350
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
550 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUIET...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* GUSTS NEAR 20 KT DIMINISH EARLY THIS EVENING.

* NORTHWEST WINDS UNDER 10 KT THURSDAY BECOMING WEST LATE IN THE
  DAY.

MDB

//DISCUSSION...UPDATED 00Z...

HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL MOVE SOUTHEAST INTO
CENTRAL ILLINOIS THURSDAY AFTERNOON. THIS WILL KEEP VFR CONDITIONS
IN PLACE THROUGH THE PERIOD. THE CURRENT BREEZY NORTHWEST WINDS
WILL EASE EARLY THIS EVENING WITH GUSTS DIMINISHING. NORTHWEST
WINDS WILL REMAIN UNDER 10 KT THURSDAY AND TREND WESTERLY LATE IN
THE DAY AND THEN LIGHT SOUTHWEST OR EVEN LIGHT AND VARIABLE
THURSDAY EVENING.

MDB


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...VFR. BREEZY SOUTHWEST WINDS.

SATURDAY...VFR. WEST TO SOUTHWEST WINDS.

SUNDAY THROUGH TUESDAY...MAINLY VFR. SOUTHWEST WINDS.

MDB

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042350
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
550 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUIET...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* GUSTS NEAR 20 KT DIMINISH EARLY THIS EVENING.

* NORTHWEST WINDS UNDER 10 KT THURSDAY BECOMING WEST LATE IN THE
  DAY.

MDB

//DISCUSSION...UPDATED 00Z...

HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL MOVE SOUTHEAST INTO
CENTRAL ILLINOIS THURSDAY AFTERNOON. THIS WILL KEEP VFR CONDITIONS
IN PLACE THROUGH THE PERIOD. THE CURRENT BREEZY NORTHWEST WINDS
WILL EASE EARLY THIS EVENING WITH GUSTS DIMINISHING. NORTHWEST
WINDS WILL REMAIN UNDER 10 KT THURSDAY AND TREND WESTERLY LATE IN
THE DAY AND THEN LIGHT SOUTHWEST OR EVEN LIGHT AND VARIABLE
THURSDAY EVENING.

MDB


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...VFR. BREEZY SOUTHWEST WINDS.

SATURDAY...VFR. WEST TO SOUTHWEST WINDS.

SUNDAY THROUGH TUESDAY...MAINLY VFR. SOUTHWEST WINDS.

MDB

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042350
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
550 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUIET...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* GUSTS NEAR 20 KT DIMINISH EARLY THIS EVENING.

* NORTHWEST WINDS UNDER 10 KT THURSDAY BECOMING WEST LATE IN THE
  DAY.

MDB

//DISCUSSION...UPDATED 00Z...

HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL MOVE SOUTHEAST INTO
CENTRAL ILLINOIS THURSDAY AFTERNOON. THIS WILL KEEP VFR CONDITIONS
IN PLACE THROUGH THE PERIOD. THE CURRENT BREEZY NORTHWEST WINDS
WILL EASE EARLY THIS EVENING WITH GUSTS DIMINISHING. NORTHWEST
WINDS WILL REMAIN UNDER 10 KT THURSDAY AND TREND WESTERLY LATE IN
THE DAY AND THEN LIGHT SOUTHWEST OR EVEN LIGHT AND VARIABLE
THURSDAY EVENING.

MDB


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...VFR. BREEZY SOUTHWEST WINDS.

SATURDAY...VFR. WEST TO SOUTHWEST WINDS.

SUNDAY THROUGH TUESDAY...MAINLY VFR. SOUTHWEST WINDS.

MDB

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 042350
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
550 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUIET...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* GUSTS NEAR 20 KT DIMINISH EARLY THIS EVENING.

* NORTHWEST WINDS UNDER 10 KT THURSDAY BECOMING WEST LATE IN THE
  DAY.

MDB

//DISCUSSION...UPDATED 00Z...

HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL MOVE SOUTHEAST INTO
CENTRAL ILLINOIS THURSDAY AFTERNOON. THIS WILL KEEP VFR CONDITIONS
IN PLACE THROUGH THE PERIOD. THE CURRENT BREEZY NORTHWEST WINDS
WILL EASE EARLY THIS EVENING WITH GUSTS DIMINISHING. NORTHWEST
WINDS WILL REMAIN UNDER 10 KT THURSDAY AND TREND WESTERLY LATE IN
THE DAY AND THEN LIGHT SOUTHWEST OR EVEN LIGHT AND VARIABLE
THURSDAY EVENING.

MDB


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...VFR. BREEZY SOUTHWEST WINDS.

SATURDAY...VFR. WEST TO SOUTHWEST WINDS.

SUNDAY THROUGH TUESDAY...MAINLY VFR. SOUTHWEST WINDS.

MDB

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 042210
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
410 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHWEST WINDS OCCASIONALLY GUSTING TO AROUND 20 KT THROUGH SUNSET.

MDB

//DISCUSSION...UPDATED 22Z...

WINDS HAVE SETTLED INTO THE 300-330 DIRECTION AND SHOULD REMAIN IN
THAT RANGE THROUGH THE REST OF THE AFTERNOON. OCCASIONAL GUSTS
AROUND 20 KT WILL DIMINISH THROUGH SUNSET.

MDB

FROM 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 042210
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
410 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHWEST WINDS OCCASIONALLY GUSTING TO AROUND 20 KT THROUGH SUNSET.

MDB

//DISCUSSION...UPDATED 22Z...

WINDS HAVE SETTLED INTO THE 300-330 DIRECTION AND SHOULD REMAIN IN
THAT RANGE THROUGH THE REST OF THE AFTERNOON. OCCASIONAL GUSTS
AROUND 20 KT WILL DIMINISH THROUGH SUNSET.

MDB

FROM 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042210
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
410 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHWEST WINDS OCCASIONALLY GUSTING TO AROUND 20 KT THROUGH SUNSET.

MDB

//DISCUSSION...UPDATED 22Z...

WINDS HAVE SETTLED INTO THE 300-330 DIRECTION AND SHOULD REMAIN IN
THAT RANGE THROUGH THE REST OF THE AFTERNOON. OCCASIONAL GUSTS
AROUND 20 KT WILL DIMINISH THROUGH SUNSET.

MDB

FROM 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042210
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
410 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHWEST WINDS OCCASIONALLY GUSTING TO AROUND 20 KT THROUGH SUNSET.

MDB

//DISCUSSION...UPDATED 22Z...

WINDS HAVE SETTLED INTO THE 300-330 DIRECTION AND SHOULD REMAIN IN
THAT RANGE THROUGH THE REST OF THE AFTERNOON. OCCASIONAL GUSTS
AROUND 20 KT WILL DIMINISH THROUGH SUNSET.

MDB

FROM 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 042110
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
310 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 042110
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
310 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042051
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
251 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH FRIDAY...

THROUGH THURSDAY NIGHT...
OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
241 PM CST

FRIDAY NIGHT THROUGH WEDNESDAY...

COMING SHORTLY.

KJB

&&

.CLIMATE...UPDATED WED 251 PM.

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.


                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 042051
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
251 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH FRIDAY...

THROUGH THURSDAY NIGHT...
OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
241 PM CST

FRIDAY NIGHT THROUGH WEDNESDAY...

COMING SHORTLY.

KJB

&&

.CLIMATE...UPDATED WED 251 PM.

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.


                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042015
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042015
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 042015
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042015
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 042015
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 042015
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041930
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
130 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041930
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
130 PM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* OCNLLY GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY
  EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041739
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041739
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041739
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041739
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041739
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041739
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* GUSTY NORTHWEST WINDS THROUGH LATE AFTERNOON OR EARLY EVENING.

KREIN

//DISCUSSION...UPDATED 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041542
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
942 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* GUSTY NORTHWEST WINDS.

KREIN

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS AND TIMING.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041542
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
942 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* GUSTY NORTHWEST WINDS.

KREIN

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS AND TIMING.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041542
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
942 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* GUSTY NORTHWEST WINDS.

KREIN

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS AND TIMING.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041411
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
811 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* GUSTY NORTHWEST WINDS.

KREIN

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS AND TIMING.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041411
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
811 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* GUSTY NORTHWEST WINDS.

KREIN

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS AND TIMING.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041153
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
553 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* GUSTY NORTHWEST WINDS.

BMD

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS.

BMD

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041153
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
553 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* GUSTY NORTHWEST WINDS.

BMD

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS.

BMD

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041153
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
553 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* GUSTY NORTHWEST WINDS.

BMD

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS.

BMD

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041153
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
553 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* GUSTY NORTHWEST WINDS.

BMD

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS.

BMD

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 041153
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
553 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* GUSTY NORTHWEST WINDS.

BMD

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS.

BMD

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 041153
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
553 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* GUSTY NORTHWEST WINDS.

BMD

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS WILL RESULT IN
VFR CONDITIONS AND BREEZY NORTHWEST WINDS THROUGH THE TAF PERIOD.
WIND GUSTS WILL LIKELY PICKUP AFTER DAYBREAK AND LAST AT LEAST
UNTIL SUNSET IF NOT A LITTLE LATER. GUIDANCE HAS BACKED OFF SOME
ON THE WIND SPEEDS TODAY SO TAPERED THE MAGNITUDE OF THE GUSTS
BACK INTO THE HIGH TEENS IN THE TAFS. MID AND HIGH LEVEL CLOUDS
ARE EXPECTED THROUGH THE PERIOD...AND LOWER COLD AIR STRATOCUMULUS
MAY FORM LATER TODAY BUT FOR NOW EXPECT COVERAGE TO REMAIN FEW TO
SCATTERED.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS.

BMD

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040917
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
316 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040917
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
316 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040917
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
316 AM CST WED MAR 4 2015

.SHORT TERM...
316 AM CST

TODAY THROUGH FRIDAY...

COLD FRONT WHICH MOVED ACROSS THE AREA LAST EVENING HAS PUSHED INTO
THE OHIO VALLEY OVERNIGHT...THOUGH PUSH OF COLDER ARCTIC ORIGIN AIR
HAS BEEN GRADUAL. AREA OF STRONGER NORTHWEST WINDS AND A SHARPER
GRADIENT TO COLDER/DRIER TEMP/DEW POINT NOTED IN 08Z SURFACE
ANALYSIS FROM EAST CENTRAL WI INTO NORTHWEST IL AND NORTHERN
MO...AND THIS WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE AREA TODAY.
THIS PERSISTENT COLD ADVECTION WILL KEEP TEMPERATURE TREND RATHER
FLAT TODAY...WITH ONLY A FEW DEGREES RISE OVER MORNING LOWS NEAR 10
ABOVE NORTHWEST...AND RELATIVELY STEADY READINGS IN THE LOWER 20S IN
THE SOUTHEAST. PARTIAL CLEARING WAS WORKING INTO WESTERN PARTS OF
THE FORECAST AREA EARLY THIS MORNING...THOUGH ADDITIONAL MID/HIGH
CLOUDS WERE NOTED UPSTREAM ACROSS THE PLAINS AND THESE WILL CONTINUE
TO SPREAD NORTHEAST ACROSS THE AREA THIS MORNING AS ANOTHER MINOR
AMPLITUDE SHORT WAVE LIFTS NORTHEAST ACROSS THE AREA AHEAD OF
POSITIVE TILT UPPER TROUGH WHICH WILL SLOWLY PUSH SOUTHEAST ACROSS
THE REGION THROUGH THURSDAY MORNING. PASSAGE OF THIS FEATURE AND THE
RESULTING HEIGHT RISES AND DEEP SUBSIDENCE BEHIND IT WILL FINALLY
ALLOW SURFACE HIGH PRESSURE TO BUILD INTO THE AREA THURSDAY AND
THURSDAY NIGHT. DURING THIS PERIOD...ARCTIC AIR WILL BE IN PLACE
WITH 850 MB TEMPS NEAR -20 C. LOWS TONIGHT WILL DIP INTO THE SINGLE
DIGITS BELOW ZERO MAINLY ACROSS NORTH CENTRAL IL WHERE CLEAR SKIES
AND LIGHTER WINDS ARE MOST LIKELY...WHILE SOME PATCHY CLOUD COVER
AND MODEST NORTHWEST WINDS WILL KEEP EASTERN/SOUTHEASTERN PARTS OF
THE CWA GENERALLY IN THE SINGLE DIGITS ABOVE ZERO. DESPITE A GOOD
AMOUNT OF SUNSHINE ON THURSDAY...SHALLOW MIXING OF COLD AIR MASS
WITHIN THE PASSING SURFACE RIDGE LOOKS TO LIMIT MAX TEMPS TO THE
LOW-MID TEENS. CLEAR SKIES AND LIGHT WINDS THURSDAY EVENING SHOULD
ALLOW A QUICK DROP IN TEMPS AGAIN INTO +/- SINGLE DIGITS...BEFORE
INCREASING SOUTH WINDS AND WARM ADVECTION DEVELOPING ALOFT WORK TO
PRODUCE STEADY/RISING TEMPERATURES OVERNIGHT PARTICULARLY ACROSS
NORTH CENTRAL IL. WIND CHILL READINGS WILL DROP INTO THE -15 TO -20
DEGREE RANGE BOTH LATE TONIGHT AND AGAIN THURSDAY NIGHT...BUT SHOULD
REMAIN JUST ABOVE ADVISORY CRITERIA EXCEPT FOR A BRIEF TIME AT THE
COLDEST SPOTS OVER NORTH CENTRAL IL.

ON FRIDAY...WHILE FLOW REMAINS NORTHWEST ALOFT THE LOW LEVEL WINDS
WILL BE GUSTY FROM THE SOUTH-SOUTHWEST. THIS WILL MARK THE BEGINNING
OF A WARMING TREND...WITH TEMPERATURES APPROACHING THE FREEZING MARK
ACROSS THE WESTERN COUNTIES OF THE CWA ALBEIT WITH THOSE GUSTY WINDS
MAINTAINING A BRISK FEEL TO THE DAY WITH WIND CHILLS IN THE TEENS.

RATZER

&&

.LONG TERM...
316 AM CST

SATURDAY THROUGH TUESDAY...

FROM THE WEEKEND INTO EARLY NEXT WEEK...THE UPPER FLOW MAINTAINS A
BROAD EASTERN CONUS UPPER TROUGH WHICH IS LESS AMPLIFIED THAN IN
RECENT WEEKS. A SERIES OF SHORT WAVE IMPULSES DOES PASS SOUTHEAST
THROUGH THE FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION.
HOWEVER...SURFACE HIGH PRESSURE BECOMES ANCHORED FROM TEXAS ACROSS
THE SOUTHEASTERN STATES AND KEEPS ANY SIGNIFICANT GULF MOISTURE
RETURN FROM REACHING THE MIDWEST. HAVE MAINTAINED A DRY FORECAST
THROUGH THE PERIOD...AS TIMING/AMPLITUDE DETAILS OF INDIVIDUAL MINOR
SHORT WAVES LOWER CONFIDENCE IN NARROWING A SHORT WINDOW OF ANY
LIGHT PRECIP POTENTIAL IN OTHERWISE FAIRLY DRY REGIME. MODERATION OF
TEMPERATURES THROUGH THE PERIOD LOOKS TO BRING US BACK TO NORMAL OR
SLIGHTLY ABOVE BY MONDAY/TUESDAY. IN ADDITION TO WORKING ON MELTING
OUR SNOWPACK...MEDIUM RANGE TEMP FORECASTS BY THE MIDDLE OF NEXT
WEEK INDICATE SOME 50 DEGREE WEATHER MAY BE IN STORE FOR OUR
WINTER-WEARY CWA.

RATZER

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CST WED MAR 4 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CST WED MAR 4 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 040903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CST WED MAR 4 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CST WED MAR 4 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...
301 AM CST

A COLD FRONT HAS DROPPED ACROSS LAKE MICHIGAN WITH HIGH PRESSURE
BUILDING INTO THE NORTHERN PLAINS TODAY RESULTING IN MODERATE
NORTHWEST WINDS. WINDS ARE EXPECTED TO PEAK AROUND 30 KT TODAY
WHICH COMBINED WITH COLDER TEMPERATURES MOVING OVER THE LAKE
COULD RESULT IN SOME FREEZING SPRAY. WINDS SHOULD TAPER GRADUALLY
TONIGHT AS THE HIGH MOVES ACROSS THE MIDWEST...THEN BACK TO THE
SOUTHWEST THROUGH THE DAY THURSDAY AS THE HIGH SETTLES ALONG THE
OHIO VALLEY. WINDS INCREASE AGAIN FRIDAY AHEAD OF A COLD
FRONT...BUT WARM ADVECTION OVER THE LAKE SHOULD HELP KEEP THE
GUSTS IN CHECK. THE COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN LATE
FRIDAY NIGHT INTO EARLY SATURDAY.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040543
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1143 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS OVER THE NEXT FEW HOURS.
* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM-HIGH CONFIDENCE IN END OF MVFR CIGS.
* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040543
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1143 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS OVER THE NEXT FEW HOURS.
* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM-HIGH CONFIDENCE IN END OF MVFR CIGS.
* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040543
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1143 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS OVER THE NEXT FEW HOURS.
* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM-HIGH CONFIDENCE IN END OF MVFR CIGS.
* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040543
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1143 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* MVFR CIGS OVER THE NEXT FEW HOURS.
* GUSTY NORTHWEST WINDS WEDNESDAY.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS TONIGHT
THROUGH WEDNESDAY WITH A MODEST NORTHWEST GRADIENT IN PLACE
ACROSS THE REGION THROUGH THE TAF PERIOD. MVFR STRATUS DESK IS
ALSO IN PLACE ACROSS THE MIDWEST THOUGH A CLEARING LINE WAS NOTED
DROPPING SOUTHEAST ACROSS IOWA AND WISCONSIN THOUGH HAS SINCE
BECOME SHROUDED UNDER HIGHER CLOUDS. BASED ON
EXTRAPOLATION...WOULD EXPECT THE MVFR CIGS TO SCATTER OUT DURING
THE OVERNIGHT HOURS...WITH VFR CONDITIONS IN PLACE THE REMAINDER
OF THE TAF PERIOD. NORTHWEST WINDS ARE EXPECTED TO BECOME GUSTY
DURING THE DAY WEDNESDAY.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM-HIGH CONFIDENCE IN END OF MVFR CIGS.
* MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN
  WIND GUST SPEEDS WEDNESDAY.

BMD

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z WEDNESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040329
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
929 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

MDB

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040329
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
929 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

MDB

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040329
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
929 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

MDB

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040329
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
929 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

MDB

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040329
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
929 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

MDB

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040329
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
929 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

MDB

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040219
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
819 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040219
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
819 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 040219
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
819 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 040219
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
819 PM CST TUE MAR 3 2015

.UPDATE...
818 PM CST

NO MAJOR CHANGES TO THE GOING FORECAST THIS EVENING. COLD FRONT
HAS CLEARED THE AREA AND COLDER AIR IS FILTERING INTO THE AREA ON
WEST TO NORTHWEST WINDS. THE RATE OF COOLING WILL INCREASE INTO
THE EARLY OVERNIGHT AND HAVE MADE LITTLE IF ANY ADJUSTMENT TO
EXPECTED LOWS BY DAYBREAK. LOW CLOUDS HAVE TEMPORARILY SCATTERED
IN SOME AREAS BUT WILL FILL BACK IN THROUGH THE REST OF THE
EVENING BEFORE ERODING FROM THE NORTHWEST LATER TONIGHT AND
WEDNESDAY MORNING. MID CLOUD COVER WILL TAKE OVER IN ITS PLACE SO
ANY CLEARING WOULD LIKELY BE BRIEF AND SPOTTY.

MDB

&&

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032323
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
523 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032323
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
523 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032323
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
523 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* OCNL GUSTS TO 20 KT THIS EVENING.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 00Z...

THE COLD FRONT HAS MOVED INTO NORTH CENTRAL IL...AND HAS PASSED
THROUGH RFD. EXPECTING OCNL GUSTS TO 20 KT AHEAD OF AND ALONG THE
FRONT...BUT THEN GUSTS DISSIPATE BEHIND THE FRONT. MVFR CIGS EXTEND
BACK THROUGH THE DAKOTAS SO VERY CONFIDENT IN MVFR CIGS THROUGH
THE NIGHT. EXPECTING CIGS TO IMPROVE TO VFR TOMORROW MORNING AS
DRIER AIR WORKS ITS WAY INTO THE REGION. NORTHWEST WINDS WILL BEGIN
GUSTING TO 20 KT BY MID MORNING AND THEN TO 25 KT IN THE
AFTERNOON. GUSTS LOOK RATHER DIURNAL AND THEY DISSIPATE IN THE
EVENING.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY THROUGH FRIDAY...VFR.

SATURDAY...MVFR CIGS PSBL.

SUNDAY...SCHC RAIN OR SNOW OVERNIGHT...MVFR CIGS PSBL.

MONDAY...MVFR CIGS PSBL IN THE MORNING.

JEE

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 032155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
355 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* WEST WINDS GUSTING TO 22 KT THIS AFTN.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEW POINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
355 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* WEST WINDS GUSTING TO 22 KT THIS AFTN.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEW POINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
355 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* MVFR CIGS EXPECTED THROUGH THE NIGHT BCMG VFR WEDNESDAY MORNING.

* WEST WINDS GUSTING TO 22 KT THIS AFTN.

* NW WINDS GUSTING TO 25 KT WEDNESDAY.

JEE

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEW POINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH CONFIDENCE IN WHEN CIGS IMPROVE TO VFR.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 032047
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
247 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 032047
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
247 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032047
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
247 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032047
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
247 PM CST TUE MAR 3 2015

.SHORT TERM...
247 PM CST

THROUGH THURSDAY...

SOMEWHAT BAGGY COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING
AND USHER IN PROGRESSIVELY COLDER AIR MASS THROUGH THE NIGHT. AHEAD
OF THE INTO THE EARLY-MID EVENING ANTICIPATE LOW STRATUS HANGING
AROUND AND LIKELY RESULTING IN NEARLY STEADY TEMPS AND HAVE GONE A
BIT ABOVE HOURLY GUIDANCE TEMPS HANGING ONTO 30S INTO THE EARLY
EVENING OVER MOST OF THE CWA BEFORE BOTTOM DROPS OUT LATE TONIGHT.
SOME PARTIAL CLEARING IS EXPECTED OVERNIGHT BUT SOME MID-HIGH CLOUDS
WILL MOVE IN AS WELL...SO NOT CURRENTLY EXPECTING SKIES TO GO CLEAR.

A COUPLE DAYS OF UNSEASONABLY COLD WEATHER LOOK TO BE ON TAP
WEDNESDAY AND THURSDAY. WEDNESDAY NIGHT HAS POTENTIAL TO GIVE
CHICAGO`S RECORD LOW A RUN FOR ITS MONEY...THOUGH GUIDANCE SUGGESTS
MID-HIGH LEVEL CLOUDINESS COULD BE RATHER EXTENSIVE FOR MUCH OF THE
NIGHT AND WINDS STAYING UP A BIT. BOTH OF THESE FACTORS COULD KEEP
TEMPS FROM REALIZING THEIR FULL FRIGID POTENTIAL...THOUGH ANY LATE
NIGHT CLEARING COULD ALLOW FOR LAST MINUTE DROPS IN TEMPS. ARCTIC
HIGH WILL BE NEAR BY THURSDAY WITH HEART OF THE ARCTIC AIR MASS
OVERHEAD TO START THE DAY...SUGGESTING THAT HIGHS COULD THREATEN
RECORD LOW MAX TEMPS. FULL SUNSHINE THURSDAY WITH LOWER ALBEDO IN
CHICAGO AND RFD METRO AREAS SHOULD ALLOW TEMPS TO MODERATE A BIT
ABOVE GUIDANCE AND HAVE TRENDED HIGHS EVER SO SLIGHTLY UPWARD.

IZZI

&&

.LONG TERM...
247 PM CST

THURSDAY NIGHT THROUGH TUESDAY...

THURSDAY NIGHT COULD BE ONE OF THOSE NIGHTS THAT SEE TEMPERATURES
CRASH DURING THE EVENING HOURS GIVEN CLEAR SKIES AND PROXIMITY OF
THE HIGH. HIGH DOES SCOOT OFF TO THE EAST OVERNIGHT AND SOUTHERLY
WINDS LOOK TO DEVELOP AFTER MIDNIGHT WHICH SHOULD ALLOW TEMPS TO
LEVEL OFF AND THEN BEGIN TO SLOWLY RISE PRIOR TO SUNRISE AND DID
REFLECT THIS TREND IN THE HOURLY TEMP GRIDS.

FRIDAY INTO NEXT WEEK LOOK TO BE FAIRLY QUIET PERIOD WITH A TREND TO
NORMAL AND THEN POTENTIALLY EVEN ABOVE NORMAL TEMPS BY EARLY NEXT
WEEK. STRONG MARCH SUN AND TEMPS WARMING ABOVE FREEZING THIS WEEKEND
DURING THE DAYTIME SHOULD BEGIN THE PROCESS OF CHIPPING AWAY AT THE
DEEP SNOW PACK/GLACIER THAT HAS BLANKETED THE REGION SINCE THE EARLY
FEBRUARY BLIZZARD. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES HEADING INTO THE
MIDDLE OF THE MONTH...THE QUICKER THE SNOW PACK MELTS THE WARMER
TEMPS COULD POTENTIALLY GET AS A MEAN RIDGE IS PROGGED TO DEVELOP OF
THE NATION`S MID SECTION.

IZZI

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX   17 (1890)       12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 032030
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
230 PM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 032030
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
230 PM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

230 PM...LOW PRESSURE OVER THE NORTHERN LAKES WILL MERGE WITH
DEEPER LOW PRESSURE OVER NORTHERN ONTARIO TONIGHT AND THEN MOVE
INTO QUEBEC WEDNESDAY MORNING. WINDS WILL BE SHIFTING WESTERLY
OVER THE NEXT FEW HOURS AND THEN MORE NORTHWEST ACROSS THE
SOUTHERN PART OF THE LAKE OVERNIGHT. THE GRADIENT WILL REMAIN
TIGHT AS HIGH PRESSURE BUILDS ACROSS THE NORTHERN AND CENTRAL
PLAINS WEDNESDAY AND WEDNESDAY NIGHT AND COMBINED WITH RETURNING
COLD AIR...WINDS TO 30KT LOOKS REASONABLE. AS THE HIGH MOVES EAST
ACROSS THE SOUTHERN LAKES AND OHIO VALLEY THURSDAY NIGHT INTO
FRIDAY...THE GRADIENT WILL TIGHTEN ACROSS THE WESTERN LAKES WITH
SOUTHWEST WINDS INCREASING BACK TO 30KT WITH SOME POTENTIAL FOR
LOW END GALES. THESE WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT AS
THE GRADIENT BEGINS TO WEAKEN. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031951
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
151 PM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031951
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
151 PM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031951
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
151 PM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* WSWLY WINDS GUSTING TO 20-25KT UNTIL FROPA EARLY THIS
  EVENING...THEN WIND SHIFTING TO WNWLY OVERNIGHT AND NWLY
  TOMORROW GUSTING TO 20KT.

* IFR VIS IN -DZ/BR FOR A COUPLE MORE HOURS...IMPROVING TO MVFR IN
  BR UNTIL FROPA.

* IFR CIGS UNTIL FROPA...THEN IMPROVING TO MVFR OVERNIGHT INTO
  EARLY TOMORROW MORNING.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031753
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1153 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* FREEZING DRIZZLE CHANGING OVER TO DRIZZLE OR OCNL LIGHT RAIN AS
  TEMPS RISE ABOVE FREEZING.

* IFR CIGS UNTIL FROPA LATE AFTERNOON/EARLY EVENING...THEN
  IMPROVING TO MVFR OVERNIGHT INTO EARLY TOMORROW MORNING.

* SSWLY WINDS GUSTING TO 25KT...VEERING TO WLY BY EARLY EVENING...
  THEN VEERING NWLY AND GUSTING TO 25KT TOMORROW.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031753
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1153 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* FREEZING DRIZZLE CHANGING OVER TO DRIZZLE OR OCNL LIGHT RAIN AS
  TEMPS RISE ABOVE FREEZING.

* IFR CIGS UNTIL FROPA LATE AFTERNOON/EARLY EVENING...THEN
  IMPROVING TO MVFR OVERNIGHT INTO EARLY TOMORROW MORNING.

* SSWLY WINDS GUSTING TO 25KT...VEERING TO WLY BY EARLY EVENING...
  THEN VEERING NWLY AND GUSTING TO 25KT TOMORROW.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031753
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1153 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* FREEZING DRIZZLE CHANGING OVER TO DRIZZLE OR OCNL LIGHT RAIN AS
  TEMPS RISE ABOVE FREEZING.

* IFR CIGS UNTIL FROPA LATE AFTERNOON/EARLY EVENING...THEN
  IMPROVING TO MVFR OVERNIGHT INTO EARLY TOMORROW MORNING.

* SSWLY WINDS GUSTING TO 25KT...VEERING TO WLY BY EARLY EVENING...
  THEN VEERING NWLY AND GUSTING TO 25KT TOMORROW.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031753
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1153 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* FREEZING DRIZZLE CHANGING OVER TO DRIZZLE OR OCNL LIGHT RAIN AS
  TEMPS RISE ABOVE FREEZING.

* IFR CIGS UNTIL FROPA LATE AFTERNOON/EARLY EVENING...THEN
  IMPROVING TO MVFR OVERNIGHT INTO EARLY TOMORROW MORNING.

* SSWLY WINDS GUSTING TO 25KT...VEERING TO WLY BY EARLY EVENING...
  THEN VEERING NWLY AND GUSTING TO 25KT TOMORROW.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031753
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1153 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* FREEZING DRIZZLE CHANGING OVER TO DRIZZLE OR OCNL LIGHT RAIN AS
  TEMPS RISE ABOVE FREEZING.

* IFR CIGS UNTIL FROPA LATE AFTERNOON/EARLY EVENING...THEN
  IMPROVING TO MVFR OVERNIGHT INTO EARLY TOMORROW MORNING.

* SSWLY WINDS GUSTING TO 25KT...VEERING TO WLY BY EARLY EVENING...
  THEN VEERING NWLY AND GUSTING TO 25KT TOMORROW.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031753
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1153 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* FREEZING DRIZZLE CHANGING OVER TO DRIZZLE OR OCNL LIGHT RAIN AS
  TEMPS RISE ABOVE FREEZING.

* IFR CIGS UNTIL FROPA LATE AFTERNOON/EARLY EVENING...THEN
  IMPROVING TO MVFR OVERNIGHT INTO EARLY TOMORROW MORNING.

* SSWLY WINDS GUSTING TO 25KT...VEERING TO WLY BY EARLY EVENING...
  THEN VEERING NWLY AND GUSTING TO 25KT TOMORROW.

KREIN

//DISCUSSION...UPDATED 18Z...

WARM...MOIST ADVECTION HAS SET UP ACROSS THE REGION IN ADVANCE OF
A STRONG COLD FRONT EXTENDING FROM NERN MN THROUGH CNTRL IOWA.
CIGS HAVE BECOME MORE UNIFORMLY 005-007 ACROSS THE REGION AS
TEMPERATURES RISE INTO THE LOWER TO MIDDLE 30S AND DEWPOINTS RISE
INTO THE UPPER 20S TO LOWER 30S. DRY AIR OVERSPREADING THE NEARLY
SATURATED LOWER LEVELS HAS TRANSITIONED PCPN OVER TO DZ WHERE SFC
TEMPS ARE ABOVE FREEZING AND FZDZ WHERE TEMPS REMAIN BELOW
FREEZING. A FEW ISOLD POCKETS OF MORE STEADY RAIN REMAIN...BUT
SHOULD BE BRIEF. EXPECT THAT MDW/GYY HAVE ALREADY TRANSITIONED
OVER TO DZ...WHILE ORD/DPA/RFD REMAIN UNDER FZDZ. A SFC WAVE ALONG
THE FRONT IS QUICKLY TRACKING NEWD ALONG THE FRONT AND HAS ALREADY
MOVED INTO WISCONSIN...WITH A 7MB/3HR PRESSURE RISE/FALL COUPLET
GENERATING WIND GUSTS TO 25KT ACROSS THE REGION. EXPECT THE DZ TO
END AS THE SFC LOW CONTINUES NEWD INTO THE UPPER GREAT
LAKES...WITH LATEST RADAR IMAGERY SHOWING A RELATIVELY SHARP BACK
EDGE TO THE PCPN MOVING EWD THROUGH NCNTRL IL. CONDITIONS SHOULD
GRADUALLY IMPROVE TO MVFR AND VFR FOLLOWING THE FROPA AS
COLDER...DRIER AIR FILTERS ACROSS THE REGION. FOLLOWING THE
FROPA...EXPECT THAT STRONG ADVECTION BEHIND THE FRONT WILL HELP
DRIVE NWLY GUSTS TO 25KT TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM CONFIDENCE IN TIMING PCPN ENDING.

* LOW CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO MVFR AND VFR.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031622
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1022 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031622
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1022 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 031622
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1022 AM CST TUE MAR 3 2015

.UPDATE...
1022 AM CST

THE MORE SIGNIFICANT PRECIP IS MOVING OFF TO THE EAST AND SHOULD SEE
PRECIP TAPER TO DRIZZLE/FREEZING DRIZZLE WITH JUST SOME INTERMITTENT
LIGHT RAIN OR FREEZING RAIN INTO THE EARLY AFTERNOON. TEMPERATURES
SHOULD CONTINUE TO INCH UPWARD AND CLIMB ABOVE FREEZING ACROSS THE
AREA IN THE NEXT COUPLE HOURS. IT IS POSSIBLE THAT WINTER WX
ADVISORY COULD NEED TO BE EXTENDED A COUPLE OF HOURS OVER NORTHERN
PORTIONS OF THE CWA...WILL CONTINUE TO MONITOR TEMP TRENDS AND MAKE
A LAST MINUTE DECISION ON THAT.

IZZI

&&

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031533
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
933 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031533
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
933 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031533
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
933 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031533
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
933 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031533
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
933 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031533
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
933 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* FREEZING RAIN TURNING TO DRIZZLE AS TEMPS RISE ABOVE FREEZING
  LATE MORNING/MIDDAY.

* GENERALLY IFR VIS THROUGH LATE MORNING AND IFR CIGS THROUGH
  EARLY AFTERNOON. CIGS IMPROVING TO MVFR MID AFTERNOON AND VIS
  IMPROVING TO VFR MID AFTERNOON.

* SOUTH WINDS GUSTING TO ARND 25KT THROUGH MID DAY...VEERING
  SOUTHWEST THIS AFTERNOON AND NORTHWEST WINDS THIS EVENING.
  GUSTINESS TO PERSIST THROUGH TONIGHT.

KREIN

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS
  IMPACTS.

* LOW CONFIDENCE IN DZ END TIME.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 031149
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
549 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* SNOW...SLEET AND FREEZING RAIN THIS MORNING EVENTUALLY TURNING
  TO RAIN/DRIZZLE AS TEMPS RISE ABOVE FREEZING LATE
  MORNING/MIDDAY. GENERALLY IFR/LIFR CONDITIONS THIS MORNING WITH
  CONDITIONS IMPROVING TO MVFR CIGS AND HIGHER VSBYS LATE AFTN AND
  EVENING.

* SOUTHEAST WINDS BECOMING GUSTY AROUND 20 KT FROM THE SOUTH BY
  LATE MORNING AND SOUTHWEST THIS AFTERNOON. WEST-NORTHWEST WINDS
  TONIGHT REMAIN GUSTY.

RATZER

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS IMPACTS.

* HIGH IN WIND TRENDS...AND IN MVFR OR BETTER CONDITIONS BY THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 031149
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
549 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* SNOW...SLEET AND FREEZING RAIN THIS MORNING EVENTUALLY TURNING
  TO RAIN/DRIZZLE AS TEMPS RISE ABOVE FREEZING LATE
  MORNING/MIDDAY. GENERALLY IFR/LIFR CONDITIONS THIS MORNING WITH
  CONDITIONS IMPROVING TO MVFR CIGS AND HIGHER VSBYS LATE AFTN AND
  EVENING.

* SOUTHEAST WINDS BECOMING GUSTY AROUND 20 KT FROM THE SOUTH BY
  LATE MORNING AND SOUTHWEST THIS AFTERNOON. WEST-NORTHWEST WINDS
  TONIGHT REMAIN GUSTY.

RATZER

//DISCUSSION...UPDATED 12Z...

AREA OF PRECIPITATION HAS OVERSPREAD THE TERMINALS EARLY THIS
MORNING...WITH SOME MODERATE SNOW AT TIMES FROM ORD
NORTH/NORTHWEST. NORTHERN TERMINALS...RFD...DPA...ORD WILL LIKELY
CONTINUE TO BE THE FOCUS FOR HEAVIER SNOW/SLEET THIS MORNING WITH
OCCASIONALLY LOWER VIS/CIG CONDITIONS RESULTING. FARTHER SOUTH
SOME DRYING IN THE MID-LEVELS IS RESULTING IN LIGHTER PRECIP WHICH
WILL AFFECT MDW/GYY...AND MAY RESULT IN MORE OF A FZRA/FZDZ TREND
RATHER THAN SNOW FOR MUCH OF THE MORNING AT THOSE LOCATIONS.
IN ANY CASE...WARMING ALOFT WILL EVENTUALLY TURN PRECIP FROM SNOW
TO SLEET/FREEZING RAIN OR DRIZZLE OVER THE NEXT FEW HOURS...AND
EVENTUALLY TO RAIN/DRIZZLE AS SURFACE TEMPS RISE ABOVE FREEZING
LATER THIS MORNING. PRECIP IS EXPECTED TO END LATER THIS AFTERNOON
AS WINDS SHIFT WEST AND DRIER AIR FILTERS IN.

SPEAKING OF WINDS...WINDS ARE CURRENTLY SOUTHEAST AROUND 10 KT BUT
WILL INCREASE 10-15 KT WITH GUSTS AROUND 20 KT BY LATE MORNING...
BACKING TO THE SOUTH AND SOUTHWEST INTO THIS AFTERNOON AS LOW
PRESSURE MOVES ACROSS WISCONSIN. TRAILING COLD FRONT WILL SHIFT
WINDS WEST THIS EVENING...WITH GUSTS 20-25 KT LINGERING INTO
TONIGHT.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM IN TIMING OF PRECIP TYPE CHANGES AND CIG/VIS IMPACTS.

* HIGH IN WIND TRENDS...AND IN MVFR OR BETTER CONDITIONS BY THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.

SATURDAY THROUGH MONDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 030903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 030903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
303 AM CST TUE MAR 3 2015

.SHORT TERM...
300 AM CST

THROUGH WEDNESDAY...

MAIN FORECAST CONCERNS THIS MORNING WILL BE DEALING WITH PRECIP TYPE
ISSUES WITH WARM FRONT LIFTING ACROSS THE REGION EARLY THIS MORNING.
SURFACE LOW IS IN PLACE ACROSS EASTERN COLORADO AND WESTERN KANSAS
EARLY WITH AXIS OF STRONGEST PRESSURE FALLS SPRAWLED ACROSS THE MID
MISSOURI VALLEY INTO SOUTHEASTERN MINNESOTA. MID LEVEL WARM
ADVECTION IS RAMPING UP ACROSS THE MIDWEST AND WILL CONTINUE TO
INCREASE ACROSS NORTHERN ILLINOIS OVER THE NEXT FEW HOURS...THEN
SHOULD START TO SPREAD NORTH AND NORTHEAST OF THE FORECAST AREA FROM
MID MORNING ON. WIDESPREAD PRECIPITATION NOTED ON RADAR ALREADY THIS
MORNING WITH REPORTS OF FREEZING RAIN AND SLEET UPSTREAM. BEST
CHANCE FOR ANY SNOW ACCUMULATIONS WITH THIS SYSTEM WILL BE ALONG AND
NORTH OF I-80...BUT PARTICULARLY CLOSER TO THE WI STATE LINE WHICH
WILL REMAIN MARGINALLY COLD ENOUGH ALOFT FOR SNOW THROUGH MID
MORNING. H9-H8 LAYER MAX WET BULB TEMPS WILL RISE ABOVE FREEZING
SOUTH OF THE I-80 CORRIDOR BY AROUND 12Z...AND ACROSS THE ENTIRE CWA
BY 15Z AT WHICH POINT SLEET OR FREEZING RAIN CAN BE EXPECTED FOR
AREAS WITH SURFACE TEMPS STILL BELOW FREEZING. GUIDANCE IS
INITIALIZING TOO COLD WITH SURFACE TEMPS THIS MORNING...AND SOME
MODELS SUCH AS THE NAM SEEM TO HOLD ON TO FREEZING TEMPS TOO
LONG...SO FEEL THE THREAT FOR FREEZING RAIN MAY BE SOMEWHAT
LIMITED...THOUGH ANY ICE ACCUMULATIONS WILL CAUSE ISSUES
PARTICULARLY WITH THE TIMING DURING THE MORNING COMMUTE. AREAS SOUTH
OF I-80 SHOULD SEE SURFACE TEMPS RISE ABOVE THE FREEZING MARK 13-15Z
AND THROUGH 15-17Z THE FREEZING LINE SHOULD LIFT UP TO THE STATE
LINE MARKING THE END OF THE FREEZING RAIN THREAT. MEANWHILE...LATE
THIS MORNING INTO THE EARLY AFTERNOON MID LEVEL DRY SLOT WILL PUNCH
IN FROM THE WEST WITH PRECIP TAPERING TO A LIGHT RAIN OR DRIZZLE
BEFORE ENDING ALTOGETHER THIS EVENING.

HIGH PRESSURE WILL BEGIN TO BUILD ACROSS THE NORTHERN PLAINS TONIGHT
WITH A MODERATE NORTHWEST GRADIENT AND COLD/DRY ADVECTION IN PLACE
TONIGHT. STEEP LOW LEVEL LAPSE RATES DEVELOP AND THERE IS SOME
INDICATION THERE MAY BE A FEW LIGHT FLURRIES THAT DEVELOP THIS
EVENING AND EARLY OVERNIGHT BEFORE DRIER AIR MOVES IN...BUT FOR NOW
CHANCES SEEM TOO LOW TO INCLUDE MENTION IN FORECAST. COLD ADVECTION
WILL DRIVE TEMPERATURES INTO THE SINGLE DIGITS IN THE NORTHWEST
CWA...AND UPPER TEENS TO LOW 20S IN THE SOUTHEAST. TEMPERATURES WILL
NOT REBOUND MUCH ON WEDNESDAY WITH HIGHS IN THE HIGH TEENS TO LOWER

DEUBELBEISS

&&

.LONG TERM...
300 AM CST

WEDNESDAY NIGHT THROUGH MONDAY...

FAIRLY QUIET WEATHER EXPECTED FROM MIDWEEK THROUGH THE WEEKEND. HIGH
PRESSURE WILL BUILD FROM THE NORTHERN PLAINS WEDNESDAY NIGHT TO
DOWNSTATE ILLINOIS THURSDAY. COLDER AIR WILL ACCOMPANY THE HIGH WITH
MODELS CONTINUING TO ADVERTISE H85 TEMPS AROUND -20C WEDNESDAY
NIGHT. HIGH PRESSURE CENTERED TO OUR WEST WILL ALLOW WESTERN
COUNTIES TO BEGIN TO CLEAR AND WINDS TO DECOUPLE ALLOWING TEMPS TO
RADIATE BELOW ZERO...THOUGH A MODEST GRADIENT AND LINGERING CLOUD
COVER IN EASTERN COUNTIES MAY PROP UP TEMPS ABOVE ZERO. HIGH
PRESSURE SHIFTS TO OUR EAST LATER ON THURSDAY AND RETURN FLOW AND
WARM ADVECTION WILL RESULT IN TEMPS LEVELING OFF OR RISING THURSDAY
NIGHT. THIS IS IN ADVANCE OF LOW PRESSURE OVER NORTHERN ONTARIO
DRAGGING A COLD FRONT ACROSS THE UPPER MIDWEST. TEMPERATURES SHOULD
BE ABLE TO RISE ABOVE FREEZING FRIDAY AND SATURDAY BEFORE THE COLD
FRONT PASSES THROUGH NORTHERN ILLINOIS SATURDAY AFTERNOON/EVENING.
FRONT IS PRETTY MOISTURE STARVED SO MAYBE A FEW FLURRIES IF IT
DOESNT COME THROUGH DRY.

DEUBELBEISS

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED OR BROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB/BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 030815
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 030815
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030815
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 030815
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
215 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...
214 AM CST

MAIN FOCUS FOR THE LAKE MICHIGAN FORECAST REMAINS IN THE NEAR
TERM...AS SOUTH WINDS INCREASE QUICKLY THIS MORNING IN ADVANCE OF AN
AREA OF LOW PRESSURE MOVING QUICKLY FROM THE PLAINS TO THE WESTERN
LAKES BY THIS EVENING. SOUTH WINDS TO 30 KT...WITH A FEW GALE FORCE
GUSTS TO 35 KT...ARE EXPECTED ON MAINLY THE SOUTHERN PORTION OF THE
LAKE. THE LOW WILL TRAIL A COLD FRONT ACROSS THE LAKE EARLY THIS
EVENING WHICH WILL SHIFT WINDS TO THE WEST INITIALLY AND MORE
NORTHWEST OVERNIGHT AND WEDNESDAY...AS THE GRADIENT CONTINUES TO
SUPPORT 25-30 KT WINDS AS HIGH PRESSURE SLOWLY BUILDS FROM THE
NORTHERN PLAINS TO THE OHIO VALLEY. THE HIGH WILL PASS SOUTHWEST OF
THE LAKES THURSDAY AND THURSDAY NIGHT ALLOWING WINDS TO EASE AND
BACK SOUTHWEST BY EARLY FRIDAY. THE GRADIENT WILL TIGHTEN UP ONCE
AGAIN FRIDAY HOWEVER...BETWEEN THE HIGH RETREATING TO THE SOUTHEAST
AND AN AREA OF LOW PRESSURE MOVING NORTH OF THE LAKES ACROSS
ONTARIO. 30 KT SOUTHWESTERLIES LIKELY FRIDAY...BEFORE THE LOW TRAILS
A COLD FRONTAL TROUGH INTO THE AREA EARLY SATURDAY AND ALLOWS WINDS
TO RELAX A BIT AND SHIFT TO THE WEST.

SMALL CRAFT HEADLINES REMAIN UP FOR THE ILLINOIS AND INDIANA
NEARSHORE TODAY THROUGH WEDNESDAY EVENING FOR THE 25-30 KT WINDS.
RECENT POLAR-ORBITING SATELLITE IMAGERY FROM MONDAY AFTERNOON SHOWS
A GOOD PORTION OF THE ILLINOIS SHORE TO BE MAINLY OPEN WATER OR THIN
ICE FLOES...THUS HAVE INCLUDED WAVE FORECAST FOR ILLINOIS WATERS
WHILE INDIANA SHORE APPEARS TO REMAIN LARGELY ICE-COVERED. THE SAME
GOES FOR WESTERN PORTIONS OF NORTHERN LAKE MICHIGAN...WHICH APPEAR
TO HAVE A FAIR AMOUNT OF OPEN WATER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019
     UNTIL NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 030600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 030600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 AM CST TUE MAR 3 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SNOW EXPECTED TO DEVELOP DURING PREDAWN HOURS...QUICKLY
  TRANSITIONING TO A SNOW/SLEET MIX AND THEN FREEZING RAIN DURING
  THE MORNING. TEMPS RISE TO/ABOVE FREEZING BY MIDDAY WITH PRECIP
  CHANGING TO RAIN/DRIZZLE.

* CIG/VIS EXPECTED TO DETERIORATE FAIRLY QUICKLY FROM VFR TO
  IFR/LIFR WITH PRECIPITATION THIS MORNING. SLOW IMPROVEMENT IN
  CONDITIONS EXPECTED LATER THIS AFTERNOON/EVENING...WITH MVFR
  CIGS LIKELY LINGERING TONIGHT.

* SOUTH-SOUTHEAST WINDS INCREASING 10-15 KT EARLY THIS MORNING AND
  BECOMING GUSTY AROUND 20 KTS AT TIMES WHILE BACKING SOUTH LATE
  THIS MORNING. SOUTHWEST WINDS GUSTING AROUND 20 KTS THIS
  AFTERNOON BECOME WEST-NORTHWEST BY EARLY EVENING AND REMAINING
  GUSTY.

RATZER

//DISCUSSION...UPDATED 06Z...

LOW PRESSURE WAS DEVELOPING OVER EASTERN COLORADO AROUND MIDNIGHT...
WITH SOUTH-SOUTHEAST WINDS INCREASING ACROSS THE PLAINS AND MIDWEST
AND STARTING TO PULL MOISTURE NORTHWARD FROM THE WESTERN GULF.
REGIONAL RADAR MOSAIC SHOWS PRECIPITATION BLOSSOMING ACROSS THE
MID-MISSISSIPPI VALLEY AND LIFTING NORTHEAST AHEAD OF WARM FRONT
DEVELOPING ACROSS MISSOURI AND KANSAS. FORECAST MODELS CONTINUE TO
DEPICT PRECIPITATION SPREADING ACROSS THE LOCAL TERMINALS ROUGHLY
10-12Z...WITH THERMAL PROFILES SUPPORTING INITIALLY SNOW...QUICKLY
MIXING WITH SLEET AND FREEZING RAIN AS TEMPERATURES WARM ALOFT.
SURFACE TEMPS LOOK TO CLIMB TO/ABOVE FREEZING BY LATE MORNING OR
MIDDAY WITH ANY LINGERING PRECIPITATION IN THE FORM OF RAIN OR
DRIZZLE AS THE BETTER FORCING WITH THE ELEVATED WARM FRONT LIFTS
NORTH OF THE AREA.

WITH DEVELOPMENT OF PRECIPITATION...GUIDANCE REMAINS STEADFAST IN
A RAPID DETERIORATION OF VFR CONDITIONS TO IFR/LIFR WITHIN A FEW
HOURS OF ONSET. CIGS SHOULD LIFT ABOVE LIFR THIS AFTERNOON AS WARM
FRONT MOVES NORTH...AND EVENTUALLY TO MVFR LATE THIS AFTERNOON AND
THIS EVENING AS A COLD FRONT PUSHES EAST ACROSS THE AREA.

SOUTH-SOUTHEAST WINDS WILL BACK MORE SOUTHEAST EARLY THIS MORNING
AND INCREASE INTO THE 10-15 KT RANGE AS THE LOW MOVES QUICKLY
ACROSS THE PLAINS. WINDS WILL BACK SOUTH BY LATE MORNING/EARLY
AFTERNOON AS THE LOW PASSES NORTH ACROSS WISCONSIN. FORECAST
SOUNDINGS SUPPORT GUSTS AROUND 20 KTS BY LATE MORNING...AND
CONTINUE TO INDICATE GUSTY CONDITIONS AS WINDS SHIFT SOUTHWEST
THIS AFTERNOON AND WEST-NORTHWEST THIS EVENING.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM IN TIMING PRECIP DEVELOPMENT AND TRANSITION OF P-TYPES AS
  WELL AS CIG/VIS IMPACTS.

* HIGH IN WINDS...AND DRY WEATHER WITH LINGERING MVFR CIGS THIS
  EVENING.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z TUESDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030317
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
917 PM CST MON MAR 2 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 030317
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
917 PM CST MON MAR 2 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030317
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
917 PM CST MON MAR 2 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030317
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
917 PM CST MON MAR 2 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 030213
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
813 PM CST MON MAR 2 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 030213
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
813 PM CST MON MAR 2 2015

.UPDATE...
758 PM CST

THE FORECAST REMAINS ON TRACK WITH THE NEXT SYSTEM OVER COLORADO
THIS EVENING. GUIDANCE CONTINUES TO SUGGEST THAT THE LOW WILL
REACH SOUTHERN WISCONSIN MID-DAY TUESDAY AND MERGE WITH A
STRONGER LOW PUSHING EAST ACROSS ONTARIO. PRECIP WILL SPREAD
ACROSS THE REGION FROM SOUTHWEST TO NORTHEAST EARLY TUESDAY
MORNING. PRECIP SHOULD INITIALLY FALL AS SNOW...BUT WILL QUICKLY
TURN OVER TO A WINTRY MIX AS TEMPERATURES WARM TO ABOVE ZERO ALOFT
AND WE LOSE SATURATION IN THE DGZ. WILL KEEP THE WINTER WEATHER
ADVISORY AS IS.

JEE

&&

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEW POINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 022352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
552 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 022352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
552 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
552 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
552 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
552 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 022352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
552 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SOUTHEAST WINDS ARND 9KT THRU THIS EVENING...TURNING SOUTHWEST
  ARND DAYBREAK AND INCREASING TO 12-15KT WITH GUSTS APPROACHING
  20-25KT SHORTLY AFT DAYBREAK TUE.

* SNOW OVERSPREADING THE AIRFIELDS ARND 10-11Z...WITH POSSIBLY A
  BURST OF MODERATE SNOW SHORTLY AFTER ONSET. SNOW BECOMES MIXED
  WITH FREEZING RAIN/SLEET THEN POSSIBLY ALL RAIN BY MIDDAY.

* VFR CONDS RAPIDLY DETERIORATE TO IFR/LIFR AROUND DAYBREAK...AND
  IFR OR LIFR CIGS COULD LINGER THRU TUE AFTN.

BEACHLER

//DISCUSSION...UPDATED 00Z...

QUIET THIS EVENING WITH VFR CONDS. CIRRUS DECK WILL CONTINUE TO
THICKEN THIS EVENING WITH ADDITIONAL MOISTURE LIFTING NORTH ACROSS
THE OZARKS TOWARDS NORTHERN IL/NORTHWEST IN AIRFIELDS...WHICH WILL
RAPIDLY LOWER CIGS TOWARDS IFR CONDS SHORTLY BEFORE DAYBREAK.
WINDS WILL TURN FROM SOUTHEAST TO SOUTHWEST AND INCREASE. GUSTS
DEVELOP AROUND DAYBREAK TO 25KT AND THEN RELAX SLIGHTLY TO 18KT
LATE TUE AFTN.

PRECIP TIMING AND TRANSITION REMAINS THE MAIN FOCUS FOR THE
OVERNIGHT HOURS THRU TUE MIDDAY. SNOW DEVELOPS PRIOR TO
DAYBREAK...AND WILL BEGIN MIXING WITH SLEET/FREEZING RAIN AROUND
13-15Z. PRIOR TO A MIXTURE OF PRECIP...A BURST OF MODERATE SNOW
MAY OCCUR AND COULD BRING VSBYS DOWN TO ARND 1/2SM OR LESS FOR A
BRIEF PERIOD. IFR VSBY IN SNOW AND LOWERING CIGS ARE LIKELY...AND
WILL LIKELY PERSIST THROUGH THE AFTN. FURTHER REDUCTIONS COULD
OCCUR TOWARDS LIFR CATEGORIES DURING THE LATE MORNING HOURS AS
WARMER AIR ALOFT BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME
FREEZING RAIN. SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING
TREND DURING THE MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING
BY MIDDAY...SO ANY LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO
LONGER PRODUCE A FREEZING THREAT.

BEACHLER


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM/HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* MEDIUM/HIGH IN PRECIP TYPE.

* HIGH ALL OTHER ELEMENTS.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

BEACHLER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022245
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
445 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022245
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
445 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 022245
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
445 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022218
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
418 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 022218
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
418 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022218
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
418 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022218
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
418 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022218
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
418 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 022218
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
418 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.CLIMATE...
417 PM CST

A FEW RECORD LOW AND AND RECORD LOW MAXIMUM TEMPERATURES ARE IN
JEOPARDY ON WEDNESDAY AND THURSDAY.

HERE ARE THE CURRENT RECORDS FOR ROCKFORD AND CHICAGO. THE ONES THAT
STAND THE BEST CHANCE TO BE REACHED ORBROKEN HAVE A STAR (*) NEXT TO
THEM.

  WED 3/4  THU 3/5
ROCKFORD

RECORD LOW-11 (2002)-11 (2002)
RECORD LOW MAX 14 (2002)* 17 (1960)*

CHICAGO
RECORD LOW-12 (1873)  0 (1978)*
RECORD LOW MAX 17 (1890)* 12 (1901)

KMD/KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022123
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
323 PM CST MON MAR 2 2015

.SHORT TERM...
317 PM CST

THROUGH WEDNESDAY...

.SHORT TERM...THROUGH WEDNESDAY

AS MENTIONED IN THE EARLIER UPDATE... A WINTER WEATHER ADVISORY
WAS ISSUED FOR THE ENTIRE AREA EARLIER IN THE SHIFT FOR LATE
TONIGHT THROUGH TUESDAY MORNING. MODELS ARE STILL SHOWING
PRECIPITATION BEGINNING AS SNOW NORTH OF INTERSTATE 80...AND SOME
FORM OF SNOW...SLEET OR FREEZING RAIN IN THE FAR SOUTH. IT COULD
BE A PRETTY GOOD BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION
BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SNOW/SLEET MAY
DOMINATE...ESPECIALLY FOR THE NORTHERN METRO AREA AND POINTS NORTH
TOWARD WISCONSIN... AND IF PRECIPITATION RATES CONTINUE A BIT
HEAVIER THIS MAY SLOW THE LOW LEVEL WARMING. BUT THE SIGNAL IS
STILL THERE FOR A SNOW-SLEET-FZRA TRANSITION AND ICE ACCUMULATION
POTENTIAL.

WHERE THE UNCERTAINTIES REMAIN IS IN REGARDS TO HOW MUCH ICE
ACCUMULATION WILL OCCUR AND HOW FAR NORTH THE IMPACTS ARE FELT. ICE IS
EXPECTED TO BE THE LEAST NORTH TOWARDS WISCONSIN AND IN THE
ROCKFORD AREA WHERE IT MAY JUST BE AN ALL SNOW/SLEET SITUATION
WHERE ADVISORY CRITERIA MAY NOT BE TECHNICALLY SATISFIED. GIVEN
THE UNCERTAINTY AND THE RUSH-HOUR TIME...FEEL IT IS THE SAFER CALL
WITH SOME SNOW/SLEET AS WELL. AND IN NW INDIANA...THE BETTER
MOISTURE ADVECTION IS FOCUSED HERE WHERE THERE IS HIGHER POTENTIAL
FOR ICE ACCUMULATION...BUT IT WILL BE A RACE AGAINST SURFACE TEMPS
AS WELL WHICH LOOK TO WARM THROUGH THE MORNING. AS MENTIONED
EARLIER...MEANWHILE...THE ECMWF/GEM ARE MORE SUPPORTIVE OF A
SNOW/SLEET SOLUTION IN MANY AREAS...ESPECIALLY NORTH OF INTERSTATE
80. IT LOOKS LIKE THE TRANSITION TIME FOR MIXED PRECIPITATION
SOUTH OF I-80 WILL OCCUR BEFORE DAYBREAK BASED ON THE NAM AND
EARLY LOOKS AT THE RAP CLOSE TO THAT TIME FRAME. IT WOULD LIKELY
BE AFTER 6-7 AM WHEN THAT TRANSITION OCCURS IN THE METRO
AREA...BUT CONFIDENCE ON THAT TIMING IS NOT SUPER HIGH.

WHILE WE ARE LOSING THE DEEPER MOISTURE IN THE AFTERNOON...WE ARE
GETTING SOME DECENT MID LEVEL FRONTOGENESIS WHICH SHOULD STILL ALLOW
US TO WRING OUT SOME PRECIPITATION IN THE AFTERNOON WHICH COULD BE A
SNOW-RAIN MIX IN THE NW...LIKELY RAIN IN THE SE...WITH EVEN SOME
-SN/DZ/FZDZ POSSIBLE ACROSS THE CHICAGO METRO AREA LATE IN THE
AFTERNOON AND EVENING.

THE UPPER TROUGH AXIS WILL GRADUALLY MOVE THROUGH THE AREA WHILE
SURFACE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. EXPECT COLDER
CONDITIONS WITH SOME HIGH CLOUDS MOVING THROUGH. HIGHS WILL BE IN
THE TEENS WEDNESDAY AND THURSDAY...WITH LOWS EARLY THURSDAY MORNING
BOTTOMING OUT AT OR BELOW ZERO. WITH THE HIGH STILL TO THE
EAST...WIND CHILLS...YES WE ARE STILL DISCUSSING WIND CHILLS IN
EARLY MARCH...GET DOWN TO -10 TO -20 BELOW. A CLIMATE SECTION TO
THE AFD WILL BE FORTHCOMING.

KMD

&&

.LONG TERM...
317 PM CST

THURSDAY THROUGH MONDAY...

THE EXTENDED PERIOD WILL START OUT VERY COLD AS A 1040 MB ARCTIC
HIGH SHIFTS ACROSS THE REGION. WITH 925 AND 850 MB TEMPERATURES
PROGGED TO BE AROUND -18 CELSIUS...THIS SHOULD ONLY ALLOW FOR HIGHS
IN THE MIDDLE TO UPPER TEENS...FOLLOWING A BITTERLY COLD AND
POTENTIALLY RECORD COLD MORNING. THE GOOD NEWS IS THAT THIS WILL BE
A PROGRESSIVE HIT OF ARCTIC AIR. IN FACT...TEMPERATURES SHOULD
QUICKLY RECOVER BY FRIDAY AS A GUSTY SOUTH-SOUTHWESTERLY FLOW SETS
UP ALONG THE NORTHWESTERN PERIPHERY OF THE EXITING SURFACE RIDGE OF
HIGH PRESSURE. THIS SHOULD SUPPORT HIGHS INTO THE LOW 30S
FRIDAY...AND POSSIBLY WELL INTO THE 30S FOR THE WEEKEND. A WEAK COLD
FRONT MAY DROP ACROSS THE AREA OVER THE WEEKEND...BUT IT APPEARS THE
DEEPER COLD WILL BE AIMED TO OUR NORTHEAST. PRECIPITATION CHANCES
ALSO APPEAR TO BE MINIMAL DURING MUCH OF THE EXTENDED PERIOD.

KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022024
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
224 PM CST MON MAR 2 2015

.UPDATE...

HAVE ECHOED THE PREVIOUS SHIFTS CONCERNS FOR MIXED PRECIPITATION
DURING THE TUESDAY MORNING COMMUTE...AND HAVE ISSUED A WINTER
WEATHER ADVISORY FOR THE ENTIRE AREA LATE TONIGHT THROUGH TUESDAY
MORNING. MODELS ARE STILL SHOWING PRECIPITATION BEGINNING AS SNOW
NORTH OF INTERSTATE 80...AND SOME FORM OF SNOW...SLEET OR POSSIBLY
EVEN FREEZING RAIN IN THE FAR SOUTH. IT COULD BE A PRETTY GOOD
BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SLEET MAY
DOMINATE AND IF PRECIPITATION RATES CONTINUE A BIT HEAVIER THIS
MAY SLOW THE LOW LEVEL WARMING...BUT THE SIGNAL IS STILL THERE
FOR FREEZING RAIN ACCUMULATION. SNOW AMOUNTS MAY BE HIGHER NEAR
THE WISCONSIN BORDER WHERE THE LOW LEVEL WARMING MAY BE A TOUCH
SLOWER.

MORE DETAILS TO FOLLOW THIS AFTERNOON.

KMD

&&

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 022024
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
224 PM CST MON MAR 2 2015

.UPDATE...

HAVE ECHOED THE PREVIOUS SHIFTS CONCERNS FOR MIXED PRECIPITATION
DURING THE TUESDAY MORNING COMMUTE...AND HAVE ISSUED A WINTER
WEATHER ADVISORY FOR THE ENTIRE AREA LATE TONIGHT THROUGH TUESDAY
MORNING. MODELS ARE STILL SHOWING PRECIPITATION BEGINNING AS SNOW
NORTH OF INTERSTATE 80...AND SOME FORM OF SNOW...SLEET OR POSSIBLY
EVEN FREEZING RAIN IN THE FAR SOUTH. IT COULD BE A PRETTY GOOD
BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SLEET MAY
DOMINATE AND IF PRECIPITATION RATES CONTINUE A BIT HEAVIER THIS
MAY SLOW THE LOW LEVEL WARMING...BUT THE SIGNAL IS STILL THERE
FOR FREEZING RAIN ACCUMULATION. SNOW AMOUNTS MAY BE HIGHER NEAR
THE WISCONSIN BORDER WHERE THE LOW LEVEL WARMING MAY BE A TOUCH
SLOWER.

MORE DETAILS TO FOLLOW THIS AFTERNOON.

KMD

&&

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...

224 PM...HIGH PRESSURE OVER THE SOUTHERN LAKES AND OHIO VALLEY
WILL MOVE EAST TO THE MID ATLANTIC AND NEW ENGLAND TUESDAY MORNING
AS LOW PRESSURE FORMS OVER THE CENTRAL PLAINS TONIGHT. THIS LOW
WILL QUICKLY MOVE NORTHEAST TUESDAY AND BE ABSORBED BY STRONGER
LOW PRESSURE OVER NORTHERN ONTARIO...AS A COLD FRONT MOVES ACROSS
LAKE MICHIGAN. THE GRADIENT WILL SLOWLY INCREASE AHEAD OF THIS LOW
TONIGHT INTO TUESDAY MORNING WITH 30 KTS EXPECTED BY TUESDAY
MORNING AND THERE COULD BE SOME LOW END GALE GUSTS BUT CONFIDENCE
REGARDING FREQUENCY IS LOW. WINDS WILL SHIFT TO THE SOUTHWEST IN
THE AFTERNOON AND THEN TO THE NORTHWEST TUESDAY NIGHT. SPEEDS WILL
LIKELY REMAIN IN THE 30 KT RANGE...ESPECIALLY ACROSS THE SOUTHERN
TWO THIRDS...AS HIGH PRESSURE BUILDS ACROSS THE PLAINS WEDNESDAY
AND COLD AIR OVERSPREADS THE REGION. THIS HIGH WILL EXTEND FROM
THE SOUTHERN PLAINS TO THE OHIO VALLEY THURSDAY AS WINDS TURN MORE
WESTERLY AND BEGIN TO SLOWLY DIMINISH. BUT AS THE HIGH DEPARTS
THURSDAY NIGHT...THE GRADIENT WILL TIGHTEN AS LOW PRESSURE MOVES
ACROSS NORTHERN ONTARIO WITH A PERIOD OF SOUTHWEST WINDS TO 30 KTS
ON FRIDAY...WITH SOME LOW END GALES POSSIBLE. CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021951
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
151 PM CST MON MAR 2 2015

.UPDATE...1146 AM CST

HAVE ECHOED THE PREVIOUS SHIFTS CONCERNS FOR MIXED PRECIPITATION
DURING THE TUESDAY MORNING COMMUTE...AND HAVE ISSUED A WINTER
WEATHER ADVISORY FOR THE ENTIRE AREA LATE TONIGHT THROUGH TUESDAY
MORNING. MODELS ARE STILL SHOWING PRECIPITATION BEGINNING AS SNOW
NORTH OF INTERSTATE 80...AND SOME FORM OF SNOW...SLEET OR POSSIBLY
EVEN FREEZING RAIN IN THE FAR SOUTH. IT COULD BE A PRETTY GOOD
BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SLEET MAY
DOMINATE AND IF PRECIPITATION RATES CONTINUE A BIT HEAVIER THIS
MAY SLOW THE LOW LEVEL WARMING...BUT THE SIGNAL IS STILL THERE
FOR FREEZING RAIN ACCUMULATION. SNOW AMOUNTS MAY BE HIGHER NEAR
THE WISCONSIN BORDER WHERE THE LOW LEVEL WARMING MAY BE A TOUCH
SLOWER.

MORE DETAILS TO FOLLOW THIS AFTERNOON.

KMD

&&

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 021800
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 PM CST MON MAR 2 2015

.UPDATE...
1146 AM CST

HAVE ECHOED THE PREVIOUS SHIFTS CONCERNS FOR MIXED PRECIPITATION
DURING THE TUESDAY MORNING COMMUTE...AND HAVE ISSUED A WINTER
WEATHER ADVISORY FOR THE ENTIRE AREA LATE TONIGHT THROUGH TUESDAY
MORNING. MODELS ARE STILL SHOWING PRECIPITATION BEGINNING AS SNOW
NORTH OF INTERSTATE 80...AND SOME FORM OF SNOW...SLEET OR POSSIBLY
EVEN FREEZING RAIN IN THE FAR SOUTH. IT COULD BE A PRETTY GOOD
BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SLEET MAY
DOMINATE AND IF PRECIPITATION RATES CONTINUE A BIT HEAVIER THIS
MAY SLOW THE LOW LEVEL WARMING...BUT THE SIGNAL IS STILL THERE
FOR FREEZING RAIN ACCUMULATION. SNOW AMOUNTS MAY BE HIGHER NEAR
THE WISCONSIN BORDER WHERE THE LOW LEVEL WARMING MAY BE A TOUCH
SLOWER.

MORE DETAILS TO FOLLOW THIS AFTERNOON.

KMD

&&

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 021800
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 PM CST MON MAR 2 2015

.UPDATE...
1146 AM CST

HAVE ECHOED THE PREVIOUS SHIFTS CONCERNS FOR MIXED PRECIPITATION
DURING THE TUESDAY MORNING COMMUTE...AND HAVE ISSUED A WINTER
WEATHER ADVISORY FOR THE ENTIRE AREA LATE TONIGHT THROUGH TUESDAY
MORNING. MODELS ARE STILL SHOWING PRECIPITATION BEGINNING AS SNOW
NORTH OF INTERSTATE 80...AND SOME FORM OF SNOW...SLEET OR POSSIBLY
EVEN FREEZING RAIN IN THE FAR SOUTH. IT COULD BE A PRETTY GOOD
BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SLEET MAY
DOMINATE AND IF PRECIPITATION RATES CONTINUE A BIT HEAVIER THIS
MAY SLOW THE LOW LEVEL WARMING...BUT THE SIGNAL IS STILL THERE
FOR FREEZING RAIN ACCUMULATION. SNOW AMOUNTS MAY BE HIGHER NEAR
THE WISCONSIN BORDER WHERE THE LOW LEVEL WARMING MAY BE A TOUCH
SLOWER.

MORE DETAILS TO FOLLOW THIS AFTERNOON.

KMD

&&

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 021800
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 PM CST MON MAR 2 2015

.UPDATE...
1146 AM CST

HAVE ECHOED THE PREVIOUS SHIFTS CONCERNS FOR MIXED PRECIPITATION
DURING THE TUESDAY MORNING COMMUTE...AND HAVE ISSUED A WINTER
WEATHER ADVISORY FOR THE ENTIRE AREA LATE TONIGHT THROUGH TUESDAY
MORNING. MODELS ARE STILL SHOWING PRECIPITATION BEGINNING AS SNOW
NORTH OF INTERSTATE 80...AND SOME FORM OF SNOW...SLEET OR POSSIBLY
EVEN FREEZING RAIN IN THE FAR SOUTH. IT COULD BE A PRETTY GOOD
BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SLEET MAY
DOMINATE AND IF PRECIPITATION RATES CONTINUE A BIT HEAVIER THIS
MAY SLOW THE LOW LEVEL WARMING...BUT THE SIGNAL IS STILL THERE
FOR FREEZING RAIN ACCUMULATION. SNOW AMOUNTS MAY BE HIGHER NEAR
THE WISCONSIN BORDER WHERE THE LOW LEVEL WARMING MAY BE A TOUCH
SLOWER.

MORE DETAILS TO FOLLOW THIS AFTERNOON.

KMD

&&

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021800
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1200 PM CST MON MAR 2 2015

.UPDATE...
1146 AM CST

HAVE ECHOED THE PREVIOUS SHIFTS CONCERNS FOR MIXED PRECIPITATION
DURING THE TUESDAY MORNING COMMUTE...AND HAVE ISSUED A WINTER
WEATHER ADVISORY FOR THE ENTIRE AREA LATE TONIGHT THROUGH TUESDAY
MORNING. MODELS ARE STILL SHOWING PRECIPITATION BEGINNING AS SNOW
NORTH OF INTERSTATE 80...AND SOME FORM OF SNOW...SLEET OR POSSIBLY
EVEN FREEZING RAIN IN THE FAR SOUTH. IT COULD BE A PRETTY GOOD
BURST OF WET SNOW INITIALLY BEFORE THE TRANSITION BEGINS.

A WARM FRONT WILL LIFT THROUGH THE AREA DURING THE MORNING HOURS.
THIS IS THE PERIOD WHERE MODELS A SHOWING A MORE SIGNIFICANT PUSH
OF PRECIPITATION. WE ARE COMING OUT OF A PRETTY COLD AIR
MASS..AND DEWPOINTS ARE STILL VERY LOW ACROSS THE AREA...WITH
DEWPOINTS ABOVE FREEZING NOT VERY CLOSE. TEMPERATURES LOOK TO
REMAIN BELOW FREEZING THROUGH AT LEAST MID MORNING AREA WIDE.
MODEST PRECIPITABLE WATER VALUES IN EXCESS OF 0.75 INCHES COUPLED
WITH A 35-40 KT LOW LEVEL JET FEEDING INTO THE LOW LEVEL FRONTAL
ZONE WOULD SUGGEST MODEST PRECIPITATION RATES DURING THIS TIME WHEN
THE LOW LEVEL (925-850 MB) TEMPERATURES ARE HEADING ABOVE
FREEZING. SOME OF THE RECENT NAM/GFS WAS SLIGHTLY COOLER IN THE
THERMAL PROFILE FOR THIS PERIOD SUGGESTING THAT SLEET MAY
DOMINATE AND IF PRECIPITATION RATES CONTINUE A BIT HEAVIER THIS
MAY SLOW THE LOW LEVEL WARMING...BUT THE SIGNAL IS STILL THERE
FOR FREEZING RAIN ACCUMULATION. SNOW AMOUNTS MAY BE HIGHER NEAR
THE WISCONSIN BORDER WHERE THE LOW LEVEL WARMING MAY BE A TOUCH
SLOWER.

MORE DETAILS TO FOLLOW THIS AFTERNOON.

KMD

&&

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021738
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1138 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021738
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1138 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 021738
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1138 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LIGHT/VARIABLE WINDS THIS AFTERNOON BEFORE FLOPPING SOUTHEAST BY
  EARLY EVENING. SOUTH-SOUTHEAST WINDS BECOMING GUSTY 20-25 KT BY
  TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

KJB

//DISCUSSION...UPDATED 18Z...

IT WILL CONTINUE TO BE A QUIET WEATHER DAY ACROSS THE AREA TODAY. A
SURFACE RIDGE OF HIGH PRESSURE PUSHING ACROSS THE AREA THIS
AFTERNOON WILL RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS...THOUGH THE WINDS SHOULD SETTLE INTO A SOUTHEASTERLY DIRECTION
BY EARLY THIS EVENING. OTHERWISE VFR CONDITIONS EXPECTED.

THE WEATHER WILL BECOME MUCH MORE PROBLEMATIC BY DAYBREAK TUESDAY.
WINDS WILL INCREASE OUT OF THE SOUTHEAST AND BECOME GUSTY DURING THE
MORNING. SNOW WILL ALSO DEVELOP OVER THE AREA JUST PRIOR TO
DAYBREAK...BEFORE MIXING WITH SLEET AND CHANGING OVER TO A PERIOD OF
FREEZING RAIN BY MID MORNING TUESDAY. IT CURRENTLY APPEARS THAT
ABOUT A 1 TO 3 HOUR PERIOD OF SNOW AND SLEET WILL OCCUR FROM ROUGHLY
11 UTC THROUGH 13 TO 15 UTC. DURING THIS PERIOD IFR VIS IN SNOW AND
LOWERING CIGS ARE LIKELY. CIGS WILL CONTINUE TO DETERIORATE INTO THE
IFR AND LIFR CATEGORIES DURING THE MORNING AS WARMER AIR ALOFT
BEGINS TO CHANGE THE SNOW AND SLEET OVER TO SOME FREEZING RAIN.
SURFACE TEMPERATURES SHOULD ALSO BE ON A WARMING TREND DURING THE
MORNING...AND ARE EXPECTED TO WARM ABOVE FREEZING BY MIDDAY...SO ANY
LINGERING PRECIP AFTER THIS TIME WILL LIKELY NO LONGER PRODUCE A
FREEZING THREAT.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
     ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
     ILZ022-ILZ023-ILZ032-ILZ033-ILZ039...3 AM TUESDAY TO NOON
     TUESDAY.

IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...3
     AM TUESDAY TO NOON TUESDAY.

LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021559
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
959 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* WEST-NORTHWEST WINDS UNDER 10 KT BECOMING LIGHT/VARIABLE THIS
  AFTERNOON BEFORE FLOPPING SOUTHEAST BY EARLY EVENING. SOUTH-
  SOUTHEAST WINDS BECOMING GUSTY 15-20 KT BY TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

RATZER/KB

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE SPREADING EAST ACROSS THE REGION TODAY WILL RESULT
IN WEST-NORTHWEST WINDS NEAR 10 KT EARLY DIMINISHING TO 5 KT OR
LESS AND FLOPPING AROUND TO SOUTHEAST BY LATE AFTERNOON. SOUTH-
SOUTHEAST WINDS WILL THEN INCREASE LATE TONIGHT AS A LOW PRESSURE
SYSTEM TAKES SHAPE ACROSS THE PLAINS TO OUR WEST...WITH WINDS
160-170 DEG GUSTING AROUND 20 KT BY TUESDAY MORNING.

PATCHY VFR HIGH CLOUDS WILL INCREASE FROM THE SOUTHWEST TODAY AND
WILL GRADUALLY THICKEN AND LOWER THROUGH THE MID-LEVELS THIS
EVENING. FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT IN
DEVELOPING PRECIPITATION NORTHWARD INTO THE AREA AHEAD OF A WARM
FRONT TOWARD SUNRISE TUESDAY. COLUMN IS INITIALLY ENTIRELY BELOW
FREEZING...THOUGH STRONG WARM PUSH ALOFT IS EXPECTED TO RESULT IN
PRECIPITATION INITIALLY IN THE FORM OF SNOW BECOMING MIXED
WITH/CHANGING TO SLEET AND THEN FREEZING RAIN DURING THE MORNING.
SURFACE TEMPERATURES WILL SLOWLY WARM WITH THE GUSTY SOUTH-
SOUTHEAST WINDS...THOUGH DO NOT LOOK TO REACH FREEZING OR ABOVE
UNTIL ABOUT NOON. WITH THE ONSET OF PRECIPITATION...VFR CIG/VIS
SHOULD RAPIDLY DETERIORATE THROUGH MVFR TO IFR/LIFR.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM IN WIND DIRECTION THIS AFTERNOON DURING FLOP FROM WNW TO
  SE.

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

RATZER/KB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021559
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
959 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* WEST-NORTHWEST WINDS UNDER 10 KT BECOMING LIGHT/VARIABLE THIS
  AFTERNOON BEFORE FLOPPING SOUTHEAST BY EARLY EVENING. SOUTH-
  SOUTHEAST WINDS BECOMING GUSTY 15-20 KT BY TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

RATZER/KB

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE SPREADING EAST ACROSS THE REGION TODAY WILL RESULT
IN WEST-NORTHWEST WINDS NEAR 10 KT EARLY DIMINISHING TO 5 KT OR
LESS AND FLOPPING AROUND TO SOUTHEAST BY LATE AFTERNOON. SOUTH-
SOUTHEAST WINDS WILL THEN INCREASE LATE TONIGHT AS A LOW PRESSURE
SYSTEM TAKES SHAPE ACROSS THE PLAINS TO OUR WEST...WITH WINDS
160-170 DEG GUSTING AROUND 20 KT BY TUESDAY MORNING.

PATCHY VFR HIGH CLOUDS WILL INCREASE FROM THE SOUTHWEST TODAY AND
WILL GRADUALLY THICKEN AND LOWER THROUGH THE MID-LEVELS THIS
EVENING. FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT IN
DEVELOPING PRECIPITATION NORTHWARD INTO THE AREA AHEAD OF A WARM
FRONT TOWARD SUNRISE TUESDAY. COLUMN IS INITIALLY ENTIRELY BELOW
FREEZING...THOUGH STRONG WARM PUSH ALOFT IS EXPECTED TO RESULT IN
PRECIPITATION INITIALLY IN THE FORM OF SNOW BECOMING MIXED
WITH/CHANGING TO SLEET AND THEN FREEZING RAIN DURING THE MORNING.
SURFACE TEMPERATURES WILL SLOWLY WARM WITH THE GUSTY SOUTH-
SOUTHEAST WINDS...THOUGH DO NOT LOOK TO REACH FREEZING OR ABOVE
UNTIL ABOUT NOON. WITH THE ONSET OF PRECIPITATION...VFR CIG/VIS
SHOULD RAPIDLY DETERIORATE THROUGH MVFR TO IFR/LIFR.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM IN WIND DIRECTION THIS AFTERNOON DURING FLOP FROM WNW TO
  SE.

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

RATZER/KB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021559
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
959 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* WEST-NORTHWEST WINDS UNDER 10 KT BECOMING LIGHT/VARIABLE THIS
  AFTERNOON BEFORE FLOPPING SOUTHEAST BY EARLY EVENING. SOUTH-
  SOUTHEAST WINDS BECOMING GUSTY 15-20 KT BY TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

RATZER/KB

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE SPREADING EAST ACROSS THE REGION TODAY WILL RESULT
IN WEST-NORTHWEST WINDS NEAR 10 KT EARLY DIMINISHING TO 5 KT OR
LESS AND FLOPPING AROUND TO SOUTHEAST BY LATE AFTERNOON. SOUTH-
SOUTHEAST WINDS WILL THEN INCREASE LATE TONIGHT AS A LOW PRESSURE
SYSTEM TAKES SHAPE ACROSS THE PLAINS TO OUR WEST...WITH WINDS
160-170 DEG GUSTING AROUND 20 KT BY TUESDAY MORNING.

PATCHY VFR HIGH CLOUDS WILL INCREASE FROM THE SOUTHWEST TODAY AND
WILL GRADUALLY THICKEN AND LOWER THROUGH THE MID-LEVELS THIS
EVENING. FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT IN
DEVELOPING PRECIPITATION NORTHWARD INTO THE AREA AHEAD OF A WARM
FRONT TOWARD SUNRISE TUESDAY. COLUMN IS INITIALLY ENTIRELY BELOW
FREEZING...THOUGH STRONG WARM PUSH ALOFT IS EXPECTED TO RESULT IN
PRECIPITATION INITIALLY IN THE FORM OF SNOW BECOMING MIXED
WITH/CHANGING TO SLEET AND THEN FREEZING RAIN DURING THE MORNING.
SURFACE TEMPERATURES WILL SLOWLY WARM WITH THE GUSTY SOUTH-
SOUTHEAST WINDS...THOUGH DO NOT LOOK TO REACH FREEZING OR ABOVE
UNTIL ABOUT NOON. WITH THE ONSET OF PRECIPITATION...VFR CIG/VIS
SHOULD RAPIDLY DETERIORATE THROUGH MVFR TO IFR/LIFR.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM IN WIND DIRECTION THIS AFTERNOON DURING FLOP FROM WNW TO
  SE.

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

RATZER/KB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 021355
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
755 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* WEST-NORTHWEST WINDS UNDER 10 KT BECOMING LIGHT/VARIABLE THIS
  AFTERNOON BEFORE FLOPPING SOUTHEAST BY EARLY EVENING. SOUTH-
  SOUTHEAST WINDS BECOMING GUSTY 15-20 KT BY TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

RATZER/KB

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE SPREADING EAST ACROSS THE REGION TODAY WILL RESULT
IN WEST-NORTHWEST WINDS NEAR 10 KT EARLY DIMINISHING TO 5 KT OR
LESS AND FLOPPING AROUND TO SOUTHEAST BY LATE AFTERNOON. SOUTH-
SOUTHEAST WINDS WILL THEN INCREASE LATE TONIGHT AS A LOW PRESSURE
SYSTEM TAKES SHAPE ACROSS THE PLAINS TO OUR WEST...WITH WINDS
160-170 DEG GUSTING AROUND 20 KT BY TUESDAY MORNING.

PATCHY VFR HIGH CLOUDS WILL INCREASE FROM THE SOUTHWEST TODAY AND
WILL GRADUALLY THICKEN AND LOWER THROUGH THE MID-LEVELS THIS
EVENING. FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT IN
DEVELOPING PRECIPITATION NORTHWARD INTO THE AREA AHEAD OF A WARM
FRONT TOWARD SUNRISE TUESDAY. COLUMN IS INITIALLY ENTIRELY BELOW
FREEZING...THOUGH STRONG WARM PUSH ALOFT IS EXPECTED TO RESULT IN
PRECIPITATION INITIALLY IN THE FORM OF SNOW BECOMING MIXED
WITH/CHANGING TO SLEET AND THEN FREEZING RAIN DURING THE MORNING.
SURFACE TEMPERATURES WILL SLOWLY WARM WITH THE GUSTY SOUTH-
SOUTHEAST WINDS...THOUGH DO NOT LOOK TO REACH FREEZING OR ABOVE
UNTIL ABOUT NOON. WITH THE ONSET OF PRECIPITATION...VFR CIG/VIS
SHOULD RAPIDLY DETERIORATE THROUGH MVFR TO IFR/LIFR.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* MEDIUM IN WIND DIRECTION THIS AFTERNOON DURING FLOP FROM WNW TO
  SE.

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

RATZER/KB

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021145
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
545 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* WEST-NORTHWEST WINDS 10 KT OR LESS BECOMING LIGHT/VARIABLE THIS
  AFTERNOON BEFORE FLOPPING SOUTHEAST BY EARLY EVENING. SOUTH-
  SOUTHEAST WINDS BECOMING GUSTY 15-20 KT BY TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

RATZER

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE SPREADING EAST ACROSS THE REGION TODAY WILL RESULT
IN WEST-NORTHWEST WINDS NEAR 10 KT EARLY DIMINISHING TO 5 KT OR
LESS AND FLOPPING AROUND TO SOUTHEAST BY LATE AFTERNOON. SOUTH-
SOUTHEAST WINDS WILL THEN INCREASE LATE TONIGHT AS A LOW PRESSURE
SYSTEM TAKES SHAPE ACROSS THE PLAINS TO OUR WEST...WITH WINDS
160-170 DEG GUSTING AROUND 20 KT BY TUESDAY MORNING.

PATCHY VFR HIGH CLOUDS WILL INCREASE FROM THE SOUTHWEST TODAY AND
WILL GRADUALLY THICKEN AND LOWER THROUGH THE MID-LEVELS THIS
EVENING. FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT IN
DEVELOPING PRECIPITATION NORTHWARD INTO THE AREA AHEAD OF A WARM
FRONT TOWARD SUNRISE TUESDAY. COLUMN IS INITIALLY ENTIRELY BELOW
FREEZING...THOUGH STRONG WARM PUSH ALOFT IS EXPECTED TO RESULT IN
PRECIPITATION INITIALLY IN THE FORM OF SNOW BECOMING MIXED
WITH/CHANGING TO SLEET AND THEN FREEZING RAIN DURING THE MORNING.
SURFACE TEMPERATURES WILL SLOWLY WARM WITH THE GUSTY SOUTH-
SOUTHEAST WINDS...THOUGH DO NOT LOOK TO REACH FREEZING OR ABOVE
UNTIL ABOUT NOON. WITH THE ONSET OF PRECIPITATION...VFR CIG/VIS
SHOULD RAPIDLY DETERIORATE THROUGH MVFR TO IFR/LIFR.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM IN WIND DIRECTION THIS AFTERNOON DURING FLOP FROM WNW TO
  SE.

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

RATZER

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 021145
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
545 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* WEST-NORTHWEST WINDS 10 KT OR LESS BECOMING LIGHT/VARIABLE THIS
  AFTERNOON BEFORE FLOPPING SOUTHEAST BY EARLY EVENING. SOUTH-
  SOUTHEAST WINDS BECOMING GUSTY 15-20 KT BY TUESDAY MORNING.

* SNOW...MIXING WITH SLEET THEN CHANGING TO FREEZING RAIN/RAIN
  EARLY TUESDAY MORNING. VFR CONDITIONS TO QUICKLY DETERIORATE TO
  IFR/LIFR IN PRECIP.

RATZER

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE SPREADING EAST ACROSS THE REGION TODAY WILL RESULT
IN WEST-NORTHWEST WINDS NEAR 10 KT EARLY DIMINISHING TO 5 KT OR
LESS AND FLOPPING AROUND TO SOUTHEAST BY LATE AFTERNOON. SOUTH-
SOUTHEAST WINDS WILL THEN INCREASE LATE TONIGHT AS A LOW PRESSURE
SYSTEM TAKES SHAPE ACROSS THE PLAINS TO OUR WEST...WITH WINDS
160-170 DEG GUSTING AROUND 20 KT BY TUESDAY MORNING.

PATCHY VFR HIGH CLOUDS WILL INCREASE FROM THE SOUTHWEST TODAY AND
WILL GRADUALLY THICKEN AND LOWER THROUGH THE MID-LEVELS THIS
EVENING. FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT IN
DEVELOPING PRECIPITATION NORTHWARD INTO THE AREA AHEAD OF A WARM
FRONT TOWARD SUNRISE TUESDAY. COLUMN IS INITIALLY ENTIRELY BELOW
FREEZING...THOUGH STRONG WARM PUSH ALOFT IS EXPECTED TO RESULT IN
PRECIPITATION INITIALLY IN THE FORM OF SNOW BECOMING MIXED
WITH/CHANGING TO SLEET AND THEN FREEZING RAIN DURING THE MORNING.
SURFACE TEMPERATURES WILL SLOWLY WARM WITH THE GUSTY SOUTH-
SOUTHEAST WINDS...THOUGH DO NOT LOOK TO REACH FREEZING OR ABOVE
UNTIL ABOUT NOON. WITH THE ONSET OF PRECIPITATION...VFR CIG/VIS
SHOULD RAPIDLY DETERIORATE THROUGH MVFR TO IFR/LIFR.

RATZER


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM IN WIND DIRECTION THIS AFTERNOON DURING FLOP FROM WNW TO
  SE.

* MEDIUM-HIGH IN PRECIP TIMING/TREND EARLY TUESDAY. MEDIUM IN
  CIG/VIS IMPACTS.

* HIGH ALL OTHER ELEMENTS.

RATZER

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

TUESDAY NIGHT...MVFR CIGS. GUSTY WEST WINDS.

WEDNESDAY...MVFR CIGS.

THURSDAY AND FRIDAY...VFR.

SATURDAY AND SUNDAY...MVFR CIGS POSSIBLE.

RATZER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/WEDNESDAY WITH 25+ KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 020929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
329 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* LIGHT WEST-NORTHWEST WINDS FLOPPING TO LIGHT SOUTHEAST BY
  EVENING. MAY BE A PERIOD OF VARIABLE DIRECTION 5 KT OR LESS THIS
  AFTERNOON. SOUTH-SOUTHEAST WINDS INCREASING TOWARD TUESDAY
  MORNING.

* SNOW/MIXED PRECIP EXPECTED TO DEVELOP BY 12Z TUESDAY
  MORNING...WITH CIG/VIS QUICKLY DETERIORATING TO MVFR/IFR/LIFR
  JUST BEYOND END OF ORD 30 HOUR TAF.

RATZER

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE BUILDING EAST ACROSS THE TERMINALS MONDAY...AND
MOVING OFF TO THE EAST BY MONDAY EVENING. CURRENT WEST WINDS
10-12 KTS WILL DIMINISH TO LESS THAN 10 KT THIS MORNING AS
GRADIENT WEAKENS. WINDS WILL CONTINUE TO DIMINISH AND WILL LIKELY
BECOME VARIABLE IN DIRECTION AS THE HIGH PASSES OVERHEAD EARLY
THIS AFTERNOON...EVENTUALLY SETTLING TO A LIGHT SOUTHEAST THIS
EVENING AS THE HIGH PULLS AWAY TO THE EAST. SOUTH-SOUTHEAST WINDS
EXPECTED TO INCREASE ABOVE 10 KT TOWARD TUESDAY MORNING...PROBABLY
WITH GUSTS 20+ KT BEYOND 12Z.

VFR HIGH/MID CLOUDS WILL GRADUALLY INCREASE FROM THE SOUTHWEST
THROUGH THIS AFTERNOON AS MOISTURE BEGINS TO SPREAD NORTH AHEAD OF
AN AREA OF A LOW PRESSURE SYSTEM WHICH WILL DEVELOP ACROSS THE
PLAINS LATER TODAY/TONIGHT. CLOUDS WILL CONTINUE TO THICKEN AND
LOWER TONIGHT IN ADVANCE OF A WARM FRONT WHICH WILL LIFT TOWARD
THE AREA TUESDAY MORNING. FORECAST MODELS ARE IN FAIRLY GOOD
AGREEMENT IN PRECIPITATION DEVELOPING FROM THE SOUTHWEST ROUGHLY
10-12Z EARLY TUESDAY...LIKELY INITIALLY IN THE FORM OF SNOW. A
QUICK DETERIORATION FROM VFR TO MVFR/IFR/POTENTIALLY LIFR IS EXPECTED.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* LOW IN WIND DIRECTION THIS AFTERNOON...BUT HIGH IN SPEEDS LESS
  THAN 10 KT.

* MEDIUM-HIGH IN TIMING ONSET OF SNOW TUESDAY MORNING.

* HIGH ALL OTHER ELEMENTS.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z MONDAY...UPDATED 00Z...

TUESDAY...SNOW MIXING WITH FREEZING RAIN AND SLEET. IFR LIKELY.

WEDNESDAY...MVFR CIGS.

THURSDAY THROUGH SATURDAY...MAINLY VFR. POSSIBLE MVFR CIGS
SATURDAY.

BEACHLER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/TUESDAY EVENING WITH 25-30 KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 020929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
329 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* LIGHT WEST-NORTHWEST WINDS FLOPPING TO LIGHT SOUTHEAST BY
  EVENING. MAY BE A PERIOD OF VARIABLE DIRECTION 5 KT OR LESS THIS
  AFTERNOON. SOUTH-SOUTHEAST WINDS INCREASING TOWARD TUESDAY
  MORNING.

* SNOW/MIXED PRECIP EXPECTED TO DEVELOP BY 12Z TUESDAY
  MORNING...WITH CIG/VIS QUICKLY DETERIORATING TO MVFR/IFR/LIFR
  JUST BEYOND END OF ORD 30 HOUR TAF.

RATZER

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE BUILDING EAST ACROSS THE TERMINALS MONDAY...AND
MOVING OFF TO THE EAST BY MONDAY EVENING. CURRENT WEST WINDS
10-12 KTS WILL DIMINISH TO LESS THAN 10 KT THIS MORNING AS
GRADIENT WEAKENS. WINDS WILL CONTINUE TO DIMINISH AND WILL LIKELY
BECOME VARIABLE IN DIRECTION AS THE HIGH PASSES OVERHEAD EARLY
THIS AFTERNOON...EVENTUALLY SETTLING TO A LIGHT SOUTHEAST THIS
EVENING AS THE HIGH PULLS AWAY TO THE EAST. SOUTH-SOUTHEAST WINDS
EXPECTED TO INCREASE ABOVE 10 KT TOWARD TUESDAY MORNING...PROBABLY
WITH GUSTS 20+ KT BEYOND 12Z.

VFR HIGH/MID CLOUDS WILL GRADUALLY INCREASE FROM THE SOUTHWEST
THROUGH THIS AFTERNOON AS MOISTURE BEGINS TO SPREAD NORTH AHEAD OF
AN AREA OF A LOW PRESSURE SYSTEM WHICH WILL DEVELOP ACROSS THE
PLAINS LATER TODAY/TONIGHT. CLOUDS WILL CONTINUE TO THICKEN AND
LOWER TONIGHT IN ADVANCE OF A WARM FRONT WHICH WILL LIFT TOWARD
THE AREA TUESDAY MORNING. FORECAST MODELS ARE IN FAIRLY GOOD
AGREEMENT IN PRECIPITATION DEVELOPING FROM THE SOUTHWEST ROUGHLY
10-12Z EARLY TUESDAY...LIKELY INITIALLY IN THE FORM OF SNOW. A
QUICK DETERIORATION FROM VFR TO MVFR/IFR/POTENTIALLY LIFR IS EXPECTED.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* LOW IN WIND DIRECTION THIS AFTERNOON...BUT HIGH IN SPEEDS LESS
  THAN 10 KT.

* MEDIUM-HIGH IN TIMING ONSET OF SNOW TUESDAY MORNING.

* HIGH ALL OTHER ELEMENTS.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z MONDAY...UPDATED 00Z...

TUESDAY...SNOW MIXING WITH FREEZING RAIN AND SLEET. IFR LIKELY.

WEDNESDAY...MVFR CIGS.

THURSDAY THROUGH SATURDAY...MAINLY VFR. POSSIBLE MVFR CIGS
SATURDAY.

BEACHLER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRADUALLY DIMINISH AND BACK TO
THE SOUTHWEST THURSDAY NIGHT. GUSTY SOUTH-SOUTHWEST WINDS RETURN
FRIDAY AS THE HIGH MOVES OFF TO THE SOUTHEAST AND LOW PRESSURE
TRACKS NORTH OF THE LAKES.

WHILE MOST OF THE IL/IN NEAR SHORE WATERS APPEAR ICE COVERED PER
SATELLITE AND WEBCAM IMAGERY...WILL CARRY A SMALL CRAFT ADVISORY
TUESDAY/TUESDAY EVENING WITH 25-30 KT WINDS DURING THAT PERIOD.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM TUESDAY TO 6 PM WEDNESDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 020929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
329 AM CST MON MAR 2 2015

.SHORT TERM...
250 AM CST

THROUGH TUESDAY...

HIGH PRESSURE CENTERED OVER THE MID MISSOURI VALLEY THIS MORNING
WILL TRANSLATE EAST ACROSS NORTHERN ILLINOIS THIS AFTERNOON AND THEN
OFF THE ATLANTIC COAST BY EARLY TUESDAY. MEANWHILE...CLOSED UPPER
LOW WITHIN A DEEP TROUGH IS IN PLACE ACROSS THE WEST COAST AND LEAD
WAVE IS PROGGED TO EJECT NORTHEAST FROM THE DESERT SOUTHWEST THIS
EVENING WITH A SURFACE LOW DEVELOPING OVER THE COLORADO FRONT RANGE
WHICH WILL LIFT INTO THE UPPER MIDWEST TUESDAY. THIS WILL BE A
CHALLENGING SYSTEM WITH THE POTENTIAL FOR MODEST SNOW ACCUMULATIONS
ON THE FRONT END...IN ADDITION TO LIGHT ICE ACCUMULATIONS...BEFORE
PRECIPITATION CHANGES OVER TO ALL RAIN. THESE DETAILS OF COURSE WILL
HINGE ON THE TRACK AND STRENGTH OF THE LOW WHICH MODELS CONTINUE TO
STRUGGLE WITH. THE 00Z EUROPEAN MODEL FITS WELL WITHING THE BEST
CLUSTERING OF THE GEFS AND HAS SHIFTED NORTH FROM PREVIOUS RUNS...A
MOVE THE GFS MADE WITH EARLIER GUIDANCE...THOUGH THE LATEST RUN IS
NORTH OF THE GEFS MEAN. SREF IS EVEN AN FARTHER NORTHERN OUTLIER.
CONTINUE TO LEAN HEAVILY ON THE ECMWF GUIDANCE BUT WITH A NORTHERN
STREAM SYSTEM PUSHING EAST ACROSS THE CANADIAN PRAIRIES AND HIGH
PRESSURE ALONG THE EAST COAST...WOULDNT BE SURPRISE TO SEE FARTHER
SHIFTS NORTH WHICH WOULD LIKELY LESSEN THE IMPACTS FROM FROZEN
PRECIP TYPE.

CURRENT EXPECTATIONS ARE THAT PRECIPITATION WILL BEGIN AS SNOW WITH
LIGHT ACCUMULATIONS POSSIBLE BEFORE MID LEVELS WARM ENOUGH FOR A
TRANSITION TO SLEET AND FREEZING RAIN DURING THE MORNING. AS
SURFACE/BOUNDARY LAYER TEMPS CONTINUE TO WARM...PRECIP SHOULD CHANGE
OVER TO RAIN FOR MOST IF NOT ALL OF THE CWA BY AFTERNOON. GIVEN THE
RAPID WARMUP...ANY SNOW/ICE ACCUMULATIONS WOULD LIKELY QUICKLY MELT
OFF. UNFORTUNATELY THE BEST CHANCES FOR FROZEN PRECIP WILL BE RIGHT
AROUND THE MORNING COMMUTE. MID LEVEL DRY SLOT PUNCHES INTO THE
REGION MID AFTERNOON INTO THE EARLY EVENING AND PRECIPITATION WILL
LIKELY TRANSITION TO A LIGHT RAIN OR DRIZZLE...THEN MOST OF THE
REMAINING PRECIPITATION SHOULD START TO PUSH EAST OF THE FORECAST
AREA THROUGH THE EVENING.

DEUBELBEISS

&&

.LONG TERM...
250 AM CST

TUESDAY NIGHT THROUGH SUNDAY...

HIGH PRESSURE WILL GRADUALLY BUILD FROM THE NORTHERN PLAINS TUESDAY
NIGHT TO THE MIDWEST THURSDAY THEN TO THE MID-ATLANTIC COAST FRIDAY
INTO SATURDAY. RIDGING WILL BE IN PLACE ACROSS NORTHERN ILLINOIS
MUCH OF THE PERIOD BRINGING AN EXTENDED PERIOD OF DRIER WEATHER. THE
HIGH WILL BE ACCOMPANIED BY COLDER AIR...WITH H85 TEMPS PUSHING -20C
MOVING ACROSS NORTHERN ILLINOIS WEDNESDAY NIGHT AND THURSDAY
MORNING. THIS WILL BE THE COLDEST MORNING IN THE FORECAST WITH NEAR
OR BELOW ZERO LOWS EXPECTED. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
NORTHERN ONTARIO FRIDAY WITH A THERMAL RIDGE OVERSPREADING NORTHERN
ILLINOIS RESULTING IN WARMER CONDITIONS BY THE END OF THE WEEK INTO
THE WEEKEND.

DEUBELBEISS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* LIGHT WEST-NORTHWEST WINDS FLOPPING TO LIGHT SOUTHEAST BY
  EVENING. MAY BE A PERIOD OF VARIABLE DIRECTION 5 KT OR LESS THIS
  AFTERNOON. SOUTH-SOUTHEAST WINDS INCREASING TOWARD TUESDAY
  MORNING.

* SNOW/MIXED PRECIP EXPECTED TO DEVELOP BY 12Z TUESDAY
  MORNING...WITH CIG/VIS QUICKLY DETERIORATING TO MVFR/IFR/LIFR
  JUST BEYOND END OF ORD 30 HOUR TAF.

RATZER

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE BUILDING EAST ACROSS THE TERMINALS MONDAY...AND
MOVING OFF TO THE EAST BY MONDAY EVENING. CURRENT WEST WINDS
10-12 KTS WILL DIMINISH TO LESS THAN 10 KT THIS MORNING AS
GRADIENT WEAKENS. WINDS WILL CONTINUE TO DIMINISH AND WILL LIKELY
BECOME VARIABLE IN DIRECTION AS THE HIGH PASSES OVERHEAD EARLY
THIS AFTERNOON...EVENTUALLY SETTLING TO A LIGHT SOUTHEAST THIS
EVENING AS THE HIGH PULLS AWAY TO THE EAST. SOUTH-SOUTHEAST WINDS
EXPECTED TO INCREASE ABOVE 10 KT TOWARD TUESDAY MORNING...PROBABLY
WITH GUSTS 20+ KT BEYOND 12Z.

VFR HIGH/MID CLOUDS WILL GRADUALLY INCREASE FROM THE SOUTHWEST
THROUGH THIS AFTERNOON AS MOISTURE BEGINS TO SPREAD NORTH AHEAD OF
AN AREA OF A LOW PRESSURE SYSTEM WHICH WILL DEVELOP ACROSS THE
PLAINS LATER TODAY/TONIGHT. CLOUDS WILL CONTINUE TO THICKEN AND
LOWER TONIGHT IN ADVANCE OF A WARM FRONT WHICH WILL LIFT TOWARD
THE AREA TUESDAY MORNING. FORECAST MODELS ARE IN FAIRLY GOOD
AGREEMENT IN PRECIPITATION DEVELOPING FROM THE SOUTHWEST ROUGHLY
10-12Z EARLY TUESDAY...LIKELY INITIALLY IN THE FORM OF SNOW. A
QUICK DETERIORATION FROM VFR TO MVFR/IFR/POTENTIALLY LIFR IS EXPECTED.

RATZER

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* LOW IN WIND DIRECTION THIS AFTERNOON...BUT HIGH IN SPEEDS LESS
  THAN 10 KT.

* MEDIUM-HIGH IN TIMING ONSET OF SNOW TUESDAY MORNING.

* HIGH ALL OTHER ELEMENTS.

RATZER

//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z MONDAY...UPDATED 00Z...

TUESDAY...SNOW MIXING WITH FREEZING RAIN AND SLEET. IFR LIKELY.

WEDNESDAY...MVFR CIGS.

THURSDAY THROUGH SATURDAY...MAINLY VFR. POSSIBLE MVFR CIGS
SATURDAY.

BEACHLER

&&

.MARINE...
217 AM CST

HIGH PRESSURE SPREADING EAST FROM THE PLAINS EASTWARD TO THE MIDWEST
AND GREAT LAKES TODAY WILL ALLOW WESTERLY WINDS TO DIMINISH QUICKLY
THIS MORNING...AS THE GRADIENT WEAKENS WITH THE APPROACH OF THE
SURFACE RIDGE AXIS. WINDS WILL BACK TO THE SOUTH-SOUTHEAST BY
TONIGHT AS THE HIGH PULLS AWAY TO THE EAST...AND WILL INCREASE INTO
THE 25 KT RANGE BY TUESDAY MORNING AS AN AREA OF LOW PRESSURE LIFTS
NORTHEAST FROM THE PLAINS TO THE MID-MISSOURI VALLEY. THE LOW IS
EXPECTED TO TRACK NORTHEAST ACROSS WISCONSIN AND NORTHERN LAKE
MICHIGAN TUESDAY...WITH WINDS FURTHER INCREASING INTO THE 30-35 KT
RANGE ON THE SOUTHERN 2/3 OR SO OF THE LAKE DURING THE DAY. CURRENT
MODEL RUNS ARE NOT AS BULLISH IN DEEPENING THE LOW AS IT APPROACHES
AND IT APPEARS THAT A BRIEF PERIOD OF MARGINAL GALE FORCE WINDS
MIDDAY-AFTERNOON TUESDAY. WILL CONTINUE TO MENTION GALE FORCE GUSTS
BUT WILL HOLD SHORT OF A GALE WARNING AT THIS TIME. WINDS WILL THEN
EASE JUST A BIT BY TUESDAY EVENING AS THE TRAILING COLD FRONT MOVES
ACROSS THE LAKE...BUT ARE EXPECTED TO REMAIN NEAR 30 KT AS THE SHIFT
TO THE WEST-NORTHWEST TUESDAY NIGHT AS COLD AIR SPREADS ACROSS THE
LAKE AND ANOTHER LARGE HIGH PRESSURE SYSTEM BUILDS FROM CANADA
SOUTHEAST ACROSS THE PLAINS. WINDS LOOK TO HOLD IN THE 25-30 KT
RANGE WEDNESDAY AS WELL...AS THE CENTER OF THE HIGH SLOWLY TRACKS
SOUTHEAST...EVENTUALLY MOVING INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THIS WILL ALLOW WINDS TO GRAD