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000
FXUS63 KILX 180801
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
301 AM CDT Fri Apr 18 2014

.DISCUSSION...
ISSUED 301 AM CDT Fri Apr 18 2014

SHORT TERM...Today through Sunday

Short-wave trough tracking through the Mississippi River Valley
will give a weak frontal boundary currently along the I-70 corridor
a shove eastward this morning. Synoptic subsidence in the wake of
the wave will cause skies to clear from west to east, with mostly
sunny skies expected across the board by midday. Forecast
soundings indicate mixing up to about 850mb, which will result in
afternoon highs mainly in the middle 60s, with upper 60s across
the southeast KILX CWA.

High pressure will build into the Great Lakes later today, then
will remain in place through the weekend. Dry airmass beneath the
ridge coupled with light E/NE flow will lead to warm days and cool
nights over the next couple of days. Have undercut MAV guidance by
a few degrees tonight, with lows dipping into the middle to upper
30s in most locations. Highs on Saturday will remain on the cooler
side of guidance as well thanks to the continued easterly
component to the wind, with highs climbing into the upper 60s and
lower 70s. Once high pressure ridge begins to shift further east,
an increasing southerly flow will bring warmer air into the region
on Easter Sunday, helping push temps well into the 70s.

LONG TERM...Monday through Thursday

Next system of interest is still slated to approach the region
Sunday night, with most 00z Apr 18 model data keeping the precip
west of Illinois until Monday. As a result of the continued
slowing trend, will only feature slight chance POPs after midnight
across the western CWA. Rain chances will increase on Monday as
wave arrives and atmosphere moistens. Given decent upper support,
adequate moisture with surface dewpoints well into the 50s, and
lifted index values dropping to between 0 and -3C, will continue
to mention isolated thunder Monday and Monday evening.
GFS/GEM/ECMWF all track upper wave well east into the Ohio River
Valley by 12z Tuesday, so am expecting slightly cooler/drier
weather for both Tuesday and Wednesday. An approaching warm front
will trigger convection across Iowa into northern Illinois
late Wednesday: however, think this will remain north of the CWA.
Next rain chance will arrive on Thursday as a cold front
approaches from the west. Still some timing discrepancies among
the operational models, but consensus points to showers/thunder
Thursday into Thursday night.

Barnes
&&

.AVIATION...
ISSUED 1051 PM CDT Thu Apr 17 2014

VFR conditions will prevail at all TAF sites next 24hrs. Mid
clouds will continue at all sites overnight but then move out
toward morning, becoming clear for the rest of the TAF period.
Winds will be light through the period.

Auten
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








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000
FXUS63 KLOT 180633
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
133 AM CDT FRI APR 18 2014

.DISCUSSION...
309 PM CDT

A RELATIVELY BENIGN WEATHER PERIOD IS IN STORE FOR THE NEXT FEW
DAYS...WITH THE ONLY CHANCE OF ANY PRECIP THROUGH SUNDAY BEING
TONIGHT. THE MAIN FORECAST CONCERNS OVER THE NEXT FEW DAYS WILL BE
TEMPERATURES...AS THERE WILL LIKELY BE SOME DECENT TEMPERATURE
GRADIENTS ACROSS THE AREA...DUE IN LARGE PART TO THE ONSHORE FLOW
EXPECTED ACROSS NORTHEASTERN ILLINOIS ON FRIDAY AND SATURDAY.

CURRENTLY THERE IS A GOOD AMOUNT OF MID AND HIGHER LEVEL CLOUDINESS
STREAMING NORTHEASTWARD ACROSS THE AREA AHEAD OF A SHEARED OUT SHORT
WAVE...CURRENTLY IN PLACE ACROSS THE MID AND LOWER MISSOURI VALLEY.
MODEL GUIDANCE CONTINUES TO SPARK OFF AN AREA OF SHOWERS ACROSS
PORTIONS OF THE REGION THIS EVENING AND OVERNIGHT AS THIS SHORT WAVE
DISTURBANCE APPROACHES AND INDUCES SOME ISENTROPIC ASCENT ACROSS THE
AREA. OVERALL...I FOLLOWED CLOSE TO THE INHERITED FORECAST...WHICH
PLACES THE CHANCES FOR THIS ACTIVITY MAINLY FROM MID EVENING THROUGH
LATE TONIGHT FOR AREAS ALONG AND SOUTH OF A LINE FROM CHICAGO TO
MENDOTA.

A 1030 MB SURFACE HIGH IS EXPECTED TO BUILD IN ACROSS THE UPPER
GREAT LAKES REGION ON FRIDAY. THIS WILL SET UP A NORTH-NORTHEASTERLY
ONSHORE FLOW ACROSS THE AREA DURING THE DAY. AS SUCH...EXPECT CHILLY
CONDITIONS ON FRIDAY ACROSS NORTHEASTERN ILLINOIS AND NORTHWESTERN
INDIANA...WHERE A ENHANCED LAKE BREEZE WILL LIKELY KEEP TEMPERATURES
IN THE 40S FORE AREAS NEAR THE LAKE. FARTHER
INLAND...HOWEVER...TEMPERATURES SHOULD WARM INTO THE 50S...WITH EVEN
SOME LOW 60S POSSIBLE WELL INLAND.

TEMPERATURES BEGIN TO MODERATE AREA-WIDE ON SATURDAY AS THE LOWER
LEVEL FLOW TURNS OUT OF THE SOUTHEAST IN RESPONSE TO LOW PRESSURE
MOVING ACROSS THE NORTHERN PLAINS AND SOUTHERN CANADA. TEMPERATURES
LOOK TO CLIMB INTO THE 60S FOR MOST AREAS...WITH THE EXCEPTION OF
FAR NORTHEAST ILLINOIS...WHERE SOUTHEASTERLY ONSHORE FLOW LOOKS TO
KEEP THINGS COOLER. SUNDAY DEFINITELY LOOKS TO BE THE BEST DAY OF
THE WEEKEND. SOUTH-SOUTHWESTERLY FLOW IS EXPECTED TO TRANSPORT AN
EVEN WARMER AIR MASS IN ACROSS THE AREA. MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT IN ADVECTING IN 15 (9) DEGREE CELSIUS 925 MB (850 MB)
TEMPERATURES. LOCAL CLIMO FOR THESE VALUES THIS TIME OF YEAR
INDICATE HIGH TEMPERATURES GETTING INTO THE LOW TO POSSIBLY MID 70S
ACROSS THE AREA.

THE NEXT CHANCE FOR PRECIPITATION LOOKS TO BE ON MONDAY AS ANOTHER
WEAK FRONTAL SYSTEM AND MID LEVEL DISTURBANCE PUSHES ACROSS THE
AREA. FOLLOWING IN THE WAKE OF THIS FRONTAL MONDAY...LOOKS TO BE
ANOTHER DAY OR TWO PERIOD OF NORTHEASTERLY ONSHORE COOLING
FLOW...WHICH WILL AGAIN COULD SET UP A DECENT THERMAL GRADIENT
BETWEEN THE LAKE SHORE AND AREAS FARTHER INLAND.

WAY OUT...TOWARDS THE END OF THE CURRENT FORECAST PERIOD...GUIDANCE
IS IN GOOD AGREEMENT IN DEVELOPING A GOOD STORM SYSTEM ACROSS THE
PLAINS..THEY JUST DIFFER SIGNIFICANTLY WITH THE TIMING. THIS  SYSTEM
LOOKS TO PRODUCE A PERIOD OF MUCH WARMER WEATHER AND ALSO ANOTHER
THREAT FOR SHOWERS AND THUNDERSTORMS AT THE END OF THE PERIOD.

KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTHEAST WINDS INCREASING TO 10-13KT BY AROUND 16Z.

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

A WEAK COOL FRONT WILL CONTINUE TO MOVE SOUTH THROUGH THE AREA
VERY EARLY THIS MORNING. WHILE SOME PATCHY 4000 FT CLOUDS ARE SEEN
IN THE WAKE OF THIS...LITTLE IN THE WAY OF SENSIBLE WEATHER IS
EXPECTED. WINDS WILL TURN NORTH TO NORTHEAST BEHIND THIS FRONT.
SPEEDS AT TAF SITES LOOK TO REMAIN BELOW 10 KT THROUGH MOST OF THE
MORNING HOURS...BEFORE AN INCREASE TO 10-13KT THIS AFTERNOON AND
EARLY TO MID EVE AS THE THERMALLY-INDUCED PRESSURE GRADIENT
INCREASES AROUND THE LAKE PERIPHERY. SOME MID TO HIGH CLOUD ARE
POSSIBLE LATE IN THE DAY INTO THIS EVE...BUT OTHERWISE NO IMPACTS
EXPECTED.

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH IN ALL FORECAST ELEMENTS.

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

SATURDAY...VFR/WX NIL.

SUNDAY...VFR/WX NIL.

MONDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS POSSIBLE.

TUESDAY...VFR/WX NIL.

WEDNESDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS
POSSIBLE.

MTF/KREIN

&&

.MARINE...
133 AM CDT

A GENERALLY QUIET PATTERN OVER THE LAKE IN TERMS OF HEADLINES IS
EXPECTED INTO THE START OF NEXT WEEK. HIGH PRESSURE WILL MOVE OVER
THE LAKE TODAY ALLOWING FOR A 10-20 KT PUSH OF ONSHORE WINDS
ACROSS ILLINOIS AND INDIANA NEARSHORE AREAS THIS AFTERNOON INTO
EARLY EVE. LOW PRESSURE WILL MOVE NORTHEAST INTO QUEBEC THIS
WEEKEND AND STEER A COLD FRONT INTO THE NORTHERN HALF OF THE LAKE
ON SUNDAY. WITH THE PARENT LOW WELL NORTH OF THE AREA AND MOVING
AWAY...THIS FRONT WILL STALL THROUGH EARLY MONDAY. SOUTHERLY
WINDS ACROSS THE AREA ON SUNDAY COULD YIELD 20 KT GUSTS OR
SLIGHTLY HIGHER IN NEARSHORE AREAS. EVENTUALLY THE FRONT WILL
CLEAR THE LAKE AS A LOW PRESSURE RIDING UP THE BOUNDARY BRINGS IT
ACROSS THE LAKE. THIS FRONT WILL TURN WINDS NORTHERLY INTO EARLY
NEXT WEEK. SOME LONG RANGE GUIDANCE MEMBERS ARE INDICATING A
POTENTIAL GUSTY SOUTHERLY PERIOD OF WINDS LATE IN THE FORECAST
/THURSDAY/.

MTF

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 180536
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1236 AM CDT FRI APR 18 2014

.DISCUSSION...
309 PM CDT

A RELATIVELY BENIGN WEATHER PERIOD IS IN STORE FOR THE NEXT FEW
DAYS...WITH THE ONLY CHANCE OF ANY PRECIP THROUGH SUNDAY BEING
TONIGHT. THE MAIN FORECAST CONCERNS OVER THE NEXT FEW DAYS WILL BE
TEMPERATURES...AS THERE WILL LIKELY BE SOME DECENT TEMPERATURE
GRADIENTS ACROSS THE AREA...DUE IN LARGE PART TO THE ONSHORE FLOW
EXPECTED ACROSS NORTHEASTERN ILLINOIS ON FRIDAY AND SATURDAY.

CURRENTLY THERE IS A GOOD AMOUNT OF MID AND HIGHER LEVEL CLOUDINESS
STREAMING NORTHEASTWARD ACROSS THE AREA AHEAD OF A SHEARED OUT SHORT
WAVE...CURRENTLY IN PLACE ACROSS THE MID AND LOWER MISSOURI VALLEY.
MODEL GUIDANCE CONTINUES TO SPARK OFF AN AREA OF SHOWERS ACROSS
PORTIONS OF THE REGION THIS EVENING AND OVERNIGHT AS THIS SHORT WAVE
DISTURBANCE APPROACHES AND INDUCES SOME ISENTROPIC ASCENT ACROSS THE
AREA. OVERALL...I FOLLOWED CLOSE TO THE INHERITED FORECAST...WHICH
PLACES THE CHANCES FOR THIS ACTIVITY MAINLY FROM MID EVENING THROUGH
LATE TONIGHT FOR AREAS ALONG AND SOUTH OF A LINE FROM CHICAGO TO
MENDOTA.

A 1030 MB SURFACE HIGH IS EXPECTED TO BUILD IN ACROSS THE UPPER
GREAT LAKES REGION ON FRIDAY. THIS WILL SET UP A NORTH-NORTHEASTERLY
ONSHORE FLOW ACROSS THE AREA DURING THE DAY. AS SUCH...EXPECT CHILLY
CONDITIONS ON FRIDAY ACROSS NORTHEASTERN ILLINOIS AND NORTHWESTERN
INDIANA...WHERE A ENHANCED LAKE BREEZE WILL LIKELY KEEP TEMPERATURES
IN THE 40S FORE AREAS NEAR THE LAKE. FARTHER
INLAND...HOWEVER...TEMPERATURES SHOULD WARM INTO THE 50S...WITH EVEN
SOME LOW 60S POSSIBLE WELL INLAND.

TEMPERATURES BEGIN TO MODERATE AREA-WIDE ON SATURDAY AS THE LOWER
LEVEL FLOW TURNS OUT OF THE SOUTHEAST IN RESPONSE TO LOW PRESSURE
MOVING ACROSS THE NORTHERN PLAINS AND SOUTHERN CANADA. TEMPERATURES
LOOK TO CLIMB INTO THE 60S FOR MOST AREAS...WITH THE EXCEPTION OF
FAR NORTHEAST ILLINOIS...WHERE SOUTHEASTERLY ONSHORE FLOW LOOKS TO
KEEP THINGS COOLER. SUNDAY DEFINITELY LOOKS TO BE THE BEST DAY OF
THE WEEKEND. SOUTH-SOUTHWESTERLY FLOW IS EXPECTED TO TRANSPORT AN
EVEN WARMER AIR MASS IN ACROSS THE AREA. MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT IN ADVECTING IN 15 (9) DEGREE CELSIUS 925 MB (850 MB)
TEMPERATURES. LOCAL CLIMO FOR THESE VALUES THIS TIME OF YEAR
INDICATE HIGH TEMPERATURES GETTING INTO THE LOW TO POSSIBLY MID 70S
ACROSS THE AREA.

THE NEXT CHANCE FOR PRECIPITATION LOOKS TO BE ON MONDAY AS ANOTHER
WEAK FRONTAL SYSTEM AND MID LEVEL DISTURBANCE PUSHES ACROSS THE
AREA. FOLLOWING IN THE WAKE OF THIS FRONTAL MONDAY...LOOKS TO BE
ANOTHER DAY OR TWO PERIOD OF NORTHEASTERLY ONSHORE COOLING
FLOW...WHICH WILL AGAIN COULD SET UP A DECENT THERMAL GRADIENT
BETWEEN THE LAKE SHORE AND AREAS FARTHER INLAND.

WAY OUT...TOWARDS THE END OF THE CURRENT FORECAST PERIOD...GUIDANCE
IS IN GOOD AGREEMENT IN DEVELOPING A GOOD STORM SYSTEM ACROSS THE
PLAINS..THEY JUST DIFFER SIGNIFICANTLY WITH THE TIMING. THIS  SYSTEM
LOOKS TO PRODUCE A PERIOD OF MUCH WARMER WEATHER AND ALSO ANOTHER
THREAT FOR SHOWERS AND THUNDERSTORMS AT THE END OF THE PERIOD.

KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* NORTHEAST WINDS INCREASING TO 10-13KT BY AROUND 16Z.


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

A WEAK COOL FRONT WILL CONTINUE TO MOVE SOUTH THROUGH THE AREA
VERY EARLY THIS MORNING. WHILE SOME PATCHY 4000 FT CLOUDS ARE SEEN
IN THE WAKE OF THIS...LITTLE IN THE WAY OF SENSIBLE WEATHER IS
EXPECTED. WINDS WILL TURN NORTH TO NORTHEAST BEHIND THIS FRONT.
SPEEDS AT TAF SITES LOOK TO REMAIN BELOW 10 KT THROUGH MOST OF THE
MORNING HOURS...BEFORE AN INCREASE TO 10-13KT THIS AFTERNOON AND
EARLY TO MID EVE AS THE THERMALLY-INDUCED PRESSURE GRADIENT
INCREASES AROUND THE LAKE PERIPHERY. SOME MID TO HIGH CLOUD ARE
POSSIBLE LATE IN THE DAY INTO THIS EVE...BUT OTHERWISE NO IMPACTS
EXPECTED.


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH IN ALL FORECAST ELEMENTS.


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

SATURDAY...VFR/WX NIL.

SUNDAY...VFR/WX NIL.

MONDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS POSSIBLE.

TUESDAY...VFR/WX NIL.

WEDNESDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS
POSSIBLE.

MTF/KREIN

&&

.MARINE...
216 PM CDT

WEAKENING LOW PRESSURE OVER NORTHEAST WISCONSIN THIS AFTERNOON
WILL CONTINUE TO LIFT NORTHEAST AND WEAKEN...REACHING NORTHEAST
ONTARIO BY DAYBREAK FRIDAY. THIS LOW HAS A FRONTAL BOUNDARY THAT
WILL CONTINUE TO SLIDE EAST ACROSS THE LAKE THIS AFTERNOON...WITH
WINDS SLOWLY TURNING WESTERLY TO NORTHWESTERLY. THE GRADIENT WILL
BE CONTINUE TO WEAKEN THIS EVENING...AS AN AREA OF HIGH PRESSURE
LOCATED ACROSS CENTRAL CANADA WILL SLIDE EAST AND ELONGATE
COVERING THE WESTERN GREAT LAKES REGION BY MIDDAY FRIDAY.

THE NEXT WEATHER SYSTEM WILL BEGIN TO DEVELOP FRIDAY NIGHT ACROSS
THE CENTRAL PLAINS...ALLOWING A TIGHTENING GRADIENT TO DEVELOP
ACROSS THE SOUTHERN HALF OF THE LAKE EARLY SATURDAY. IT DOES NOT
APPEAR AT THIS TIME ANY SUBSTANTIAL INCREASE IN THE WINDS WILL
OCCUR. OTHERWISE THE NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL
BE FROM EARLY NEXT WEEK ON AS A STRONGER LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BEACHLER

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KILX 180451
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1151 PM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 858 PM CDT Thu Apr 17 2014

Mid and high clouds still blanket the area this evening and will
continue into the overnight hours. Radar is showing very limited
returns along the IL river, but these should advect toward the
east the remainder of the night. Current forecast has 20pct pops
for tonight and think this remains a reasonable forecast. Winds
and temps look fine as well. So no update planned at this time.

Auten

&&

.AVIATION...
ISSUED 1051 PM CDT Thu Apr 17 2014

VFR conditions will prevail at all TAF sites next 24hrs. Mid
clouds will continue at all sites overnight but then move out
toward morning, becoming clear for the rest of the TAF period.
Winds will be light through the period.

Auten

&&

.PREV DISCUSSION...
ISSUED 253 PM CDT Thu Apr 17 2014

SHORT TERM...Tonight through Monday:

Cold front currently crossing the forecast area is coming through
dry. However, a post frontal band of forcing tonight associated
with coupled jet streaks/associated mid level frontogenesis may be
able to squeeze out some very light rain or sprinkles. However,
the dry airmass in place will keep the precipitation to a minimum.

Then, upper level/surface ridging will build into/across the area
Friday into Sunday. This will provide quiet weather and moderating
temperatures through the period. Temperatures should be well above
normal, in the 70s, for the weekend.

A slow moving system, one that has been trending slower, is
expected to impact the area by Monday. This system should provide
the best chance for rainfall during the next week. Monday will be
a bit cooler with this system in the area, but the cooling in its
wake will be minimal.

LONG TERM...Tuesday through Thursday:

Ridging builds in for Tuesday and Wednesday in the wake of
Monday`s system. This scenario is supportive of quiet weather and
high temperatures mainly in the 70s.

The next system, also a slow mover is currently progged to arrive
by Thursday or Friday. While the details still need to be worked
out with respect to timing, have carried slight chance/chance PoPs
starting Thursday to account for the eventual arrival of this system.

Bak


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 180245
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
945 PM CDT THU APR 17 2014

.DISCUSSION...
309 PM CDT

A RELATIVELY BENIGN WEATHER PERIOD IS IN STORE FOR THE NEXT FEW
DAYS...WITH THE ONLY CHANCE OF ANY PRECIP THROUGH SUNDAY BEING
TONIGHT. THE MAIN FORECAST CONCERNS OVER THE NEXT FEW DAYS WILL BE
TEMPERATURES...AS THERE WILL LIKELY BE SOME DECENT TEMPERATURE
GRADIENTS ACROSS THE AREA...DUE IN LARGE PART TO THE ONSHORE FLOW
EXPECTED ACROSS NORTHEASTERN ILLINOIS ON FRIDAY AND SATURDAY.

CURRENTLY THERE IS A GOOD AMOUNT OF MID AND HIGHER LEVEL CLOUDINESS
STREAMING NORTHEASTWARD ACROSS THE AREA AHEAD OF A SHEARED OUT SHORT
WAVE...CURRENTLY IN PLACE ACROSS THE MID AND LOWER MISSOURI VALLEY.
MODEL GUIDANCE CONTINUES TO SPARK OFF AN AREA OF SHOWERS ACROSS
PORTIONS OF THE REGION THIS EVENING AND OVERNIGHT AS THIS SHORT WAVE
DISTURBANCE APPROACHES AND INDUCES SOME ISENTROPIC ASCENT ACROSS THE
AREA. OVERALL...I FOLLOWED CLOSE TO THE INHERITED FORECAST...WHICH
PLACES THE CHANCES FOR THIS ACTIVITY MAINLY FROM MID EVENING THROUGH
LATE TONIGHT FOR AREAS ALONG AND SOUTH OF A LINE FROM CHICAGO TO
MENDOTA.

A 1030 MB SURFACE HIGH IS EXPECTED TO BUILD IN ACROSS THE UPPER
GREAT LAKES REGION ON FRIDAY. THIS WILL SET UP A NORTH-NORTHEASTERLY
ONSHORE FLOW ACROSS THE AREA DURING THE DAY. AS SUCH...EXPECT CHILLY
CONDITIONS ON FRIDAY ACROSS NORTHEASTERN ILLINOIS AND NORTHWESTERN
INDIANA...WHERE A ENHANCED LAKE BREEZE WILL LIKELY KEEP TEMPERATURES
IN THE 40S FORE AREAS NEAR THE LAKE. FARTHER
INLAND...HOWEVER...TEMPERATURES SHOULD WARM INTO THE 50S...WITH EVEN
SOME LOW 60S POSSIBLE WELL INLAND.

TEMPERATURES BEGIN TO MODERATE AREA-WIDE ON SATURDAY AS THE LOWER
LEVEL FLOW TURNS OUT OF THE SOUTHEAST IN RESPONSE TO LOW PRESSURE
MOVING ACROSS THE NORTHERN PLAINS AND SOUTHERN CANADA. TEMPERATURES
LOOK TO CLIMB INTO THE 60S FOR MOST AREAS...WITH THE EXCEPTION OF
FAR NORTHEAST ILLINOIS...WHERE SOUTHEASTERLY ONSHORE FLOW LOOKS TO
KEEP THINGS COOLER. SUNDAY DEFINITELY LOOKS TO BE THE BEST DAY OF
THE WEEKEND. SOUTH-SOUTHWESTERLY FLOW IS EXPECTED TO TRANSPORT AN
EVEN WARMER AIR MASS IN ACROSS THE AREA. MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT IN ADVECTING IN 15 (9) DEGREE CELSIUS 925 MB (850 MB)
TEMPERATURES. LOCAL CLIMO FOR THESE VALUES THIS TIME OF YEAR
INDICATE HIGH TEMPERATURES GETTING INTO THE LOW TO POSSIBLY MID 70S
ACROSS THE AREA.

THE NEXT CHANCE FOR PRECIPITATION LOOKS TO BE ON MONDAY AS ANOTHER
WEAK FRONTAL SYSTEM AND MID LEVEL DISTURBANCE PUSHES ACROSS THE
AREA. FOLLOWING IN THE WAKE OF THIS FRONTAL MONDAY...LOOKS TO BE
ANOTHER DAY OR TWO PERIOD OF NORTHEASTERLY ONSHORE COOLING
FLOW...WHICH WILL AGAIN COULD SET UP A DECENT THERMAL GRADIENT
BETWEEN THE LAKE SHORE AND AREAS FARTHER INLAND.

WAY OUT...TOWARDS THE END OF THE CURRENT FORECAST PERIOD...GUIDANCE
IS IN GOOD AGREEMENT IN DEVELOPING A GOOD STORM SYSTEM ACROSS THE
PLAINS..THEY JUST DIFFER SIGNIFICANTLY WITH THE TIMING. THIS  SYSTEM
LOOKS TO PRODUCE A PERIOD OF MUCH WARMER WEATHER AND ALSO ANOTHER
THREAT FOR SHOWERS AND THUNDERSTORMS AT THE END OF THE PERIOD.

KJB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* WINDS SHIFTING FROM WSWLY TO NELY LATE EVENING.

KREIN

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

THE LOW PRESSURE SYSTEM OVER NRN WISCONSIN IS WEAKENING RAPIDLY AS
IT MOVES OVER NRN LAKE MICHIGAN EARLY THIS EVENING. AN ASSOCIATED
WEAK COLD FRONT EXTENDS SWWD INTO SRN MO...BUT THE BOUNDARY IS
VERY DIFFUSE OVER NRN IL. THROUGH THE EARLY EVENING...THE BOUNDARY
IS EXPECTED TO WASH OUT AND THAT WINDS SHOULD TURN NELY AS EITHER
A LATE LAKE BREEZE OR INVERTED TROUGH FORMS ALONG THE LAKEFRONT
AND MOVES INLAND. THE LATEST RUNS OF THE HIGH RES SHORT RANGE
MODEL GUIDANCE INDICATE THAT WINDS AT ORD/MDW/GYY COULD TURN NELY
AS EARLY AS ARND 02Z. WINDS SHOULD THEN REMAIN GENERALLY NELY AT
THE TERMINALS THROUGH THE REMAINDER OF THE FCST PERIOD AS HIGH
PRESSURE BUILDS ACROSS THE UPPER MISSISSIPPI VALLEY AND ACROSS THE
WESTERN GREAT LAKES REGIONS. A MID LEVEL DISTURBANCE TRACKING NEWD
THROUGH THE MIDDLE MISSISSIPPI VALLEY COULD BRING SOME RAIN TO
CNTRL IL AND NRN IN THIS EVENING...BUT ANTICIPATE THAT ANY PCPN
SHOULD REMAIN SOUTH OF THE TERMINALS...BUT THERE IS A CHANCE THAT
GYY COULD SEE SOME RAIN LATE THIS EVENING IF THE PCPN CAN OVERCOME
THE LOW LEVEL DRY AIR AND REACH THE SFC. OTHERWISE...CONDITIONS AT
THE TERMINALS SHOULD BE VFR/WX NIL THROUGH THE DAY TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM CONFIDENCE IN TIMING OF WIND SHIFT...WITH HIGHER
  CONFIDENCE IN WIND TRENDS LATTE TONIGHT AND TOMORROW.

* MEDIUM TO HIGH CONFIDENCE THAT ANY PCPN WILL REMAIN SOUTH OF THE
  TERMINALS.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KREIN

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

SATURDAY...VFR/WX NIL.

SUNDAY...VFR/WX NIL.

MONDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS POSSIBLE.

TUESDAY...VFR/WX NIL.

WEDNESDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS
POSSIBLE.

KREIN

&&

.MARINE...
216 PM CDT

WEAKENING LOW PRESSURE OVER NORTHEAST WISCONSIN THIS AFTERNOON
WILL CONTINUE TO LIFT NORTHEAST AND WEAKEN...REACHING NORTHEAST
ONTARIO BY DAYBREAK FRIDAY. THIS LOW HAS A FRONTAL BOUNDARY THAT
WILL CONTINUE TO SLIDE EAST ACROSS THE LAKE THIS AFTERNOON...WITH
WINDS SLOWLY TURNING WESTERLY TO NORTHWESTERLY. THE GRADIENT WILL
BE CONTINUE TO WEAKEN THIS EVENING...AS AN AREA OF HIGH PRESSURE
LOCATED ACROSS CENTRAL CANADA WILL SLIDE EAST AND ELONGATE
COVERING THE WESTERN GREAT LAKES REGION BY MIDDAY FRIDAY.

THE NEXT WEATHER SYSTEM WILL BEGIN TO DEVELOP FRIDAY NIGHT ACROSS
THE CENTRAL PLAINS...ALLOWING A TIGHTENING GRADIENT TO DEVELOP
ACROSS THE SOUTHERN HALF OF THE LAKE EARLY SATURDAY. IT DOES NOT
APPEAR AT THIS TIME ANY SUBSTANTIAL INCREASE IN THE WINDS WILL
OCCUR. OTHERWISE THE NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL
BE FROM EARLY NEXT WEEK ON AS A STRONGER LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BEACHLER

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 180158
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
858 PM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 858 PM CDT Thu Apr 17 2014

Mid and high clouds still blanket the area this evening and will
continue into the overnight hours. Radar is showing very limited
returns along the IL river, but these should advect toward the
east the remainder of the night. Current forecast has 20pct pops
for tonight and think this remains a reasonable forecast. Winds
and temps look fine as well. So no update planned at this time.

Auten
&&

.AVIATION...
ISSUED 643 PM CDT Thu Apr 17 2014

VFR conditions will prevail at all TAF sites next 24hrs. Mid and
high clouds will remain over all sites tonight and through the
overnight hours. Then skies will clear tomorrow early morning and
continue into the afternoon. Winds will be light through the
period, with directions variable this evening, then becoming
northwest overnight and through tomorrow; though with speeds less
than 6kts, winds may be variable tomorrow as well.

Auten
&&

.PREV DISCUSSION...
ISSUED 253 PM CDT Thu Apr 17 2014

SHORT TERM...Tonight through Monday:

Cold front currently crossing the forecast area is coming through
dry. However, a post frontal band of forcing tonight associated
with coupled jet streaks/associated mid level frontogenesis may be
able to squeeze out some very light rain or sprinkles. However,
the dry airmass in place will keep the precipitation to a minimum.

Then, upper level/surface ridging will build into/across the area
Friday into Sunday. This will provide quiet weather and moderating
temperatures through the period. Temperatures should be well above
normal, in the 70s, for the weekend.

A slow moving system, one that has been trending slower, is
expected to impact the area by Monday. This system should provide
the best chance for rainfall during the next week. Monday will be
a bit cooler with this system in the area, but the cooling in its
wake will be minimal.

LONG TERM...Tuesday through Thursday:

Ridging builds in for Tuesday and Wednesday in the wake of
Monday`s system. This scenario is supportive of quiet weather and
high temperatures mainly in the 70s.

The next system, also a slow mover is currently progged to arrive
by Thursday or Friday. While the details still need to be worked
out with respect to timing, have carried slight chance/chance PoPs
starting Thursday to account for the eventual arrival of this system.

Bak

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 172343
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
643 PM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 253 PM CDT Thu Apr 17 2014

SHORT TERM...Tonight through Monday:

Cold front currently crossing the forecast area is coming through
dry. However, a post frontal band of forcing tonight associated
with coupled jet streaks/associated mid level frontogenesis may be
able to squeeze out some very light rain or sprinkles. However,
the dry airmass in place will keep the precipitation to a minimum.

Then, upper level/surface ridging will build into/across the area
Friday into Sunday. This will provide quiet weather and moderating
temperatures through the period. Temperatures should be well above
normal, in the 70s, for the weekend.

A slow moving system, one that has been trending slower, is
expected to impact the area by Monday. This system should provide
the best chance for rainfall during the next week. Monday will be
a bit cooler with this system in the area, but the cooling in its
wake will be minimal.

LONG TERM...Tuesday through Thursday:

Ridging builds in for Tuesday and Wednesday in the wake of
Monday`s system. This scenario is supportive of quiet weather and
high temperatures mainly in the 70s.

The next system, also a slow mover is currently progged to arrive
by Thursday or Friday. While the details still need to be worked
out with respect to timing, have carried slight chance/chance PoPs
starting Thursday to account for the eventual arrival of this system.

Bak

&&

.AVIATION...
ISSUED 643 PM CDT Thu Apr 17 2014

VFR conditions will prevail at all TAF sites next 24hrs. Mid and
high clouds will remain over all sites tonight and through the
overnight hours. Then skies will clear tomorrow early morning and
continue into the afternoon. Winds will be light through the
period, with directions variable this evening, then becoming
northwest overnight and through tomorrow; though with speeds less
than 6kts, winds may be variable tomorrow as well.

Auten

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 172343
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
643 PM CDT THU APR 17 2014

.DISCUSSION...
309 PM CDT

A RELATIVELY BENIGN WEATHER PERIOD IS IN STORE FOR THE NEXT FEW
DAYS...WITH THE ONLY CHANCE OF ANY PRECIP THROUGH SUNDAY BEING
TONIGHT. THE MAIN FORECAST CONCERNS OVER THE NEXT FEW DAYS WILL BE
TEMPERATURES...AS THERE WILL LIKELY BE SOME DECENT TEMPERATURE
GRADIENTS ACROSS THE AREA...DUE IN LARGE PART TO THE ONSHORE FLOW
EXPECTED ACROSS NORTHEASTERN ILLINOIS ON FRIDAY AND SATURDAY.

CURRENTLY THERE IS A GOOD AMOUNT OF MID AND HIGHER LEVEL CLOUDINESS
STREAMING NORTHEASTWARD ACROSS THE AREA AHEAD OF A SHEARED OUT SHORT
WAVE...CURRENTLY IN PLACE ACROSS THE MID AND LOWER MISSOURI VALLEY.
MODEL GUIDANCE CONTINUES TO SPARK OFF AN AREA OF SHOWERS ACROSS
PORTIONS OF THE REGION THIS EVENING AND OVERNIGHT AS THIS SHORT WAVE
DISTURBANCE APPROACHES AND INDUCES SOME ISENTROPIC ASCENT ACROSS THE
AREA. OVERALL...I FOLLOWED CLOSE TO THE INHERITED FORECAST...WHICH
PLACES THE CHANCES FOR THIS ACTIVITY MAINLY FROM MID EVENING THROUGH
LATE TONIGHT FOR AREAS ALONG AND SOUTH OF A LINE FROM CHICAGO TO
MENDOTA.

A 1030 MB SURFACE HIGH IS EXPECTED TO BUILD IN ACROSS THE UPPER
GREAT LAKES REGION ON FRIDAY. THIS WILL SET UP A NORTH-NORTHEASTERLY
ONSHORE FLOW ACROSS THE AREA DURING THE DAY. AS SUCH...EXPECT CHILLY
CONDITIONS ON FRIDAY ACROSS NORTHEASTERN ILLINOIS AND NORTHWESTERN
INDIANA...WHERE A ENHANCED LAKE BREEZE WILL LIKELY KEEP TEMPERATURES
IN THE 40S FORE AREAS NEAR THE LAKE. FARTHER
INLAND...HOWEVER...TEMPERATURES SHOULD WARM INTO THE 50S...WITH EVEN
SOME LOW 60S POSSIBLE WELL INLAND.

TEMPERATURES BEGIN TO MODERATE AREA-WIDE ON SATURDAY AS THE LOWER
LEVEL FLOW TURNS OUT OF THE SOUTHEAST IN RESPONSE TO LOW PRESSURE
MOVING ACROSS THE NORTHERN PLAINS AND SOUTHERN CANADA. TEMPERATURES
LOOK TO CLIMB INTO THE 60S FOR MOST AREAS...WITH THE EXCEPTION OF
FAR NORTHEAST ILLINOIS...WHERE SOUTHEASTERLY ONSHORE FLOW LOOKS TO
KEEP THINGS COOLER. SUNDAY DEFINITELY LOOKS TO BE THE BEST DAY OF
THE WEEKEND. SOUTH-SOUTHWESTERLY FLOW IS EXPECTED TO TRANSPORT AN
EVEN WARMER AIR MASS IN ACROSS THE AREA. MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT IN ADVECTING IN 15 (9) DEGREE CELSIUS 925 MB (850 MB)
TEMPERATURES. LOCAL CLIMO FOR THESE VALUES THIS TIME OF YEAR
INDICATE HIGH TEMPERATURES GETTING INTO THE LOW TO POSSIBLY MID 70S
ACROSS THE AREA.

THE NEXT CHANCE FOR PRECIPITATION LOOKS TO BE ON MONDAY AS ANOTHER
WEAK FRONTAL SYSTEM AND MID LEVEL DISTURBANCE PUSHES ACROSS THE
AREA. FOLLOWING IN THE WAKE OF THIS FRONTAL MONDAY...LOOKS TO BE
ANOTHER DAY OR TWO PERIOD OF NORTHEASTERLY ONSHORE COOLING
FLOW...WHICH WILL AGAIN COULD SET UP A DECENT THERMAL GRADIENT
BETWEEN THE LAKE SHORE AND AREAS FARTHER INLAND.

WAY OUT...TOWARDS THE END OF THE CURRENT FORECAST PERIOD...GUIDANCE
IS IN GOOD AGREEMENT IN DEVELOPING A GOOD STORM SYSTEM ACROSS THE
PLAINS..THEY JUST DIFFER SIGNIFICANTLY WITH THE TIMING. THIS  SYSTEM
LOOKS TO PRODUCE A PERIOD OF MUCH WARMER WEATHER AND ALSO ANOTHER
THREAT FOR SHOWERS AND THUNDERSTORMS AT THE END OF THE PERIOD.

KJB

&&

.AVIATION...

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

* A LATE LAKE BREEZE TURNING WINDS FROM WSWLY TO NELY EARLY
  EVENING.

KREIN

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

THE LOW PRESSURE SYSTEM OVER NRN WISCONSIN IS WEAKENING RAPIDLY AS
IT MOVES OVER NRN LAKE MICHIGAN EARLY THIS EVENING. AN ASSOCIATED
WEAK COLD FRONT EXTENDS SWWD INTO SRN MO...BUT THE BOUNDARY IS
VERY DIFFUSE OVER NRN IL. THROUGH THE EARLY EVENING...THE BOUNDARY
IS EXPECTED TO WASH OUT AND THAT WINDS SHOULD TURN NELY AS EITHER
A LATE LAKE BREEZE OR INVERTED TROUGH FORMS ALONG THE LAKEFRONT
AND MOVES INLAND. THE LATEST RUNS OF THE HIGH RES SHORT RANGE
MODEL GUIDANCE INDICATE THAT WINDS AT ORD/MDW/GYY COULD TURN NELY
AS EARLY AS ARND 02Z. WINDS SHOULD THEN REMAIN GENERALLY NELY AT
THE TERMINALS THROUGH THE REMAINDER OF THE FCST PERIOD AS HIGH
PRESSURE BUILDS ACROSS THE UPPER MISSISSIPPI VALLEY AND ACROSS THE
WESTERN GREAT LAKES REGIONS. A MID LEVEL DISTURBANCE TRACKING NEWD
THROUGH THE MIDDLE MISSISSIPPI VALLEY COULD BRING SOME RAIN TO
CNTRL IL AND NRN IN THIS EVENING...BUT ANTICIPATE THAT ANY PCPN
SHOULD REMAIN SOUTH OF THE TERMINALS...BUT THERE IS A CHANCE THAT
GYY COULD SEE SOME RAIN LATE THIS EVENING IF THE PCPN CAN OVERCOME
THE LOW LEVEL DRY AIR AND REACH THE SFC. OTHERWISE...CONDITIONS AT
THE TERMINALS SHOULD BE VFR/WX NIL THROUGH THE DAY TOMORROW.

KREIN


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

* MEDIUM CONFIDENCE IN TIMING OF EARLY EVENING WIND SHIFT...WITH
  HIGHER CONFIDENCE IN WIND TRENDS LATTE TONIGHT AND TOMORROW.

* MEDIUM TO HIGH CONFIDENCE THAT ANY PCPN WILL REMAIN SOUTH OF THE
  TERMINALS.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KREIN

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

SATURDAY...VFR/WX NIL.

SUNDAY...VFR/WX NIL.

MONDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS POSSIBLE.

TUESDAY...VFR/WX NIL.

WEDNESDAY...CHANCE RAIN WITH MVFR CIGS/VIS LIKELY. IFR CIGS
POSSIBLE.

KREIN

&&

.MARINE...
216 PM CDT

WEAKENING LOW PRESSURE OVER NORTHEAST WISCONSIN THIS AFTERNOON
WILL CONTINUE TO LIFT NORTHEAST AND WEAKEN...REACHING NORTHEAST
ONTARIO BY DAYBREAK FRIDAY. THIS LOW HAS A FRONTAL BOUNDARY THAT
WILL CONTINUE TO SLIDE EAST ACROSS THE LAKE THIS AFTERNOON...WITH
WINDS SLOWLY TURNING WESTERLY TO NORTHWESTERLY. THE GRADIENT WILL
BE CONTINUE TO WEAKEN THIS EVENING...AS AN AREA OF HIGH PRESSURE
LOCATED ACROSS CENTRAL CANADA WILL SLIDE EAST AND ELONGATE
COVERING THE WESTERN GREAT LAKES REGION BY MIDDAY FRIDAY.

THE NEXT WEATHER SYSTEM WILL BEGIN TO DEVELOP FRIDAY NIGHT ACROSS
THE CENTRAL PLAINS...ALLOWING A TIGHTENING GRADIENT TO DEVELOP
ACROSS THE SOUTHERN HALF OF THE LAKE EARLY SATURDAY. IT DOES NOT
APPEAR AT THIS TIME ANY SUBSTANTIAL INCREASE IN THE WINDS WILL
OCCUR. OTHERWISE THE NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL
BE FROM EARLY NEXT WEEK ON AS A STRONGER LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BEACHLER

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 172153
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
453 PM CDT THU APR 17 2014

.DISCUSSION...
309 PM CDT

A RELATIVELY BENIGN WEATHER PERIOD IS IN STORE FOR THE NEXT FEW
DAYS...WITH THE ONLY CHANCE OF ANY PRECIP THROUGH SUNDAY BEING
TONIGHT. THE MAIN FORECAST CONCERNS OVER THE NEXT FEW DAYS WILL BE
TEMPERATURES...AS THERE WILL LIKELY BE SOME DECENT TEMPERATURE
GRADIENTS ACROSS THE AREA...DUE IN LARGE PART TO THE ONSHORE FLOW
EXPECTED ACROSS NORTHEASTERN ILLINOIS ON FRIDAY AND SATURDAY.

CURRENTLY THERE IS A GOOD AMOUNT OF MID AND HIGHER LEVEL CLOUDINESS
STREAMING NORTHEASTWARD ACROSS THE AREA AHEAD OF A SHEARED OUT SHORT
WAVE...CURRENTLY IN PLACE ACROSS THE MID AND LOWER MISSOURI VALLEY.
MODEL GUIDANCE CONTINUES TO SPARK OFF AN AREA OF SHOWERS ACROSS
PORTIONS OF THE REGION THIS EVENING AND OVERNIGHT AS THIS SHORT WAVE
DISTURBANCE APPROACHES AND INDUCES SOME ISENTROPIC ASCENT ACROSS THE
AREA. OVERALL...I FOLLOWED CLOSE TO THE INHERITED FORECAST...WHICH
PLACES THE CHANCES FOR THIS ACTIVITY MAINLY FROM MID EVENING THROUGH
LATE TONIGHT FOR AREAS ALONG AND SOUTH OF A LINE FROM CHICAGO TO
MENDOTA.

A 1030 MB SURFACE HIGH IS EXPECTED TO BUILD IN ACROSS THE UPPER
GREAT LAKES REGION ON FRIDAY. THIS WILL SET UP A NORTH-NORTHEASTERLY
ONSHORE FLOW ACROSS THE AREA DURING THE DAY. AS SUCH...EXPECT CHILLY
CONDITIONS ON FRIDAY ACROSS NORTHEASTERN ILLINOIS AND NORTHWESTERN
INDIANA...WHERE A ENHANCED LAKE BREEZE WILL LIKELY KEEP TEMPERATURES
IN THE 40S FORE AREAS NEAR THE LAKE. FARTHER
INLAND...HOWEVER...TEMPERATURES SHOULD WARM INTO THE 50S...WITH EVEN
SOME LOW 60S POSSIBLE WELL INLAND.

TEMPERATURES BEGIN TO MODERATE AREA-WIDE ON SATURDAY AS THE LOWER
LEVEL FLOW TURNS OUT OF THE SOUTHEAST IN RESPONSE TO LOW PRESSURE
MOVING ACROSS THE NORTHERN PLAINS AND SOUTHERN CANADA. TEMPERATURES
LOOK TO CLIMB INTO THE 60S FOR MOST AREAS...WITH THE EXCEPTION OF
FAR NORTHEAST ILLINOIS...WHERE SOUTHEASTERLY ONSHORE FLOW LOOKS TO
KEEP THINGS COOLER. SUNDAY DEFINITELY LOOKS TO BE THE BEST DAY OF
THE WEEKEND. SOUTH-SOUTHWESTERLY FLOW IS EXPECTED TO TRANSPORT AN
EVEN WARMER AIR MASS IN ACROSS THE AREA. MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT IN ADVECTING IN 15 (9) DEGREE CELSIUS 925 MB (850 MB)
TEMPERATURES. LOCAL CLIMO FOR THESE VALUES THIS TIME OF YEAR
INDICATE HIGH TEMPERATURES GETTING INTO THE LOW TO POSSIBLY MID 70S
ACROSS THE AREA.

THE NEXT CHANCE FOR PRECIPITATION LOOKS TO BE ON MONDAY AS ANOTHER
WEAK FRONTAL SYSTEM AND MID LEVEL DISTURBANCE PUSHES ACROSS THE
AREA. FOLLOWING IN THE WAKE OF THIS FRONTAL MONDAY...LOOKS TO BE
ANOTHER DAY OR TWO PERIOD OF NORTHEASTERLY ONSHORE COOLING
FLOW...WHICH WILL AGAIN COULD SET UP A DECENT THERMAL GRADIENT
BETWEEN THE LAKE SHORE AND AREAS FARTHER INLAND.

WAY OUT...TOWARDS THE END OF THE CURRENT FORECAST PERIOD...GUIDANCE
IS IN GOOD AGREEMENT IN DEVELOPING A GOOD STORM SYSTEM ACROSS THE
PLAINS..THEY JUST DIFFER SIGNIFICANTLY WITH THE TIMING. THIS  SYSTEM
LOOKS TO PRODUCE A PERIOD OF MUCH WARMER WEATHER AND ALSO ANOTHER
THREAT FOR SHOWERS AND THUNDERSTORMS AT THE END OF THE PERIOD.

KJB

&&

.AVIATION...

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

* WINDS BECOME NORTH LATE THIS EVENING AND THEN EAST ARND 10 KT BY
  LATE FRIDAY MORNING.

KREIN

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

LOW PRESSURE IS SLOWLY WEAKENING AND SHIFTING NORTHEAST OVER
WISCONSIN. ITS COLD FRONT IS MOVING THROUGH THE EASTERN TERMINALS
NOW AND EXPECTING WINDS TO TURN WEST BEHIND THE FRONT. THE MVFR TO
IFR CIGS TO OUR NORTH AND WEST APPEAR TO BE DISSIPATING AND NOT
MOVING INTO NORTHERN IL. SHOULD SEE THE MVFR CIGS OVER RFD SCATTER
AND LIFT OVER THE NEXT COUPLE OF HOURS...AND HAVE MEDIUM
CONFIDENCE ON THE TIMING. THE CIGS MAY LINGER A BIT LONGER OVER
RFD THAN EXPECTED.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
DIMINISHING AND ALSO BECOMING NORTH BY LATE THIS EVENING. THE
UPPER LEVEL TROUGH SWINGS THROUGH THIS EVENING AS WELL AND
GUIDANCE CONTINUES TO SHOW SCATTERED RAIN SHOWERS ALONG AND EAST
OF I-55 THIS EVENING. GYY WOULD HAVE THE BEST CHANCE OF SEEING ANY
PRECIP...BUT THAT CHANCE IS VERY LOW. THEREFORE KEPT ALL OF THE
TAFS DRY FOR NOW.

WINDS CONTINUE TO VEER TO THE EAST TOMORROW WITH WINDS INCREASING
TO ARND 10 KT BY THE LATE MORNING.

JEE

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

* HIGH CONFIDENCE IN WIND SHIFTS...MEDIUM CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KREIN

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
216 PM CDT

WEAKENING LOW PRESSURE OVER NORTHEAST WISCONSIN THIS AFTERNOON
WILL CONTINUE TO LIFT NORTHEAST AND WEAKEN...REACHING NORTHEAST
ONTARIO BY DAYBREAK FRIDAY. THIS LOW HAS A FRONTAL BOUNDARY THAT
WILL CONTINUE TO SLIDE EAST ACROSS THE LAKE THIS AFTERNOON...WITH
WINDS SLOWLY TURNING WESTERLY TO NORTHWESTERLY. THE GRADIENT WILL
BE CONTINUE TO WEAKEN THIS EVENING...AS AN AREA OF HIGH PRESSURE
LOCATED ACROSS CENTRAL CANADA WILL SLIDE EAST AND ELONGATE
COVERING THE WESTERN GREAT LAKES REGION BY MIDDAY FRIDAY.

THE NEXT WEATHER SYSTEM WILL BEGIN TO DEVELOP FRIDAY NIGHT ACROSS
THE CENTRAL PLAINS...ALLOWING A TIGHTENING GRADIENT TO DEVELOP
ACROSS THE SOUTHERN HALF OF THE LAKE EARLY SATURDAY. IT DOES NOT
APPEAR AT THIS TIME ANY SUBSTANTICAL INCREASE IN THE WINDS WILL
OCCUR. OTHERWISE THE NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL
BE FROM EARLY NEXT WEEK ON AS A STRONGER LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BEACHLER

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 172009
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 PM CDT THU APR 17 2014

.DISCUSSION...
309 PM CDT

A RELATIVELY BENIGN WEATHER PERIOD IS IN STORE FOR THE NEXT FEW
DAYS...WITH THE ONLY CHANCE OF ANY PRECIP THROUGH SUNDAY BEING
TONIGHT. THE MAIN FORECAST CONCERNS OVER THE NEXT FEW DAYS WILL BE
TEMPERATURES...AS THERE WILL LIKELY BE SOME DECENT TEMPERATURE
GRADIENTS ACROSS THE AREA...DUE IN LARGE PART TO THE ONSHORE FLOW
EXPECTED ACROSS NORTHEASTERN ILLINOIS ON FRIDAY AND SATURDAY.

CURRENTLY THERE IS A GOOD AMOUNT OF MID AND HIGHER LEVEL CLOUDINESS
STREAMING NORTHEASTWARD ACROSS THE AREA AHEAD OF A SHEARED OUT SHORT
WAVE...CURRENTLY IN PLACE ACROSS THE MID AND LOWER MISSOURI VALLEY.
MODEL GUIDANCE CONTINUES TO SPARK OFF AN AREA OF SHOWERS ACROSS
PORTIONS OF THE REGION THIS EVENING AND OVERNIGHT AS THIS SHORT WAVE
DISTURBANCE APPROACHES AND INDUCES SOME ISENTROPIC ASCENT ACROSS THE
AREA. OVERALL...I FOLLOWED CLOSE TO THE INHERITED FORECAST...WHICH
PLACES THE CHANCES FOR THIS ACTIVITY MAINLY FROM MID EVENING THROUGH
LATE TONIGHT FOR AREAS ALONG AND SOUTH OF A LINE FROM CHICAGO TO
MENDOTA.

A 1030 MB SURFACE HIGH IS EXPECTED TO BUILD IN ACROSS THE UPPER
GREAT LAKES REGION ON FRIDAY. THIS WILL SET UP A NORTH-NORTHEASTERLY
ONSHORE FLOW ACROSS THE AREA DURING THE DAY. AS SUCH...EXPECT CHILLY
CONDITIONS ON FRIDAY ACROSS NORTHEASTERN ILLINOIS AND NORTHWESTERN
INDIANA...WHERE A ENHANCED LAKE BREEZE WILL LIKELY KEEP TEMPERATURES
IN THE 40S FORE AREAS NEAR THE LAKE. FARTHER
INLAND...HOWEVER...TEMPERATURES SHOULD WARM INTO THE 50S...WITH EVEN
SOME LOW 60S POSSIBLE WELL INLAND.

TEMPERATURES BEGIN TO MODERATE AREA-WIDE ON SATURDAY AS THE LOWER
LEVEL FLOW TURNS OUT OF THE SOUTHEAST IN RESPONSE TO LOW PRESSURE
MOVING ACROSS THE NORTHERN PLAINS AND SOUTHERN CANADA. TEMPERATURES
LOOK TO CLIMB INTO THE 60S FOR MOST AREAS...WITH THE EXCEPTION OF
FAR NORTHEAST ILLINOIS...WHERE SOUTHEASTERLY ONSHORE FLOW LOOKS TO
KEEP THINGS COOLER. SUNDAY DEFINITELY LOOKS TO BE THE BEST DAY OF
THE WEEKEND. SOUTH-SOUTHWESTERLY FLOW IS EXPECTED TO TRANSPORT AN
EVEN WARMER AIR MASS IN ACROSS THE AREA. MODEL GUIDANCE IS IN VERY
GOOD AGREEMENT IN ADVECTING IN 15 (9) DEGREE CELSIUS 925 MB (850 MB)
TEMPERATURES. LOCAL CLIMO FOR THESE VALUES THIS TIME OF YEAR
INDICATE HIGH TEMPERATURES GETTING INTO THE LOW TO POSSIBLY MID 70S
ACROSS THE AREA.

THE NEXT CHANCE FOR PRECIPITATION LOOKS TO BE ON MONDAY AS ANOTHER
WEAK FRONTAL SYSTEM AND MID LEVEL DISTURBANCE PUSHES ACROSS THE
AREA. FOLLOWING IN THE WAKE OF THIS FRONTAL MONDAY...LOOKS TO BE
ANOTHER DAY OR TWO PERIOD OF NORTHEASTERLY ONSHORE COOLING
FLOW...WHICH WILL AGAIN COULD SET UP A DECENT THERMAL GRADIENT
BETWEEN THE LAKE SHORE AND AREAS FARTHER INLAND.

WAY OUT...TOWARDS THE END OF THE CURRENT FORECAST PERIOD...GUIDANCE
IS IN GOOD AGREEMENT IN DEVELOPING A GOOD STORM SYSTEM ACROSS THE
PLAINS..THEY JUST DIFFER SIGNIFICANTLY WITH THE TIMING. THIS  SYSTEM
LOOKS TO PRODUCE A PERIOD OF MUCH WARMER WEATHER AND ALSO ANOTHER
THREAT FOR SHOWERS AND THUNDERSTORMS AT THE END OF THE PERIOD.

KJB

&&

.AVIATION...

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

* WINDS BECOME NORTH LATE THIS EVENING AND THEN EAST ARND 10 KT BY
  LATE FRIDAY MORNING.

JEE

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

LOW PRESSURE IS SLOWLY WEAKENING AND SHIFTING NORTHEAST OVER
WISCONSIN. ITS COLD FRONT IS MOVING THROUGH THE EASTERN TERMINALS
NOW AND EXPECTING WINDS TO TURN WEST BEHIND THE FRONT. THE MVFR TO
IFR CIGS TO OUR NORTH AND WEST APPEAR TO BE DISSIPATING AND NOT
MOVING INTO NORTHERN IL. SHOULD SEE THE MVFR CIGS OVER RFD SCATTER
AND LIFT OVER THE NEXT COUPLE OF HOURS...AND HAVE MEDIUM
CONFIDENCE ON THE TIMING. THE CIGS MAY LINGER A BIT LONGER OVER
RFD THAN EXPECTED.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
DIMINISHING AND ALSO BECOMING NORTH BY LATE THIS EVENING. THE
UPPER LEVEL TROUGH SWINGS THROUGH THIS EVENING AS WELL AND
GUIDANCE CONTINUES TO SHOW SCATTERED RAIN SHOWERS ALONG AND EAST
OF I-55 THIS EVENING. GYY WOULD HAVE THE BEST CHANCE OF SEEING ANY
PRECIP...BUT THAT CHANCE IS VERY LOW. THEREFORE KEPT ALL OF THE
TAFS DRY FOR NOW.

WINDS CONTINUE TO VEER TO THE EAST TOMORROW WITH WINDS INCREASING
TO ARND 10 KT BY THE LATE MORNING.

JEE

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

* HIGH CONFIDENCE IN WIND SHIFTS...MEDIUM CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
216 PM CDT

WEAKENING LOW PRESSURE OVER NORTHEAST WISCONSIN THIS AFTERNOON
WILL CONTINUE TO LIFT NORTHEAST AND WEAKEN...REACHING NORTHEAST
ONTARIO BY DAYBREAK FRIDAY. THIS LOW HAS A FRONTAL BOUNDARY THAT
WILL CONTINUE TO SLIDE EAST ACROSS THE LAKE THIS AFTERNOON...WITH
WINDS SLOWLY TURNING WESTERLY TO NORTHWESTERLY. THE GRADIENT WILL
BE CONTINUE TO WEAKEN THIS EVENING...AS AN AREA OF HIGH PRESSURE
LOCATED ACROSS CENTRAL CANADA WILL SLIDE EAST AND ELONGATE
COVERING THE WESTERN GREAT LAKES REGION BY MIDDAY FRIDAY.

THE NEXT WEATHER SYSTEM WILL BEGIN TO DEVELOP FRIDAY NIGHT ACROSS
THE CENTRAL PLAINS...ALLOWING A TIGHTENING GRADIENT TO DEVELOP
ACROSS THE SOUTHERN HALF OF THE LAKE EARLY SATURDAY. IT DOES NOT
APPEAR AT THIS TIME ANY SUBSTANTICAL INCREASE IN THE WINDS WILL
OCCUR. OTHERWISE THE NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL
BE FROM EARLY NEXT WEEK ON AS A STRONGER LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BEACHLER

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 172005
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
305 PM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

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

* WINDS BECOME NORTH LATE THIS EVENING AND THEN EAST ARND 10 KT BY
  LATE FRIDAY MORNING.

JEE

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

LOW PRESSURE IS SLOWLY WEAKENING AND SHIFTING NORTHEAST OVER
WISCONSIN. ITS COLD FRONT IS MOVING THROUGH THE EASTERN TERMINALS
NOW AND EXPECTING WINDS TO TURN WEST BEHIND THE FRONT. THE MVFR TO
IFR CIGS TO OUR NORTH AND WEST APPEAR TO BE DISSIPATING AND NOT
MOVING INTO NORTHERN IL. SHOULD SEE THE MVFR CIGS OVER RFD SCATTER
AND LIFT OVER THE NEXT COUPLE OF HOURS...AND HAVE MEDIUM
CONFIDENCE ON THE TIMING. THE CIGS MAY LINGER A BIT LONGER OVER
RFD THAN EXPECTED.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
DIMINISHING AND ALSO BECOMING NORTH BY LATE THIS EVENING. THE
UPPER LEVEL TROUGH SWINGS THROUGH THIS EVENING AS WELL AND
GUIDANCE CONTINUES TO SHOW SCATTERED RAIN SHOWERS ALONG AND EAST
OF I-55 THIS EVENING. GYY WOULD HAVE THE BEST CHANCE OF SEEING ANY
PRECIP...BUT THAT CHANCE IS VERY LOW. THEREFORE KEPT ALL OF THE
TAFS DRY FOR NOW.

WINDS CONTINUE TO VEER TO THE EAST TOMORROW WITH WINDS INCREASING
TO ARND 10 KT BY THE LATE MORNING.

JEE

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

* HIGH CONFIDENCE IN WIND SHIFTS...MEDIUM CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
216 PM CDT

WEAKENING LOW PRESSURE OVER NORTHEAST WISCONSIN THIS AFTERNOON
WILL CONTINUE TO LIFT NORTHEAST AND WEAKEN...REACHING NORTHEAST
ONTARIO BY DAYBREAK FRIDAY. THIS LOW HAS A FRONTAL BOUNDARY THAT
WILL CONTINUE TO SLIDE EAST ACROSS THE LAKE THIS AFTERNOON...WITH
WINDS SLOWLY TURNING WESTERLY TO NORTHWESTERLY. THE GRADIENT WILL
BE CONTINUE TO WEAKEN THIS EVENING...AS AN AREA OF HIGH PRESSURE
LOCATED ACROSS CENTRAL CANADA WILL SLIDE EAST AND ELONGATE
COVERING THE WESTERN GREAT LAKES REGION BY MIDDAY FRIDAY.

THE NEXT WEATHER SYSTEM WILL BEGIN TO DEVELOP FRIDAY NIGHT ACROSS
THE CENTRAL PLAINS...ALLOWING A TIGHTENING GRADIENT TO DEVELOP
ACROSS THE SOUTHERN HALF OF THE LAKE EARLY SATURDAY. IT DOES NOT
APPEAR AT THIS TIME ANY SUBSTANTICAL INCREASE IN THE WINDS WILL
OCCUR. OTHERWISE THE NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL
BE FROM EARLY NEXT WEEK ON AS A STRONGER LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BEACHLER

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 171953
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
253 PM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 253 PM CDT Thu Apr 17 2014

SHORT TERM...Tonight through Monday:

Cold front currently crossing the forecast area is coming through
dry. However, a post frontal band of forcing tonight associated
with coupled jet streaks/associated mid level frontogenesis may be
able to squeeze out some very light rain or sprinkles. However,
the dry airmass in place will keep the precipitation to a minimum.

Then, upper level/surface ridging will build into/across the area
Friday into Sunday. This will provide quiet weather and moderating
temperatures through the period. Temperatures should be well above
normal, in the 70s, for the weekend.

A slow moving system, one that has been trending slower, is
expected to impact the area by Monday. This system should provide
the best chance for rainfall during the next week. Monday will be
a bit cooler with this system in the area, but the cooling in its
wake will be minimal.

LONG TERM...Tuesday through Thursday:

Ridging builds in for Tuesday and Wednesday in the wake of
Monday`s system. This scenario is supportive of quiet weather and
high temperatures mainly in the 70s.

The next system, also a slow mover is currently progged to arrive
by Thursday or Friday. While the details still need to be worked
out with respect to timing, have carried slight chance/chance PoPs
starting Thursday to account for the eventual arrival of this system.

Bak
&&

.AVIATION...
ISSUED 1250 PM CDT Thu Apr 17 2014
Weak cold front moving through the FA this afternoon expected to
stall and remain in place through the overnight hours. For the
most part, the front remains dry with sct remnant low clouds from
this mornings stratus. Another wave to the SW will move NE along
the boundary resulting in some showery activity tonight. Most of
the activity should be confined to 03-06z... but may see some
lingering showers, particularly in the east to 08-09z. For the
most part, winds are also light and somewhat variable close to the
front. For now, keeping the cigs VFR, however...should a
widespread rainfall occur through the overnight and increase the
RH in the boundary layer, the morning may need to be adjusted.
Confidence in showers are low...so keeping anything less than VFR
out of the morning.

HJS
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 171928
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
228 PM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

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

* WINDS BECOME NORTH LATE THIS EVENING AND THEN EAST ARND 10 KT BY
  LATE FRIDAY MORNING.

JEE

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

LOW PRESSURE IS SLOWLY WEAKENING AND SHIFTING NORTHEAST OVER
WISCONSIN. ITS COLD FRONT IS MOVING THROUGH THE EASTERN TERMINALS
NOW AND EXPECTING WINDS TO TURN WEST BEHIND THE FRONT. THE MVFR TO
IFR CIGS TO OUR NORTH AND WEST APPEAR TO BE DISSIPATING AND NOT
MOVING INTO NORTHERN IL. SHOULD SEE THE MVFR CIGS OVER RFD SCATTER
AND LIFT OVER THE NEXT COUPLE OF HOURS...AND HAVE MEDIUM
CONFIDENCE ON THE TIMING. THE CIGS MAY LINGER A BIT LONGER OVER
RFD THAN EXPECTED.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
DIMINISHING AND ALSO BECOMING NORTH BY LATE THIS EVENING. THE
UPPER LEVEL TROUGH SWINGS THROUGH THIS EVENING AS WELL AND
GUIDANCE CONTINUES TO SHOW SCATTERED RAIN SHOWERS ALONG AND EAST
OF I-55 THIS EVENING. GYY WOULD HAVE THE BEST CHANCE OF SEEING ANY
PRECIP...BUT THAT CHANCE IS VERY LOW. THEREFORE KEPT ALL OF THE
TAFS DRY FOR NOW.

WINDS CONTINUE TO VEER TO THE EAST TOMORROW WITH WINDS INCREASING
TO ARND 10 KT BY THE LATE MORNING.

JEE

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

* HIGH CONFIDENCE IN WIND SHIFTS...MEDIUM CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
216 PM CDT

WEAKENING LOW PRESSURE OVER NORTHEAST WISCONSIN THIS AFTERNOON
WILL CONTINUE TO LIFT NORTHEAST AND WEAKEN...REACHING NORTHEAST
ONTARIO BY DAYBREAK FRIDAY. THIS LOW HAS A FRONTAL BOUNDARY THAT
WILL CONTINUE TO SLIDE EAST ACROSS THE LAKE THIS AFTERNOON...WITH
WINDS SLOWLY TURNING WESTERLY TO NORTHWESTERLY. THE GRADIENT WILL
BE CONTINUE TO WEAKEN THIS EVENING...AS AN AREA OF HIGH PRESSURE
LOCATED ACROSS CENTRAL CANADA WILL SLIDE EAST AND ELONGATE
COVERING THE WESTERN GREAT LAKES REGION BY MIDDAY FRIDAY.

THE NEXT WEATHER SYSTEM WILL BEGIN TO DEVELOP FRIDAY NIGHT ACROSS
THE CENTRAL PLAINS...ALLOWING A TIGHTENING GRADIENT TO DEVELOP
ACROSS THE SOUTHERN HALF OF THE LAKE EARLY SATURDAY. IT DOES NOT
APPEAR AT THIS TIME ANY SUBSTANTICAL INCREASE IN THE WINDS WILL
OCCUR. OTHERWISE THE NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL
BE FROM EARLY NEXT WEEK ON AS A STRONGER LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BEACHLER

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 171758
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1258 PM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 1045 AM CDT Thu Apr 17 2014
Low pressure system making its way through Wisconsin this morning
dragging a cold front across the state. Measurable precip not
expected for the day along the boundary. Some weak echoes showing
up on radar NW of the boundary however with some of the llvl
clouds. Will keep an eye on the potential for precip...but
anticipate little more than possibly a sprinkle before 00Z. Have
boosted the high temps in the far east as the boundary is not
likely to make it too much further then I-55 and just barely
adjusted a couple of temps. Not even enough to warrant a zone
update. Wave to the SW still expected to ripple through the region
and along the boundary later this evening and produce a bit of
rainfall across the area. Best chances are in the center of the
state/along the boundary as it slows.



&&

.AVIATION...
ISSUED 1250 PM CDT Thu Apr 17 2014
Weak cold front moving through the FA this afternoon expected to
stall and remain in place through the overnight hours. For the
most part, the front remains dry with sct remnant low clouds from
this mornings stratus. Another wave to the SW will move NE along
the boundary resulting in some showery activity tonight. Most of
the activity should be confined to 03-06z... but may see some
lingering showers, particularly in the east to 08-09z. For the
most part, winds are also light and somewhat variable close to the
front. For now, keeping the cigs VFR, however...should a
widespread rainfall occur through the overnight and increase the
RH in the boundary layer, the morning may need to be adjusted.
Confidence in showers are low...so keeping anything less than VFR
out of the morning.


HJS
&&

.PREV DISCUSSION...
ISSUED 238 AM CDT Thu Apr 17 2014

SHORT TERM...Today through Saturday

Low pressure analyzed over western Wisconsin on 07z/2am surface
analysis will continue to lift northeastward today, dragging a
weak cold front into central Illinois. Boundary will make only
slow progress eastward and will eventually stall along the I-57
corridor this afternoon. Little in the way of sensible weather
will accompany the front other than a few mid/high clouds.
Afternoon high temperatures will range from the upper 50s west of
the Illinois River to the middle 60s south of I-70.

Short-wave trough currently evident on water vapor imagery over
the Texas panhandle will track E/NE, passing south of Illinois
late tonight into Friday. Enough synoptic lift will be generated
by this feature to perhaps trigger a few light showers along/near
the stationary frontal boundary. Mitigating factor for precip will
be lack of moisture, as air mass remains very dry in the wake of
the early week cold front that penetrated well into the Gulf of
Mexico. Surface dew points have only recovered into the middle 50s
across coastal Texas, with models projecting 40-45F dew points
reaching central Illinois tonight. Forecast soundings remain dry
below 850mb, so am not expecting much in the way of precip. Will
hold on to low chance PoPs tonight, with scant rainfall amounts of
only a couple hundredths of an inch at best.

Once upper wave passes by to the south, surface high pressure will
resume control of the weather on Friday. After some lingering
sprinkles/clouds across the east during the morning, sunshine will
return across the board by afternoon with highs climbing into the
lower to middle 60s. As the high shifts off to the east, increasing
southerly winds will bring even warmer air into the region on
Saturday resulting in highs reaching the upper 60s and lower 70s.

LONG TERM...Sunday through Wednesday

As has been the case for the past few days, the latest model suite
has once again delayed the onset of the next storm system early
next week. One upper wave is expected to track across southern
Canada over the weekend, while another slower-moving southern
stream wave will track out of the Desert Southwest into the lower
Mississippi River Valley by Monday. The GFS had previously been
the fastest model with this southern stream feature, introducing
precip as early as Easter Sunday. 00z Apr 17 run of the GFS has
now slowed the system and is in much better agreement with the
more consistent ECMWF/GEM, which have featured a dry Sunday for
the past couple of runs. As a result of this model consensus, have
removed mention of rain on Easter and have boosted highs into the
lower 70s. Showers will spread into the western KILX CWA Sunday
night, but will become most prevalent on Monday. Have hit PoPs
hardest and lowered highs into the upper 60s on Monday accordingly.
Have also added mention of isolated thunder due to Lifted Index
values dropping to between 0 and -2C Monday afternoon. There are
some indications that the precip may be delayed even further into
Monday night and early Tuesday. Will hold on to chance PoPs across
the E/SE on Monday night, but will return to a dry forecast on
Tuesday. Once this system exits the region, an approaching warm
front may trigger a few showers across northern Illinois on
Wednesday, but the main weather story in the extended will be the
warm conditions as temps routinely climb above normal into the 70s
next week.

Barnes


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 171749
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1249 PM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

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

* WINDS BECOME NORTH LATE THIS EVENING AND THEN EAST ARND 10 KT BY
  LATE FRIDAY MORNING.

JEE

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

LOW PRESSURE IS SLOWLY WEAKENING AND SHIFTING NORTHEAST OVER
WISCONSIN. ITS COLD FRONT IS MOVING THROUGH THE EASTERN TERMINALS
NOW AND EXPECTING WINDS TO TURN WEST BEHIND THE FRONT. THE MVFR TO
IFR CIGS TO OUR NORTH AND WEST APPEAR TO BE DISSIPATING AND NOT
MOVING INTO NORTHERN IL. SHOULD SEE THE MVFR CIGS OVER RFD SCATTER
AND LIFT OVER THE NEXT COUPLE OF HOURS...AND HAVE MEDIUM
CONFIDENCE ON THE TIMING. THE CIGS MAY LINGER A BIT LONGER OVER
RFD THAN EXPECTED.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
DIMINISHING AND ALSO BECOMING NORTH BY LATE THIS EVENING. THE
UPPER LEVEL TROUGH SWINGS THROUGH THIS EVENING AS WELL AND
GUIDANCE CONTINUES TO SHOW SCATTERED RAIN SHOWERS ALONG AND EAST
OF I-55 THIS EVENING. GYY WOULD HAVE THE BEST CHANCE OF SEEING ANY
PRECIP...BUT THAT CHANCE IS VERY LOW. THEREFORE KEPT ALL OF THE
TAFS DRY FOR NOW.

WINDS CONTINUE TO VEER TO THE EAST TOMORROW WITH WINDS INCREASING
TO ARND 10 KT BY THE LATE MORNING.

JEE


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

* HIGH CONFIDENCE IN WIND SHIFTS...MEDIUM CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
313 AM CDT

WEAKENING AREA OF LOW PRESSURE WILL LIFT FROM IOWA INTO WISCONSIN
TODAY WITH MODERATE SOUTHERLY FLOW AHEAD OF THE LOW. A SMALL CRAFT
ADVISORY REMAINS IN EFFECT...PRIMARILY FOR THE ILLINOIS NEARSHORE
WATERS...BUT EXPECT CONDITIONS TO IMPROVE BY MID MORNING AFTER WINDS
TURN WESTERLY AND DIMINISH BEHIND A COLD FRONT. HIGH PRESSURE WILL
BUILD ACROSS THE REGION AND SHOULD KEEP WINDS RELATIVELY LIGHT
FRIDAY THOUGH SATURDAY...THEN WINDS FRESHEN UP SOME SATURDAY NIGHT
INTO SUNDAY AHEAD OF ANOTHER WEAK LOW. OTHERWISE...IT APPEARS THE
NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL BE FROM MIDWEEK ON
NEXT WEEK AS A POTENTIALLY MORE SIGNIFICANT LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BMD

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 171601
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1101 AM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

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

* WINDS BCMG WEST THIS AFTN...THEN NE BY FRIDAY MORNING.

JEE

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

LOW PRESSURE IS SLOWLY LIFTING ACROSS WISCONSIN WITH A COLD FRONT
PUSHING EAST INTO NORTH CENTRAL ILLINOIS EARLY THIS MORNING. S TO
SSE WINDS AHEAD OF THE FRONT WILL BE IN PLACE EARLY...THEN WILL VEER
TO THE SW BY MID TO LATE THIS MORNING. THERE IS CURRENTLY A BROAD
MVFR/IFR STRATUS DECK IN PLACE ACROSS MUCH OF IOWA BEHIND THE FRONT.
EXPECT THESE CIGS TO PUSH EAST ACROSS RFD...BUT FOR NOW DO
ANTICIPATE IT MOVING INTO THE CHICAGO TERMINALS AS THE FRONT
CONTINUES TO WEAKEN. HIGH PRESSURE WILL BUILD INTO THE UPPER MIDWEST
TONIGHT CAUSING WINDS TO VEER TO THE NORTH..AND POSSIBLY
NORTHEAST....THOUGH SHOULD BE FAIRLY LIGHT...LESS THAN 5 KT MUCH OF
THE LATE EVENING AND OVERNIGHT HOURS. LIGHT WINDS IN PLACE TOMORROW
WILL ALLOW AN EARLY AFTERNOON LAKE BREEZE TO PUSH INLAND FRIDAY WITH
WINDS PICKING UP SLIGHTLY OUT OF THE NORTHEAST.

BMD

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

* HIGH CONFIDENCE IN WIND TRENDS...LOW-MEDIUM IN TIMING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
313 AM CDT

WEAKENING AREA OF LOW PRESSURE WILL LIFT FROM IOWA INTO WISCONSIN
TODAY WITH MODERATE SOUTHERLY FLOW AHEAD OF THE LOW. A SMALL CRAFT
ADVISORY REMAINS IN EFFECT...PRIMARILY FOR THE ILLINOIS NEARSHORE
WATERS...BUT EXPECT CONDITIONS TO IMPROVE BY MID MORNING AFTER WINDS
TURN WESTERLY AND DIMINISH BEHIND A COLD FRONT. HIGH PRESSURE WILL
BUILD ACROSS THE REGION AND SHOULD KEEP WINDS RELATIVELY LIGHT
FRIDAY THOUGH SATURDAY...THEN WINDS FRESHEN UP SOME SATURDAY NIGHT
INTO SUNDAY AHEAD OF ANOTHER WEAK LOW. OTHERWISE...IT APPEARS THE
NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL BE FROM MIDWEEK ON
NEXT WEEK AS A POTENTIALLY MORE SIGNIFICANT LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BMD

&&

.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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 171552
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1052 AM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 1045 AM CDT Thu Apr 17 2014
Low pressure system making its way through Wisconsin this morning
dragging a cold front across the state. Measurable precip not
expected for the day along the boundary. Some weak echoes showing
up on radar NW of the boundary however with some of the llvl
clouds. Will keep an eye on the potential for precip...but
anticipate little more than possibly a sprinkle before 00Z. Have
boosted the high temps in the far east as the boundary is not
likely to make it too much further then I-55 and just barely
adjusted a couple of temps. Not even enough to warrant a zone
update. Wave to the SW still expected to ripple through the region
and along the boundary later this evening and produce a bit of
rainfall across the area. Best chances are in the center of the
state/along the boundary as it slows.

HJS
&&

.AVIATION...
ISSUED 630 AM CDT Thu Apr 17 2014

Core of low level jet starting to move northeast out of central
Illinois. Initial stages of our 12Z balloon sounding have peak
winds around 35 knots at 1200 feet, with region radars showing the
stronger winds now in northeast Illinois. Have thus removed LLWS
mention at all sites.

VFR conditions to prevail through the period. Do have some concern
for a large area of MVFR ceilings that was edging into far western
Illinois and extended northeast along the Iowa border. Latest HRRR
guidance wants to bring this as far east as KPIA, but low level
winds would suggest a more northeast component to the moment,
taking a close pass at KPIA in a couple hours. Weakening cold
front will result in a gradual switch to westerly winds today,
then more of a light/variable component overnight. Ceilings
expected to lower to around 5000 feet this evening as an upper
disturbance moves across the state. Moisture below 7000 feet is
somewhat lacking, but some of the models, as well as SREF
probability graphics, showing some light precip potential for the
KSPI-KCMI corridor. Have only gone with a PROB30 group for now due
to the questionable amount of coverage.

Geelhart
&&

.PREV DISCUSSION...
ISSUED 238 AM CDT Thu Apr 17 2014

SHORT TERM...Today through Saturday

Low pressure analyzed over western Wisconsin on 07z/2am surface
analysis will continue to lift northeastward today, dragging a
weak cold front into central Illinois. Boundary will make only
slow progress eastward and will eventually stall along the I-57
corridor this afternoon. Little in the way of sensible weather
will accompany the front other than a few mid/high clouds.
Afternoon high temperatures will range from the upper 50s west of
the Illinois River to the middle 60s south of I-70.

Short-wave trough currently evident on water vapor imagery over
the Texas panhandle will track E/NE, passing south of Illinois
late tonight into Friday. Enough synoptic lift will be generated
by this feature to perhaps trigger a few light showers along/near
the stationary frontal boundary. Mitigating factor for precip will
be lack of moisture, as air mass remains very dry in the wake of
the early week cold front that penetrated well into the Gulf of
Mexico. Surface dew points have only recovered into the middle 50s
across coastal Texas, with models projecting 40-45F dew points
reaching central Illinois tonight. Forecast soundings remain dry
below 850mb, so am not expecting much in the way of precip. Will
hold on to low chance PoPs tonight, with scant rainfall amounts of
only a couple hundredths of an inch at best.

Once upper wave passes by to the south, surface high pressure will
resume control of the weather on Friday. After some lingering
sprinkles/clouds across the east during the morning, sunshine will
return across the board by afternoon with highs climbing into the
lower to middle 60s. As the high shifts off to the east, increasing
southerly winds will bring even warmer air into the region on
Saturday resulting in highs reaching the upper 60s and lower 70s.

LONG TERM...Sunday through Wednesday

As has been the case for the past few days, the latest model suite
has once again delayed the onset of the next storm system early
next week. One upper wave is expected to track across southern
Canada over the weekend, while another slower-moving southern
stream wave will track out of the Desert Southwest into the lower
Mississippi River Valley by Monday. The GFS had previously been
the fastest model with this southern stream feature, introducing
precip as early as Easter Sunday. 00z Apr 17 run of the GFS has
now slowed the system and is in much better agreement with the
more consistent ECMWF/GEM, which have featured a dry Sunday for
the past couple of runs. As a result of this model consensus, have
removed mention of rain on Easter and have boosted highs into the
lower 70s. Showers will spread into the western KILX CWA Sunday
night, but will become most prevalent on Monday. Have hit PoPs
hardest and lowered highs into the upper 60s on Monday accordingly.
Have also added mention of isolated thunder due to Lifted Index
values dropping to between 0 and -2C Monday afternoon. There are
some indications that the precip may be delayed even further into
Monday night and early Tuesday. Will hold on to chance PoPs across
the E/SE on Monday night, but will return to a dry forecast on
Tuesday. Once this system exits the region, an approaching warm
front may trigger a few showers across northern Illinois on
Wednesday, but the main weather story in the extended will be the
warm conditions as temps routinely climb above normal into the 70s
next week.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 171402
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
902 AM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

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

* WINDS BCMG WEST THIS AFTN...THEN NE BY FRIDAY MORNING.

* MVFR CIGS ARE PSBL THIS AFTN THROUGH TONIGHT.

JEE

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

LOW PRESSURE IS SLOWLY LIFTING ACROSS WISCONSIN WITH A COLD FRONT
PUSHING EAST INTO NORTH CENTRAL ILLINOIS EARLY THIS MORNING. S TO
SSE WINDS AHEAD OF THE FRONT WILL BE IN PLACE EARLY...THEN WILL VEER
TO THE SW BY MID TO LATE THIS MORNING. THERE IS CURRENTLY A BROAD
MVFR/IFR STRATUS DECK IN PLACE ACROSS MUCH OF IOWA BEHIND THE FRONT.
EXPECT THESE CIGS TO PUSH EAST ACROSS RFD...BUT FOR NOW DO
ANTICIPATE IT MOVING INTO THE CHICAGO TERMINALS AS THE FRONT
CONTINUES TO WEAKEN. HIGH PRESSURE WILL BUILD INTO THE UPPER MIDWEST
TONIGHT CAUSING WINDS TO VEER TO THE NORTH..AND POSSIBLY
NORTHEAST....THOUGH SHOULD BE FAIRLY LIGHT...LESS THAN 5 KT MUCH OF
THE LATE EVENING AND OVERNIGHT HOURS. LIGHT WINDS IN PLACE TOMORROW
WILL ALLOW AN EARLY AFTERNOON LAKE BREEZE TO PUSH INLAND FRIDAY WITH
WINDS PICKING UP SLIGHTLY OUT OF THE NORTHEAST.

BMD

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

* HIGH CONFIDENCE IN WIND TRENDS...LOW-MEDIUM IN TIMING.

* LOW CONFIDENCE IN IF MVFR CIGS MOVE IN.

JEE

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
313 AM CDT

WEAKENING AREA OF LOW PRESSURE WILL LIFT FROM IOWA INTO WISCONSIN
TODAY WITH MODERATE SOUTHERLY FLOW AHEAD OF THE LOW. A SMALL CRAFT
ADVISORY REMAINS IN EFFECT...PRIMARILY FOR THE ILLINOIS NEARSHORE
WATERS...BUT EXPECT CONDITIONS TO IMPROVE BY MID MORNING AFTER WINDS
TURN WESTERLY AND DIMINISH BEHIND A COLD FRONT. HIGH PRESSURE WILL
BUILD ACROSS THE REGION AND SHOULD KEEP WINDS RELATIVELY LIGHT
FRIDAY THOUGH SATURDAY...THEN WINDS FRESHEN UP SOME SATURDAY NIGHT
INTO SUNDAY AHEAD OF ANOTHER WEAK LOW. OTHERWISE...IT APPEARS THE
NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL BE FROM MIDWEEK ON
NEXT WEEK AS A POTENTIALLY MORE SIGNIFICANT LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KLOT 171139
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
639 AM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

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

* SHIFTING WINDS THROUGH THE DAY.
* POTENTIAL FOR MVFR CIGS.

BMD

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

LOW PRESSURE IS SLOWLY LIFTING ACROSS WISCONSIN WITH A COLD FRONT
PUSHING EAST INTO NORTH CENTRAL ILLINOIS EARLY THIS MORNING. S TO
SSE WINDS AHEAD OF THE FRONT WILL BE IN PLACE EARLY...THEN WILL VEER
TO THE SW BY MID TO LATE THIS MORNING. THERE IS CURRENTLY A BROAD
MVFR/IFR STRATUS DECK IN PLACE ACROSS MUCH OF IOWA BEHIND THE FRONT.
EXPECT THESE CIGS TO PUSH EAST ACROSS RFD...BUT FOR NOW DO
ANTICIPATE IT MOVING INTO THE CHICAGO TERMINALS AS THE FRONT
CONTINUES TO WEAKEN. HIGH PRESSURE WILL BUILD INTO THE UPPER MIDWEST
TONIGHT CAUSING WINDS TO VEER TO THE NORTH..AND POSSIBLY
NORTHEAST....THOUGH SHOULD BE FAIRLY LIGHT...LESS THAN 5 KT MUCH OF
THE LATE EVENING AND OVERNIGHT HOURS. LIGHT WINDS IN PLACE TOMORROW
WILL ALLOW AN EARLY AFTERNOON LAKE BREEZE TO PUSH INLAND FRIDAY WITH
WINDS PICKING UP SLIGHTLY OUT OF THE NORTHEAST.

BMD


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

* HIGH CONFIDENCE IN THE GENERAL TRENDS FOR WINDS...BUT LOW-MEDIUM
  CONFIDENCE IN THE SPECIFIC TIMING.
* LOW CONFIDENCE THAT MVFR STRATUS WILL SPREAD EAST INTO CHICAGO
  TODAY.

BMD

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

FRIDAY NIGHT...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...CHC RAIN. MVFR/IFR PSBL.
TUESDAY...VFR.
WEDNESDAY...SLT CHC RAIN.

BMD

&&

.MARINE...
313 AM CDT

WEAKENING AREA OF LOW PRESSURE WILL LIFT FROM IOWA INTO WISCONSIN
TODAY WITH MODERATE SOUTHERLY FLOW AHEAD OF THE LOW. A SMALL CRAFT
ADVISORY REMAINS IN EFFECT...PRIMARILY FOR THE ILLINOIS NEARSHORE
WATERS...BUT EXPECT CONDITIONS TO IMPROVE BY MID MORNING AFTER WINDS
TURN WESTERLY AND DIMINISH BEHIND A COLD FRONT. HIGH PRESSURE WILL
BUILD ACROSS THE REGION AND SHOULD KEEP WINDS RELATIVELY LIGHT
FRIDAY THOUGH SATURDAY...THEN WINDS FRESHEN UP SOME SATURDAY NIGHT
INTO SUNDAY AHEAD OF ANOTHER WEAK LOW. OTHERWISE...IT APPEARS THE
NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL BE FROM MIDWEEK ON
NEXT WEEK AS A POTENTIALLY MORE SIGNIFICANT LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KILX 171131
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
631 AM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 238 AM CDT Thu Apr 17 2014

SHORT TERM...Today through Saturday

Low pressure analyzed over western Wisconsin on 07z/2am surface
analysis will continue to lift northeastward today, dragging a
weak cold front into central Illinois. Boundary will make only
slow progress eastward and will eventually stall along the I-57
corridor this afternoon. Little in the way of sensible weather
will accompany the front other than a few mid/high clouds.
Afternoon high temperatures will range from the upper 50s west of
the Illinois River to the middle 60s south of I-70.

Short-wave trough currently evident on water vapor imagery over
the Texas panhandle will track E/NE, passing south of Illinois
late tonight into Friday. Enough synoptic lift will be generated
by this feature to perhaps trigger a few light showers along/near
the stationary frontal boundary. Mitigating factor for precip will
be lack of moisture, as air mass remains very dry in the wake of
the early week cold front that penetrated well into the Gulf of
Mexico. Surface dew points have only recovered into the middle 50s
across coastal Texas, with models projecting 40-45F dew points
reaching central Illinois tonight. Forecast soundings remain dry
below 850mb, so am not expecting much in the way of precip. Will
hold on to low chance PoPs tonight, with scant rainfall amounts of
only a couple hundredths of an inch at best.

Once upper wave passes by to the south, surface high pressure will
resume control of the weather on Friday. After some lingering
sprinkles/clouds across the east during the morning, sunshine will
return across the board by afternoon with highs climbing into the
lower to middle 60s. As the high shifts off to the east, increasing
southerly winds will bring even warmer air into the region on
Saturday resulting in highs reaching the upper 60s and lower 70s.

LONG TERM...Sunday through Wednesday

As has been the case for the past few days, the latest model suite
has once again delayed the onset of the next storm system early
next week. One upper wave is expected to track across southern
Canada over the weekend, while another slower-moving southern
stream wave will track out of the Desert Southwest into the lower
Mississippi River Valley by Monday. The GFS had previously been
the fastest model with this southern stream feature, introducing
precip as early as Easter Sunday. 00z Apr 17 run of the GFS has
now slowed the system and is in much better agreement with the
more consistent ECMWF/GEM, which have featured a dry Sunday for
the past couple of runs. As a result of this model consensus, have
removed mention of rain on Easter and have boosted highs into the
lower 70s. Showers will spread into the western KILX CWA Sunday
night, but will become most prevalent on Monday. Have hit PoPs
hardest and lowered highs into the upper 60s on Monday accordingly.
Have also added mention of isolated thunder due to Lifted Index
values dropping to between 0 and -2C Monday afternoon. There are
some indications that the precip may be delayed even further into
Monday night and early Tuesday. Will hold on to chance PoPs across
the E/SE on Monday night, but will return to a dry forecast on
Tuesday. Once this system exits the region, an approaching warm
front may trigger a few showers across northern Illinois on
Wednesday, but the main weather story in the extended will be the
warm conditions as temps routinely climb above normal into the 70s
next week.

Barnes


&&

.AVIATION...
ISSUED 630 AM CDT Thu Apr 17 2014

Core of low level jet starting to move northeast out of central
Illinois. Initial stages of our 12Z balloon sounding have peak
winds around 35 knots at 1200 feet, with region radars showing the
stronger winds now in northeast Illinois. Have thus removed LLWS
mention at all sites.

VFR conditions to prevail through the period. Do have some concern
for a large area of MVFR ceilings that was edging into far western
Illinois and extended northeast along the Iowa border. Latest HRRR
guidance wants to bring this as far east as KPIA, but low level
winds would suggest a more northeast component to the moment,
taking a close pass at KPIA in a couple hours. Weakening cold
front will result in a gradual switch to westerly winds today,
then more of a light/variable component overnight. Ceilings
expected to lower to around 5000 feet this evening as an upper
disturbance moves across the state. Moisture below 7000 feet is
somewhat lacking, but some of the models, as well as SREF
probability graphics, showing some light precip potential for the
KSPI-KCMI corridor. Have only gone with a PROB30 group for now due
to the questionable amount of coverage.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 170908
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
408 AM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

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

* SSE WINDS VEERING TO WEST BY MIDDAY THURSDAY...THEN NORTH
  TO NORTHEAST LATE THURSDAY EVENING.
* POTENTIAL FOR LOW LEVEL WIND SHEAR EARLY THURSDAY MORNING.

BMD

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

LOW PRESSURE LIES OVER FAR NORTHEASTERN IOWA TONIGHT AND WILL FILL
AS IT LIFTS TO NORTHERN WISCONSIN BY MID MORNING THURSDAY. A COLD
FRONT STRETCHES SOUTH INTO CENTRAL MISSOURI. AHEAD OF THE
FRONT...STRONG LOW-MID LEVEL WINDS COULD RESULT IN LLWS...WITH THE
BEST CHANCES AT RFD WHICH WILL BE CLOSER IN PROXIMITY TO THE LOW
LEVEL JET. THE COLD FRONT WILL MOVE ACROSS NORTHERN ILLINOIS LATE
MORNING INTO EARLY AFTERNOON WITH PRECIP ALONG THE FRONT FAIRLY
UNLIKELY. WINDS TURN WSW BEHIND THE FRONT AND EVENTUALLY
NORTHWESTERLY IN THE EVENING. WINDS WILL CONTINUE TO VEER TO THE
NORTHEAST THURSDAY NIGHT.

BMD

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

* MEDIUM CONFIDENCE IN WIND DIRECTION/TIMING CHANGES IN DIRECTION.
* LOW CONFIDENCE IN LLWS.

BMD

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...CHC RAIN. MVFR POSSIBLE.

MONDAY...CHC RAIN EARLY. OTRW...VFR/WX NIL.

TUESDAY...VFR. WX NIL.

WEDNESDAY...SLIGHT CHC RAIN. MVFR POSSIBLE.

KREIN

&&

.MARINE...
313 AM CDT

WEAKENING AREA OF LOW PRESSURE WILL LIFT FROM IOWA INTO WISCONSIN
TODAY WITH MODERATE SOUTHERLY FLOW AHEAD OF THE LOW. A SMALL CRAFT
ADVISORY REMAINS IN EFFECT...PRIMARILY FOR THE ILLINOIS NEARSHORE
WATERS...BUT EXPECT CONDITIONS TO IMPROVE BY MID MORNING AFTER WINDS
TURN WESTERLY AND DIMINISH BEHIND A COLD FRONT. HIGH PRESSURE WILL
BUILD ACROSS THE REGION AND SHOULD KEEP WINDS RELATIVELY LIGHT
FRIDAY THOUGH SATURDAY...THEN WINDS FRESHEN UP SOME SATURDAY NIGHT
INTO SUNDAY AHEAD OF ANOTHER WEAK LOW. OTHERWISE...IT APPEARS THE
NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL BE FROM MIDWEEK ON
NEXT WEEK AS A POTENTIALLY MORE SIGNIFICANT LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KILX 170854
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
354 AM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 238 AM CDT Thu Apr 17 2014

SHORT TERM...Today through Saturday

Low pressure analyzed over western Wisconsin on 07z/2am surface
analysis will continue to lift northeastward today, dragging a
weak cold front into central Illinois. Boundary will make only
slow progress eastward and will eventually stall along the I-57
corridor this afternoon. Little in the way of sensible weather
will accompany the front other than a few mid/high clouds.
Afternoon high temperatures will range from the upper 50s west of
the Illinois River to the middle 60s south of I-70.

Short-wave trough currently evident on water vapor imagery over
the Texas panhandle will track E/NE, passing south of Illinois
late tonight into Friday. Enough synoptic lift will be generated
by this feature to perhaps trigger a few light showers along/near
the stationary frontal boundary. Mitigating factor for precip will
be lack of moisture, as airmass remains very dry in the wake of
the early week cold front that penetrated well into the Gulf of
Mexico. Surface dewpoints have only recovered into the middle 50s
across coastal Texas, with models projecting 40-45F dewpoints
reaching central Illinois tonight. Forecast soundings remain dry
below 850mb, so am not expecting much in the way of precip. Will
hold on to low chance POPs tonight, with scant rainfall amounts of
only a couple hundredths of an inch at best.

Once upper wave passes by to the south, surface high pressure will
resume control of the weather on Friday. After some lingering
sprinkles/clouds across the east during the morning, sunshine will
return across the board by afternoon with highs climbing into the
lower to middle 60s. As the high shifts off to the east, increasing
southerly winds will bring even warmer air into the region on
Saturday resulting in highs reaching the upper 60s and lower 70s.

LONG TERM...Sunday through Wednesday

As has been the case for the past few days, the latest model suite
has once again delayed the onset of the next storm system early
next week. One upper wave is expected to track across southern
Canada over the weekend, while another slower-moving southern
stream wave will track out of the Desert Southwest into the lower
Mississippi River Valley by Monday. The GFS had previously been
the fastest model with this southern stream feature, introducing
precip as early as Easter Sunday. 00z Apr 17 run of the GFS has
now slowed the system and is in much better agreement with the
more consistent ECMWF/GEM, which have featured a dry Sunday for
the past couple of runs. As a result of this model consensus, have
removed mention of rain on Easter and have boosted highs into the
lower 70s. Showers will spread into the western KILX CWA Sunday
night, but will become most prevalent on Monday. Have hit POPs
hardest and lowered highs into the upper 60s on Monday accordingly.
Have also added mention of isolated thunder due to Lifted Index
values dropping to between 0 and -2C Monday afternoon. There are
some indications that the precip may be delayed even further into
Monday night and early Tuesday. Will hold on to chance POPs across
the E/SE on Monday night, but will return to a dry forecast on
Tuesday. Once this system exits the region, an approaching warm
front may trigger a few showers across northern Illinois on
Wednesday, but the main weather story in the extended will be the
warm conditions as temps routinely climb above normal into the 70s
next week.

Barnes

&&

.AVIATION...
ISSUED 351 AM CDT Thu Apr 17 2014

Have updated all TAF sites to include mention of LLWS for the next
few hours. Wind profiles from area Doppler radars showing low level
jet of 45-55 knots around 2500 feet, ahead of the cold front that
is pushing through eastern Iowa and central Missouri. Will
continue to see this for a few more hours, with some diminishing
occurring after sunrise as the front moves into western Illinois.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 170814
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
314 AM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHEAST WINDS VEERING TO WEST BY MIDDAY THURSDAY...THEN NORTH
  TO NORTHEAST LATE THURSDAY EVENING.
* POTENTIAL FOR LOW LEVEL WIND SHEAR OVERNIGHT INTO THURSDAY MORNING.

BMD

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

LOW PRESSURE LIES OVER FAR NORTHEASTERN IOWA TONIGHT AND WILL FILL
AS IT LIFTS TO NORTHERN WISCONSIN BY MID MORNING THURSDAY. A COLD
FRONT STRETCHES SOUTH INTO CENTRAL MISSOURI. AHEAD OF THE
FRONT...STRONG LOW-MID LEVEL WINDS COULD RESULT IN LLWS...WITH THE
BEST CHANCES AT RFD WHICH WILL BE CLOSER IN PROXIMITY TO THE LOW
LEVEL JET. THE COLD FRONT WILL MOVE ACROSS NORTHERN ILLINOIS LATE
MORNING INTO EARLY AFTERNOON WITH PRECIP ALONG THE FRONT FAIRLY
UNLIKELY. WINDS TURN WSW BEHIND THE FRONT AND EVENTUALLY
NORTHWESTERLY IN THE EVENING. WINDS WILL CONTINUE TO VEER TO THE
NORTHEAST THURSDAY NIGHT.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN WIND DIRECTION/TIMING CHANGES IN DIRECTION.
* LOW CONFIDENCE IN LLWS.

BMD

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...CHC RAIN. MVFR POSSIBLE.

MONDAY...CHC RAIN EARLY. OTRW...VFR/WX NIL.

TUESDAY...VFR. WX NIL.

WEDNESDAY...SLIGHT CHC RAIN. MVFR POSSIBLE.

KREIN

&&

.MARINE...
313 AM CDT

WEAKENING AREA OF LOW PRESSURE WILL LIFT FROM IOWA INTO WISCONSIN
TODAY WITH MODERATE SOUTHERLY FLOW AHEAD OF THE LOW. A SMALL CRAFT
ADVISORY REMAINS IN EFFECT...PRIMARILY FOR THE ILLINOIS NEARSHORE
WATERS...BUT EXPECT CONDITIONS TO IMPROVE BY MID MORNING AFTER WINDS
TURN WESTERLY AND DIMINISH BEHIND A COLD FRONT. HIGH PRESSURE WILL
BUILD ACROSS THE REGION AND SHOULD KEEP WINDS RELATIVELY LIGHT
FRIDAY THOUGH SATURDAY...THEN WINDS FRESHEN UP SOME SATURDAY NIGHT
INTO SUNDAY AHEAD OF ANOTHER WEAK LOW. OTHERWISE...IT APPEARS THE
NEXT CHANCE FOR MODERATE TO STRONG WINDS WILL BE FROM MIDWEEK ON
NEXT WEEK AS A POTENTIALLY MORE SIGNIFICANT LOW PRESSURE SYSTEM COULD
IMPACT THE REGION.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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000
FXUS63 KLOT 170757
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
257 AM CDT THU APR 17 2014

.DISCUSSION...
257 AM CDT

QUIESCENT WEATHER IS SET TO CONTINUE INTO THIS WEEKEND WITH AN
ENJOYABLE WEEKEND SHAPING UP IF YOU ARE A FAN OF 60S AND
POTENTIALLY 70S BY SUNDAY. THESE TEMPERATURES WERE THE PRIMARY
FORECAST CHALLENGE THIS MORNING.

SYNOPSIS...
THE MAIN ROSSBY WAVE ON THIS SIDE OF THE GLOBE IS RETRACTING
NORTHEAST FROM EASTERN CANADA WITH STILL LOW HEIGHTS AND A BROAD
BUT LOW AMPLIFIED TROUGH LEFT IN ITS WAKE ACROSS SOUTHERN CANADA
AND THE CENTRAL CONUS. WITHIN THAT FEATURE THERE ARE MULTIPLE
PERTURBATIONS WITH THE MOST WELL-DEFINED CIRCULATION ACROSS THE
UPPER GREAT LAKES AND RESPONSIBLE FOR OVER A FOOT OF SNOW FOR
PARTS OF THE TWIN CITIES INTO NORTHERN WI YESTERDAY INTO LAST
NIGHT. A NARROW PLUME OF MID-LEVEL PACIFIC MOISTURE ASSOCIATED
WITH THIS WAVE IS DRIFTING OVER THE AREA THIS MORNING. THAT IS
MOST OF THE CONTRIBUTION TO MEAGER 0.3 TO 0.4 REGIONAL PWATS
SAMPLED LAST EVE...AS THE LOW-LEVELS REMAIN QUITE DRY AND ACT AS A
HINDRANCE FOR MUCH OR ANY PRECIP ACROSS THE AREA TONIGHT. AT THE
SURFACE...THE SYSTEM LOW IS ENTERING WESTERN WI EARLY THIS MORNING
WITH A SURFACE COLD FRONT EXTENDING SOUTHWARD INTO IA AND MO. THE
BAROCLINICITY AND CONVERGENCE ALONG THIS FRONT WILL WEAKEN
CONSIDERABLY THIS AFTERNOON INTO EVENING AS IT MOVES INTO THE
AREA.

TODAY AND TONIGHT...
CLOUD COVER SHOULD UNDULATE SOME TODAY WITH THE PACIFIC MOISTURE
ALOFT AND SOME LOWER CLOUDS OOZING INTO NORTH CENTRAL IL BEHIND
THE SURFACE COLD FRONT. THERE LIKELY WILL BE A SHARP INCREASE IN
MID/HIGH CLOUDS THIS AFTERNOON FOR AREAS ALONG AND EAST OF
INTERSTATE 55 AS A SHEARING IMPULSE ACROSS WESTERN KS THIS MORNING
APPROACHES THE AREA. THE 850MB/925MB TEMPERATURE CLIMATOLOGY WOULD
SUPPORT UPPER 50S TO MID 60S ACROSS THE AREA...BUT THAT AS USUAL
WILL DEPEND ON DURATION OF SOME OF THE AFOREMENTIONED CLOUD COVER.
OFFSHORE FLOW IS EXPECTED ACROSS DOWNTOWN CHICAGO SO NO LAKE
COOLING TODAY...BUT AS WINDS TURN NORTHERLY THIS EVE AND A LAKE
COMPONENT LIKELY PUSHES INLAND...A FAIRLY QUICK DROP TO AROUND 40
DEGREES COULD OCCUR DURING THE MID TO LATE EVE. MOISTURE AND LIFT
SUPPORT FOR ANY RAIN WITH THE SHEARED WAVE TONIGHT CONTINUES TO
LOOK LESS AND LESS IMPRESSIVE...AND REALLY ONLY FOR AREAS ALONG
AND EAST OF INTERSTATE 55 IS THERE A LOW CHANCE. HAVE REFINED THE
TEMPORAL RESOLUTION SOME...BUT ALL IN ALL THIS IS A LOW CHANCE AND
QPF EVENT.

FRIDAY AND BEYOND...
BUILDING UPPER HEIGHTS OVER SURFACE RIDGING WILL BE SEEN ON FRIDAY.
THE LIGHT SURFACE FLOW SHOULD ALLOW FOR A SHARP LAKE BREEZE TO
DEVELOP WITH AROUND A 10 DEGREES CONTRAST FROM DOWNTOWN CHICAGO TO
OUTLYING AREAS. MOST OUTLYING AREAS MAY SEE SIMILAR TEMPERATURES TO
THAT OF TODAY.

THEN MODERATION WILL UNFOLD THIS WEEKEND AS GUIDANCE IS IN GOOD
AGREEMENT OF 500MB HEIGHTS ABOVE 570DM AND 850MB TEMPERATURES
CLIMBING TO 6C TO 10C THROUGH THE WEEKEND. THE MAIN JET STREAM
AXIS WILL BE IN SOUTHERN CANADA AND A CLOSED LOW OVER THE
SOUTHEAST U.S. WILL KEEP THE PATTERN LESS PROGRESSIVE AT OUR
LATITUDE THIS WEEKEND THAN ORIGINALLY FORECAST. WE CONTINUE THE
TREND OF THE PREVIOUS SHIFT TO COLLABORATE AN INCREASE IN
TEMPERATURES...NAMELY ON SUNDAY WITH SOUTHERLY FLOW UP TO THE LAKE
FRONT AND LESS CLOUD COVER. CLIMATOLOGY WOULD SUPPORT 70 DEGREE
TEMPERATURES UP TO THE NORTHERN FORECAST AREA AND DEPENDING ON
CLOUD COVER COULD REALIZE EVEN WARMER. THE NEXT SYSTEM IS FORECAST
TO MOVE OVER THE AREA AROUND MONDAY BUT AGAIN CONFIDENCE ON THIS
TIMING IS LOW. DEW POINTS LOOK TO BE UP INTO THE 50S AND POSSIBLY
LOWER/MID 60S WITH THIS PASSAGE...SO AS MENTIONED BEFORE A
POSSIBLE CHANCE FOR THUNDER. BUT THE SYNOPTIC LOOK AND MAGNITUDE
OF THIS SYSTEM WITHIN MODEL GUIDANCE PRESENTLY DOES NOT LOOK
IMPRESSIVE.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHEAST WINDS VEERING TO WEST BY MIDDAY THURSDAY...THEN NORTH
  TO NORTHEAST LATE THURSDAY EVENING.
* POTENTIAL FOR LOW LEVEL WIND SHEAR OVERNIGHT INTO THURSDAY MORNING.

BMD

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

LOW PRESSURE LIES OVER FAR NORTHEASTERN IOWA TONIGHT AND WILL FILL
AS IT LIFTS TO NORTHERN WISCONSIN BY MID MORNING THURSDAY. A COLD
FRONT STRETCHES SOUTH INTO CENTRAL MISSOURI. AHEAD OF THE
FRONT...STRONG LOW-MID LEVEL WINDS COULD RESULT IN LLWS...WITH THE
BEST CHANCES AT RFD WHICH WILL BE CLOSER IN PROXIMITY TO THE LOW
LEVEL JET. THE COLD FRONT WILL MOVE ACROSS NORTHERN ILLINOIS LATE
MORNING INTO EARLY AFTERNOON WITH PRECIP ALONG THE FRONT FAIRLY
UNLIKELY. WINDS TURN WSW BEHIND THE FRONT AND EVENTUALLY
NORTHWESTERLY IN THE EVENING. WINDS WILL CONTINUE TO VEER TO THE
NORTHEAST THURSDAY NIGHT.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN WIND DIRECTION/TIMING CHANGES IN DIRECTION.
* LOW CONFIDENCE IN LLWS.

BMD

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...CHC RAIN. MVFR POSSIBLE.

MONDAY...CHC RAIN EARLY. OTRW...VFR/WX NIL.

TUESDAY...VFR. WX NIL.

WEDNESDAY...SLIGHT CHC RAIN. MVFR POSSIBLE.

KREIN

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM THURSDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KILX 170738
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
238 AM CDT Thu Apr 17 2014

.DISCUSSION...
ISSUED 238 AM CDT Thu Apr 17 2014

SHORT TERM...Today through Saturday

Low pressure analyzed over western Wisconsin on 07z/2am surface
analysis will continue to lift northeastward today, dragging a
weak cold front into central Illinois. Boundary will make only
slow progress eastward and will eventually stall along the I-57
corridor this afternoon. Little in the way of sensible weather
will accompany the front other than a few mid/high clouds.
Afternoon high temperatures will range from the upper 50s west of
the Illinois River to the middle 60s south of I-70.

Short-wave trough currently evident on water vapor imagery over
the Texas panhandle will track E/NE, passing south of Illinois
late tonight into Friday. Enough synoptic lift will be generated
by this feature to perhaps trigger a few light showers along/near
the stationary frontal boundary. Mitigating factor for precip will
be lack of moisture, as airmass remains very dry in the wake of
the early week cold front that penetrated well into the Gulf of
Mexico. Surface dewpoints have only recovered into the middle 50s
across coastal Texas, with models projecting 40-45F dewpoints
reaching central Illinois tonight. Forecast soundings remain dry
below 850mb, so am not expecting much in the way of precip. Will
hold on to low chance POPs tonight, with scant rainfall amounts of
only a couple hundredths of an inch at best.

Once upper wave passes by to the south, surface high pressure will
resume control of the weather on Friday. After some lingering
sprinkles/clouds across the east during the morning, sunshine will
return across the board by afternoon with highs climbing into the
lower to middle 60s. As the high shifts off to the east, increasing
southerly winds will bring even warmer air into the region on
Saturday resulting in highs reaching the upper 60s and lower 70s.

LONG TERM...Sunday through Wednesday

As has been the case for the past few days, the latest model suite
has once again delayed the onset of the next storm system early
next week. One upper wave is expected to track across southern
Canada over the weekend, while another slower-moving southern
stream wave will track out of the Desert Southwest into the lower
Mississippi River Valley by Monday. The GFS had previously been
the fastest model with this southern stream feature, introducing
precip as early as Easter Sunday. 00z Apr 17 run of the GFS has
now slowed the system and is in much better agreement with the
more consistent ECMWF/GEM, which have featured a dry Sunday for
the past couple of runs. As a result of this model consensus, have
removed mention of rain on Easter and have boosted highs into the
lower 70s. Showers will spread into the western KILX CWA Sunday
night, but will become most prevalent on Monday. Have hit POPs
hardest and lowered highs into the upper 60s on Monday accordingly.
Have also added mention of isolated thunder due to Lifted Index
values dropping to between 0 and -2C Monday afternoon. There are
some indications that the precip may be delayed even further into
Monday night and early Tuesday. Will hold on to chance POPs across
the E/SE on Monday night, but will return to a dry forecast on
Tuesday. Once this system exits the region, an approaching warm
front may trigger a few showers across northern Illinois on
Wednesday, but the main weather story in the extended will be the
warm conditions as temps routinely climb above normal into the 70s
next week.

Barnes
&&

.AVIATION...
ISSUED 1135 PM CDT Wed Apr 16 2014

Despite an approaching cold front, the lower atmosphere will
remain relatively dry, resulting in VFR conditions for the next 24
hours.

The front, which is currently from central Iowa to southeast
Kansas, will slowly move into central Illinois during the late
morning. This will result in the south winds shifting to the W-WSW.
The front is expected to weaken as it will have very little upper
support and moisture to work with. This will keep clouds bases at
VFR levels, with any potential for light precipitation holding off
until after 06z Friday. The weak frontal boundary will also cause
the surface winds in central and eastern Illinois to become very
light after sunset Thursday evening.

Miller
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 170531
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1231 AM CDT THU APR 17 2014

.DISCUSSION...
331 PM CDT

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH PRECIP AND TEMP TRENDS
THURSDAY INTO FRIDAY...AND THEN WITH A DEFINITE WARMING TREND THIS
WEEKEND INTO NEXT WEEK.

WITH VORT MAX SHIFTING EAST/NORTHEAST ACROSS THE CENTRAL CONUS
THIS AFTERNOON...ATTENDANT SURFACE LOW CONTINUES TO SLOWLY SHIFT
EAST THROUGH EASTERN NEBRASKA AND IOWA THIS AFTERNOON AS A FAIRLY
TIGHT PRESSURE GRADIENT HAS ESTABLISHED ITSELF ACROSS THE CWA.
SOUTH TO SOUTHEAST HAVE PICKED UP THIS AFTERNOON WITH SOME
LOCATIONS ACROSS NORTHERN ILLINOIS GUSTING UP TO 30 TO 35 MPH. AS
THIS SURFACE LOW PUSHES NORTHEAST THROUGH IOWA AND INTO SOUTHERN
WISCONSIN TONIGHT...EXPECT WINDS TO TURN MORE SOUTH/SOUTHWEST
WHILE DIMINISHING BUT STILL GUSTING TO AROUND 25 TO 30 MPH FOR A
TIME THIS EVENING. BEST FORCING REMAINS WELL NORTH OF THE CWA AS
THIS VORT MAX AND LOW MOVE ACROSS THE REGION...WITH THE CWA
REMAINING DRY TONIGHT. MOST GUIDANCE IN AGREEMENT WITH A DRY
FORECAST TONIGHT...BUT STILL THINK THERE COULD BE A BRIEF LIGHT
SHOWER OR AT LEAST SOME SPRINKLES RIGHT ALONG THE
ILLINOIS/WISCONSIN BORDER WITH THE WAA PUSH OVERNIGHT. HAVE NOT
MADE MENTION OF THIS WITH LOWER CONFIDENCE AT THIS POSSIBILITY AND
DUE TO THE FACT THAT IF IT WERE TO OCCUR...ANTICIPATE ANYTHING
THAT FALLS TO ONCE AGAIN BE ON THE LIGHTER SIDE AND BRIEF. EXPECT
CURRENT CLEAR OR PARTLY CLOUDY SKIES IN PLACE TO SEE SOME INCREASE
IN CLOUD COVER TONIGHT...WITH A PERIOD OF CLOUDY SKIES LATER
TONIGHT ESPECIALLY OVER THE NORTHERN HALF OF THE CWA WITH OTHER
LOCATIONS SOUTH TO BE MORE PARTLY CLOUDY.

SURFACE LOW WILL CONTINUE NORTHEAST ON THURSDAY WEAKENING
SIGNIFICANTLY BY MID DAY AS UPPER SUPPORT IS QUICKLY LOST.
PERSISTENT WAA AND SOUTH/SOUTHWEST FLOW SHOULD ALLOW FOR SURFACE
TEMPS TO RISE INTO THE UPPER 50S AND LOWERS 60S THURSDAY...EVEN
WITH PARTLY CLOUDY/PARTLY SUNNY SKIES IN PLACE. INITIAL DRY
CONDITIONS AS SURFACE TROUGH/FRONT PUSH THROUGH THURSDAY WILL BE
REPLACE WITH AN INCREASE IN RAIN CHANCES LATER IN THE DAY AS
MID/UPPER LEVEL TROUGH SWING ACROSS THE REGION. IT DOES APPEAR AS
THIS RAIN WILL ONCE AGAIN BE ON THE LIGHTER SIDE AND STAY CONFINED
TO THE SOUTHEAST TWO THIRDS OF THE CWA...AND HAVE MAINTAINED HIGH
CHANCE POPS THURSDAY NIGHT. EXPECT ANY LINGERING RAIN TO QUICKLY
EXIT FRIDAY MORNING AS DRIER/COOLER AIR MOVES ACROSS THE
CWA...WITH SLIGHTLY COOLER TEMPS ESPECIALLY NEAR THE LAKE.
ALTHOUGH...IT DOES APPEAR THAT AN OVERALL WARMING TREND WILL START
THIS WEEKEND AND LIKELY CONTINUE INTO NEXT WEEK. HAVE CONTINUED
THIS WARMING TREND BY MAKING SLIGHT UPWARD ADJUSTMENTS ABOVE
GUIDANCE. WITH THIS WARMING TREND A LIKELY INCREASE IN MOISTURE
WILL OCCUR AS WELL AND AS PRECIP CHANCES ARRIVE EARLY NEXT
WEEK...THERE WILL ALSO BE POSSIBILITIES FOR THUNDER. CONFIDENCE IS
LOW WITH THIS POSSIBILITY AND SO HAVE LEFT OUT ANY MENTION OF
THUNDER AT THIS TIME...BUT COULD SEE A TREND TOWARDS THIS SOLUTION
POSSIBLE OVER THE NEXT COUPLE OF DAYS.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHEAST WINDS VEERING TO WEST BY MIDDAY THURSDAY...THEN NORTH
  TO NORTHEAST LATE THURSDAY EVENING.
* POTENTIAL FOR LOW LEVEL WIND SHEAR OVERNIGHT INTO THURSDAY MORNING.

BMD

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

LOW PRESSURE LIES OVER FAR NORTHEASTERN IOWA TONIGHT AND WILL FILL
AS IT LIFTS TO NORTHERN WISCONSIN BY MID MORNING THURSDAY. A COLD
FRONT STRETCHES SOUTH INTO CENTRAL MISSOURI. AHEAD OF THE
FRONT...STRONG LOW-MID LEVEL WINDS COULD RESULT IN LLWS...WITH THE
BEST CHANCES AT RFD WHICH WILL BE CLOSER IN PROXIMITY TO THE LOW
LEVEL JET. THE COLD FRONT WILL MOVE ACROSS NORTHERN ILLINOIS LATE
MORNING INTO EARLY AFTERNOON WITH PRECIP ALONG THE FRONT FAIRLY
UNLIKELY. WINDS TURN WSW BEHIND THE FRONT AND EVENTUALLY
NORTHWESTERLY IN THE EVENING. WINDS WILL CONTINUE TO VEER TO THE
NORTHEAST THURSDAY NIGHT.

BMD


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN WIND DIRECTION/TIMING CHANGES IN DIRECTION.
* LOW CONFIDENCE IN LLWS.

BMD

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...CHC RAIN. MVFR POSSIBLE.

MONDAY...CHC RAIN EARLY. OTRW...VFR/WX NIL.

TUESDAY...VFR. WX NIL.

WEDNESDAY...SLIGHT CHC RAIN. MVFR POSSIBLE.

KREIN

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM THURSDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KILX 170436
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1136 PM CDT Wed Apr 16 2014

.DISCUSSION...
ISSUED 900 PM CDT Wed Apr 16 2014

Made minor adjustments to the forecast to slightly increase the
cloud cover and drop the overnight low temperatures a tad.

The latest surface analysis indicated a cold front extending from
low pressure in north central IA through NW MO to extreme northern
TX. A moderate to strong pressure gradient will keep the S to SSE
winds going at 10 to 15 mph in central IL through much of the
night. The gusts have dropped off in most locations, and should
diminish in the rest of central IL soon.

Less of a pressure gradient will be present in eastern IL
overnight. This will combine with very dry air/dew points in the
20s, to allow temperatures to dip into the mid 30s. Forecast
soundings and high resolution model moisture profiles indicate
that most of the significant cloud cover will be along and west of
the IL River valley tonight.



&&

.AVIATION...
ISSUED 1135 PM CDT Wed Apr 16 2014

Despite an approaching cold front, the lower atmosphere will
remain relatively dry, resulting in VFR conditions for the next 24
hours.

The front, which is currently from central Iowa to southeast
Kansas, will slowly move into central Illinois during the late
morning. This will result in the south winds shifting to the W-WSW.
The front is expected to weaken as it will have very little upper
support and moisture to work with. This will keep clouds bases at
VFR levels, with any potential for light precipitation holding off
until after 06z Friday. The weak frontal boundary will also cause
the surface winds in central and eastern Illinois to become very
light after sunset Thursday evening.

Miller
&&

.PREV DISCUSSION...
ISSUED 211 PM CDT Wed Apr 16 2014
High pressure dominating the eastern half of the country from the
Mississippi River Valley eastward. Low pressure developing over
the Plains expected to move into the Midwest this evening bringing
a cold front in its wake. Relatively dry atmosphere in place will
limit the rain chances at this point...but a wave rippling along
this boundary will be the next problem in the forecast. The next
system in the forecast will bring pops for the end of the weekend
and into the next work week. Models having some consistency for
the early system...but having some major timing issues for the
weekend precip. For now, forecast remains more of a blend of the
ECMWF and the NAM, while ignoring the far more aggressive GFS in
both cases.

SHORT TERM...Tonight through Friday...
Prolonged southerly flow over the region today has pushed warmer
temps into the FA this afternoon. This continues through the
overnight, resulting in a far warmer morning as lows tonight drop
to the upper 30s and lower 40s. Some clouds anticipated as a weak
boundary moves into the region tomorrow...somewhat tempering the
climb...warmer conditions with highs from the upper 50s to lower
60s. Agree with previous forecast that the dry atmosphere will be
hard pressed to produce rainfall tomorrow afternoon as a shortwave
ripples along the slowing boundary in Central Illinois. Once the
system has a chance to saturate, the pops go up for the overnight
Thursday night through to Friday morning, wrapping up by midday.

LONG TERM...Friday through Tuesday...
A general warming trend kicks in on Saturday as the warm
temperatures that were building under a midlevel ridge over the
west starts to shift eastward. Next chance for precip approaching
Sat night with two waves, one in the northern stream across
southern Canada... and the southern one a broader open wave over
the southern Plains. Between the two, a rather diffuse and
widespread area of rain for Sunday into Monday. GFS is far more
aggressive with the onset...and lingering the precip. Whereas even
the GFS was previously showing a dry Easter morning...it is
showing issues with run to run consistency. Have eliminated the
differentiation btwn Sun morning and evening for now. But the
best chances for precip will be later that night and into Monday.
On the other side of the precip, a warming trend continues for the
region with milder and drier weather. Max temps reaching into the
70s by Tuesday.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 170245
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
945 PM CDT WED APR 16 2014

.DISCUSSION...
331 PM CDT

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH PRECIP AND TEMP TRENDS
THURSDAY INTO FRIDAY...AND THEN WITH A DEFINITE WARMING TREND THIS
WEEKEND INTO NEXT WEEK.

WITH VORT MAX SHIFTING EAST/NORTHEAST ACROSS THE CENTRAL CONUS
THIS AFTERNOON...ATTENDANT SURFACE LOW CONTINUES TO SLOWLY SHIFT
EAST THROUGH EASTERN NEBRASKA AND IOWA THIS AFTERNOON AS A FAIRLY
TIGHT PRESSURE GRADIENT HAS ESTABLISHED ITSELF ACROSS THE CWA.
SOUTH TO SOUTHEAST HAVE PICKED UP THIS AFTERNOON WITH SOME
LOCATIONS ACROSS NORTHERN ILLINOIS GUSTING UP TO 30 TO 35 MPH. AS
THIS SURFACE LOW PUSHES NORTHEAST THROUGH IOWA AND INTO SOUTHERN
WISCONSIN TONIGHT...EXPECT WINDS TO TURN MORE SOUTH/SOUTHWEST
WHILE DIMINISHING BUT STILL GUSTING TO AROUND 25 TO 30 MPH FOR A
TIME THIS EVENING. BEST FORCING REMAINS WELL NORTH OF THE CWA AS
THIS VORT MAX AND LOW MOVE ACROSS THE REGION...WITH THE CWA
REMAINING DRY TONIGHT. MOST GUIDANCE IN AGREEMENT WITH A DRY
FORECAST TONIGHT...BUT STILL THINK THERE COULD BE A BRIEF LIGHT
SHOWER OR AT LEAST SOME SPRINKLES RIGHT ALONG THE
ILLINOIS/WISCONSIN BORDER WITH THE WAA PUSH OVERNIGHT. HAVE NOT
MADE MENTION OF THIS WITH LOWER CONFIDENCE AT THIS POSSIBILITY AND
DUE TO THE FACT THAT IF IT WERE TO OCCUR...ANTICIPATE ANYTHING
THAT FALLS TO ONCE AGAIN BE ON THE LIGHTER SIDE AND BRIEF. EXPECT
CURRENT CLEAR OR PARTLY CLOUDY SKIES IN PLACE TO SEE SOME INCREASE
IN CLOUD COVER TONIGHT...WITH A PERIOD OF CLOUDY SKIES LATER
TONIGHT ESPECIALLY OVER THE NORTHERN HALF OF THE CWA WITH OTHER
LOCATIONS SOUTH TO BE MORE PARTLY CLOUDY.

SURFACE LOW WILL CONTINUE NORTHEAST ON THURSDAY WEAKENING
SIGNIFICANTLY BY MID DAY AS UPPER SUPPORT IS QUICKLY LOST.
PERSISTENT WAA AND SOUTH/SOUTHWEST FLOW SHOULD ALLOW FOR SURFACE
TEMPS TO RISE INTO THE UPPER 50S AND LOWERS 60S THURSDAY...EVEN
WITH PARTLY CLOUDY/PARTLY SUNNY SKIES IN PLACE. INITIAL DRY
CONDITIONS AS SURFACE TROUGH/FRONT PUSH THROUGH THURSDAY WILL BE
REPLACE WITH AN INCREASE IN RAIN CHANCES LATER IN THE DAY AS
MID/UPPER LEVEL TROUGH SWING ACROSS THE REGION. IT DOES APPEAR AS
THIS RAIN WILL ONCE AGAIN BE ON THE LIGHTER SIDE AND STAY CONFINED
TO THE SOUTHEAST TWO THIRDS OF THE CWA...AND HAVE MAINTAINED HIGH
CHANCE POPS THURSDAY NIGHT. EXPECT ANY LINGERING RAIN TO QUICKLY
EXIT FRIDAY MORNING AS DRIER/COOLER AIR MOVES ACROSS THE
CWA...WITH SLIGHTLY COOLER TEMPS ESPECIALLY NEAR THE LAKE.
ALTHOUGH...IT DOES APPEAR THAT AN OVERALL WARMING TREND WILL START
THIS WEEKEND AND LIKELY CONTINUE INTO NEXT WEEK. HAVE CONTINUED
THIS WARMING TREND BY MAKING SLIGHT UPWARD ADJUSTMENTS ABOVE
GUIDANCE. WITH THIS WARMING TREND A LIKELY INCREASE IN MOISTURE
WILL OCCUR AS WELL AND AS PRECIP CHANCES ARRIVE EARLY NEXT
WEEK...THERE WILL ALSO BE POSSIBILITIES FOR THUNDER. CONFIDENCE IS
LOW WITH THIS POSSIBILITY AND SO HAVE LEFT OUT ANY MENTION OF
THUNDER AT THIS TIME...BUT COULD SEE A TREND TOWARDS THIS SOLUTION
POSSIBLE OVER THE NEXT COUPLE OF DAYS.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* LLWS CONDITIONS DEVELOPING OVERNIGHT WHEN GUSTS SUBSIDE IN MORE
  STABLE CONDITIONS.

KREIN

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

STRONG...GUSTY SSELY WINDS WILL REMAIN A CONCERN UNTIL SHORTLY
AFTER SUNSET...AND THEN LLWS WILL BECOME THE MAIN FORECAST
CONCERN. A STRONG PRESSURE GRADIENT REMAINS IN PLACE ACROSS THE
REGION BETWEEN LOW PRESSURE MOVING THROUGH IOWA AND HIGH PRESSURE
OVER NEW ENGLAND. AS THE LOW LIFTS NEWD THROUGH WISCONSIN
TONIGHT...THE PRESSURE GRADIENT WILL RELAX...LEADING TO DECREASING
SUSTAINED WINDS. DEEP LAYER MIXING WILL ALSO SUBSIDE AS A SURFACE
BASED INVERSION DEVELOPS AFTER SUNSET WITH THE DRY AIRMASS AT THE
SFC COOLING RAPIDLY. WITH WINDS AT THE TOP OF THE INVERSION
EXPECTED TO REMAIN SWLY AT ARND 40 KT...ABOVE SSELY WINDS ARND 10
KT AT THE SFC...LLWS WILL BE A DISTINCT POSSIBILITY...SO HAVE ADDED
LLWS GROUPS TO ALL SITES. WIND DIRECTION WILL GRADUALLY VEER MORE
LY OVERNIGHT AS A COLD FRONT APPROACHES THE REGION. WITH THE SFC
LOW EXPECTED TO BECOME NRLY STNRY OVER CNTRL WI BY TOMORROW
MORNING...THE ASSOCIATED COLD FRONT WILL BE SLOW TO PUSH THROUGH
THE REGION...BUT ANTICIPATE THAT WINDS WILL EVENTUALLY VEER SWLY
TO WLY THROUGH THE DAY TOMORROW. THERE MAY BE SOME GUSTINESS IN
THE COLD ADVECTION BEHIND THE FRONT...BUT WINDS ALOFT ARE EXPECTED
TO BE MUCH LIGHTER TOMORROW WITH GUSTS ONLY REACHING ARND 18-20 KT.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.

* MEDIUM TO HIGH CONFIDENCE IN LLWS POTENTIAL.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KREIN

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...CHC RAIN. MVFR POSSIBLE.

MONDAY...CHC RAIN EARLY. OTRW...VFR/WX NIL.

TUESDAY...VFR. WX NIL.

WEDNESDAY...SLIGHT CHC RAIN. MVFR POSSIBLE.

KREIN

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM THURSDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KILX 170200
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
900 PM CDT Wed Apr 16 2014

.DISCUSSION...
ISSUED 900 PM CDT Wed Apr 16 2014

Made minor adjustments to the forecast to slightly increase the
cloud cover and drop the overnight low temperatures a tad.

The latest surface analysis indicated a cold front extending from
low pressure in north central IA through NW MO to extreme northern
TX. A moderate to strong pressure gradient will keep the S to SSE
winds going at 10 to 15 mph in central IL through much of the
night. The gusts have dropped off in most locations, and should
diminish in the rest of central IL soon.

Less of a pressure gradient will be present in eastern IL
overnight. This will combine with very dry air/dew points in the
20s, to allow temperatures to dip into the mid 30s. Forecast
soundings and high resolution model moisture profiles indicate
that most of the significant cloud cover will be along and west of
the IL River valley tonight.

Miller
&&

.AVIATION...
ISSUED 646 PM CDT Wed Apr 16 2014

VFR conditions can be expected in all of central and eastern
Illinois the next 24 hours.

The main concern for early this evening will be the gusty south
winds. Wind gusts in excess of 25 knots will continue through at
least 00z and then drop off by 01z as the momentum transfer in the
lower atmosphere weakens. The wind will continue at 10 to 15 knots
from the south-southeast much of the night, but without the gusts.

A broken cirrus shield will cover the whole area through the
night. The lower and middle atmosphere is quite dry, so the
upstream clouds will have a hard time reaching central Illinois
late tonight and Thursday morning. Satellite interpolation and
moisture fields in the 850-700 mb layer on the GFS and NAM
indicate that a period of broken mid clouds may reach KPIA, but
not much farther than that.

The cold front extending from low pressure in central Iowa into
central Kansas will only slowly approach Thursday. The front is
expecting to reach the IL River Valley around mid-morning and
slowly advance toward east central IL by late afternoon and weaken
considerably. Upper level support, and just enough low level
moisture from the southwest, is not expected to interact with this
boundary until late Thursday evening, so the next 24 hours will be
dry.

Miller
&&

.PREV DISCUSSION...
ISSUED 211 PM CDT Wed Apr 16 2014
High pressure dominating the eastern half of the country from the
Mississippi River Valley eastward. Low pressure developing over
the Plains expected to move into the Midwest this evening bringing
a cold front in its wake. Relatively dry atmosphere in place will
limit the rain chances at this point...but a wave rippling along
this boundary will be the next problem in the forecast. The next
system in the forecast will bring pops for the end of the weekend
and into the next work week. Models having some consistency for
the early system...but having some major timing issues for the
weekend precip. For now, forecast remains more of a blend of the
ECMWF and the NAM, while ignoring the far more aggressive GFS in
both cases.

SHORT TERM...Tonight through Friday...
Prolonged southerly flow over the region today has pushed warmer
temps into the FA this afternoon. This continues through the
overnight, resulting in a far warmer morning as lows tonight drop
to the upper 30s and lower 40s. Some clouds anticipated as a weak
boundary moves into the region tomorrow...somewhat tempering the
climb...warmer conditions with highs from the upper 50s to lower
60s. Agree with previous forecast that the dry atmosphere will be
hard pressed to produce rainfall tomorrow afternoon as a shortwave
ripples along the slowing boundary in Central Illinois. Once the
system has a chance to saturate, the pops go up for the overnight
Thursday night through to Friday morning, wrapping up by midday.

LONG TERM...Friday through Tuesday...
A general warming trend kicks in on Saturday as the warm
temperatures that were building under a midlevel ridge over the
west starts to shift eastward. Next chance for precip approaching
Sat night with two waves, one in the northern stream across
southern Canada... and the southern one a broader open wave over
the southern Plains. Between the two, a rather diffuse and
widespread area of rain for Sunday into Monday. GFS is far more
aggressive with the onset...and lingering the precip. Whereas even
the GFS was previously showing a dry Easter morning...it is
showing issues with run to run consistency. Have eliminated the
differentiation btwn Sun morning and evening for now. But the
best chances for precip will be later that night and into Monday.
On the other side of the precip, a warming trend continues for the
region with milder and drier weather. Max temps reaching into the
70s by Tuesday.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 162350
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
650 PM CDT WED APR 16 2014

.DISCUSSION...
331 PM CDT

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH PRECIP AND TEMP TRENDS
THURSDAY INTO FRIDAY...AND THEN WITH A DEFINITE WARMING TREND THIS
WEEKEND INTO NEXT WEEK.

WITH VORT MAX SHIFTING EAST/NORTHEAST ACROSS THE CENTRAL CONUS
THIS AFTERNOON...ATTENDANT SURFACE LOW CONTINUES TO SLOWLY SHIFT
EAST THROUGH EASTERN NEBRASKA AND IOWA THIS AFTERNOON AS A FAIRLY
TIGHT PRESSURE GRADIENT HAS ESTABLISHED ITSELF ACROSS THE CWA.
SOUTH TO SOUTHEAST HAVE PICKED UP THIS AFTERNOON WITH SOME
LOCATIONS ACROSS NORTHERN ILLINOIS GUSTING UP TO 30 TO 35 MPH. AS
THIS SURFACE LOW PUSHES NORTHEAST THROUGH IOWA AND INTO SOUTHERN
WISCONSIN TONIGHT...EXPECT WINDS TO TURN MORE SOUTH/SOUTHWEST
WHILE DIMINISHING BUT STILL GUSTING TO AROUND 25 TO 30 MPH FOR A
TIME THIS EVENING. BEST FORCING REMAINS WELL NORTH OF THE CWA AS
THIS VORT MAX AND LOW MOVE ACROSS THE REGION...WITH THE CWA
REMAINING DRY TONIGHT. MOST GUIDANCE IN AGREEMENT WITH A DRY
FORECAST TONIGHT...BUT STILL THINK THERE COULD BE A BRIEF LIGHT
SHOWER OR AT LEAST SOME SPRINKLES RIGHT ALONG THE
ILLINOIS/WISCONSIN BORDER WITH THE WAA PUSH OVERNIGHT. HAVE NOT
MADE MENTION OF THIS WITH LOWER CONFIDENCE AT THIS POSSIBILITY AND
DUE TO THE FACT THAT IF IT WERE TO OCCUR...ANTICIPATE ANYTHING
THAT FALLS TO ONCE AGAIN BE ON THE LIGHTER SIDE AND BRIEF. EXPECT
CURRENT CLEAR OR PARTLY CLOUDY SKIES IN PLACE TO SEE SOME INCREASE
IN CLOUD COVER TONIGHT...WITH A PERIOD OF CLOUDY SKIES LATER
TONIGHT ESPECIALLY OVER THE NORTHERN HALF OF THE CWA WITH OTHER
LOCATIONS SOUTH TO BE MORE PARTLY CLOUDY.

SURFACE LOW WILL CONTINUE NORTHEAST ON THURSDAY WEAKENING
SIGNIFICANTLY BY MID DAY AS UPPER SUPPORT IS QUICKLY LOST.
PERSISTENT WAA AND SOUTH/SOUTHWEST FLOW SHOULD ALLOW FOR SURFACE
TEMPS TO RISE INTO THE UPPER 50S AND LOWERS 60S THURSDAY...EVEN
WITH PARTLY CLOUDY/PARTLY SUNNY SKIES IN PLACE. INITIAL DRY
CONDITIONS AS SURFACE TROUGH/FRONT PUSH THROUGH THURSDAY WILL BE
REPLACE WITH AN INCREASE IN RAIN CHANCES LATER IN THE DAY AS
MID/UPPER LEVEL TROUGH SWING ACROSS THE REGION. IT DOES APPEAR AS
THIS RAIN WILL ONCE AGAIN BE ON THE LIGHTER SIDE AND STAY CONFINED
TO THE SOUTHEAST TWO THIRDS OF THE CWA...AND HAVE MAINTAINED HIGH
CHANCE POPS THURSDAY NIGHT. EXPECT ANY LINGERING RAIN TO QUICKLY
EXIT FRIDAY MORNING AS DRIER/COOLER AIR MOVES ACROSS THE
CWA...WITH SLIGHTLY COOLER TEMPS ESPECIALLY NEAR THE LAKE.
ALTHOUGH...IT DOES APPEAR THAT AN OVERALL WARMING TREND WILL START
THIS WEEKEND AND LIKELY CONTINUE INTO NEXT WEEK. HAVE CONTINUED
THIS WARMING TREND BY MAKING SLIGHT UPWARD ADJUSTMENTS ABOVE
GUIDANCE. WITH THIS WARMING TREND A LIKELY INCREASE IN MOISTURE
WILL OCCUR AS WELL AND AS PRECIP CHANCES ARRIVE EARLY NEXT
WEEK...THERE WILL ALSO BE POSSIBILITIES FOR THUNDER. CONFIDENCE IS
LOW WITH THIS POSSIBILITY AND SO HAVE LEFT OUT ANY MENTION OF
THUNDER AT THIS TIME...BUT COULD SEE A TREND TOWARDS THIS SOLUTION
POSSIBLE OVER THE NEXT COUPLE OF DAYS.

RODRIGUEZ

&&

.AVIATION...

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

* STRONG AND GUSTY SSE WINDS CREATING CROSSWIND ISSUES ON EAST-
  WEST RUNWAYS THROUGH SUNSET.

* LLWS CONDITIONS DEVELOPING OVERNIGHT WHEN GUSTS SUBSIDE IN MORE
  STABLE CONDITIONS.

KREIN

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

STRONG...GUSTY SSELY WINDS WILL REMAIN A CONCERN UNTIL SHORTLY
AFTER SUNSET...AND THEN LLWS WILL BECOME THE MAIN FORECAST
CONCERN. A STRONG PRESSURE GRADIENT REMAINS IN PLACE ACROSS THE
REGION BETWEEN LOW PRESSURE MOVING THROUGH IOWA AND HIGH PRESSURE
OVER NEW ENGLAND. AS THE LOW LIFTS NEWD THROUGH WISCONSIN
TONIGHT...THE PRESSURE GRADIENT WILL RELAX...LEADING TO DECREASING
SUSTAINED WINDS. DEEP LAYER MIXING WILL ALSO SUBSIDE AS A SURFACE
BASED INVERSION DEVELOPS AFTER SUNSET WITH THE DRY AIRMASS AT THE
SFC COOLING RAPIDLY. WITH WINDS AT THE TOP OF THE INVERSION
EXPECTED TO REMAIN SWLY AT ARND 40 KT...ABOVE SSELY WINDS ARND 10
KT AT THE SFC...LLWS WILL BE A DISTINCT POSSIBILITY...SO HAVE ADDED
LLWS GROUPS TO ALL SITES. WIND DIRECTION WILL GRADUALLY VEER MORE
LY OVERNIGHT AS A COLD FRONT APPROACHES THE REGION. WITH THE SFC
LOW EXPECTED TO BECOME NRLY STNRY OVER CNTRL WI BY TOMORROW
MORNING...THE ASSOCIATED COLD FRONT WILL BE SLOW TO PUSH THROUGH
THE REGION...BUT ANTICIPATE THAT WINDS WILL EVENTUALLY VEER SWLY
TO WLY THROUGH THE DAY TOMORROW. THERE MAY BE SOME GUSTINESS IN
THE COLD ADVECTION BEHIND THE FRONT...BUT WINDS ALOFT ARE EXPECTED
TO BE MUCH LIGHTER TOMORROW WITH GUSTS ONLY REACHING ARND 18-20 KT.

KREIN

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

* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.

* MEDIUM TO HIGH CONFIDENCE IN LLWS POTENTIAL.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KREIN

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...CHC RAIN. MVFR POSSIBLE.

MONDAY...CHC RAIN EARLY. OTRW...VFR/WX NIL.

TUESDAY...VFR. WX NIL.

WEDNESDAY...SLIGHT CHC RAIN. MVFR POSSIBLE.

KREIN

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM THURSDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KILX 162347
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
647 PM CDT Wed Apr 16 2014

.DISCUSSION...
ISSUED 211 PM CDT Wed Apr 16 2014
High pressure dominating the eastern half of the country from the
Mississippi River Valley eastward. Low pressure developing over
the Plains expected to move into the Midwest this evening bringing
a cold front in its wake. Relatively dry atmosphere in place will
limit the rain chances at this point...but a wave rippling along
this boundary will be the next problem in the forecast. The next
system in the forecast will bring pops for the end of the weekend
and into the next work week. Models having some consistency for
the early system...but having some major timing issues for the
weekend precip. For now, forecast remains more of a blend of the
ECMWF and the NAM, while ignoring the far more aggressive GFS in
both cases.

SHORT TERM...Tonight through Friday...
Prolonged southerly flow over the region today has pushed warmer
temps into the FA this afternoon. This continues through the
overnight, resulting in a far warmer morning as lows tonight drop
to the upper 30s and lower 40s. Some clouds anticipated as a weak
boundary moves into the region tomorrow...somewhat tempering the
climb...warmer conditions with highs from the upper 50s to lower
60s. Agree with previous forecast that the dry atmosphere will be
hard pressed to produce rainfall tomorrow afternoon as a shortwave
ripples along the slowing boundary in Central Illinois. Once the
system has a chance to saturate, the pops go up for the overnight
Thursday night through to Friday morning, wrapping up by midday.

LONG TERM...Friday through Tuesday...
A general warming trend kicks in on Saturday as the warm
temperatures that were building under a midlevel ridge over the
west starts to shift eastward. Next chance for precip approaching
Sat night with two waves, one in the northern stream across
southern Canada... and the southern one a broader open wave over
the southern Plains. Between the two, a rather diffuse and
widespread area of rain for Sunday into Monday. GFS is far more
aggressive with the onset...and lingering the precip. Whereas even
the GFS was previously showing a dry Easter morning...it is
showing issues with run to run consistency. Have eliminated the
differentiation btwn Sun morning and evening for now. But the
best chances for precip will be later that night and into Monday.
On the other side of the precip, a warming trend continues for the
region with milder and drier weather. Max temps reaching into the
70s by Tuesday.



&&

.AVIATION...
ISSUED 646 PM CDT Wed Apr 16 2014

VFR conditions can be expected in all of central and eastern
Illinois the next 24 hours.

The main concern for early this evening will be the gusty south
winds. Wind gusts in excess of 25 knots will continue through at
least 00z and then drop off by 01z as the momentum transfer in the
lower atmosphere weakens. The wind will continue at 10 to 15 knots
from the south-southeast much of the night, but without the gusts.

A broken cirrus shield will cover the whole area through the
night. The lower and middle atmosphere is quite dry, so the
upstream clouds will have a hard time reaching central Illinois
late tonight and Thursday morning. Satellite interpolation and
moisture fields in the 850-700 mb layer on the GFS and NAM
indicate that a period of broken mid clouds may reach KPIA, but
not much farther than that.

The cold front extending from low pressure in central Iowa into
central Kansas will only slowly approach Thursday. The front is
expecting to reach the IL River Valley around mid-morning and
slowly advance toward east central IL by late afternoon and weaken
considerably. Upper level support, and just enough low level
moisture from the southwest, is not expected to interact with this
boundary until late Thursday evening, so the next 24 hours will be
dry.

Miller
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 162206
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
506 PM CDT WED APR 16 2014

.DISCUSSION...
331 PM CDT

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH PRECIP AND TEMP TRENDS
THURSDAY INTO FRIDAY...AND THEN WITH A DEFINITE WARMING TREND THIS
WEEKEND INTO NEXT WEEK.

WITH VORT MAX SHIFTING EAST/NORTHEAST ACROSS THE CENTRAL CONUS
THIS AFTERNOON...ATTENDANT SURFACE LOW CONTINUES TO SLOWLY SHIFT
EAST THROUGH EASTERN NEBRASKA AND IOWA THIS AFTERNOON AS A FAIRLY
TIGHT PRESSURE GRADIENT HAS ESTABLISHED ITSELF ACROSS THE CWA.
SOUTH TO SOUTHEAST HAVE PICKED UP THIS AFTERNOON WITH SOME
LOCATIONS ACROSS NORTHERN ILLINOIS GUSTING UP TO 30 TO 35 MPH. AS
THIS SURFACE LOW PUSHES NORTHEAST THROUGH IOWA AND INTO SOUTHERN
WISCONSIN TONIGHT...EXPECT WINDS TO TURN MORE SOUTH/SOUTHWEST
WHILE DIMINISHING BUT STILL GUSTING TO AROUND 25 TO 30 MPH FOR A
TIME THIS EVENING. BEST FORCING REMAINS WELL NORTH OF THE CWA AS
THIS VORT MAX AND LOW MOVE ACROSS THE REGION...WITH THE CWA
REMAINING DRY TONIGHT. MOST GUIDANCE IN AGREEMENT WITH A DRY
FORECAST TONIGHT...BUT STILL THINK THERE COULD BE A BRIEF LIGHT
SHOWER OR AT LEAST SOME SPRINKLES RIGHT ALONG THE
ILLINOIS/WISCONSIN BORDER WITH THE WAA PUSH OVERNIGHT. HAVE NOT
MADE MENTION OF THIS WITH LOWER CONFIDENCE AT THIS POSSIBILITY AND
DUE TO THE FACT THAT IF IT WERE TO OCCUR...ANTICIPATE ANYTHING
THAT FALLS TO ONCE AGAIN BE ON THE LIGHTER SIDE AND BRIEF. EXPECT
CURRENT CLEAR OR PARTLY CLOUDY SKIES IN PLACE TO SEE SOME INCREASE
IN CLOUD COVER TONIGHT...WITH A PERIOD OF CLOUDY SKIES LATER
TONIGHT ESPECIALLY OVER THE NORTHERN HALF OF THE CWA WITH OTHER
LOCATIONS SOUTH TO BE MORE PARTLY CLOUDY.

SURFACE LOW WILL CONTINUE NORTHEAST ON THURSDAY WEAKENING
SIGNIFICANTLY BY MID DAY AS UPPER SUPPORT IS QUICKLY LOST.
PERSISTENT WAA AND SOUTH/SOUTHWEST FLOW SHOULD ALLOW FOR SURFACE
TEMPS TO RISE INTO THE UPPER 50S AND LOWERS 60S THURSDAY...EVEN
WITH PARTLY CLOUDY/PARTLY SUNNY SKIES IN PLACE. INITIAL DRY
CONDITIONS AS SURFACE TROUGH/FRONT PUSH THROUGH THURSDAY WILL BE
REPLACE WITH AN INCREASE IN RAIN CHANCES LATER IN THE DAY AS
MID/UPPER LEVEL TROUGH SWING ACROSS THE REGION. IT DOES APPEAR AS
THIS RAIN WILL ONCE AGAIN BE ON THE LIGHTER SIDE AND STAY CONFINED
TO THE SOUTHEAST TWO THIRDS OF THE CWA...AND HAVE MAINTAINED HIGH
CHANCE POPS THURSDAY NIGHT. EXPECT ANY LINGERING RAIN TO QUICKLY
EXIT FRIDAY MORNING AS DRIER/COOLER AIR MOVES ACROSS THE
CWA...WITH SLIGHTLY COOLER TEMPS ESPECIALLY NEAR THE LAKE.
ALTHOUGH...IT DOES APPEAR THAT AN OVERALL WARMING TREND WILL START
THIS WEEKEND AND LIKELY CONTINUE INTO NEXT WEEK. HAVE CONTINUED
THIS WARMING TREND BY MAKING SLIGHT UPWARD ADJUSTMENTS ABOVE
GUIDANCE. WITH THIS WARMING TREND A LIKELY INCREASE IN MOISTURE
WILL OCCUR AS WELL AND AS PRECIP CHANCES ARRIVE EARLY NEXT
WEEK...THERE WILL ALSO BE POSSIBILITIES FOR THUNDER. CONFIDENCE IS
LOW WITH THIS POSSIBILITY AND SO HAVE LEFT OUT ANY MENTION OF
THUNDER AT THIS TIME...BUT COULD SEE A TREND TOWARDS THIS SOLUTION
POSSIBLE OVER THE NEXT COUPLE OF DAYS.

RODRIGUEZ

&&

.AVIATION...

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

* STRONG AND GUSTY SSE WINDS CREATING CROSSWIND ISSUES ON EAST-
  WEST RUNWAYS.

* POSSIBLE LLWS OVERNIGHT WHEN GUSTS RELAX IN MORE STABLE
  CONDITIONS.

KREIN

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

A LOW PRESSURE CENTER LIFTING ACROSS IOWA INTO WISCONSIN TODAY AND
TONIGHT WILL SUPPORT GUSTY SSE WINDS OVER THE LOCAL TERMINALS TODAY.
GUSTS SHOULD DIMINISH OVERNIGHT WITH SFC COOLING AND BETTER LOW
LEVEL STABILITY...THOUGH STRONG WINDS ALOFT MAY CREATE MARGINAL
LLWS CONDITIONS. WINDS GRADUALLY TURN SOUTHWEST TOWARD MORNING
THEN AROUND TO THE WEST LATE TOMORROW AFTER THE LOW CROSSES LAKE
SUPERIOR AND A TRAILING COLD FRONT PASSES THROUGH THE AREA. PRECIP
CHANCES WITH THIS SYSTEM APPEAR LOW UNTIL LATE TOMORROW.

LENNING

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

* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.

* MEDIUM CONFIDENCE IN LLWS POTENTIAL.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KREIN

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

THURSDAY NIGHT...CHC RAIN. MVFR PSBL.
FRIDAY...SLT CHC RAIN. MVFR PSBL.
SATURDAY...VFR.
SUNDAY...CHC RAIN.
MONDAY...SLT CHC RAIN.
TUESDAY...VFR.

BMD

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM THURSDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KLOT 162032
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
332 PM CDT WED APR 16 2014

.DISCUSSION...
331 PM CDT

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH PRECIP AND TEMP TRENDS
THURSDAY INTO FRIDAY...AND THEN WITH A DEFINITE WARMING TREND THIS
WEEKEND INTO NEXT WEEK.

WITH VORT MAX SHIFTING EAST/NORTHEAST ACROSS THE CENTRAL CONUS
THIS AFTERNOON...ATTENDANT SURFACE LOW CONTINUES TO SLOWLY SHIFT
EAST THROUGH EASTERN NEBRASKA AND IOWA THIS AFTERNOON AS A FAIRLY
TIGHT PRESSURE GRADIENT HAS ESTABLISHED ITSELF ACROSS THE CWA.
SOUTH TO SOUTHEAST HAVE PICKED UP THIS AFTERNOON WITH SOME
LOCATIONS ACROSS NORTHERN ILLINOIS GUSTING UP TO 30 TO 35 MPH. AS
THIS SURFACE LOW PUSHES NORTHEAST THROUGH IOWA AND INTO SOUTHERN
WISCONSIN TONIGHT...EXPECT WINDS TO TURN MORE SOUTH/SOUTHWEST
WHILE DIMINISHING BUT STILL GUSTING TO AROUND 25 TO 30 MPH FOR A
TIME THIS EVENING. BEST FORCING REMAINS WELL NORTH OF THE CWA AS
THIS VORT MAX AND LOW MOVE ACROSS THE REGION...WITH THE CWA
REMAINING DRY TONIGHT. MOST GUIDANCE IN AGREEMENT WITH A DRY
FORECAST TONIGHT...BUT STILL THINK THERE COULD BE A BRIEF LIGHT
SHOWER OR AT LEAST SOME SPRINKLES RIGHT ALONG THE
ILLINOIS/WISCONSIN BORDER WITH THE WAA PUSH OVERNIGHT. HAVE NOT
MADE MENTION OF THIS WITH LOWER CONFIDENCE AT THIS POSSIBILITY AND
DUE TO THE FACT THAT IF IT WERE TO OCCUR...ANTICIPATE ANYTHING
THAT FALLS TO ONCE AGAIN BE ON THE LIGHTER SIDE AND BRIEF. EXPECT
CURRENT CLEAR OR PARTLY CLOUDY SKIES IN PLACE TO SEE SOME INCREASE
IN CLOUD COVER TONIGHT...WITH A PERIOD OF CLOUDY SKIES LATER
TONIGHT ESPECIALLY OVER THE NORTHERN HALF OF THE CWA WITH OTHER
LOCATIONS SOUTH TO BE MORE PARTLY CLOUDY.

SURFACE LOW WILL CONTINUE NORTHEAST ON THURSDAY WEAKENING
SIGNIFICANTLY BY MID DAY AS UPPER SUPPORT IS QUICKLY LOST.
PERSISTENT WAA AND SOUTH/SOUTHWEST FLOW SHOULD ALLOW FOR SURFACE
TEMPS TO RISE INTO THE UPPER 50S AND LOWERS 60S THURSDAY...EVEN
WITH PARTLY CLOUDY/PARTLY SUNNY SKIES IN PLACE. INITIAL DRY
CONDITIONS AS SURFACE TROUGH/FRONT PUSH THROUGH THURSDAY WILL BE
REPLACE WITH AN INCREASE IN RAIN CHANCES LATER IN THE DAY AS
MID/UPPER LEVEL TROUGH SWING ACROSS THE REGION. IT DOES APPEAR AS
THIS RAIN WILL ONCE AGAIN BE ON THE LIGHTER SIDE AND STAY CONFINED
TO THE SOUTHEAST TWO THIRDS OF THE CWA...AND HAVE MAINTAINED HIGH
CHANCE POPS THURSDAY NIGHT. EXPECT ANY LINGERING RAIN TO QUICKLY
EXIT FRIDAY MORNING AS DRIER/COOLER AIR MOVES ACROSS THE
CWA...WITH SLIGHTLY COOLER TEMPS ESPECIALLY NEAR THE LAKE.
ALTHOUGH...IT DOES APPEAR THAT AN OVERALL WARMING TREND WILL START
THIS WEEKEND AND LIKELY CONTINUE INTO NEXT WEEK. HAVE CONTINUED
THIS WARMING TREND BY MAKING SLIGHT UPWARD ADJUSTMENTS ABOVE
GUIDANCE. WITH THIS WARMING TREND A LIKELY INCREASE IN MOISTURE
WILL OCCUR AS WELL AND AS PRECIP CHANCES ARRIVE EARLY NEXT
WEEK...THERE WILL ALSO BE POSSIBILITIES FOR THUNDER. CONFIDENCE IS
LOW WITH THIS POSSIBILITY AND SO HAVE LEFT OUT ANY MENTION OF
THUNDER AT THIS TIME...BUT COULD SEE A TREND TOWARDS THIS SOLUTION
POSSIBLE OVER THE NEXT COUPLE OF DAYS.

RODRIGUEZ

&&

.AVIATION...

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

* STRONG AND GUSTY SSE WINDS CREATING CROSSWIND ISSUES ON EAST-
  WEST RUNWAYS.

* POSSIBLE LLWS TONIGHT WHEN GUSTS RELAX IN MORE STABLE
  CONDITIONS.

LENNING

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

A LOW PRESSURE CENTER LIFTING ACROSS IOWA INTO WISCONSIN TODAY AND
TONIGHT WILL SUPPORT GUSTY SSE WINDS OVER THE LOCAL TERMINALS TODAY.
GUSTS SHOULD DIMINISH OVERNIGHT WITH SFC COOLING AND BETTER LOW
LEVEL STABILITY...THOUGH STRONG WINDS ALOFT MAY CREATE MARGINAL
LLWS CONDITIONS. WINDS GRADUALLY TURN SOUTHWEST TOWARD MORNING
THEN AROUND TO THE WEST LATE TOMORROW AFTER THE LOW CROSSES LAKE
SUPERIOR AND A TRAILING COLD FRONT PASSES THROUGH THE AREA. PRECIP
CHANCES WITH THIS SYSTEM APPEAR LOW UNTIL LATE TOMORROW.

LENNING

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

* GENERALLY HIGH CONFIDENCE IN ALL ELEMENTS THOUGH LESS SURE
  ABOUT LLWS TONIGHT. GUSTS MAY ALSO RELAX A BIT EARLIER THAN 03Z.

LENNING

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

THURSDAY NIGHT...CHC RAIN. MVFR PSBL.
FRIDAY...SLT CHC RAIN. MVFR PSBL.
SATURDAY...VFR.
SUNDAY...CHC RAIN.
MONDAY...SLT CHC RAIN.
TUESDAY...VFR.

BMD

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM THURSDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KLOT 161955
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CDT WED APR 16 2014

.DISCUSSION...
313 AM CDT

WEATHER WITHOUT ANY SIGNIFICANT IMPACTS LOOKS TO BE THE RULE THROUGH
THE EARLY PART OF THE WEEKEND WITH MUCH OF THE ATTENTION ON
TEMPERATURES AND WIND SPEEDS TODAY AND THEN SMALL CHANCES FOR
PRECIPITATION THURSDAY NIGHT AND FRIDAY.

TODAY AND TONIGHT...
THE UPPER TROUGH RESPONSIBLE FOR THE CHILLY DAY YESTERDAY IS
ADVANCING EAST OVER EASTERN CANADA AND NEW ENGLAND AND IS
RESPONSIBLE FOR PORTIONS OF AT LEAST 22 STATES UNDER FREEZE WARNINGS
THIS MORNING! STRONG MID-LEVEL DRYING IS SEEN ALL THE WAY DOWN TO
THE NORTHERN GULF AND AT THE SURFACE THE DRY AIR HAS ADVANCED
SOUTHWARD ALL THE WAY INTO THE GULF WITH SEVERAL PLATFORMS/BUOYS
REPORTING DEW POINTS IN THE 30S. SO BASICALLY THE GULF IS NOT
AVAILABLE FOR THE NEXT SYSTEM PASSING ACROSS THE REGION TONIGHT AND
THAT WILL BE A MAIN REASON WE LOOK TO REMAIN PRECIPITATION FREE.
THIS SYSTEM IS A FAIRLY WELL-DEFINED LOW AMPLITUDE UPPER WAVE THAT
IS MOVING EAST ACROSS SD THIS MORNING AND WILL FOLLOW ITS PARENT JET
STREAK/DIVERGENCE ALOFT TO THE EAST NORTHEAST OVER THE UPPER GREAT
LAKES TONIGHT WHERE A SNOW STORM IS FORECAST ACROSS NORTHERN WI/U.P.
OF MICHIGAN.

THE QUICK EASTWARD PROGRESSION OF THE SYSTEM SURFACE LOW BY
AFTERNOON WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOCAL AREA.
WHILE THERE WILL BE SOME HIGH CLOUDS...MIXING WILL AID THE PRESSURE
GRADIENT IN CREATING SUSTAINED SPEEDS AROUND 20 MPH AND GUSTS PLUS
10 MPH OF THAT. SOME 35 MPH GUSTS SHOULD EVEN BE REALIZED IN NORTH
CENTRAL IL. TEMPERATURES LOOK TO BOUNCE BACK 15 DEGREES OR EVEN
HIGHER THAN YESTERDAY GIVEN WARMING OF THE BOUNDARY LAYER AND
LOW-LEVEL ADVECTION. A SLIGHT COMPONENT OFF THE LAKE INTO CITY OF
CHICAGO AND NORTHWARD WILL KEEP THESE LAKE ADJACENT AREAS A HANDFUL
OF DEGREES COOLER...BUT COMPARED TO 33 DEGREES YESTERDAY...THE
FORECAST OF AROUND 50 TODAY FOR THESE LOCATIONS SHOULD BE WELCOME.
OUTLYING AREAS LOOK TO REACH THE MID 50S. UPSTREAM DEW POINTS ARE IN
THE UPPER TEENS TO MID 20S ACROSS DOWNSTATE IL/IN INTO THE TENNESSEE
RIVER VALLEY...SO EXPECTING A FAIRLY DRY AIR MASS TODAY WITH
HUMIDITY IN THE 25-35 PERCENT RANGE IN MOST AREAS.

AS THE UPPER WAVE PASSES TO THE NORTH TONIGHT THE PACIFIC MOISTURE
REMAINS NORTH AS WELL AND THE WARM AIR ADVECTION ASCENT HERE REMAINS
WITHIN A LOW PWAT ATMOSPHERE. WOULD NOT BE SURPRISED TO SEE SOME
RADAR ECHOES/VIRGA ACROSS FAR NORTHERN IL BUT THAT SHOULD BE ABOUT
IT. WITH MORE CLOUD COVER TONIGHT AND SOUTHERLY WINDS OF 10-20 MPH
CONTINUING...LOWS LOOK TO ONLY DIP INTO THE LOWER-MID 40S.

THURSDAY AND FRIDAY...
THE SYSTEM SURFACE FRONT/TROUGH IS EXPECTED TO MOVE INTO THE
FORECAST AREA THURSDAY MORNING AND BECOME STATIONARY. THIS DOES NOT
LOOK TO BE A VERY PRONOUNCED BAROCLINIC BOUNDARY. HAVE CONSIDERABLY
LOWERED CLOUD COVER DURING THURSDAY MORNING AND EARLY AFTERNOON AND
WITH THAT BOOSTED TEMPERATURES SOME...WITH 55 TO 60 PROBABLE. A
SHEARING UPPER WAVE IS EXPECTED TO MOVE NORTHEAST OVER THE BOUNDARY
THURSDAY NIGHT. A LOOK AT THE DPROG/DT...OR TREND...OF SEVERAL
MODELS OVER THE PAST FOUR CYCLES SHOW CONSIDERABLY LESS FORCING AND
MOISTURE AVAILABILITY FOR PRECIPITATION. HAVE CONTINUED THE FORECAST
TREND TO CUT BACK POPS BUT ALSO TO CONFINE THE AREA WHERE
CONVERGENCE/FRONTOGENESIS IS DEPICTED NEAR THE BOUNDARY. BY FRIDAY
THE ENVELOPE OF GUIDANCE HAS FORCING EAST OF THE AREA...HOWEVER ONE
FINAL SEPARATE MID-LEVEL IMPULSE SEEN ON THE NCEP MODELS PASSES OVER
THE AREA FRIDAY AFTERNOON. CONTINUE A SMALL CHANCE OF RAIN SHOWERS
WITH THIS. THE NORTH TO NORTHEAST FLOW BEHIND THE FRONT ON FRIDAY
SHOULD LEAD TO A DECENT TEMPERATURE DIFFERENCE FROM NEAR THE LAKE TO
OUTLYING AREAS...WITH MID 40S TO MID 50S PRESENTLY FORECAST ACROSS
THAT CROSS SECTION. LOCAL CLIMATOLOGICAL RESEARCH FAVORS SUCH A
SPREAD THIS TIME OF YEAR WITH ONSHORE FLOW.

THIS WEEKEND INTO EARLY NEXT WEEK...
WHILE THE FLOW IS PROGRESSIVE ACROSS THE FAR NORTHERN CONUS/SOUTHERN
CANADA IT LOOKS TO BE FAR ENOUGH NORTH TO HAVE LITTLE INFLUENCE ON
THE AREA SATURDAY AND POTENTIALLY EVEN SUNDAY...ESPECIALLY IF GOING
TOWARD THE EC AND GEM WHICH WE HAVE LEANED OUR FORECAST. THESE
MODELS INDICATE THAT A CLOSED UPPER LOW OVER THE SOUTHEAST U.S.
DEPICTED BY MODELS LATE IN THE WEEKEND MAY LEAD TO A SLOWING OF THE
NEXT SYSTEM TO APPROACH THE AREA FROM THE ROCKIES...MORE SO SUNDAY
NIGHT AND MONDAY. TEMPERATURES LOOK TO BE BACK TO NORMAL SUNDAY AND
MONDAY.

MTF

&&

.AVIATION...

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

* STRONG AND GUSTY SSE WINDS CREATING CROSSWIND ISSUES ON EAST-
  WEST RUNWAYS.

* POSSIBLE LLWS TONIGHT WHEN GUSTS RELAX IN MORE STABLE
  CONDITIONS.

LENNING

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

A LOW PRESSURE CENTER LIFTING ACROSS IOWA INTO WISCONSIN TODAY AND
TONIGHT WILL SUPPORT GUSTY SSE WINDS OVER THE LOCAL TERMINALS TODAY.
GUSTS SHOULD DIMINISH OVERNIGHT WITH SFC COOLING AND BETTER LOW
LEVEL STABILITY...THOUGH STRONG WINDS ALOFT MAY CREATE MARGINAL
LLWS CONDITIONS. WINDS GRADUALLY TURN SOUTHWEST TOWARD MORNING
THEN AROUND TO THE WEST LATE TOMORROW AFTER THE LOW CROSSES LAKE
SUPERIOR AND A TRAILING COLD FRONT PASSES THROUGH THE AREA. PRECIP
CHANCES WITH THIS SYSTEM APPEAR LOW UNTIL LATE TOMORROW.

LENNING

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

* GENERALLY HIGH CONFIDENCE IN ALL ELEMENTS THOUGH LESS SURE
  ABOUT LLWS TONIGHT. GUSTS MAY ALSO RELAX A BIT EARLIER THAN 03Z.

LENNING

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

THURSDAY NIGHT...CHC RAIN. MVFR PSBL.
FRIDAY...SLT CHC RAIN. MVFR PSBL.
SATURDAY...VFR.
SUNDAY...CHC RAIN.
MONDAY...SLT CHC RAIN.
TUESDAY...VFR.

BMD

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KILX 161947
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
247 PM CDT Wed Apr 16 2014

.DISCUSSION...
ISSUED 211 PM CDT Wed Apr 16 2014
High pressure dominating the eastern half of the country from the
Mississippi River Valley eastward. Low pressure developing over
the Plains expected to move into the Midwest this evening bringing
a cold front in its wake. Relatively dry atmosphere in place will
limit the rain chances at this point...but a wave rippling along
this boundary will be the next problem in the forecast. The next
system in the forecast will bring pops for the end of the weekend
and into the next work week. Models having some consistency for
the early system...but having some major timing issues for the
weekend precip. For now, forecast remains more of a blend of the
ECMWF and the NAM, while ignoring the far more aggressive GFS in
both cases.

SHORT TERM...Tonight through Friday...
Prolonged southerly flow over the region today has pushed warmer
temps into the FA this afternoon. This continues through the
overnight, resulting in a far warmer morning as lows tonight drop
to the upper 30s and lower 40s. Some clouds anticipated as a weak
boundary moves into the region tomorrow...somewhat tempering the
climb...warmer conditions with highs from the upper 50s to lower
60s. Agree with previous forecast that the dry atmosphere will be
hard pressed to produce rainfall tomorrow afternoon as a shortwave
ripples along the slowing boundary in Central Illinois. Once the
system has a chance to saturate, the pops go up for the overnight
Thursday night through to Friday morning, wrapping up by midday.

LONG TERM...Friday through Tuesday...
A general warming trend kicks in on Saturday as the warm
temperatures that were building under a midlevel ridge over the
west starts to shift eastward. Next chance for precip approaching
Sat night with two waves, one in the northern stream across
southern Canada... and the southern one a broader open wave over
the southern Plains. Between the two, a rather diffuse and
widespread area of rain for Sunday into Monday. GFS is far more
aggressive with the onset...and lingering the precip. Whereas even
the GFS was previously showing a dry Easter morning...it is
showing issues with run to run consistency. Have eliminated the
differentiation btwn Sun morning and evening for now. But the
best chances for precip will be later that night and into Monday.
On the other side of the precip, a warming trend continues for the
region with milder and drier weather. Max temps reaching into the
70s by Tuesday.

HJS
&&

.AVIATION...
ISSUED 1218 PM CDT Wed Apr 16 2014

pressure gradient between 1032 MB high over the eastern Great
Lakes and a slowly filling Great Plains low is producing winds
gusts around 30 kts at terminals at midday. Gust should diminish
slowly this afternoon as high moves further east and the low
continues to fill. Winds should diminish even more quickly around
00z. A weak pre-frontal trough associated with the low is expected
to move into Illinois Thursday afternoon and produce a wind shift
to the northwest.

An increase in clouds and the development of CIGs is likely
late tonight and Thursday as a series of fast-moving northern
stream waves move across the Midwest. low-level moisture is
lacking and any CIGs are expected to remain IFR.

Barker
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 161903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
203 PM CDT WED APR 16 2014

.DISCUSSION...
313 AM CDT

WEATHER WITHOUT ANY SIGNIFICANT IMPACTS LOOKS TO BE THE RULE THROUGH
THE EARLY PART OF THE WEEKEND WITH MUCH OF THE ATTENTION ON
TEMPERATURES AND WIND SPEEDS TODAY AND THEN SMALL CHANCES FOR
PRECIPITATION THURSDAY NIGHT AND FRIDAY.

TODAY AND TONIGHT...
THE UPPER TROUGH RESPONSIBLE FOR THE CHILLY DAY YESTERDAY IS
ADVANCING EAST OVER EASTERN CANADA AND NEW ENGLAND AND IS
RESPONSIBLE FOR PORTIONS OF AT LEAST 22 STATES UNDER FREEZE WARNINGS
THIS MORNING! STRONG MID-LEVEL DRYING IS SEEN ALL THE WAY DOWN TO
THE NORTHERN GULF AND AT THE SURFACE THE DRY AIR HAS ADVANCED
SOUTHWARD ALL THE WAY INTO THE GULF WITH SEVERAL PLATFORMS/BUOYS
REPORTING DEW POINTS IN THE 30S. SO BASICALLY THE GULF IS NOT
AVAILABLE FOR THE NEXT SYSTEM PASSING ACROSS THE REGION TONIGHT AND
THAT WILL BE A MAIN REASON WE LOOK TO REMAIN PRECIPITATION FREE.
THIS SYSTEM IS A FAIRLY WELL-DEFINED LOW AMPLITUDE UPPER WAVE THAT
IS MOVING EAST ACROSS SD THIS MORNING AND WILL FOLLOW ITS PARENT JET
STREAK/DIVERGENCE ALOFT TO THE EAST NORTHEAST OVER THE UPPER GREAT
LAKES TONIGHT WHERE A SNOW STORM IS FORECAST ACROSS NORTHERN WI/U.P.
OF MICHIGAN.

THE QUICK EASTWARD PROGRESSION OF THE SYSTEM SURFACE LOW BY
AFTERNOON WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOCAL AREA.
WHILE THERE WILL BE SOME HIGH CLOUDS...MIXING WILL AID THE PRESSURE
GRADIENT IN CREATING SUSTAINED SPEEDS AROUND 20 MPH AND GUSTS PLUS
10 MPH OF THAT. SOME 35 MPH GUSTS SHOULD EVEN BE REALIZED IN NORTH
CENTRAL IL. TEMPERATURES LOOK TO BOUNCE BACK 15 DEGREES OR EVEN
HIGHER THAN YESTERDAY GIVEN WARMING OF THE BOUNDARY LAYER AND
LOW-LEVEL ADVECTION. A SLIGHT COMPONENT OFF THE LAKE INTO CITY OF
CHICAGO AND NORTHWARD WILL KEEP THESE LAKE ADJACENT AREAS A HANDFUL
OF DEGREES COOLER...BUT COMPARED TO 33 DEGREES YESTERDAY...THE
FORECAST OF AROUND 50 TODAY FOR THESE LOCATIONS SHOULD BE WELCOME.
OUTLYING AREAS LOOK TO REACH THE MID 50S. UPSTREAM DEW POINTS ARE IN
THE UPPER TEENS TO MID 20S ACROSS DOWNSTATE IL/IN INTO THE TENNESSEE
RIVER VALLEY...SO EXPECTING A FAIRLY DRY AIR MASS TODAY WITH
HUMIDITY IN THE 25-35 PERCENT RANGE IN MOST AREAS.

AS THE UPPER WAVE PASSES TO THE NORTH TONIGHT THE PACIFIC MOISTURE
REMAINS NORTH AS WELL AND THE WARM AIR ADVECTION ASCENT HERE REMAINS
WITHIN A LOW PWAT ATMOSPHERE. WOULD NOT BE SURPRISED TO SEE SOME
RADAR ECHOES/VIRGA ACROSS FAR NORTHERN IL BUT THAT SHOULD BE ABOUT
IT. WITH MORE CLOUD COVER TONIGHT AND SOUTHERLY WINDS OF 10-20 MPH
CONTINUING...LOWS LOOK TO ONLY DIP INTO THE LOWER-MID 40S.

THURSDAY AND FRIDAY...
THE SYSTEM SURFACE FRONT/TROUGH IS EXPECTED TO MOVE INTO THE
FORECAST AREA THURSDAY MORNING AND BECOME STATIONARY. THIS DOES NOT
LOOK TO BE A VERY PRONOUNCED BAROCLINIC BOUNDARY. HAVE CONSIDERABLY
LOWERED CLOUD COVER DURING THURSDAY MORNING AND EARLY AFTERNOON AND
WITH THAT BOOSTED TEMPERATURES SOME...WITH 55 TO 60 PROBABLE. A
SHEARING UPPER WAVE IS EXPECTED TO MOVE NORTHEAST OVER THE BOUNDARY
THURSDAY NIGHT. A LOOK AT THE DPROG/DT...OR TREND...OF SEVERAL
MODELS OVER THE PAST FOUR CYCLES SHOW CONSIDERABLY LESS FORCING AND
MOISTURE AVAILABILITY FOR PRECIPITATION. HAVE CONTINUED THE FORECAST
TREND TO CUT BACK POPS BUT ALSO TO CONFINE THE AREA WHERE
CONVERGENCE/FRONTOGENESIS IS DEPICTED NEAR THE BOUNDARY. BY FRIDAY
THE ENVELOPE OF GUIDANCE HAS FORCING EAST OF THE AREA...HOWEVER ONE
FINAL SEPARATE MID-LEVEL IMPULSE SEEN ON THE NCEP MODELS PASSES OVER
THE AREA FRIDAY AFTERNOON. CONTINUE A SMALL CHANCE OF RAIN SHOWERS
WITH THIS. THE NORTH TO NORTHEAST FLOW BEHIND THE FRONT ON FRIDAY
SHOULD LEAD TO A DECENT TEMPERATURE DIFFERENCE FROM NEAR THE LAKE TO
OUTLYING AREAS...WITH MID 40S TO MID 50S PRESENTLY FORECAST ACROSS
THAT CROSS SECTION. LOCAL CLIMATOLOGICAL RESEARCH FAVORS SUCH A
SPREAD THIS TIME OF YEAR WITH ONSHORE FLOW.

THIS WEEKEND INTO EARLY NEXT WEEK...
WHILE THE FLOW IS PROGRESSIVE ACROSS THE FAR NORTHERN CONUS/SOUTHERN
CANADA IT LOOKS TO BE FAR ENOUGH NORTH TO HAVE LITTLE INFLUENCE ON
THE AREA SATURDAY AND POTENTIALLY EVEN SUNDAY...ESPECIALLY IF GOING
TOWARD THE EC AND GEM WHICH WE HAVE LEANED OUR FORECAST. THESE
MODELS INDICATE THAT A CLOSED UPPER LOW OVER THE SOUTHEAST U.S.
DEPICTED BY MODELS LATE IN THE WEEKEND MAY LEAD TO A SLOWING OF THE
NEXT SYSTEM TO APPROACH THE AREA FROM THE ROCKIES...MORE SO SUNDAY
NIGHT AND MONDAY. TEMPERATURES LOOK TO BE BACK TO NORMAL SUNDAY AND
MONDAY.

MTF

&&

.AVIATION...

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

* STRONG SSE WINDS AND GUSTS POSING POTENTIAL CROSSWIND ISSUES
  THIS AFTERNOON AND EVENING.

* LLWS POSSIBLE OVERNIGHT AS GUSTS DIMINISH.

LENNING

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

A LOW PRESSURE CENTER LIFTING ACROSS IOWA INTO WISCONSIN TODAY AND
TONIGHT WILL SUPPORT GUSTY SSE WINDS OVER THE LOCAL TERMINALS TODAY.
GUSTS SHOULD DIMINISH OVERNIGHT WITH SFC COOLING AND BETTER LOW
LEVEL STABILITY...THOUGH STRONG WINDS ALOFT MAY CREATE MARGINAL
LLWS CONDITIONS. WINDS GRADUALLY TURN SOUTHWEST TOWARD MORNING
THEN AROUND TO THE WEST LATE TOMORROW AFTER THE LOW CROSSES LAKE
SUPERIOR AND A TRAILING COLD FRONT PASSES THROUGH THE AREA. PRECIP
CHANCES WITH THIS SYSTEM APPEAR LOW UNTIL LATE TOMORROW.

LENNING

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

* HIGH CONFIDENCE IN ALL ELEMENTS EXCEPT FOR LLWS TONIGHT.

LENNING

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

THURSDAY NIGHT...CHC RAIN. MVFR PSBL.
FRIDAY...SLT CHC RAIN. MVFR PSBL.
SATURDAY...VFR.
SUNDAY...CHC RAIN.
MONDAY...SLT CHC RAIN.
TUESDAY...VFR.

BMD

&&

.MARINE...
203 PM CDT

LOW PRESSURE...CURRENTLY ACROSS FAR WESTERN IOWA...WILL SHIFT
NORTHEASTWARD ACROSS THE UPPER LAKES REGION BY LATE
THURSDAY...WHILE WEAKENING. THIS WILL RESULT IN A CONTINUATION OF
THE SOUTH-SOUTHEASTERLY WINDS ACROSS THE LAKE TONIGHT AROUND 30 KT
RANGE. HOWEVER...AS A WEAK FRONTAL BOUNDARY MOVES ACROSS THE LAKE ON
THURSDAY...THE WINDS ABATE AND BECOME WEST-NORTHWESTERLY BY THURSDAY
EVENING. GENERALLY LIGHT NORTHERLY FLOW IS EXPECTED FRIDAY AND INTO
EARLY SATURDAY AS A WEAK SURFACE RIDGE OF HIGH PRESSURE BUILDS OVER
THE LAKE. THE WINDS LOOK TO INCREASE AGAIN OUT OF THE
SOUTH-SOUTHEAST LATER SATURDAY/SATURDAY EVENING AS THIS SURFACE
RIDGE SHIFTS EAST OF THE LAKES AND ANOTHER LOW TAKES SHAPE ACROSS
THE PLAINS.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 AM THURSDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KLOT 161811
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
111 PM CDT WED APR 16 2014

.DISCUSSION...
313 AM CDT

WEATHER WITHOUT ANY SIGNIFICANT IMPACTS LOOKS TO BE THE RULE THROUGH
THE EARLY PART OF THE WEEKEND WITH MUCH OF THE ATTENTION ON
TEMPERATURES AND WIND SPEEDS TODAY AND THEN SMALL CHANCES FOR
PRECIPITATION THURSDAY NIGHT AND FRIDAY.

TODAY AND TONIGHT...
THE UPPER TROUGH RESPONSIBLE FOR THE CHILLY DAY YESTERDAY IS
ADVANCING EAST OVER EASTERN CANADA AND NEW ENGLAND AND IS
RESPONSIBLE FOR PORTIONS OF AT LEAST 22 STATES UNDER FREEZE WARNINGS
THIS MORNING! STRONG MID-LEVEL DRYING IS SEEN ALL THE WAY DOWN TO
THE NORTHERN GULF AND AT THE SURFACE THE DRY AIR HAS ADVANCED
SOUTHWARD ALL THE WAY INTO THE GULF WITH SEVERAL PLATFORMS/BUOYS
REPORTING DEW POINTS IN THE 30S. SO BASICALLY THE GULF IS NOT
AVAILABLE FOR THE NEXT SYSTEM PASSING ACROSS THE REGION TONIGHT AND
THAT WILL BE A MAIN REASON WE LOOK TO REMAIN PRECIPITATION FREE.
THIS SYSTEM IS A FAIRLY WELL-DEFINED LOW AMPLITUDE UPPER WAVE THAT
IS MOVING EAST ACROSS SD THIS MORNING AND WILL FOLLOW ITS PARENT JET
STREAK/DIVERGENCE ALOFT TO THE EAST NORTHEAST OVER THE UPPER GREAT
LAKES TONIGHT WHERE A SNOW STORM IS FORECAST ACROSS NORTHERN WI/U.P.
OF MICHIGAN.

THE QUICK EASTWARD PROGRESSION OF THE SYSTEM SURFACE LOW BY
AFTERNOON WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOCAL AREA.
WHILE THERE WILL BE SOME HIGH CLOUDS...MIXING WILL AID THE PRESSURE
GRADIENT IN CREATING SUSTAINED SPEEDS AROUND 20 MPH AND GUSTS PLUS
10 MPH OF THAT. SOME 35 MPH GUSTS SHOULD EVEN BE REALIZED IN NORTH
CENTRAL IL. TEMPERATURES LOOK TO BOUNCE BACK 15 DEGREES OR EVEN
HIGHER THAN YESTERDAY GIVEN WARMING OF THE BOUNDARY LAYER AND
LOW-LEVEL ADVECTION. A SLIGHT COMPONENT OFF THE LAKE INTO CITY OF
CHICAGO AND NORTHWARD WILL KEEP THESE LAKE ADJACENT AREAS A HANDFUL
OF DEGREES COOLER...BUT COMPARED TO 33 DEGREES YESTERDAY...THE
FORECAST OF AROUND 50 TODAY FOR THESE LOCATIONS SHOULD BE WELCOME.
OUTLYING AREAS LOOK TO REACH THE MID 50S. UPSTREAM DEW POINTS ARE IN
THE UPPER TEENS TO MID 20S ACROSS DOWNSTATE IL/IN INTO THE TENNESSEE
RIVER VALLEY...SO EXPECTING A FAIRLY DRY AIR MASS TODAY WITH
HUMIDITY IN THE 25-35 PERCENT RANGE IN MOST AREAS.

AS THE UPPER WAVE PASSES TO THE NORTH TONIGHT THE PACIFIC MOISTURE
REMAINS NORTH AS WELL AND THE WARM AIR ADVECTION ASCENT HERE REMAINS
WITHIN A LOW PWAT ATMOSPHERE. WOULD NOT BE SURPRISED TO SEE SOME
RADAR ECHOES/VIRGA ACROSS FAR NORTHERN IL BUT THAT SHOULD BE ABOUT
IT. WITH MORE CLOUD COVER TONIGHT AND SOUTHERLY WINDS OF 10-20 MPH
CONTINUING...LOWS LOOK TO ONLY DIP INTO THE LOWER-MID 40S.

THURSDAY AND FRIDAY...
THE SYSTEM SURFACE FRONT/TROUGH IS EXPECTED TO MOVE INTO THE
FORECAST AREA THURSDAY MORNING AND BECOME STATIONARY. THIS DOES NOT
LOOK TO BE A VERY PRONOUNCED BAROCLINIC BOUNDARY. HAVE CONSIDERABLY
LOWERED CLOUD COVER DURING THURSDAY MORNING AND EARLY AFTERNOON AND
WITH THAT BOOSTED TEMPERATURES SOME...WITH 55 TO 60 PROBABLE. A
SHEARING UPPER WAVE IS EXPECTED TO MOVE NORTHEAST OVER THE BOUNDARY
THURSDAY NIGHT. A LOOK AT THE DPROG/DT...OR TREND...OF SEVERAL
MODELS OVER THE PAST FOUR CYCLES SHOW CONSIDERABLY LESS FORCING AND
MOISTURE AVAILABILITY FOR PRECIPITATION. HAVE CONTINUED THE FORECAST
TREND TO CUT BACK POPS BUT ALSO TO CONFINE THE AREA WHERE
CONVERGENCE/FRONTOGENESIS IS DEPICTED NEAR THE BOUNDARY. BY FRIDAY
THE ENVELOPE OF GUIDANCE HAS FORCING EAST OF THE AREA...HOWEVER ONE
FINAL SEPARATE MID-LEVEL IMPULSE SEEN ON THE NCEP MODELS PASSES OVER
THE AREA FRIDAY AFTERNOON. CONTINUE A SMALL CHANCE OF RAIN SHOWERS
WITH THIS. THE NORTH TO NORTHEAST FLOW BEHIND THE FRONT ON FRIDAY
SHOULD LEAD TO A DECENT TEMPERATURE DIFFERENCE FROM NEAR THE LAKE TO
OUTLYING AREAS...WITH MID 40S TO MID 50S PRESENTLY FORECAST ACROSS
THAT CROSS SECTION. LOCAL CLIMATOLOGICAL RESEARCH FAVORS SUCH A
SPREAD THIS TIME OF YEAR WITH ONSHORE FLOW.

THIS WEEKEND INTO EARLY NEXT WEEK...
WHILE THE FLOW IS PROGRESSIVE ACROSS THE FAR NORTHERN CONUS/SOUTHERN
CANADA IT LOOKS TO BE FAR ENOUGH NORTH TO HAVE LITTLE INFLUENCE ON
THE AREA SATURDAY AND POTENTIALLY EVEN SUNDAY...ESPECIALLY IF GOING
TOWARD THE EC AND GEM WHICH WE HAVE LEANED OUR FORECAST. THESE
MODELS INDICATE THAT A CLOSED UPPER LOW OVER THE SOUTHEAST U.S.
DEPICTED BY MODELS LATE IN THE WEEKEND MAY LEAD TO A SLOWING OF THE
NEXT SYSTEM TO APPROACH THE AREA FROM THE ROCKIES...MORE SO SUNDAY
NIGHT AND MONDAY. TEMPERATURES LOOK TO BE BACK TO NORMAL SUNDAY AND
MONDAY.

MTF

&&

.AVIATION...

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

* STRONG SSE WINDS AND GUSTS POSING POTENTIAL CROSSWIND ISSUES
  THIS AFTERNOON AND EVENING.

* LLWS POSSIBLE OVERNIGHT AS GUSTS DIMINISH.

LENNING

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

A LOW PRESSURE CENTER LIFTING ACROSS IOWA INTO WISCONSIN TODAY AND
TONIGHT WILL SUPPORT GUSTY SSE WINDS OVER THE LOCAL TERMINALS TODAY.
GUSTS SHOULD DIMINISH OVERNIGHT WITH SFC COOLING AND BETTER LOW
LEVEL STABILITY...THOUGH STRONG WINDS ALOFT MAY CREATE MARGINAL
LLWS CONDITIONS. WINDS GRADUALLY TURN SOUTHWEST TOWARD MORNING
THEN AROUND TO THE WEST LATE TOMORROW AFTER THE LOW CROSSES LAKE
SUPERIOR AND A TRAILING COLD FRONT PASSES THROUGH THE AREA. PRECIP
CHANCES WITH THIS SYSTEM APPEAR LOW UNTIL LATE TOMORROW.

LENNING


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

* HIGH CONFIDENCE IN ALL ELEMENTS EXCEPT FOR LLWS TONIGHT.

LENNING

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

THURSDAY NIGHT...CHC RAIN. MVFR PSBL.
FRIDAY...SLT CHC RAIN. MVFR PSBL.
SATURDAY...VFR.
SUNDAY...CHC RAIN.
MONDAY...SLT CHC RAIN.
TUESDAY...VFR.

BMD

&&

.MARINE...
242 AM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN TODAY
WHILE LOW PRESSURE MOVES EAST ACROSS THE NORTHERN PLAINS ALLOWING A
SOUTHERLY GRADIENT TO SET UP ACROSS LAKE MICHIGAN. WINDS WILL
STEADILY INCREASE THROUGH THE DAY TOPPING OUT AROUND 30 KT THIS
EVENING AND TONIGHT. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
THE INDIANA AND ILLINOIS NEARSHORE WATERS TODAY THROUGH TONIGHT.
STABLE CONDITIONS WILL PREVENT STRONGER WINDS FROM REACHING THE LAKE
SURFACE. THE LOW WILL BEGIN TO FILL THURSDAY AS IT LIFTS ACROSS FAR
NORTHERN LAKE MICHIGAN...THEN HIGH PRESSURE WILL BUILD OVER LAKE
MICHIGAN LATE IT THE WEEK INTO THE WEEKEND.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KILX 161719
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1219 PM CDT Wed Apr 16 2014

.DISCUSSION...
ISSUED 1021 AM CDT WED APR 16 2014

Low pressure in South Dakota will move east into Iowa and then
northeast toward Lake Huron. As it progresses, a warm front will
lift across IL, putting our forecast area in the warm sector by
this evening. During the day, southerly winds will increase as the
pressure gradient tightens between departing high pressure and the
SD low. 12z RAP forecast soundings show mixing heights up to
825-850 mb. That should allow momentum transfer of wind speeds
around 25 mph with some gusts to 35 mph. We expect to remain below
wind advisory criteria of 30-39 mph sustained winds for an hour or
more. Peak winds appear to be in the Noon to 3 pm time frame.

Mixing of dry air from the mid levels will help the surface temps
climb about 10 to 15 deg warmer than yesterday. Lightly filtered
sunshine will also help boost high temps, with readings in the mid
to upper 50s by 3-4 pm.

We should remain dry until the cold front pushes across IL
sometime late Thursday/Thursday night. Still, limited moisture
will keep rain chances and amounts on the low side.

Our current forecast grids look on track over the next 12-24 hours,
especially temps, dewpoints, winds and sky. No formal update will
be needed this morning.

Shimon
&&

.AVIATION...
ISSUED 1218 PM CDT Wed Apr 16 2014

pressure gradient between 1032 MB high over the eastern Great
Lakes and a slowly filling Great Plains low is producing winds
gusts around 30 kts at terminals at midday. Gust should diminish
slowly this afternoon as high moves further east and the low
continues to fill. Winds should diminish even more quickly around
00z. A weak pre-frontal trough associated with the low is expected
to move into Illinois Thursday afternoon and produce a wind shift
to the northwest.

An increase in clouds and the development of CIGs is likely
late tonight and Thursday as a series of fast-moving northern
stream waves move across the Midwest. low-level moisture is
lacking and any CIGs are expected to remain IFR.

Barker
&&

.PREV DISCUSSION...
ISSUED 249 AM CDT WED APR 16 2014

SHORT TERM...Today through Friday

Winds will increase markedly across central Illinois today as
gradient tightens between departing high pressure system and low
tracking from the Dakotas into southern Minnesota. Models are not
quite as strong with the winds as they were in previous runs, so
am not concerned about reaching Wind Advisory criteria. BUFKIT
momentum transfer at KPIA shows 33kt winds at the top of the mixed
layer this afternoon, as opposed to 43kt on the prior run just 24
hours ago. Despite this decrease in momentum, think S/SE winds
will gust to between 30 and 35mph across the western half of the
KILX CWA, with gusts to around 25mph further east near the
Indiana border. This strong southerly flow will help bring much
warmer air into the region. Extent of warming will be mitigated
somewhat by an easterly component to the wind and mixing heights
lowering to less than 5000ft. Resulting afternoon highs will range
from the middle 50s east to around 60 far west.

As southern Minnesota low lifts toward Lake Superior, it will
drag a weak cold front into the Illinois River Valley by dawn
Thursday. This boundary will become stationary along the I-55
corridor during the day Thursday, creating little in the way of
sensible weather. A mid-level short-wave will approach from the
southwest late in the day and will eventually interact with the
front to perhaps produce a few light showers. Current surface
analysis shows a very dry air mass has settled across the eastern
half of the CONUS all the way to the Gulf of Mexico. In fact,
buoys in the northern Gulf are currently showing dew points as low
as the middle to upper 30s. With so much dry air to the south, do
not think front will have enough moisture to work with in order to
produce precip across the area on Thursday. GFS is the only model
that is holding on to QPF across the Illinois River Valley
Thursday afternoon, but think this is overdone. Will therefore go
with a dry forecast across the board. There are even some
indications that dry conditions will continue Thursday night into
Friday as the upper wave arrives. At this point, will leave chance
PoPs for showers in the forecast Thursday night into Friday
morning as synoptic lift associated with the wave will likely be
enough to squeeze a few light showers out of the dry air mass. Once
the wave passes, dry weather will return Friday afternoon and
night.

LONG TERM...Saturday through Tuesday

After a warm/dry day on Saturday, attention turns to next
approaching system for early next week. Models have been trending
slower with its approach, with most 00z Apr 16 guidance suggesting
Easter Sunday may remain largely dry. GFS is the most aggressive
model in driving precip eastward into the area, but even it has
backed off and keeps rain at bay until Sunday afternoon at the
earliest. GEM focuses best rain chances Sunday night into Monday,
while ECMWF is even slower and advertises mainly a Monday rain
event. As a result of the distinct slowing trend, have trimmed
PoPs accordingly. Will keep Saturday night and Sunday morning dry,
then will bring chance PoPs into the picture across the western
CWA Sunday afternoon. Will highlight the Sunday night/Monday time
frame with the highest PoPs, followed by a return to dry weather
on Tuesday. Aside from the early week rain chances, the extended
forecast will feature warmer weather, with model guidance
suggesting temps reaching the 70s by Tuesday.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 161525 CCA
AFDILX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE LINCOLN IL
1024 AM CDT WED APR 16 2014

.DISCUSSION...
ISSUED 1021 AM CDT WED APR 16 2014

LOW PRESSURE IN SOUTH DAKOTA WILL MOVE EAST INTO IOWA AND THEN
NORTHEAST TOWARD LAKE HURON. AS IT PROGRESSES, A WARM FRONT WILL
LIFT ACROSS IL, PUTTING OUR FORECAST AREA IN THE WARM SECTOR BY
THIS EVENING. DURING THE DAY, SOUTHERLY WINDS WILL INCREASE AS THE
PRESSURE GRADIENT TIGHTENS BETWEEN DEPARTING HIGH PRESSURE AND THE
SD LOW. 12Z RAP FORECAST SOUNDINGS SHOW MIXING HEIGHTS UP TO
825-850 MB. THAT SHOULD ALLOW MOMENTUM TRANSFER OF WIND SPEEDS
AROUND 25 MPH WITH SOME GUSTS TO 35 MPH. WE EXPECT TO REMAIN BELOW
WIND ADVISORY CRITERIA OF 30-39 MPH SUSTAINED WINDS FOR AN HOUR OR
MORE. PEAK WINDS APPEAR TO BE IN THE NOON TO 3 PM TIME FRAME.

MIXING OF DRY AIR FROM THE MID LEVELS WILL HELP THE SURFACE TEMPS
CLIMB ABOUT 10 TO 15 DEG WARMER THAN YESTERDAY. LIGHTLY FILTERED
SUNSHINE WILL ALSO HELP BOOST HIGH TEMPS, WITH READINGS IN THE MID
TO UPPER 50S BY 3-4 PM.

WE SHOULD REMAIN DRY UNTIL THE COLD FRONT PUSHES ACROSS IL
SOMETIME LATE THURSDAY/THURSDAY NIGHT. STILL, LIMITED MOISTURE
WILL KEEP RAIN CHANCES AND AMOUNTS ON THE LOW SIDE.

OUR CURRENT FORECAST GRIDS LOOK ON TRACK OVER THE NEXT 12-24 HOURS,
ESPECIALLY TEMPS, DEWPOINTS, WINDS AND SKY. NO FORMAL UPDATE WILL
BE NEEDED THIS MORNING.

SHIMON
&&

.AVIATION...
ISSUED 556 AM CDT WED APR 16 2014

LITTLE CHANGE NEEDED TO PREVIOUS TAF SET. WIND WILL BE THE MAIN
CONCERN THROUGH THIS AFTERNOON. SOUTHERLY WIND GUSTS AROUND 30
KNOTS ARE EXPECTED TO DEVELOP NEAR ALL TAF SITES BY LATE MORNING,
AND CONTINUE THROUGH THE AFTERNOON. MAY SEE SOME EVEN HIGHER AT
KPIA. WE WILL LOSE THE GUSTS WITH SUNSET, BUT SUSTAINED WINDS WILL
STILL AVERAGE AROUND 15 KNOTS MUCH OF THE NIGHT. LATE IN THE
PERIOD, WINDS WILL START TO SHIFT MORE TO THE SOUTHWEST, AHEAD OF
A COLD FRONT WHICH WILL MOVE THROUGH THE AREA LATER ON THURSDAY.

GEELHART
&&

.PREV DISCUSSION...
ISSUED 249 AM CDT WED APR 16 2014

SHORT TERM...TODAY THROUGH FRIDAY

WINDS WILL INCREASE MARKEDLY ACROSS CENTRAL ILLINOIS TODAY AS
GRADIENT TIGHTENS BETWEEN DEPARTING HIGH PRESSURE SYSTEM AND LOW
TRACKING FROM THE DAKOTAS INTO SOUTHERN MINNESOTA. MODELS ARE NOT
QUITE AS STRONG WITH THE WINDS AS THEY WERE IN PREVIOUS RUNS, SO
AM NOT CONCERNED ABOUT REACHING WIND ADVISORY CRITERIA. BUFKIT
MOMENTUM TRANSFER AT KPIA SHOWS 33KT WINDS AT THE TOP OF THE MIXED
LAYER THIS AFTERNOON, AS OPPOSED TO 43KT ON THE PRIOR RUN JUST 24
HOURS AGO. DESPITE THIS DECREASE IN MOMENTUM, THINK S/SE WINDS
WILL GUST TO BETWEEN 30 AND 35MPH ACROSS THE WESTERN HALF OF THE
KILX CWA, WITH GUSTS TO AROUND 25MPH FURTHER EAST NEAR THE
INDIANA BORDER. THIS STRONG SOUTHERLY FLOW WILL HELP BRING MUCH
WARMER AIR INTO THE REGION. EXTENT OF WARMING WILL BE MITIGATED
SOMEWHAT BY AN EASTERLY COMPONENT TO THE WIND AND MIXING HEIGHTS
LOWERING TO LESS THAN 5000FT. RESULTING AFTERNOON HIGHS WILL RANGE
FROM THE MIDDLE 50S EAST TO AROUND 60 FAR WEST.

AS SOUTHERN MINNESOTA LOW LIFTS TOWARD LAKE SUPERIOR, IT WILL
DRAG A WEAK COLD FRONT INTO THE ILLINOIS RIVER VALLEY BY DAWN
THURSDAY. THIS BOUNDARY WILL BECOME STATIONARY ALONG THE I-55
CORRIDOR DURING THE DAY THURSDAY, CREATING LITTLE IN THE WAY OF
SENSIBLE WEATHER. A MID-LEVEL SHORT-WAVE WILL APPROACH FROM THE
SOUTHWEST LATE IN THE DAY AND WILL EVENTUALLY INTERACT WITH THE
FRONT TO PERHAPS PRODUCE A FEW LIGHT SHOWERS. CURRENT SURFACE
ANALYSIS SHOWS A VERY DRY AIR MASS HAS SETTLED ACROSS THE EASTERN
HALF OF THE CONUS ALL THE WAY TO THE GULF OF MEXICO. IN FACT,
BUOYS IN THE NORTHERN GULF ARE CURRENTLY SHOWING DEW POINTS AS LOW
AS THE MIDDLE TO UPPER 30S. WITH SO MUCH DRY AIR TO THE SOUTH, DO
NOT THINK FRONT WILL HAVE ENOUGH MOISTURE TO WORK WITH IN ORDER TO
PRODUCE PRECIP ACROSS THE AREA ON THURSDAY. GFS IS THE ONLY MODEL
THAT IS HOLDING ON TO QPF ACROSS THE ILLINOIS RIVER VALLEY
THURSDAY AFTERNOON, BUT THINK THIS IS OVERDONE. WILL THEREFORE GO
WITH A DRY FORECAST ACROSS THE BOARD. THERE ARE EVEN SOME
INDICATIONS THAT DRY CONDITIONS WILL CONTINUE THURSDAY NIGHT INTO
FRIDAY AS THE UPPER WAVE ARRIVES. AT THIS POINT, WILL LEAVE CHANCE
POPS FOR SHOWERS IN THE FORECAST THURSDAY NIGHT INTO FRIDAY
MORNING AS SYNOPTIC LIFT ASSOCIATED WITH THE WAVE WILL LIKELY BE
ENOUGH TO SQUEEZE A FEW LIGHT SHOWERS OUT OF THE DRY AIR MASS. ONCE
THE WAVE PASSES, DRY WEATHER WILL RETURN FRIDAY AFTERNOON AND
NIGHT.

LONG TERM...SATURDAY THROUGH TUESDAY

AFTER A WARM/DRY DAY ON SATURDAY, ATTENTION TURNS TO NEXT
APPROACHING SYSTEM FOR EARLY NEXT WEEK. MODELS HAVE BEEN TRENDING
SLOWER WITH ITS APPROACH, WITH MOST 00Z APR 16 GUIDANCE SUGGESTING
EASTER SUNDAY MAY REMAIN LARGELY DRY. GFS IS THE MOST AGGRESSIVE
MODEL IN DRIVING PRECIP EASTWARD INTO THE AREA, BUT EVEN IT HAS
BACKED OFF AND KEEPS RAIN AT BAY UNTIL SUNDAY AFTERNOON AT THE
EARLIEST. GEM FOCUSES BEST RAIN CHANCES SUNDAY NIGHT INTO MONDAY,
WHILE ECMWF IS EVEN SLOWER AND ADVERTISES MAINLY A MONDAY RAIN
EVENT. AS A RESULT OF THE DISTINCT SLOWING TREND, HAVE TRIMMED
POPS ACCORDINGLY. WILL KEEP SATURDAY NIGHT AND SUNDAY MORNING DRY,
THEN WILL BRING CHANCE POPS INTO THE PICTURE ACROSS THE WESTERN
CWA SUNDAY AFTERNOON. WILL HIGHLIGHT THE SUNDAY NIGHT/MONDAY TIME
FRAME WITH THE HIGHEST POPS, FOLLOWED BY A RETURN TO DRY WEATHER
ON TUESDAY. ASIDE FROM THE EARLY WEEK RAIN CHANCES, THE EXTENDED
FORECAST WILL FEATURE WARMER WEATHER, WITH MODEL GUIDANCE
SUGGESTING TEMPS REACHING THE 70S BY TUESDAY.

BARNES

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$










000
FXUS63 KILX 161521
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1021 AM CDT Wed Apr 16 2014

.DISCUSSION...
ISSUED 1021 AM CDT Wed Apr 16 2014

Low pressure in South Dakota sill move east into Iowa and then
northeast toward Lake Huron. As it progresses, a warm front will
lift across IL, putting our forecast area in the warm sector by
this evening. During the day, southerly winds will increase as the
pressure gradient tightens between departing high pressure and the
SD low. 12z RAP forecast soundings show mixing heights up to
825-850 mb. That should allow momentum transfer of wind speeds
around 25 mph with some gusts to 35 mph. We expect to remain
below wind advisory criteria of 30-39 mph sustained winds for an
hour or more. Peak winds appear to be in the Noon to 3 pm time
frame.

Mixing of dry air from the mid levels will help the surface temps
climb about 10 to 15 deg warmer than yesterday. Lightly filtered
sunshine will also help boost high temps, with readings in the mid
to upper 50s by 3-4 pm.

We should remain dry until the cold front pushes across IL
sometime late Thursday/Thursday night. Still, limited moisture
will keep rain chances and amounts on the low side.

Our current forecast grids look on track over the next 12-24 hours,
especially temps, dewpoints, winds and sky. No formal update will
be needed this morning.

Shimon
&&

.AVIATION...
ISSUED 556 AM CDT Wed Apr 16 2014

Little change needed to previous TAF set. Wind will be the main
concern through this afternoon. Southerly wind gusts around 30
knots are expected to develop near all TAF sites by late morning,
and continue through the afternoon. May see some even higher at
KPIA. We will lose the gusts with sunset, but sustained winds will
still average around 15 knots much of the night. Late in the
period, winds will start to shift more to the southwest, ahead of
a cold front which will move through the area later on Thursday.

Geelhart
&&

.PREV DISCUSSION...
ISSUED 249 AM CDT Wed Apr 16 2014

SHORT TERM...Today through Friday

Winds will increase markedly across central Illinois today as
gradient tightens between departing high pressure system and low
tracking from the Dakotas into southern Minnesota. Models are not
quite as strong with the winds as they were in previous runs, so
am not concerned about reaching Wind Advisory criteria. BUFKIT
momentum transfer at KPIA shows 33kt winds at the top of the mixed
layer this afternoon, as opposed to 43kt on the prior run just 24
hours ago. Despite this decrease in momentum, think S/SE winds
will gust to between 30 and 35mph across the western half of the
KILX CWA, with gusts to around 25mph further east near the
Indiana border. This strong southerly flow will help bring much
warmer air into the region. Extent of warming will be mitigated
somewhat by an easterly component to the wind and mixing heights
lowering to less than 5000ft. Resulting afternoon highs will range
from the middle 50s east to around 60 far west.

As southern Minnesota low lifts toward Lake Superior, it will
drag a weak cold front into the Illinois River Valley by dawn
Thursday. This boundary will become stationary along the I-55
corridor during the day Thursday, creating little in the way of
sensible weather. A mid-level short-wave will approach from the
southwest late in the day and will eventually interact with the
front to perhaps produce a few light showers. Current surface
analysis shows a very dry air mass has settled across the eastern
half of the CONUS all the way to the Gulf of Mexico. In fact,
buoys in the northern Gulf are currently showing dew points as low
as the middle to upper 30s. With so much dry air to the south, do
not think front will have enough moisture to work with in order to
produce precip across the area on Thursday. GFS is the only model
that is holding on to QPF across the Illinois River Valley
Thursday afternoon, but think this is overdone. Will therefore go
with a dry forecast across the board. There are even some
indications that dry conditions will continue Thursday night into
Friday as the upper wave arrives. At this point, will leave chance
PoPs for showers in the forecast Thursday night into Friday
morning as synoptic lift associated with the wave will likely be
enough to squeeze a few light showers out of the dry air mass. Once
the wave passes, dry weather will return Friday afternoon and
night.

LONG TERM...Saturday through Tuesday

After a warm/dry day on Saturday, attention turns to next
approaching system for early next week. Models have been trending
slower with its approach, with most 00z Apr 16 guidance suggesting
Easter Sunday may remain largely dry. GFS is the most aggressive
model in driving precip eastward into the area, but even it has
backed off and keeps rain at bay until Sunday afternoon at the
earliest. GEM focuses best rain chances Sunday night into Monday,
while ECMWF is even slower and advertises mainly a Monday rain
event. As a result of the distinct slowing trend, have trimmed
PoPs accordingly. Will keep Saturday night and Sunday morning dry,
then will bring chance PoPs into the picture across the western
CWA Sunday afternoon. Will highlight the Sunday night/Monday time
frame with the highest PoPs, followed by a return to dry weather
on Tuesday. Aside from the early week rain chances, the extended
forecast will feature warmer weather, with model guidance
suggesting temps reaching the 70s by Tuesday.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 161411
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
911 AM CDT WED APR 16 2014

.DISCUSSION...
313 AM CDT

WEATHER WITHOUT ANY SIGNIFICANT IMPACTS LOOKS TO BE THE RULE THROUGH
THE EARLY PART OF THE WEEKEND WITH MUCH OF THE ATTENTION ON
TEMPERATURES AND WIND SPEEDS TODAY AND THEN SMALL CHANCES FOR
PRECIPITATION THURSDAY NIGHT AND FRIDAY.

TODAY AND TONIGHT...
THE UPPER TROUGH RESPONSIBLE FOR THE CHILLY DAY YESTERDAY IS
ADVANCING EAST OVER EASTERN CANADA AND NEW ENGLAND AND IS
RESPONSIBLE FOR PORTIONS OF AT LEAST 22 STATES UNDER FREEZE WARNINGS
THIS MORNING! STRONG MID-LEVEL DRYING IS SEEN ALL THE WAY DOWN TO
THE NORTHERN GULF AND AT THE SURFACE THE DRY AIR HAS ADVANCED
SOUTHWARD ALL THE WAY INTO THE GULF WITH SEVERAL PLATFORMS/BUOYS
REPORTING DEW POINTS IN THE 30S. SO BASICALLY THE GULF IS NOT
AVAILABLE FOR THE NEXT SYSTEM PASSING ACROSS THE REGION TONIGHT AND
THAT WILL BE A MAIN REASON WE LOOK TO REMAIN PRECIPITATION FREE.
THIS SYSTEM IS A FAIRLY WELL-DEFINED LOW AMPLITUDE UPPER WAVE THAT
IS MOVING EAST ACROSS SD THIS MORNING AND WILL FOLLOW ITS PARENT JET
STREAK/DIVERGENCE ALOFT TO THE EAST NORTHEAST OVER THE UPPER GREAT
LAKES TONIGHT WHERE A SNOW STORM IS FORECAST ACROSS NORTHERN WI/U.P.
OF MICHIGAN.

THE QUICK EASTWARD PROGRESSION OF THE SYSTEM SURFACE LOW BY
AFTERNOON WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOCAL AREA.
WHILE THERE WILL BE SOME HIGH CLOUDS...MIXING WILL AID THE PRESSURE
GRADIENT IN CREATING SUSTAINED SPEEDS AROUND 20 MPH AND GUSTS PLUS
10 MPH OF THAT. SOME 35 MPH GUSTS SHOULD EVEN BE REALIZED IN NORTH
CENTRAL IL. TEMPERATURES LOOK TO BOUNCE BACK 15 DEGREES OR EVEN
HIGHER THAN YESTERDAY GIVEN WARMING OF THE BOUNDARY LAYER AND
LOW-LEVEL ADVECTION. A SLIGHT COMPONENT OFF THE LAKE INTO CITY OF
CHICAGO AND NORTHWARD WILL KEEP THESE LAKE ADJACENT AREAS A HANDFUL
OF DEGREES COOLER...BUT COMPARED TO 33 DEGREES YESTERDAY...THE
FORECAST OF AROUND 50 TODAY FOR THESE LOCATIONS SHOULD BE WELCOME.
OUTLYING AREAS LOOK TO REACH THE MID 50S. UPSTREAM DEW POINTS ARE IN
THE UPPER TEENS TO MID 20S ACROSS DOWNSTATE IL/IN INTO THE TENNESSEE
RIVER VALLEY...SO EXPECTING A FAIRLY DRY AIR MASS TODAY WITH
HUMIDITY IN THE 25-35 PERCENT RANGE IN MOST AREAS.

AS THE UPPER WAVE PASSES TO THE NORTH TONIGHT THE PACIFIC MOISTURE
REMAINS NORTH AS WELL AND THE WARM AIR ADVECTION ASCENT HERE REMAINS
WITHIN A LOW PWAT ATMOSPHERE. WOULD NOT BE SURPRISED TO SEE SOME
RADAR ECHOES/VIRGA ACROSS FAR NORTHERN IL BUT THAT SHOULD BE ABOUT
IT. WITH MORE CLOUD COVER TONIGHT AND SOUTHERLY WINDS OF 10-20 MPH
CONTINUING...LOWS LOOK TO ONLY DIP INTO THE LOWER-MID 40S.

THURSDAY AND FRIDAY...
THE SYSTEM SURFACE FRONT/TROUGH IS EXPECTED TO MOVE INTO THE
FORECAST AREA THURSDAY MORNING AND BECOME STATIONARY. THIS DOES NOT
LOOK TO BE A VERY PRONOUNCED BAROCLINIC BOUNDARY. HAVE CONSIDERABLY
LOWERED CLOUD COVER DURING THURSDAY MORNING AND EARLY AFTERNOON AND
WITH THAT BOOSTED TEMPERATURES SOME...WITH 55 TO 60 PROBABLE. A
SHEARING UPPER WAVE IS EXPECTED TO MOVE NORTHEAST OVER THE BOUNDARY
THURSDAY NIGHT. A LOOK AT THE DPROG/DT...OR TREND...OF SEVERAL
MODELS OVER THE PAST FOUR CYCLES SHOW CONSIDERABLY LESS FORCING AND
MOISTURE AVAILABILITY FOR PRECIPITATION. HAVE CONTINUED THE FORECAST
TREND TO CUT BACK POPS BUT ALSO TO CONFINE THE AREA WHERE
CONVERGENCE/FRONTOGENESIS IS DEPICTED NEAR THE BOUNDARY. BY FRIDAY
THE ENVELOPE OF GUIDANCE HAS FORCING EAST OF THE AREA...HOWEVER ONE
FINAL SEPARATE MID-LEVEL IMPULSE SEEN ON THE NCEP MODELS PASSES OVER
THE AREA FRIDAY AFTERNOON. CONTINUE A SMALL CHANCE OF RAIN SHOWERS
WITH THIS. THE NORTH TO NORTHEAST FLOW BEHIND THE FRONT ON FRIDAY
SHOULD LEAD TO A DECENT TEMPERATURE DIFFERENCE FROM NEAR THE LAKE TO
OUTLYING AREAS...WITH MID 40S TO MID 50S PRESENTLY FORECAST ACROSS
THAT CROSS SECTION. LOCAL CLIMATOLOGICAL RESEARCH FAVORS SUCH A
SPREAD THIS TIME OF YEAR WITH ONSHORE FLOW.

THIS WEEKEND INTO EARLY NEXT WEEK...
WHILE THE FLOW IS PROGRESSIVE ACROSS THE FAR NORTHERN CONUS/SOUTHERN
CANADA IT LOOKS TO BE FAR ENOUGH NORTH TO HAVE LITTLE INFLUENCE ON
THE AREA SATURDAY AND POTENTIALLY EVEN SUNDAY...ESPECIALLY IF GOING
TOWARD THE EC AND GEM WHICH WE HAVE LEANED OUR FORECAST. THESE
MODELS INDICATE THAT A CLOSED UPPER LOW OVER THE SOUTHEAST U.S.
DEPICTED BY MODELS LATE IN THE WEEKEND MAY LEAD TO A SLOWING OF THE
NEXT SYSTEM TO APPROACH THE AREA FROM THE ROCKIES...MORE SO SUNDAY
NIGHT AND MONDAY. TEMPERATURES LOOK TO BE BACK TO NORMAL SUNDAY AND
MONDAY.

MTF

&&

.AVIATION...

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

* INCREASING WIND SPEEDS AND GUSTS WITH SOUTHERLY OR SOUTH
  SOUTHEASTERLY CROSSWINDS TODAY.

* POTENTIAL LLWS OVERNIGHT.

LENNING

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

LOW PRESSURE LIES OVER SD/NE THIS MORNING AND WILL MOVE EAST INTO
WISCONSIN THIS EVENING...SLOWLY WEAKENING AS IT DOES. SOUTHERLY
WINDS WILL RAMP UP AHEAD OF THE LOW THIS MORNING...WITH GUSTS
STARTING IN THE 14-15Z HOUR AND RAMPING UP ABOVE 25KT BY AROUND
18-19Z. EXPECT GUSTS TO BECOME LESS FREQUENT STARTING MID TO LATE
THIS EVENING...THOUGH WILL MAINTAIN A MODERATE SUSTAINED WIND SPEED
THROUGH THE OVERNIGHT HOURS. A LOW LEVEL JET IS PROGGED TO DEVELOP
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS TONIGHT AND MAY RESULT
IN LOW LEVEL WIND SHEAR AT RFD...BUT SHOULD REMAIN JUST BELOW
CRITERIA AT THE CHICAGO TERMINALS. VFR CONDITIONS ARE EXPECTED TO
PREVAIL THROUGH THE TAF PERIOD.

BMD

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

* LOW CONFIDENCE IN LLWS TONIGHT.

* MEDIUM TO HIGH CONFIDENCE IN WINDS/GUSTS THIS AFTERNOON THROUGH
  TONIGHT.

* HIGH CONFIDENCE IN REMAINING FORECAST ELEMENTS.

LENNING

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

THURSDAY NIGHT...CHC RAIN. MVFR PSBL.
FRIDAY...SLT CHC RAIN. MVFR PSBL.
SATURDAY...VFR.
SUNDAY...CHC RAIN.
MONDAY...SLT CHC RAIN.
TUESDAY...VFR.

BMD

&&

.MARINE...
242 AM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN TODAY
WHILE LOW PRESSURE MOVES EAST ACROSS THE NORTHERN PLAINS ALLOWING A
SOUTHERLY GRADIENT TO SET UP ACROSS LAKE MICHIGAN. WINDS WILL
STEADILY INCREASE THROUGH THE DAY TOPPING OUT AROUND 30 KT THIS
EVENING AND TONIGHT. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
THE INDIANA AND ILLINOIS NEARSHORE WATERS TODAY THROUGH TONIGHT.
STABLE CONDITIONS WILL PREVENT STRONGER WINDS FROM REACHING THE LAKE
SURFACE. THE LOW WILL BEGIN TO FILL THURSDAY AS IT LIFTS ACROSS FAR
NORTHERN LAKE MICHIGAN...THEN HIGH PRESSURE WILL BUILD OVER LAKE
MICHIGAN LATE IT THE WEEK INTO THE WEEKEND.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KLOT 161139
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
639 AM CDT WED APR 16 2014

.DISCUSSION...
313 AM CDT

WEATHER WITHOUT ANY SIGNIFICANT IMPACTS LOOKS TO BE THE RULE THROUGH
THE EARLY PART OF THE WEEKEND WITH MUCH OF THE ATTENTION ON
TEMPERATURES AND WIND SPEEDS TODAY AND THEN SMALL CHANCES FOR
PRECIPITATION THURSDAY NIGHT AND FRIDAY.

TODAY AND TONIGHT...
THE UPPER TROUGH RESPONSIBLE FOR THE CHILLY DAY YESTERDAY IS
ADVANCING EAST OVER EASTERN CANADA AND NEW ENGLAND AND IS
RESPONSIBLE FOR PORTIONS OF AT LEAST 22 STATES UNDER FREEZE WARNINGS
THIS MORNING! STRONG MID-LEVEL DRYING IS SEEN ALL THE WAY DOWN TO
THE NORTHERN GULF AND AT THE SURFACE THE DRY AIR HAS ADVANCED
SOUTHWARD ALL THE WAY INTO THE GULF WITH SEVERAL PLATFORMS/BUOYS
REPORTING DEW POINTS IN THE 30S. SO BASICALLY THE GULF IS NOT
AVAILABLE FOR THE NEXT SYSTEM PASSING ACROSS THE REGION TONIGHT AND
THAT WILL BE A MAIN REASON WE LOOK TO REMAIN PRECIPITATION FREE.
THIS SYSTEM IS A FAIRLY WELL-DEFINED LOW AMPLITUDE UPPER WAVE THAT
IS MOVING EAST ACROSS SD THIS MORNING AND WILL FOLLOW ITS PARENT JET
STREAK/DIVERGENCE ALOFT TO THE EAST NORTHEAST OVER THE UPPER GREAT
LAKES TONIGHT WHERE A SNOW STORM IS FORECAST ACROSS NORTHERN WI/U.P.
OF MICHIGAN.

THE QUICK EASTWARD PROGRESSION OF THE SYSTEM SURFACE LOW BY
AFTERNOON WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOCAL AREA.
WHILE THERE WILL BE SOME HIGH CLOUDS...MIXING WILL AID THE PRESSURE
GRADIENT IN CREATING SUSTAINED SPEEDS AROUND 20 MPH AND GUSTS PLUS
10 MPH OF THAT. SOME 35 MPH GUSTS SHOULD EVEN BE REALIZED IN NORTH
CENTRAL IL. TEMPERATURES LOOK TO BOUNCE BACK 15 DEGREES OR EVEN
HIGHER THAN YESTERDAY GIVEN WARMING OF THE BOUNDARY LAYER AND
LOW-LEVEL ADVECTION. A SLIGHT COMPONENT OFF THE LAKE INTO CITY OF
CHICAGO AND NORTHWARD WILL KEEP THESE LAKE ADJACENT AREAS A HANDFUL
OF DEGREES COOLER...BUT COMPARED TO 33 DEGREES YESTERDAY...THE
FORECAST OF AROUND 50 TODAY FOR THESE LOCATIONS SHOULD BE WELCOME.
OUTLYING AREAS LOOK TO REACH THE MID 50S. UPSTREAM DEW POINTS ARE IN
THE UPPER TEENS TO MID 20S ACROSS DOWNSTATE IL/IN INTO THE TENNESSEE
RIVER VALLEY...SO EXPECTING A FAIRLY DRY AIR MASS TODAY WITH
HUMIDITY IN THE 25-35 PERCENT RANGE IN MOST AREAS.

AS THE UPPER WAVE PASSES TO THE NORTH TONIGHT THE PACIFIC MOISTURE
REMAINS NORTH AS WELL AND THE WARM AIR ADVECTION ASCENT HERE REMAINS
WITHIN A LOW PWAT ATMOSPHERE. WOULD NOT BE SURPRISED TO SEE SOME
RADAR ECHOES/VIRGA ACROSS FAR NORTHERN IL BUT THAT SHOULD BE ABOUT
IT. WITH MORE CLOUD COVER TONIGHT AND SOUTHERLY WINDS OF 10-20 MPH
CONTINUING...LOWS LOOK TO ONLY DIP INTO THE LOWER-MID 40S.

THURSDAY AND FRIDAY...
THE SYSTEM SURFACE FRONT/TROUGH IS EXPECTED TO MOVE INTO THE
FORECAST AREA THURSDAY MORNING AND BECOME STATIONARY. THIS DOES NOT
LOOK TO BE A VERY PRONOUNCED BAROCLINIC BOUNDARY. HAVE CONSIDERABLY
LOWERED CLOUD COVER DURING THURSDAY MORNING AND EARLY AFTERNOON AND
WITH THAT BOOSTED TEMPERATURES SOME...WITH 55 TO 60 PROBABLE. A
SHEARING UPPER WAVE IS EXPECTED TO MOVE NORTHEAST OVER THE BOUNDARY
THURSDAY NIGHT. A LOOK AT THE DPROG/DT...OR TREND...OF SEVERAL
MODELS OVER THE PAST FOUR CYCLES SHOW CONSIDERABLY LESS FORCING AND
MOISTURE AVAILABILITY FOR PRECIPITATION. HAVE CONTINUED THE FORECAST
TREND TO CUT BACK POPS BUT ALSO TO CONFINE THE AREA WHERE
CONVERGENCE/FRONTOGENESIS IS DEPICTED NEAR THE BOUNDARY. BY FRIDAY
THE ENVELOPE OF GUIDANCE HAS FORCING EAST OF THE AREA...HOWEVER ONE
FINAL SEPARATE MID-LEVEL IMPULSE SEEN ON THE NCEP MODELS PASSES OVER
THE AREA FRIDAY AFTERNOON. CONTINUE A SMALL CHANCE OF RAIN SHOWERS
WITH THIS. THE NORTH TO NORTHEAST FLOW BEHIND THE FRONT ON FRIDAY
SHOULD LEAD TO A DECENT TEMPERATURE DIFFERENCE FROM NEAR THE LAKE TO
OUTLYING AREAS...WITH MID 40S TO MID 50S PRESENTLY FORECAST ACROSS
THAT CROSS SECTION. LOCAL CLIMATOLOGICAL RESEARCH FAVORS SUCH A
SPREAD THIS TIME OF YEAR WITH ONSHORE FLOW.

THIS WEEKEND INTO EARLY NEXT WEEK...
WHILE THE FLOW IS PROGRESSIVE ACROSS THE FAR NORTHERN CONUS/SOUTHERN
CANADA IT LOOKS TO BE FAR ENOUGH NORTH TO HAVE LITTLE INFLUENCE ON
THE AREA SATURDAY AND POTENTIALLY EVEN SUNDAY...ESPECIALLY IF GOING
TOWARD THE EC AND GEM WHICH WE HAVE LEANED OUR FORECAST. THESE
MODELS INDICATE THAT A CLOSED UPPER LOW OVER THE SOUTHEAST U.S.
DEPICTED BY MODELS LATE IN THE WEEKEND MAY LEAD TO A SLOWING OF THE
NEXT SYSTEM TO APPROACH THE AREA FROM THE ROCKIES...MORE SO SUNDAY
NIGHT AND MONDAY. TEMPERATURES LOOK TO BE BACK TO NORMAL SUNDAY AND
MONDAY.

MTF

&&

.AVIATION...

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

* GUSTY SOUTH WINDS DEVELOPING THIS MORNING AND AFTERNOON...WITH
  OVER 30 KTS AT TIMES DURING THE AFTERNOON.
* POTENTIAL FOR LOW LEVEL WIND SHEAR THIS EVENING AND TONIGHT.

BMD

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

LOW PRESSURE LIES OVER SD/NE THIS MORNING AND WILL MOVE EAST INTO
WISCONSIN THIS EVENING...SLOWLY WEAKENING AS IT DOES. SOUTHERLY
WINDS WILL RAMP UP AHEAD OF THE LOW THIS MORNING...WITH GUSTS
STARTING IN THE 14-15Z HOUR AND RAMPING UP ABOVE 25KT BY AROUND
18-19Z. EXPECT GUSTS TO BECOME LESS FREQUENT STARTING MID TO LATE
THIS EVENING...THOUGH WILL MAINTAIN A MODERATE SUSTAINED WIND SPEED
THROUGH THE OVERNIGHT HOURS. A LOW LEVEL JET IS PROGGED TO DEVELOP
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS TONIGHT AND MAY RESULT
IN LOW LEVEL WIND SHEAR AT RFD...BUT SHOULD REMAIN JUST BELOW
CRITERIA AT THE CHICAGO TERMINALS. VFR CONDITIONS ARE EXPECTED TO
PREVAIL THROUGH THE TAF PERIOD.

BMD


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

* LOW CONFIDENCE IN LLWS WEDNESDAY NIGHT.
* MEDIUM CONFIDENCE IN MAGNITUDE OF WIND/GUSTS THIS AFTERNOON
  THROUGH TONIGHT.
* HIGH CONFIDENCE IN REMAINING FORECAST ELEMENTS.

BMD

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

THURSDAY NIGHT...CHC RAIN. MVFR PSBL.
FRIDAY...SLT CHC RAIN. MVFR PSBL.
SATURDAY...VFR.
SUNDAY...CHC RAIN.
MONDAY...SLT CHC RAIN.
TUESDAY...VFR.

BMD

&&

.MARINE...
242 AM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN TODAY
WHILE LOW PRESSURE MOVES EAST ACROSS THE NORTHERN PLAINS ALLOWING A
SOUTHERLY GRADIENT TO SET UP ACROSS LAKE MICHIGAN. WINDS WILL
STEADILY INCREASE THROUGH THE DAY TOPPING OUT AROUND 30 KT THIS
EVENING AND TONIGHT. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
THE INDIANA AND ILLINOIS NEARSHORE WATERS TODAY THROUGH TONIGHT.
STABLE CONDITIONS WILL PREVENT STRONGER WINDS FROM REACHING THE LAKE
SURFACE. THE LOW WILL BEGIN TO FILL THURSDAY AS IT LIFTS ACROSS FAR
NORTHERN LAKE MICHIGAN...THEN HIGH PRESSURE WILL BUILD OVER LAKE
MICHIGAN LATE IT THE WEEK INTO THE WEEKEND.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM WEDNESDAY TO 4 AM THURSDAY.

&&

$$

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

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






000
FXUS63 KILX 161104
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
604 AM CDT Wed Apr 16 2014

.DISCUSSION...
ISSUED 249 AM CDT Wed Apr 16 2014

SHORT TERM...Today through Friday

Winds will increase markedly across central Illinois today as
gradient tightens between departing high pressure system and low
tracking from the Dakotas into southern Minnesota. Models are not
quite as strong with the winds as they were in previous runs, so
am not concerned about reaching Wind Advisory criteria. BUFKIT
momentum transfer at KPIA shows 33kt winds at the top of the mixed
layer this afternoon, as opposed to 43kt on the prior run just 24
hours ago. Despite this decrease in momentum, think S/SE winds
will gust to between 30 and 35mph across the western half of the
KILX CWA, with gusts to around 25mph further east near the
Indiana border. This strong southerly flow will help bring much
warmer air into the region. Extent of warming will be mitigated
somewhat by an easterly component to the wind and mixing heights
lowering to less than 5000ft. Resulting afternoon highs will range
from the middle 50s east to around 60 far west.

As southern Minnesota low lifts toward Lake Superior, it will
drag a weak cold front into the Illinois River Valley by dawn
Thursday. This boundary will become stationary along the I-55
corridor during the day Thursday, creating little in the way of
sensible weather. A mid-level short-wave will approach from the
southwest late in the day and will eventually interact with the
front to perhaps produce a few light showers. Current surface
analysis shows a very dry air mass has settled across the eastern
half of the CONUS all the way to the Gulf of Mexico. In fact,
buoys in the northern Gulf are currently showing dew points as low
as the middle to upper 30s. With so much dry air to the south, do
not think front will have enough moisture to work with in order to
produce precip across the area on Thursday. GFS is the only model
that is holding on to QPF across the Illinois River Valley
Thursday afternoon, but think this is overdone. Will therefore go
with a dry forecast across the board. There are even some
indications that dry conditions will continue Thursday night into
Friday as the upper wave arrives. At this point, will leave chance
PoPs for showers in the forecast Thursday night into Friday
morning as synoptic lift associated with the wave will likely be
enough to squeeze a few light showers out of the dry air mass. Once
the wave passes, dry weather will return Friday afternoon and
night.

LONG TERM...Saturday through Tuesday

After a warm/dry day on Saturday, attention turns to next
approaching system for early next week. Models have been trending
slower with its approach, with most 00z Apr 16 guidance suggesting
Easter Sunday may remain largely dry. GFS is the most aggressive
model in driving precip eastward into the area, but even it has
backed off and keeps rain at bay until Sunday afternoon at the
earliest. GEM focuses best rain chances Sunday night into Monday,
while ECMWF is even slower and advertises mainly a Monday rain
event. As a result of the distinct slowing trend, have trimmed
PoPs accordingly. Will keep Saturday night and Sunday morning dry,
then will bring chance PoPs into the picture across the western
CWA Sunday afternoon. Will highlight the Sunday night/Monday time
frame with the highest PoPs, followed by a return to dry weather
on Tuesday. Aside from the early week rain chances, the extended
forecast will feature warmer weather, with model guidance
suggesting temps reaching the 70s by Tuesday.

Barnes

&&

.AVIATION...
ISSUED 556 AM CDT Wed Apr 16 2014

Little change needed to previous TAF set. Wind will be the main
concern through this afternoon. Southerly wind gusts around 30
knots are expected to develop near all TAF sites by late morning,
and continue through the afternoon. May see some even higher at
KPIA. We will lose the gusts with sunset, but sustained winds will
still average around 15 knots much of the night. Late in the
period, winds will start to shift more to the southwest, ahead of
a cold front which will move through the area later on Thursday.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING until 9 AM CDT this morning FOR ILZ052-054-056-
061>063-066>068-071>073.

&&

$$






000
FXUS63 KLOT 160917
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
417 AM CDT WED APR 16 2014

.DISCUSSION...
313 AM CDT

WEATHER WITHOUT ANY SIGNIFICANT IMPACTS LOOKS TO BE THE RULE THROUGH
THE EARLY PART OF THE WEEKEND WITH MUCH OF THE ATTENTION ON
TEMPERATURES AND WIND SPEEDS TODAY AND THEN SMALL CHANCES FOR
PRECIPITATION THURSDAY NIGHT AND FRIDAY.

TODAY AND TONIGHT...
THE UPPER TROUGH RESPONSIBLE FOR THE CHILLY DAY YESTERDAY IS
ADVANCING EAST OVER EASTERN CANADA AND NEW ENGLAND AND IS
RESPONSIBLE FOR PORTIONS OF AT LEAST 22 STATES UNDER FREEZE WARNINGS
THIS MORNING! STRONG MID-LEVEL DRYING IS SEEN ALL THE WAY DOWN TO
THE NORTHERN GULF AND AT THE SURFACE THE DRY AIR HAS ADVANCED
SOUTHWARD ALL THE WAY INTO THE GULF WITH SEVERAL PLATFORMS/BUOYS
REPORTING DEW POINTS IN THE 30S. SO BASICALLY THE GULF IS NOT
AVAILABLE FOR THE NEXT SYSTEM PASSING ACROSS THE REGION TONIGHT AND
THAT WILL BE A MAIN REASON WE LOOK TO REMAIN PRECIPITATION FREE.
THIS SYSTEM IS A FAIRLY WELL-DEFINED LOW AMPLITUDE UPPER WAVE THAT
IS MOVING EAST ACROSS SD THIS MORNING AND WILL FOLLOW ITS PARENT JET
STREAK/DIVERGENCE ALOFT TO THE EAST NORTHEAST OVER THE UPPER GREAT
LAKES TONIGHT WHERE A SNOW STORM IS FORECAST ACROSS NORTHERN WI/U.P.
OF MICHIGAN.

THE QUICK EASTWARD PROGRESSION OF THE SYSTEM SURFACE LOW BY
AFTERNOON WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOCAL AREA.
WHILE THERE WILL BE SOME HIGH CLOUDS...MIXING WILL AID THE PRESSURE
GRADIENT IN CREATING SUSTAINED SPEEDS AROUND 20 MPH AND GUSTS PLUS
10 MPH OF THAT. SOME 35 MPH GUSTS SHOULD EVEN BE REALIZED IN NORTH
CENTRAL IL. TEMPERATURES LOOK TO BOUNCE BACK 15 DEGREES OR EVEN
HIGHER THAN YESTERDAY GIVEN WARMING OF THE BOUNDARY LAYER AND
LOW-LEVEL ADVECTION. A SLIGHT COMPONENT OFF THE LAKE INTO CITY OF
CHICAGO AND NORTHWARD WILL KEEP THESE LAKE ADJACENT AREAS A HANDFUL
OF DEGREES COOLER...BUT COMPARED TO 33 DEGREES YESTERDAY...THE
FORECAST OF AROUND 50 TODAY FOR THESE LOCATIONS SHOULD BE WELCOME.
OUTLYING AREAS LOOK TO REACH THE MID 50S. UPSTREAM DEW POINTS ARE IN
THE UPPER TEENS TO MID 20S ACROSS DOWNSTATE IL/IN INTO THE TENNESSEE
RIVER VALLEY...SO EXPECTING A FAIRLY DRY AIR MASS TODAY WITH
HUMIDITY IN THE 25-35 PERCENT RANGE IN MOST AREAS.

AS THE UPPER WAVE PASSES TO THE NORTH TONIGHT THE PACIFIC MOISTURE
REMAINS NORTH AS WELL AND THE WARM AIR ADVECTION ASCENT HERE REMAINS
WITHIN A LOW PWAT ATMOSPHERE. WOULD NOT BE SURPRISED TO SEE SOME
RADAR ECHOES/VIRGA ACROSS FAR NORTHERN IL BUT THAT SHOULD BE ABOUT
IT. WITH MORE CLOUD COVER TONIGHT AND SOUTHERLY WINDS OF 10-20 MPH
CONTINUING...LOWS LOOK TO ONLY DIP INTO THE LOWER-MID 40S.

THURSDAY AND FRIDAY...
THE SYSTEM SURFACE FRONT/TROUGH IS EXPECTED TO MOVE INTO THE
FORECAST AREA THURSDAY MORNING AND BECOME STATIONARY. THIS DOES NOT
LOOK TO BE A VERY PRONOUNCED BAROCLINIC BOUNDARY. HAVE CONSIDERABLY
LOWERED CLOUD COVER DURING THURSDAY MORNING AND EARLY AFTERNOON AND
WITH THAT BOOSTED TEMPERATURES SOME...WITH 55 TO 60 PROBABLE. A
SHEARING UPPER WAVE IS EXPECTED TO MOVE NORTHEAST OVER THE BOUNDARY
THURSDAY NIGHT. A LOOK AT THE DPROG/DT...OR TREND...OF SEVERAL
MODELS OVER THE PAST FOUR CYCLES SHOW CONSIDERABLY LESS FORCING AND
MOISTURE AVAILABILITY FOR PRECIPITATION. HAVE CONTINUED THE FORECAST
TREND TO CUT BACK POPS BUT ALSO TO CONFINE THE AREA WHERE
CONVERGENCE/FRONTOGENESIS IS DEPICTED NEAR THE BOUNDARY. BY FRIDAY
THE ENVELOPE OF GUIDANCE HAS FORCING EAST OF THE AREA...HOWEVER ONE
FINAL SEPARATE MID-LEVEL IMPULSE SEEN ON THE NCEP MODELS PASSES OVER
THE AREA FRIDAY AFTERNOON. CONTINUE A SMALL CHANCE OF RAIN SHOWERS
WITH THIS. THE NORTH TO NORTHEAST FLOW BEHIND THE FRONT ON FRIDAY
SHOULD LEAD TO A DECENT TEMPERATURE DIFFERENCE FROM NEAR THE LAKE TO
OUTLYING AREAS...WITH MID 40S TO MID 50S PRESENTLY FORECAST ACROSS
THAT CROSS SECTION. LOCAL CLIMATOLOGICAL RESEARCH FAVORS SUCH A
SPREAD THIS TIME OF YEAR WITH ONSHORE FLOW.

THIS WEEKEND INTO EARLY NEXT WEEK...
WHILE THE FLOW IS PROGRESSIVE ACROSS THE FAR NORTHERN CONUS/SOUTHERN
CANADA IT LOOKS TO BE FAR ENOUGH NORTH TO HAVE LITTLE INFLUENCE ON
THE AREA SATURDAY AND POTENTIALLY EVEN SUNDAY...ESPECIALLY IF GOING
TOWARD THE EC AND GEM WHICH WE HAVE LEANED OUR FORECAST. THESE
MODELS INDICATE THAT A CLOSED UPPER LOW OVER THE SOUTHEAST U.S.
DEPICTED BY MODELS LATE IN THE WEEKEND MAY LEAD TO A SLOWING OF THE
NEXT SYSTEM TO APPROACH THE AREA FROM THE ROCKIES...MORE SO SUNDAY
NIGHT AND MONDAY. TEMPERATURES LOOK TO BE BACK TO NORMAL SUNDAY AND
MONDAY.

MTF

&&

.AVIATION...

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

* GUSTY SOUTH WINDS DEVELOPING DURING THE DAY WEDNESDAY...WITH
  OVER 30 KTS AT TIMES DURING THE AFTERNOON.
* LOW LEVEL WIND SHEAR WEDNESDAY EVENING/NIGHT.

BMD

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

OVERNIGHT HOURS WILL REMAIN QUIET WITH VFR CONDITIONS AND A LIGHT
SSE BREEZE DEVELOPING. LOW PRESSURE WILL TRANSLATE EAST ACROSS THE
NORTHERN PLAINS OVERNIGHT WITH THE GRADIENT INCREASING THROUGH THE
PERIOD. BY MID MORNING WEDNESDAY...EXPECT TO START MIXING DOWN MID
20 KT GUSTS...AND BY EARLY AFTERNOON...GUSTS TO AROUND 30 KT ARE
POSSIBLE. WITH THE SURFACE LOW STARTING TO FILL AND SOME DEGREE OF
DECOUPLING WEDNESDAY NIGHT...WIND GUSTS AT THE SURFACE SHOULD TAPER
SOME MID TO LATE IN THE EVENING. MEANWHILE...A 50 KT OR SO LOW LEVEL
JET IS PROGGED TO DEVELOP...ESPECIALLY OVER NORTH CENTRAL ILLINOIS
AND COULD SET THE STAGE FOR MARGINAL LOW LEVEL WIND SHEAR. OPTED TO
REMOVE THE LLWS AT ORD AS IT APPEARS THE THREAT WILL BE BETTER
FARTHER WEST SUCH AS AT RFD. AS THE LOW MOVES EAST...EXPECT AN
INCREASE IN HIGH AND MID LEVEL CLOUD COVER...BUT VFR CONDITIONS WILL
PREVAIL THROUGH THE CURRENT TAF PERIOD.

BMD

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

* LOW CONFIDENCE IN LLWS WEDNESDAY NIGHT.
* MEDIUM CONFIDENCE IN MAGNITUDE OF WINDS/GUSTS DURING THE
  AFTERNOON/EVENING.
* HIGH CONFIDENCE IN REMAINING FORECAST ELEMENTS.

BMD

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

THURSDAY...CHC RA LATE AFTN/NGT. MAINLY VFR.

FRIDAY...CHC RA/MVFR EARLY...THEN VFR.

SATURDAY...VFR.

SUNDAY...CHC RA.

MONDAY...SLGT CHC RA.

RATZER

&&

.MARINE...
242 AM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN TODAY
WHILE LOW PRESSURE MOVES EAST ACROSS THE NORTHERN PLAINS ALLOWING A
SOUTHERLY GRADIENT TO SET UP ACROSS LAKE MICHIGAN. WINDS WILL
STEADILY INCREASE THROUGH THE DAY TOPPING OUT AROUND 30 KT THIS
EVENING AND TONIGHT. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
THE INDIANA AND ILLINOIS NEARSHORE WATERS TODAY THROUGH TONIGHT.
STABLE CONDITIONS WILL PREVENT STRONGER WINDS FROM REACHING THE LAKE
SURFACE. THE LOW WILL BEGIN TO FILL THURSDAY AS IT LIFTS ACROSS FAR
NORTHERN LAKE MICHIGAN...THEN HIGH PRESSURE WILL BUILD OVER LAKE
MICHIGAN LATE IT THE WEEK INTO THE WEEKEND.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM WEDNESDAY TO 4 AM THURSDAY.

&&

$$

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