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000
FXUS63 KLOT 241928
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
228 PM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* GUSTY SOUTHEAST WINDS THIS AFTERNOON AND EVENING...DIMINISHING
  MID EVENING...THEN TURNING TO THE NORTHWEST OVERNIGHT INTO EARLY
  FRIDAY.
* CHANCES FOR SHOWERS THIS EVENING/TONIGHT RESULTING IN MVFR
  CONDITIONS.

BMD

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

A BROAD AREA OF LOW PRESSURE LIES OVER THE PLAINS THIS AFTERNOON.
AHEAD OF THE LOW THIS AFTERNOON AND EVENING...EXPECT GUSTY SOUTHEAST
WINDS TO CONTINUE ACROSS NORTHERN ILLINOIS...WITH GUSTS PUSHING 30
KT AT TIMES. THIS LOW WILL CONSOLIDATE AS IT MOVES EAST ACROSS
CENTRAL ILLINOIS LATE THIS EVENING/TONIGHT. SHOWERS ALONG WITH
LOWERING CIGS WILL ACCOMPANY THE LOW THIS EVENING. CIGS ARE EXPECTED
TO LOWER TO MVFR...AND CANNOT COMPLETELY RULE OUT IFR AT THIS
TIME...THOUGH THERE ARE BETTER CHANCES FOR CIGS BOTTOMING OUT IN THE
010-015 RANGE. WINDS MAY GO VARIABLE FOR A BRIEF PERIOD AS AN
INVERTED TROUGH PUSHES ACROSS THE AREA...THEN EXPECT WINDS TO BECOME
NNW TO NW BEHIND THE TROUGH WITH CONDITIONS QUICKLY RETURNING TO VFR.

BMD

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

* MEDIUM-HIGH CONFIDENCE IN PRECIP TIMING/IMPACTS TO VSBY THIS
  EVENING.
* HIGH CONFIDENCE IN MVFR CIGS...LOW CONFIDENCE IN IFR.
* HIGH CONFIDENCE IN WIND DIRECTION/SPEED THIS AFTERNOON AND EVENING.

BMD

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

FRIDAY NIGHT...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

WEDNESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
158 PM CDT

TWO WEAK LOW PRESSURE CENTERS WERE LOCATED WEST OF LAKE MICHIGAN.
ONE WAS STEADILY WEAKENING OVER CENTRAL IOWA...WHILE A SECOND WAS
BEGINNING TO STRENGTHEN ACROSS CENTRAL MISSOURI. THE TWO LOW
PRESSURES ARE EXPECTED TO CONSOLIDATE THIS EVENING...THEN STEADILY
LIFT NORTHEAST/EAST ACROSS CENTRAL ILLINOIS OVERNIGHT. IN THE
MEANTIME...WINDS WILL GENERALLY REMAIN EASTERLY TO SOUTHEASTERLY.
A TIGHT GRADIENT DOES EXIST...WHICH HAS RESULTED IN WINDS AT TIMES
GUSTING TO 30KT THIS AFTN. GUIDANCE HAS BEEN CONSISTENT IN
DEPICTING WINDS DIMINISHING TONIGHT...THEN WINDS WILL TURN
WEST/NORTHWEST. THIS WILL ALLOW THE WAVES TO SUBSIDE ACROSS THE
NORTH/NORTHWEST PORTIONS OF THE LAKE...WHILE WAVES BEGIN TO BUILD
ONCE AGAIN FOR THE INDIANA NEARSHORE WATERS FRIDAY MIDDAY THROUGH
FRIDAY NIGHT.

HIGH PRESSURE WILL SLIDE EAST ACROSS MANITOBA TO NORTH OF LAKE
SUPERIOR EARLY SATURDAY. THIS WILL ALLOW WINDS TO TURN NORTHERLY
EARLY SATURDAY THEN NORTHEAST TO EASTERLY ACROSS THE LAKE BY
SATURDAY AFTERNOON. THEN A PROLONGED PERIOD OF GENERALLY EASTERLY
WINDS IS EXPECTED ACROSS THE LAKE SUNDAY THROUGH TUESDAY.

BEACHLER

&&

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





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000
FXUS63 KILX 241759
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1259 PM CDT Thu Apr 24 2014

.DISCUSSION...
ISSUED 1046 AM CDT Thu Apr 24 2014

Area of low pressure currently located near Kansas City will track
slowly E/NE into west-central Illinois by this evening. While
showers and thunderstorms are prevalent ahead of this feature
across central and western Missouri, the airmass further east over
Illinois remains rather dry. 15z/10am surface dewpoints are only
in the middle to upper 30s, while the 12z KILX upper air sounding
showed a large amount of dry air below 700mb. With a southeasterly
low-level flow ahead of the system, am not expecting much moisture
advection before the low and its associated front arrive. High-res
models such as the HRRR and the NAM12 are suggesting that the
eastward progression of the precip will be slower than previously
expected and this seems reasonable given the current conditions.
Have therefore trimmed POPs back today. Will keep the entire KILX
CWA dry through midday, then will slowly advance precip eastward
this afternoon. Will continue with a dry forecast east of the
I-57 corridor through the entire afternoon, with POPs gradually
ramping up to categorical further west across the Illinois River
Valley. Also made adjustments to sky cover to feature more
sunshine across the E/SE. Zone update will be issued shortly.


Barnes
&&

.AVIATION...
ISSUED 1259 PM CDT Thu Apr 24 2014

Showers are beginning to spread into the Illinois River Valley and
may impact KPIA over the next couple of hours. However, overall
trend has been for precip to diminish as it moves eastward into the
dry airmass over Illinois. As atmosphere slowly moistens and upper
wave and its associated cold front approach from the west, showers
will gradually become more prevalent across west-central Illinois
late this afternoon, then will spread eastward across the
remainder of the area during the evening. Most model guidance
suggests KCMI will remain dry until mid-evening at the earliest.
Time-height cross-sections generally reveal MVFR ceilings with
skies clearing from west to east after midnight. Will end the
showers and clear skies at KPIA at 08z, then further east to KCMI
by around 12z. Winds will initially be gusty from the southeast
this afternoon, then will become northwesterly after FROPA later
this evening.

Barnes
&&

.PREV DISCUSSION...
ISSUED 330 AM CDT Thu Apr 24 2014

SHORT TERM...Today through Sunday

00Z models continue to be slower with cold frontal passage and
associated convection and that is the biggest change in the
forecast package. Most areas will be dry this morning with showers
and thunderstorms affecting areas from I-55 west this afternoon
and possibly getting as far east as I-57 late this afternoon. SPC
keeps slight risk of severe storms in southern IL south of our
CWA. Though there is a 5% risk of damaging wind gusts in far sw CWA
from Springfield to Lawrenceville south late this afternoon and
evening. Upper level trof over CO/NM with embedded short wave to
move into IL overnight while a cold front moves east across IL
during tonight. Have increased pops this evening due to slower
movement of front and then decreasing pops from west to east
behind cold front during overnight. Highs today in the upper 60s
nw over IL river valley to mid 70s se of I-70. Lows tonight 45-50F
over central IL and 50-55F in southeast IL. Rainfall amounts this
afternoon and tonight of a half to three quarter inch with locally
three quarter to 1 inch west of I-55.

Storm system to pass east of IL across IN/OH Friday morning with
more sunshine returning and mild highs in the low to mid 70s and
warmest over sw counties. Even a few degrees warmer on Saturday as
models have 850 mb temps of 12-14C. Still appears dry Friday
through the day on Saturday with partly to mostly sunny skies Sat.
Rather mild again on Sunday with highs in the upper 60s to mid 70s.
Models have trended warmer this weekend ahead of next storm system
over the Rockies. Continue chances of showers and isolated
thunderstorms Saturday night and Sunday as warm air advection
regime sets up again.

LONG TERM...Sunday night through Thursday

Extended models like GFS, ECMWF and GEM develop a strong/large cutoff
upper level low near CO Sunday morning and then move it into the MO
valley Tue and mid MS river valley during middle of next week.
This to bring an unsettled weather pattern with daily chance of
showers and isolated thunderstorms from Sunday through Thursday
with highest chances Sunday night through Tuesday. Mild temps
early in the week to cool by middle of next week as upper level
low moves near IL. Widespread rainfall amounts of 1-2 inches
expected during this time with heaviest amounts southern areas.
Seasonable highs in the upper 60s and lower 70s Monday cool into
the low to mid 50s Wed/Thu.

07


&&

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

$$








000
FXUS63 KLOT 241751
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1251 PM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* GUSTY SOUTHEAST WINDS THIS AFTERNOON AND EVENING...DIMINISHING
  MID EVENING...THEN TURNING TO THE NORTHWEST OVERNIGHT INTO EARLY
  FRIDAY.
* CHANCES FOR SHOWERS THIS EVENING/TONIGHT RESULTING IN MVFR
  CONDITIONS.

BMD

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

A BROAD AREA OF LOW PRESSURE LIES OVER THE PLAINS THIS AFTERNOON.
AHEAD OF THE LOW THIS AFTERNOON AND EVENING...EXPECT GUSTY SOUTHEAST
WINDS TO CONTINUE ACROSS NORTHERN ILLINOIS...WITH GUSTS PUSHING 30
KT AT TIMES. THIS LOW WILL CONSOLIDATE AS IT MOVES EAST ACROSS
CENTRAL ILLINOIS LATE THIS EVENING/TONIGHT. SHOWERS ALONG WITH
LOWERING CIGS WILL ACCOMPANY THE LOW THIS EVENING. CIGS ARE EXPECTED
TO LOWER TO MVFR...AND CANNOT COMPLETELY RULE OUT IFR AT THIS
TIME...THOUGH THERE ARE BETTER CHANCES FOR CIGS BOTTOMING OUT IN THE
010-015 RANGE. WINDS MAY GO VARIABLE FOR A BRIEF PERIOD AS AN
INVERTED TROUGH PUSHES ACROSS THE AREA...THEN EXPECT WINDS TO BECOME
NNW TO NW BEHIND THE TROUGH WITH CONDITIONS QUICKLY RETURNING TO VFR.

BMD


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

* MEDIUM-HIGH CONFIDENCE IN PRECIP TIMING/IMPACTS TO VSBY THIS
  EVENING.
* HIGH CONFIDENCE IN MVFR CIGS...LOW CONFIDENCE IN IFR.
* HIGH CONFIDENCE IN WIND DIRECTION/SPEED THIS AFTERNOON AND EVENING.

BMD

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

FRIDAY NIGHT...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

WEDNESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
443 AM CDT

LIGHTER FLOW REMAINING OVER THE LAKE EARLY THIS MORNING WITH
WEAKER SURFACE PATTERN STILL IN PLACE. ALTHOUGH...EXPECT EAST TO
SOUTHEAST WINDS TO RAPIDLY INCREASE THROUGH MID MORNING AND THEN
ESPECIALLY INTO THE AFTERNOON WHEN TO 30 KT WINDS WILL BE
OBSERVED...IN RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE.
EAST TO SOUTHEAST WINDS WILL STILL REMAIN TO 30 KT THIS EVENING
BUT SLOWLY DIMINISH AS THIS TROUGH OF LOW PRESSURE MOVES THROUGH
THE REGION. WINDS WILL BEGIN TURNING TO THE WEST/NORTHEAST ON THE
BACKSIDE OF THIS SYSTEM LATE TONIGHT INTO FRIDAY BEFORE TURNING
MORE NORTHERLY FRIDAY NIGHT INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 10 PM 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 241611
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1111 AM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* STRONG/GUSTY SOUTHEAST WINDS TODAY.

* SHOWERS LATER TONIGHT INTO EARLY FRIDAY MORNING.

* LOW END MVFR CEILINGS LIKELY TONIGHT INTO EARLY FRIDAY
  MORNING...WITH A POSSIBILITY FOR IFR CEILINGS.

RODRIGUEZ/DEUBELBEISS

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

VFR CEILINGS IN PLACE THIS MORNING WITH ANY LINGERING SHOWERS WELL
NORTH/NORTHEAST OF THE TERMINALS AT THIS TIME. EXPECT DRY
CONDITIONS FOR MOST OF TODAY AND EVENING WITH ONLY MID/HIGH HIGH
LEVEL CLOUD COVER LIKELY FOR MOST OF TODAY. A SLOWER EVOLUTION OF
THE APPROACHING SYSTEM TODAY IS APPEARING LIKELY AND HAVE PUSHED
BACK TIMING OF SHOWERS TO LATER TONIGHT WHEN THIS TROUGH OF LOW
PRESSURE FINALLY ARRIVES. ALTHOUGH THERE DOES STILL APPEAR TO BE
SOME POSSIBLE ISOLATED LIGHT SHOWERS BEFORE THEN...EXPECT ANY
SHOWERS TO BRIEF AND LIGHT AND SO HAVE REMOVED THE VCSH MENTION
FOR EARLIER THIS EVENING. NOT EXPECTED THUNDER WITH THE SHOWERS
TONIGHT AS BEST INSTABILITY/MOISTURE WILL REMAIN WELL SOUTH OF ALL
THE TERMINALS. VFR CEILINGS THIS EVENING WILL LIKELY FALL TO LOW
END MVFR FOR A TIME TONIGHT INTO EARLY FRIDAY MORNING...WITH A
POSSIBILITY FOR SOME PERIODS OF IFR. CONFIDENCE IS LOW WITH
REGARDS TO THE IFR AND SO HAVE LEFT OUT ANY MENTION IN THE TAFS.

EAST SOUTHEAST WINDS ARE IN PLACE THIS MORNING AND ARE STEADILY
INCREASING AT THIS HOUR. WITH THE SURFACE GRADIENT BECOMING
ORGANIZED THIS MORNING...EXPECT WINDS/GUSTS TO RAPIDLY INCREASE
OVER THE NEXT COUPLE OF HOURS AND REMAIN HIGH THROUGH THE
AFTERNOON. GUSTS OF AROUND 30KT ARE POSSIBLE FOR A TIME
TODAY...BEFORE WINDS/GUSTS DIMINISH LATE IN THE AFTERNOON AND
EARLY EVENING. PERSISTENT SOUTHEAST WINDS WILL LIKELY BECOME MORE
VARIABLE WITHIN THE TROUGH/PRECIP AXIS LATER TONIGHT BEFORE
TURNING TO THE NORTHWEST ON THE BACKSIDE OF THIS SYSTEM...STAYING
THIS DIRECTION INTO FRIDAY.

RODRIGUEZ

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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* MEDIUM HIGH CONFIDENCE WITH SHOWERS AND TIMING TONIGHT.

* MEDIUM HIGH CONFIDENCE WITH MVFR CEILINGS...WITH LOW CONFIDENCE
  FOR POSSIBLE IFR CEILINGS.

RODRIGUEZ/DEUBELBEISS

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

FRIDAY NIGHT...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

WEDNESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
443 AM CDT

LIGHTER FLOW REMAINING OVER THE LAKE EARLY THIS MORNING WITH
WEAKER SURFACE PATTERN STILL IN PLACE. ALTHOUGH...EXPECT EAST TO
SOUTHEAST WINDS TO RAPIDLY INCREASE THROUGH MID MORNING AND THEN
ESPECIALLY INTO THE AFTERNOON WHEN TO 30 KT WINDS WILL BE
OBSERVED...IN RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE.
EAST TO SOUTHEAST WINDS WILL STILL REMAIN TO 30 KT THIS EVENING
BUT SLOWLY DIMINISH AS THIS TROUGH OF LOW PRESSURE MOVES THROUGH
THE REGION. WINDS WILL BEGIN TURNING TO THE WEST/NORTHEAST ON THE
BACKSIDE OF THIS SYSTEM LATE TONIGHT INTO FRIDAY BEFORE TURNING
MORE NORTHERLY FRIDAY NIGHT INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 10 PM 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 241546
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1046 AM CDT Thu Apr 24 2014

.DISCUSSION...
ISSUED 1046 AM CDT Thu Apr 24 2014

Area of low pressure currently located near Kansas City will track
slowly E/NE into west-central Illinois by this evening. While
showers and thunderstorms are prevalent ahead of this feature
across central and western Missouri, the airmass further east over
Illinois remains rather dry. 15z/10am surface dewpoints are only
in the middle to upper 30s, while the 12z KILX upper air sounding
showed a large amount of dry air below 700mb. With a southeasterly
low-level flow ahead of the system, am not expecting much moisture
advection before the low and its associated front arrive. High-res
models such as the HRRR and the NAM12 are suggesting that the
eastward progression of the precip will be slower than previously
expected and this seems reasonable given the current conditions.
Have therefore trimmed POPs back today. Will keep the entire KILX
CWA dry through midday, then will slowly advance precip eastward
this afternoon. Will continue with a dry forecast east of the
I-57 corridor through the entire afternoon, with POPs gradually
ramping up to categorical further west across the Illinois River
Valley. Also made adjustments to sky cover to feature more
sunshine across the E/SE. Zone update will be issued shortly.

Barnes
&&

.AVIATION...
ISSUED 625 AM CDT Thu Apr 24 2014

Several forecast concerns this period include surface wind gusts
later this morning into this afternoon and a deterioration in
cigs this evening as showers and scattered TSRA affect the TAF
sites. Band of showers was located over east central Iowa, tracking
mainly to the northeast and not expected to affect our TAF
locations this morning. However, as a frontal boundary out to our
west make progress to the east later today, the threat for showers
and storms will increase from west to east in the 20z-01z time
frame. Widespread rain and isold TSRA will be the story this
evening with the cigs gradually lowering to MVFR with some brief
IFR cigs possible where some of the heavier showers/storms move
through. Steadier light rains will follow later this evening
before the system shifts off to our east late tonight. Surface
winds will be out of the southeast at 15 to 25 kts today with
a few gusts around 30 kts at times. FROPA is not expected until
or just after 03z at PIA with CMI the last to see the wind shift
by 08z.

Smith
&&

.PREV DISCUSSION...
ISSUED 330 AM CDT Thu Apr 24 2014

SHORT TERM...Today through Sunday

00Z models continue to be slower with cold frontal passage and
associated convection and that is the biggest change in the
forecast package. Most areas will be dry this morning with showers
and thunderstorms affecting areas from I-55 west this afternoon
and possibly getting as far east as I-57 late this afternoon. SPC
keeps slight risk of severe storms in southern IL south of our
CWA. Though there is a 5% risk of damaging wind gusts in far sw CWA
from Springfield to Lawrenceville south late this afternoon and
evening. Upper level trof over CO/NM with embedded short wave to
move into IL overnight while a cold front moves east across IL
during tonight. Have increased pops this evening due to slower
movement of front and then decreasing pops from west to east
behind cold front during overnight. Highs today in the upper 60s
nw over IL river valley to mid 70s se of I-70. Lows tonight 45-50F
over central IL and 50-55F in southeast IL. Rainfall amounts this
afternoon and tonight of a half to three quarter inch with locally
three quarter to 1 inch west of I-55.

Storm system to pass east of IL across IN/OH Friday morning with
more sunshine returning and mild highs in the low to mid 70s and
warmest over sw counties. Even a few degrees warmer on Saturday as
models have 850 mb temps of 12-14C. Still appears dry Friday
through the day on Saturday with partly to mostly sunny skies Sat.
Rather mild again on Sunday with highs in the upper 60s to mid 70s.
Models have trended warmer this weekend ahead of next storm system
over the Rockies. Continue chances of showers and isolated
thunderstorms Saturday night and Sunday as warm air advection
regime sets up again.

LONG TERM...Sunday night through Thursday

Extended models like GFS, ECMWF and GEM develop a strong/large cutoff
upper level low near CO Sunday morning and then move it into the MO
valley Tue and mid MS river valley during middle of next week.
This to bring an unsettled weather pattern with daily chance of
showers and isolated thunderstorms from Sunday through Thursday
with highest chances Sunday night through Tuesday. Mild temps
early in the week to cool by middle of next week as upper level
low moves near IL. Widespread rainfall amounts of 1-2 inches
expected during this time with heaviest amounts southern areas.
Seasonable highs in the upper 60s and lower 70s Monday cool into
the low to mid 50s Wed/Thu.

07

&&

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

$$








000
FXUS63 KLOT 241402
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
902 AM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* STRONG/GUSTY SOUTHEAST WINDS TODAY.

* SHOWERS LATER TONIGHT INTO EARLY FRIDAY MORNING.

* LOW END MVFR CEILINGS LIKELY TONIGHT INTO EARLY FRIDAY
  MORNING...WITH A POSSIBILITY FOR IFR CEILINGS.

RODRIGUEZ/DEUBELBEISS

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

VFR CEILINGS IN PLACE THIS MORNING WITH ANY LINGERING SHOWERS WELL
NORTH/NORTHEAST OF THE TERMINALS AT THIS TIME. EXPECT DRY
CONDITIONS FOR MOST OF TODAY AND EVENING WITH ONLY MID/HIGH HIGH
LEVEL CLOUD COVER LIKELY FOR MOST OF TODAY. A SLOWER EVOLUTION OF
THE APPROACHING SYSTEM TODAY IS APPEARING LIKELY AND HAVE PUSHED
BACK TIMING OF SHOWERS TO LATER TONIGHT WHEN THIS TROUGH OF LOW
PRESSURE FINALLY ARRIVES. ALTHOUGH THERE DOES STILL APPEAR TO BE
SOME POSSIBLE ISOLATED LIGHT SHOWERS BEFORE THEN...EXPECT ANY
SHOWERS TO BRIEF AND LIGHT AND SO HAVE REMOVED THE VCSH MENTION
FOR EARLIER THIS EVENING. NOT EXPECTED THUNDER WITH THE SHOWERS
TONIGHT AS BEST INSTABILITY/MOISTURE WILL REMAIN WELL SOUTH OF ALL
THE TERMINALS. VFR CEILINGS THIS EVENING WILL LIKELY FALL TO LOW
END MVFR FOR A TIME TONIGHT INTO EARLY FRIDAY MORNING...WITH A
POSSIBILITY FOR SOME PERIODS OF IFR. CONFIDENCE IS LOW WITH
REGARDS TO THE IFR AND SO HAVE LEFT OUT ANY MENTION IN THE TAFS.

EAST SOUTHEAST WINDS ARE IN PLACE THIS MORNING AND ARE STEADILY
INCREASING AT THIS HOUR. WITH THE SURFACE GRADIENT BECOMING
ORGANIZED THIS MORNING...EXPECT WINDS/GUSTS TO RAPIDLY INCREASE
OVER THE NEXT COUPLE OF HOURS AND REMAIN HIGH THROUGH THE
AFTERNOON. GUSTS OF AROUND 30KT ARE POSSIBLE FOR A TIME
TODAY...BEFORE WINDS/GUSTS DIMINISH LATE IN THE AFTERNOON AND
EARLY EVENING. PERSISTENT SOUTHEAST WINDS WILL LIKELY BECOME MORE
VARIABLE WITHIN THE TROUGH/PRECIP AXIS LATER TONIGHT BEFORE
TURNING TO THE NORTHWEST ON THE BACKSIDE OF THIS SYSTEM...STAYING
THIS DIRECTION INTO FRIDAY.

RODRIGUEZ

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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* MEDIUM HIGH CONFIDENCE WITH SHOWERS AND TIMING TONIGHT.

* MEDIUM HIGH CONFIDENCE WITH MVFR CEILINGS...WITH LOW CONFIDENCE
  FOR POSSIBLE IFR CEILINGS.

RODRIGUEZ/DEUBELBEISS

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

FRIDAY NIGHT...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

WEDNESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
443 AM CDT

LIGHTER FLOW REMAINING OVER THE LAKE EARLY THIS MORNING WITH
WEAKER SURFACE PATTERN STILL IN PLACE. ALTHOUGH...EXPECT EAST TO
SOUTHEAST WINDS TO RAPIDLY INCREASE THROUGH MID MORNING AND THEN
ESPECIALLY INTO THE AFTERNOON WHEN TO 30 KT WINDS WILL BE
OBSERVED...IN RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE.
EAST TO SOUTHEAST WINDS WILL STILL REMAIN TO 30 KT THIS EVENING
BUT SLOWLY DIMINISH AS THIS TROUGH OF LOW PRESSURE MOVES THROUGH
THE REGION. WINDS WILL BEGIN TURNING TO THE WEST/NORTHEAST ON THE
BACKSIDE OF THIS SYSTEM LATE TONIGHT INTO FRIDAY BEFORE TURNING
MORE NORTHERLY FRIDAY NIGHT INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 10 PM 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 241157
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
657 AM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* STRONG/GUSTY SOUTHEAST WINDS TODAY.

* SHOWERS LATER TONIGHT INTO EARLY FRIDAY MORNING.

* LOW END MVFR CEILINGS LIKELY TONIGHT INTO EARLY FRIDAY
  MORNING...WITH A POSSIBILITY FOR IFR CEILINGS.

RODRIGUEZ

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

VFR CEILINGS IN PLACE THIS MORNING WITH ANY LINGERING SHOWERS WELL
NORTH/NORTHEAST OF THE TERMINALS AT THIS TIME. EXPECT DRY
CONDITIONS FOR MOST OF TODAY AND EVENING WITH ONLY MID/HIGH HIGH
LEVEL CLOUD COVER LIKELY FOR MOST OF TODAY. A SLOWER EVOLUTION OF
THE APPROACHING SYSTEM TODAY IS APPEARING LIKELY AND HAVE PUSHED
BACK TIMING OF SHOWERS TO LATER TONIGHT WHEN THIS TROUGH OF LOW
PRESSURE FINALLY ARRIVES. ALTHOUGH THERE DOES STILL APPEAR TO BE
SOME POSSIBLE ISOLATED LIGHT SHOWERS BEFORE THEN...EXPECT ANY
SHOWERS TO BRIEF AND LIGHT AND SO HAVE REMOVED THE VCSH MENTION
FOR EARLIER THIS EVENING. NOT EXPECTED THUNDER WITH THE SHOWERS
TONIGHT AS BEST INSTABILITY/MOISTURE WILL REMAIN WELL SOUTH OF ALL
THE TERMINALS. VFR CEILINGS THIS EVENING WILL LIKELY FALL TO LOW
END MVFR FOR A TIME TONIGHT INTO EARLY FRIDAY MORNING...WITH A
POSSIBILITY FOR SOME PERIODS OF IFR. CONFIDENCE IS LOW WITH
REGARDS TO THE IFR AND SO HAVE LEFT OUT ANY MENTION IN THE TAFS.

EAST SOUTHEAST WINDS ARE IN PLACE THIS MORNING AND ARE STEADILY
INCREASING AT THIS HOUR. WITH THE SURFACE GRADIENT BECOMING
ORGANIZED THIS MORNING...EXPECT WINDS/GUSTS TO RAPIDLY INCREASE
OVER THE NEXT COUPLE OF HOURS AND REMAIN HIGH THROUGH THE
AFTERNOON. GUSTS OF AROUND 30KT ARE POSSIBLE FOR A TIME
TODAY...BEFORE WINDS/GUSTS DIMINISH LATE IN THE AFTERNOON AND
EARLY EVENING. PERSISTENT SOUTHEAST WINDS WILL LIKELY BECOME MORE
VARIABLE WITHIN THE TROUGH/PRECIP AXIS LATER TONIGHT BEFORE
TURNING TO THE NORTHWEST ON THE BACKSIDE OF THIS SYSTEM...STAYING
THIS DIRECTION INTO FRIDAY.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* MEDIUM HIGH CONFIDENCE WITH SHOWERS AND TIMING TONIGHT.

* MEDIUM HIGH CONFIDENCE WITH MVFR CEILINGS...WITH LOW CONFIDENCE
  FOR POSSIBLE IFR CEILINGS.

RODRIGUEZ

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

FRIDAY NIGHT...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

WEDNESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
443 AM CDT

LIGHTER FLOW REMAINING OVER THE LAKE EARLY THIS MORNING WITH
WEAKER SURFACE PATTERN STILL IN PLACE. ALTHOUGH...EXPECT EAST TO
SOUTHEAST WINDS TO RAPIDLY INCREASE THROUGH MID MORNING AND THEN
ESPECIALLY INTO THE AFTERNOON WHEN TO 30 KT WINDS WILL BE
OBSERVED...IN RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE.
EAST TO SOUTHEAST WINDS WILL STILL REMAIN TO 30 KT THIS EVENING
BUT SLOWLY DIMINISH AS THIS TROUGH OF LOW PRESSURE MOVES THROUGH
THE REGION. WINDS WILL BEGIN TURNING TO THE WEST/NORTHEAST ON THE
BACKSIDE OF THIS SYSTEM LATE TONIGHT INTO FRIDAY BEFORE TURNING
MORE NORTHERLY FRIDAY NIGHT INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 241132
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
632 AM CDT Thu Apr 24 2014

.DISCUSSION...
ISSUED 330 AM CDT Thu Apr 24 2014

SHORT TERM...Today through Sunday

00Z models continue to be slower with cold frontal passage and
associated convection and that is the biggest change in the
forecast package. Most areas will be dry this morning with showers
and thunderstorms affecting areas from I-55 west this afternoon
and possibly getting as far east as I-57 late this afternoon. SPC
keeps slight risk of severe storms in southern IL south of our
CWA. Though there is a 5% risk of damaging wind gusts in far sw CWA
from Springfield to Lawrenceville south late this afternoon and
evening. Upper level trof over CO/NM with embedded short wave to
move into IL overnight while a cold front moves east across IL
during tonight. Have increased pops this evening due to slower
movement of front and then decreasing pops from west to east
behind cold front during overnight. Highs today in the upper 60s
nw over IL river valley to mid 70s se of I-70. Lows tonight 45-50F
over central IL and 50-55F in southeast IL. Rainfall amounts this
afternoon and tonight of a half to three quarter inch with locally
three quarter to 1 inch west of I-55.

Storm system to pass east of IL across IN/OH Friday morning with
more sunshine returning and mild highs in the low to mid 70s and
warmest over sw counties. Even a few degrees warmer on Saturday as
models have 850 mb temps of 12-14C. Still appears dry Friday
through the day on Saturday with partly to mostly sunny skies Sat.
Rather mild again on Sunday with highs in the upper 60s to mid 70s.
Models have trended warmer this weekend ahead of next storm system
over the Rockies. Continue chances of showers and isolated
thunderstorms Saturday night and Sunday as warm air advection
regime sets up again.

LONG TERM...Sunday night through Thursday

Extended models like GFS, ECMWF and GEM develop a strong/large cutoff
upper level low near CO Sunday morning and then move it into the MO
valley Tue and mid MS river valley during middle of next week.
This to bring an unsettled weather pattern with daily chance of
showers and isolated thunderstorms from Sunday through Thursday
with highest chances Sunday night through Tuesday. Mild temps
early in the week to cool by middle of next week as upper level
low moves near IL. Widespread rainfall amounts of 1-2 inches
expected during this time with heaviest amounts southern areas.
Seasonable highs in the upper 60s and lower 70s Monday cool into
the low to mid 50s Wed/Thu.

07

&&

.AVIATION...
ISSUED 625 AM CDT Thu Apr 24 2014

Several forecast concerns this period include surface wind gusts
later this morning into this afternoon and a deterioration in
cigs this evening as showers and scattered TSRA affect the TAF
sites. Band of showers was located over east central Iowa, tracking
mainly to the northeast and not expected to affect our TAF
locations this morning. However, as a frontal boundary out to our
west make progress to the east later today, the threat for showers
and storms will increase from west to east in the 20z-01z time
frame. Widespread rain and isold TSRA will be the story this
evening with the cigs gradually lowering to MVFR with some brief
IFR cigs possible where some of the heavier showers/storms move
through. Steadier light rains will follow later this evening
before the system shifts off to our east late tonight. Surface
winds will be out of the southeast at 15 to 25 kts today with
a few gusts around 30 kts at times. FROPA is not expected until
or just after 03z at PIA with CMI the last to see the wind shift
by 08z.

Smith
&&

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

$$





000
FXUS63 KLOT 240944
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
444 AM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* STRONG/GUSTY SOUTHEAST WINDS TODAY.

* SHRA LATER THIS EVENING W/ ISOL TSRA.

* POSSIBLE LOW END MVFR CEILINGS LATE IN THE FORECAST PERIOD.

RODRIGUEZ

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

TERMINALS REMAIN ON EASTERN FRINGE OF PERSISTENT SHOWER
DEVELOPMENT AT THIS HOUR...AND NOW EXPECT THIS TO CONTINUE OVER
THE NEXT COUPLE OF HOURS BEFORE THIS PRECIP SHIELD ALL LIFTS TO
THE NORTH OF THE TERMINALS LATER THIS MORNING. ALTHOUGH...STILL
CONFIDENT THIS WILL REMAIN LIGHT WITH VFR CONDITIONS CONTINUING.
A LULL IN THE ACTIVITY AS WELL AS CLOUD COVER WILL LIKELY OCCUR
FOR THE REMAINDER OF THE DAY BEFORE THE NEXT SYSTEM CURRENTLY WELL
WEST OF THE TERMINALS SLOWLY APPROACHES. VFR CEILINGS WILL RETURN
LATE THIS AFTERNOON INTO THE EVENING AS WELL AS
SHOWER/THUNDERSTORM CHANCES. MAINTAINED JUST SHOWERS IN THE TAFS
WITH LOW CONFIDENCE OF TSRA AT THIS TIME...WITH EVEN SOME
POSSIBILITY OF DELAYING THE ONSET OF VCSH/-SHAR WITH LATER
FORECASTS. SOUTHEAST WINDS WILL RAMP UP RATHER QUICKLY LATER THIS
MORNING WITH STRONG GUSTS TO AROUND 30 KT LIKELY BEFORE A SLOW
DOWNWARD TREND OCCURS LATER THIS AFTERNOON. WITH CONFIDENCE LOWER
WITH REGARDS TO OVERALL TIMING OF THIS SYSTEM...HAVE LEFT OUT ANY
MENTION OF WIND SHIFT TO THE NORTHWEST AND POSSIBLE LOW END MVFR
CEILINGS VERY LATE IN THE FORECAST PERIOD FOR ORD.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH SHOWERS LATER THIS EVENING...WITH LOW
  MEDIUM CONFIDENCE ON EXACT TIMING AND TSRA.

* LOW CONFIDENCE WITH LOW END MVFR CEILING CHANCES.

RODRIGUEZ

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

* FRIDAY AND SATURDAY...DRY/VFR.
* SUNDAY THROUGH TUESDAY...CHANCE OF SHRA. MVFR POSSIBLE.

&&

.MARINE...
443 AM CDT

LIGHTER FLOW REMAINING OVER THE LAKE EARLY THIS MORNING WITH
WEAKER SURFACE PATTERN STILL IN PLACE. ALTHOUGH...EXPECT EAST TO
SOUTHEAST WINDS TO RAPIDLY INCREASE THROUGH MID MORNING AND THEN
ESPECIALLY INTO THE AFTERNOON WHEN TO 30 KT WINDS WILL BE
OBSERVED...IN RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE.
EAST TO SOUTHEAST WINDS WILL STILL REMAIN TO 30 KT THIS EVENING
BUT SLOWLY DIMINISH AS THIS TROUGH OF LOW PRESSURE MOVES THROUGH
THE REGION. WINDS WILL BEGIN TURNING TO THE WEST/NORTHEAST ON THE
BACKSIDE OF THIS SYSTEM LATE TONIGHT INTO FRIDAY BEFORE TURNING
MORE NORTHERLY FRIDAY NIGHT INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 240909
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
409 AM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* STRONG/GUSTY SOUTHEAST WINDS TODAY.

* SHRA LATER THIS EVENING W/ ISOL TSRA.

* POSSIBLE LOW END MVFR CEILINGS LATE IN THE FORECAST PERIOD.

RODRIGUEZ

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

TERMINALS REMAIN ON EASTERN FRINGE OF PERSISTENT SHOWER
DEVELOPMENT AT THIS HOUR...AND NOW EXPECT THIS TO CONTINUE OVER
THE NEXT COUPLE OF HOURS BEFORE THIS PRECIP SHIELD ALL LIFTS TO
THE NORTH OF THE TERMINALS LATER THIS MORNING. ALTHOUGH...STILL
CONFIDENT THIS WILL REMAIN LIGHT WITH VFR CONDITIONS CONTINUING.
A LULL IN THE ACTIVITY AS WELL AS CLOUD COVER WILL LIKELY OCCUR
FOR THE REMAINDER OF THE DAY BEFORE THE NEXT SYSTEM CURRENTLY WELL
WEST OF THE TERMINALS SLOWLY APPROACHES. VFR CEILINGS WILL RETURN
LATE THIS AFTERNOON INTO THE EVENING AS WELL AS
SHOWER/THUNDERSTORM CHANCES. MAINTAINED JUST SHOWERS IN THE TAFS
WITH LOW CONFIDENCE OF TSRA AT THIS TIME...WITH EVEN SOME
POSSIBILITY OF DELAYING THE ONSET OF VCSH/-SHAR WITH LATER
FORECASTS. SOUTHEAST WINDS WILL RAMP UP RATHER QUICKLY LATER THIS
MORNING WITH STRONG GUSTS TO AROUND 30 KT LIKELY BEFORE A SLOW
DOWNWARD TREND OCCURS LATER THIS AFTERNOON. WITH CONFIDENCE LOWER
WITH REGARDS TO OVERALL TIMING OF THIS SYSTEM...HAVE LEFT OUT ANY
MENTION OF WIND SHIFT TO THE NORTHWEST AND POSSIBLE LOW END MVFR
CEILINGS VERY LATE IN THE FORECAST PERIOD FOR ORD.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH SHOWERS LATER THIS EVENING...WITH LOW
  MEDIUM CONFIDENCE ON EXACT TIMING AND TSRA.

* LOW CONFIDENCE WITH LOW END MVFR CEILING CHANCES.

RODRIGUEZ

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

* FRIDAY AND SATURDAY...DRY/VFR.
* SUNDAY THROUGH TUESDAY...CHANCE OF SHRA. MVFR POSSIBLE.

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 240853
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
353 AM CDT THU APR 24 2014

.DISCUSSION...
351 AM CDT

MAIN FOCUS THIS MORNING IS WITH SLOWER PROGRESSION OF SURFACE LOW
AND COLD FRONT AND ASSOCIATED RAIN ESPECIALLY LATE TODAY/TONIGHT.
BREEZY/MILD DAY FRIDAY...BEFORE SECOND COLD FRONT PASSES FRIDAY
EVENING AND SETS STAGE FOR PROLONGED PERIOD OF COOL/WET WEATHER
ESPECIALLY SATURDAY NIGHT-WEDNESDAY.

BAND OF SHOWERS/GRAUPEL WITH LEAD SHORT WAVE TROUGH CONTINUES TO
LIFT NORTHEAST ACROSS NORTH/NORTHEAST PARTS OF THE CWA AT 0830Z.
DRYING EVIDENT UPSTREAM INTO WESTERN IL/MO...WITH NEAR TERM GUIDANCE
IN GOOD AGREEMENT IN SUGGESTING MOST OF FORECAST AREA WILL SEE DRY
WEATHER FOR MUCH OF THE MORNING/EARLY AFTERNOON HOURS AS INITIAL
ELEVATED WARM FRONTAL PRECIP LIFTS NORTH OF THE AREA. TREND IN MODEL
GUIDANCE OVER THE PAST 24 HOURS HAS BEEN TO SLOW EASTWARD
PROGRESSION OF COLD FRONT...WITH DEEPER SOUTHERN STREAM SHORT WAVE
ALSO RESULTING IN SURFACE LOW REFLECTION TRACKING FARTHER SOUTH
ACROSS CENTRAL IL. OVERALL...ONLY REAL CHANGE TO GOING FORECAST WAS
TO SLOW ARRIVAL AND DEPARTURE OF HIGHER POPS WITH THE FRONT THROUGH
TONIGHT.  WITH STEADIER RAINFALL TONIGHT...STILL LOOKS TO BE ABOUT A
HALF INCH AREA WIDE. FORECAST SOUNDINGS INDICATE LAPSE RATES NOT
PARTICULARLY IMPRESSIVE...AND HAVE ONLY INDICATED ISOLATED THUNDER
MAINLY WITH APPROACH OF COLD LATE TODAY/TONIGHT. FRONT CLEARS
EASTERN CWA AROUND SUNRISE FRIDAY MORNING...WITH WEAK FLAT SURFACE
RIDGE DEVELOPING ACROSS THE AREA DURING THE DAY. DEEPER MIXING AND
SUBSIDENCE INDICATE FRIDAY MAY BE THE MILDEST DAY OF THE STRETCH
WITH MID 60S-LOW 70S EXPECTED FROM FAR NORTH TO FAR SOUTH.

AS INDICATED OVER THE PAST FEW DAYS...ANOTHER COLD FRONT ASSOCIATED
WITH NORTHERN STREAM DISTURBANCE DOES SETTLE SOUTH ACROSS THE
FORECAST AREA FRIDAY EVENING. MODELS CONTINUE TO HAVE SOME
DIFFICULTY PINNING DOWN EXACT TIMING/PLACEMENT OF THE FRONT AS IT
SLOWS UP OVER CENTRAL IL/IN FRIDAY NIGHT...THOUGH MOST GUIDANCE DOES
INDICATE POTENTIAL FOR SOME SPOTTY LIGHT PRECIP AS FRONT UNDERCUTS
WEST-SOUTHWEST FLOW ALOFT. WITH CONFIDENCE IN TIMING/PLACEMENT OF
ANY LIGHT SHOWERS RATHER LOW...HAVE BROAD-BRUSHED SLIGHT CHANCE
OVERNIGHT THOUGH NOT EXPECTING RAIN TO AMOUNT TO MUCH.

BRIEF INTRUSION OF HIGH PRESSURE RIDGING FROM THE NORTH ON SATURDAY
EXPECTED TO YIELD DRY BUT COOLER WEATHER...BEFORE STATIONARY FRONTAL
BOUNDARY TO OUR SOUTH BECOMES FOCUS FOR PRECIP DEVELOPMENT SATURDAY
NIGHT THROUGH THE EXTENDED PORTION OF THE FORECAST AS CLOSED UPPER
LOW AND ITS ASSOCIATED SURFACE CIRCULATION SLOWLY WOBBLES FROM THE
PLAINS TO THE GREAT LAKES REGION THROUGH THE MIDDLE OF NEXT WEEK.
COOL AND GENERALLY WET WEATHER TO PREDOMINATE...WITH EAST-NORTHEAST
LOW LEVEL WINDS AND PERSISTENT MOIST ASCENT FROM THE SOUTH ABOVE THE
STATIONARY BAROCLINIC ZONE TO OUR SOUTH. GUIDANCE HAS TRENDED
GENERALLY WARMER ALOFT SUNDAY-TUESDAY...THOUGH AFOREMENTIONED LOW
LEVEL WINDS OFF LAKE MICHIGAN WILL LIKELY MAKE FOR A FAIRLY LARGE
GRADIENT FROM NORTH TO SOUTH FOR MUCH OF THE PERIOD...WITH HIGHS
ALONG THE LAKE IN THE 40S...WHILE 60S ARE MORE PREVALENT SOUTH OF
THE I-80 CORRIDOR.

RATZER

&&

.AVIATION...

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

* PERIODS OF LIGHT RAIN THROUGH EARLY THIS MORNING.

* STRONG/GUSTY SOUTHEAST WINDS TODAY.

* SHRA LATER THIS EVENING W/ ISOL TSRA.

* POSSIBLE LOW END MVFR CEILINGS LATE IN THE FORECAST PERIOD.

RODRIGUEZ

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

TERMINALS REMAIN ON EASTERN FRINGE OF PERSISTENT SHOWER
DEVELOPMENT AT THIS HOUR...AND NOW EXPECT THIS TO CONTINUE OVER
THE NEXT COUPLE OF HOURS BEFORE THIS PRECIP SHIELD ALL LIFTS TO
THE NORTH OF THE TERMINALS LATER THIS MORNING. ALTHOUGH...STILL
CONFIDENT THIS WILL REMAIN LIGHT WITH VFR CONDITIONS CONTINUING.
A LULL IN THE ACTIVITY AS WELL AS CLOUD COVER WILL LIKELY OCCUR
FOR THE REMAINDER OF THE DAY BEFORE THE NEXT SYSTEM CURRENTLY WELL
WEST OF THE TERMINALS SLOWLY APPROACHES. VFR CEILINGS WILL RETURN
LATE THIS AFTERNOON INTO THE EVENING AS WELL AS
SHOWER/THUNDERSTORM CHANCES. MAINTAINED JUST SHOWERS IN THE TAFS
WITH LOW CONFIDENCE OF TSRA AT THIS TIME...WITH EVEN SOME
POSSIBILITY OF DELAYING THE ONSET OF VCSH/-SHAR WITH LATER
FORECASTS. SOUTHEAST WINDS WILL RAMP UP RATHER QUICKLY LATER THIS
MORNING WITH STRONG GUSTS TO AROUND 30 KT LIKELY BEFORE A SLOW
DOWNWARD TREND OCCURS LATER THIS AFTERNOON. WITH CONFIDENCE LOWER
WITH REGARDS TO OVERALL TIMING OF THIS SYSTEM...HAVE LEFT OUT ANY
MENTION OF WIND SHIFT TO THE NORTHWEST AND POSSIBLE LOW END MVFR
CEILINGS VERY LATE IN THE FORECAST PERIOD FOR ORD.

RODRIGUEZ

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

* HIGH CONFIDENCE WITH RAIN AND VFR CONDITIONS.

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH SHOWERS LATER THIS EVENING...WITH LOW
  MEDIUM CONFIDENCE ON EXACT TIMING AND TSRA.

* LOW CONFIDENCE WITH LOW END MVFR CEILING CHANCES.

RODRIGUEZ

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

* FRIDAY AND SATURDAY...DRY/VFR.
* SUNDAY THROUGH TUESDAY...CHANCE OF SHRA. MVFR POSSIBLE.

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 240830
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
330 AM CDT Thu Apr 24 2014

.DISCUSSION...
ISSUED 330 AM CDT Thu Apr 24 2014

SHORT TERM...Today through Sunday

00Z models continue to be slower with cold frontal passage and
associated convection and that is the biggest change in the
forecast package. Most areas will be dry this morning with showers
and thunderstorms affecting areas from I-55 west this afternoon
and possibly getting as far east as I-57 late this afternoon. SPC
keeps slight risk of severe storms in southern IL south of our
CWA. Though there is a 5% risk of damaging wind gusts in far sw CWA
from Springfield to Lawrenceville south late this afternoon and
evening. Upper level trof over CO/NM with embedded short wave to
move into IL overnight while a cold front moves east across IL
during tonight. Have increased pops this evening due to slower
movement of front and then decreasing pops from west to east
behind cold front during overnight. Highs today in the upper 60s
nw over IL river valley to mid 70s se of I-70. Lows tonight 45-50F
over central IL and 50-55F in southeast IL. Rainfall amounts this
afternoon and tonight of a half to three quarter inch with locally
three quarter to 1 inch west of I-55.

Storm system to pass east of IL across IN/OH Friday morning with
more sunshine returning and mild highs in the low to mid 70s and
warmest over sw counties. Even a few degrees warmer on Saturday as
models have 850 mb temps of 12-14C. Still appears dry Friday
through the day on Saturday with partly to mostly sunny skies Sat.
Rather mild again on Sunday with highs in the upper 60s to mid 70s.
Models have trended warmer this weekend ahead of next storm system
over the Rockies. Continue chances of showers and isolated
thunderstorms Saturday night and Sunday as warm air advection
regime sets up again.

LONG TERM...Sunday night through Thursday

Extended models like GFS, ECMWF and GEM develop a strong/large cutoff
upper level low near CO Sunday morning and then move it into the MO
valley Tue and mid MS river valley during middle of next week.
This to bring an unsettled weather pattern with daily chance of
showers and isolated thunderstorms from Sunday through Thursday
with highest chances Sunday night through Tuesday. Mild temps
early in the week to cool by middle of next week as upper level
low moves near IL. Widespread rainfall amounts of 1-2 inches
expected during this time with heaviest amounts southern areas.
Seasonable highs in the upper 60s and lower 70s Monday cool into
the low to mid 50s Wed/Thu.

07

&&

.AVIATION...
ISSUED 1155 PM CDT Wed Apr 23 2014

A break in the precipitation will occur as a tongue of dry air
follows the initial wave of warm advection precip. The warm front
will develop near the Missouri-Illinois border tomorrow morning,
then progress eastward tomorrow afternoon just ahead of the cold
front. A slower trend is being depicted in the 00z models, and
thunder chances will be focused mainly between 23z and 05z from
west to east. There should be a period of steady rains in the warm
sector ahead of the cold front, with thunder chances highest during
that time as well. A VCTS was included starting at 23z in PIA and
03z at CMI. A tempo for MVFR or possibly IFR may be needed for a
couple hours tomorrow evening.

Winds will increase quickly tomorrow morning, as the nose of an
850mb LLJ advances into western IL. Gusts early in the morning may
actually be a few knots higher than the afternoon based on the
strength of the LLJ as depicted in the HopWRF and RAP. A few gusts
may top out over 30kt for PIA/SPI between 14z-16z. Wind directions
will be SE for the first 12-15 hours of the TAFs, then it will
shift toward the south into the afternoon as wind speeds remain
strong in the 18g28kt range. By evening, wind speeds should
subside a bit as the pressure gradient weakens near the cold
front.

Shimon
&&

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

$$








000
FXUS63 KLOT 240549
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1249 AM CDT THU APR 24 2014

.DISCUSSION...
931 PM CDT

SHOWERS CONTINUE TO MOVE/DEVELOP EASTWARD ACROSS NORTHERN ILLINOIS
EARLY THIS EVENING WITHIN A ZONE OF INCREASING ISENTROPIC ASCENT
ALONG THE WESTERN PERIPHERY OF A SURFACE RIDGE OF HIGH PRESSURE. THIS
ACTIVITY IS EXPECTED TO CONTINUE MOVING EASTWARD ACROSS NORTHERN
ILLINOIS LATE THIS EVENING...AND LIKELY ENDING PRIOR TO DAYBREAK
THURSDAY AS THE BETTER FORCING AND MOISTENING SHIFTS TO THE NORTH
AND EAST OF THE REGION. THEREFORE...NO BIG CHANGES ARE NEEDED TO THE
GOING FORECAST FOR TONIGHT.

THURSDAY IS SHAPING UP TO BE A BREEZY AND A MILDER DAY ACROSS THE
AREA AS SOUTHEASTERLY FLOW RAMPS UP IN RESPONSE TO AN AREA OF LOW
PRESSURE APPROACHING WESTERN ILLINOIS DURING THE AFTERNOON. IT
APPEARS THAT IN SPITE OF THE SOUTH-SOUTHEASTERLY WIND
COMPONENT...THAT WINDS COULD BE VERY GUSTY...UP IN THE 30 TO 35 KT
RANGE...DURING THE AFTERNOON. ALSO...IT APPEARS THAT THESE
SOUTHEASTERLY WINDS WILL TRANSPORT A DRIER LOWER LEVEL AIR MASS IN
ACROSS THE AREA DURING THE DAY...AND THIS COULD LEAD TO LOWER
SURFACE DEW POINTS THAN CURRENTLY FORECAST...ESPECIALLY ACROSS THE
EASTERN HALF OF THE AREA. WITH THIS IN MIND...I HAVE BACKED OFF ON
POPS DURING THE AFTERNOON THURSDAY...WITH A LIKELY SLOWER EVOLUTION
OF THE PRECIPITATION. IT APPEARS THE MAIN FORCING AND MOISTURE WILL
NOT ARRIVE ACROSS THE AREA UNTIL THURSDAY EVENING. AT THIS TIME I
HAVE LEFT SOME LOW END POPS IN DURING THE AFTERNOON...BUT IF THESE
TRENDS CONTINUE...WE MAY BE ABLE TO GO DRY ALL AFTERNOON ON
THURSDAY...ESPECIALLY ACROSS THE EASTERN HALF OF THE AREA. PERIODS
OF RAIN STILL APPEAR TO BE A GOOD BET THURSDAY NIGHT.

KJB

//PREV DISCUSSION...
310 PM CDT

SYNOPSIS...ANOTHER PLEASANT DAY TODAY...BUT SHOWERS MOVE IN FROM THE
WEST THIS EVENING. SHOWERS AND STORMS ARE EXPECTED TOMORROW
AFTERNOON AND EVENING WITH A DRY AND WARM END TO THE WORK WEEK.
THIS WEEKEND LOOKS TO HAVE BELOW NORMAL TEMPERATURES WITH SHOWERS
AND PERHAPS SOME THUNDERSTORMS ALONG AND SOUTH OF I-80 FOR THE FIRST
HALF OF NEXT WEEK.

REST OF TODAY AND TONIGHT...
A LARGE UPPER LEVEL RIDGE IS OVER THE CENTRAL PLAINS WHILE A SURFACE
HIGH IS CENTERED OVER LAKE MICHIGAN. THE RIDGE PASSES OVERHEAD
TONIGHT WHILE THE SURFACE HIGH PUSHES EAST TO THE NORTHERN OHIO
VALLEY THROUGH EASTERN QUEBEC.

A WEAK SHORTWAVE IS OVER EASTERN NEBRASKA AND WESTERN IOWA WITH
SHOWERS OVER WESTERN IOWA.  THE SHOWERS WILL CONTINUE TO PUSH
EAST...BUT WITH DEWPOINT DEPRESSIONS AT 20+ DEGREES...THINKING THE
SHOWERS WILL DISSIPATE A BIT BEFORE MOVING INTO CENTRAL IL. AS SUCH
THINKING THE FIRST SHOWERS WILL ENTER THE FAR EASTERN CWA AFTER 5PM
CST.  USED THE LOCAL ARW...RAP...AND HRRR TO CREATE THE POPS FOR THE
REST OF TODAY AND TONIGHT. THINKING A BAND OF SCATTERED SHOWERS WILL
SLOWLY CROSS NORTHERN IL THIS EVENING IN ASSOCIATION WITH AN UPPER
LEVEL VORTICITY STREAMER. THE BEST COVERAGE WILL BE BETWEEN MIDNIGHT
AND 4 AM CST WITH A CHANCE OF LIGHT RAIN SHOWERS NORTH OF I-80. THE
BAND THEN LIFTS NORTH EARLY THURSDAY MORNING AS THE RIDGE MOVES
DIRECTLY OVERHEAD. NOT EXPECTING ANY SIGNIFICANT PRECIP
ACCUMULATIONS.

CLOUD COVER WILL INCREASE THROUGH THIS AFTERNOON AND LOOKING AT MIN
TEMPS IN THE UPPER 30S TO MID 40S ACROSS THE CWA.

TOMORROW AND TOMORROW NIGHT...
AN UPPER LEVEL TROUGH MOVES OVER THE PLAINS TOMORROW MORNING AND THE
TROUGH PASSES OVER THE REGION TOMORROW NIGHT. THE UPPER LEVEL LOW
ASSOCIATED WITH THE TROUGH PASSES FARTHER NORTH...ALONG THE
US/CANADA BORDER.  THE SURFACE LOW ALSO BEGINS OVER THE PLAINS
THURSDAY MORNING AND THEN MOVES OVER IL THURSDAY EVENING. GUIDANCE
HAS THE LOW PROGRESSING A BIT SLOWER AND MADE THE NECESSARY
ADJUSTMENTS.

RAIN AND SOME STORMS MOVE IN FROM THE WEST THROUGH THE MORNING AND
EARLY AFTERNOON.  INSTABILITY IS NOT EXTREMELY IMPRESSIVE WITH THE
SYSTEM SO KEPT ONLY A CHANCE OF THUNDER. QPF AMOUNTS ON THE OTHER
HAND COULD BE IMPRESSIVE WITH TOTALS AROUND A HALF INCH OF RAIN.

WINDS WILL ALSO BE SHIFTING FROM SOUTHEAST IN THE MORNING TO OUT OF
THE WEST OVERNIGHT BEHIND THE LOW.  LOOKING AT A BREEZY AFTERNOON
WITH SOUTH WINDS GUSTING TO 35 MPH.  THE AMPLE WAA WILL LEAD TO MAX
TEMPS FROM AROUND 60 ALONG THE IL/WI BORDER TO THE UPPER 60S IF NOT
70 IN THE SOUTHERN CWA.

FRIDAY AND SATURDAY...
THE UPPER LEVEL LOW CONTINUES TO SHIFT EAST REACHING NEW ENGLAND BY
SATURDAY AFTERNOON/EVENING.  THE SURFACE LOW SHIFTS EAST AND
EXPECTING PRECIP TO COME TO AN END EARLY FRIDAY MORNING.  WEST WINDS
WILL BE GUSTING TO ARND 30 MPH FRIDAY AND AM THINKING THERE COULD BE
SOME DRY AIR MIXING DOWN TO THE SURFACE SO LOWERED DEWPOINTS A BIT.

THE AIR BEHIND THE COLD FRONT IS NOT REALLY ALL THAT COLD SINCE MAX
TEMPS ON FRIDAY LOOK TO BE AROUND 70 DEGREES.  A BACK DOOR COLD
FRONT SLIDES DOWN FROM THE NORTH IN THE EVENING. SOME GUIDANCE
MEMBERS FEATURE A BAND OF PRECIP FORMING AHEAD OF THE FRONT OVER FAR
NORTHERN IL AND NW INDIANA. PUT IN A CHANCE OF PRECIP SINCE FORCING
LOOKS GOOD...BUT HAVE LOW CONFIDENCE IN THE BAND OF PRECIP ACTUALLY
FORMING. AS SUCH KEPT POPS IN THE CHANCE RANGE.  WINDS TURN
NORTHEAST BEHIND THE FRONT AND OVERNIGHT LOWS WILL BE IN THE UPPER
30S TO MID 40S.

SOME GUIDANCE MEMBERS KEEP A BAND OF PRECIP OVER THE REGION SATURDAY
MORNING...BUT WITH HIGH PRESSURE MOVING OVER THE REGION HAVE LOW
CONFIDENCE AND WENT WITH A DRY FORECAST SATURDAY.  SKIES WILL CLEAR
BUT THE COOLER AIR OFF THE LAKE WILL RESULT IN HIGHS IN THE UPPER
40S TO MID 50S ALONG THE LAKE...AND THEN IN THE LOW TO MID 60S IN
THE OUTLYING AREAS.

GUIDANCE FEATURES PRECIP MOVING IN AHEAD OF THE NEXT LOW SATURDAY
NIGHT. HAVE LOW CONFIDENCE IN THIS ROUND OF PRECIP AS WELL...BUT
LEFT A CHANCE OF RAIN IN THE FORECAST.  OVERNIGHT LOWS WILL RANGE
FROM THE UPPER 30S TO THE MID 40S.

EXTENDED...SUNDAY THROUGH TUESDAY...
AN UPPER LEVEL CLOSED LOW SHIFTS OVER THE GREAT PLAINS SUNDAY
EVENING/NIGHT. GUIDANCE DIFFERS ON ITS EXACT PATH EARLY NEXT WEEK
BUT DOES HAVE THE UPPER LEVEL LOW OVER THE REGION THROUGH AT LEAST
MID WEEK.  ITS ASSOCIATED SURFACE LOW MOVES OVER THE PLAINS LATE
SUNDAY NIGHT/MONDAY MORNING AND SLIDES SOUTH OF THE CWA MONDAY
NIGHT. THE 12Z GUIDANCE AGREED A BIT MORE ABOUT THE SURFACE LOWS
PATH...AND HAVE IT MOVING THROUGH SOUTHERN IL TUESDAY.

IN TWO WORDS EARLY NEXT WEEK LOOKS CHILLY AND WET.  A BOUNDARY OVER
NORTHERN IL BRINGS THE LIFT FOR THE FIRST WAVE OF PRECIP EARLY ON
SUNDAY...BUT THEN MULTIPLE VORTICITY STREAMERS PASS THROUGH THE
REGION AS THE LOW SLOWLY SHIFTS EAST. THIS WILL RESULT IN A CHANCE
OF PRECIP THROUGHOUT THE EXTENDED. WILL INCLUDE A SLIGHT CHANCE OF
THUNDER ALONG AND SOUTH OF I-80 WHERE THERE WILL BE LIMITED ELEVATED
INSTABILITY BUT ENOUGH TO PERHAPS SUPPORT A COUPLE OF THUNDERSTORMS
SUNDAY NIGHT AND MONDAY. THE UPPER LEVEL JET DIPS FAR SOUTH THROUGH
TEXAS ALLOWING COOL AIR TO SPREAD ACROSS THE REGION. AS SUCH HIGHS
WILL VARY BETWEEN THE LOW 50S NORTH TO MID 60S SOUTH WITH A COOLING
TREND THROUGH TUESDAY.  LUCKILY OVERNIGHT LOWS LOOK LIKE THEY WILL
REMAIN ABOVE FREEZING.

JEE

&&

.AVIATION...

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

* PERIODS OF LIGHT RAIN THROUGH EARLY THIS MORNING.

* STRONG/GUSTY SOUTHEAST WINDS TODAY.

* SHRA LATER THIS EVENING W/ ISOL TSRA.

* POSSIBLE LOW END MVFR CEILINGS LATE IN THE FORECAST PERIOD.

RODRIGUEZ

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

TERMINALS REMAIN ON EASTERN FRINGE OF PERSISTENT SHOWER
DEVELOPMENT AT THIS HOUR...AND NOW EXPECT THIS TO CONTINUE OVER
THE NEXT COUPLE OF HOURS BEFORE THIS PRECIP SHIELD ALL LIFTS TO
THE NORTH OF THE TERMINALS LATER THIS MORNING. ALTHOUGH...STILL
CONFIDENT THIS WILL REMAIN LIGHT WITH VFR CONDITIONS CONTINUING.
A LULL IN THE ACTIVITY AS WELL AS CLOUD COVER WILL LIKELY OCCUR
FOR THE REMAINDER OF THE DAY BEFORE THE NEXT SYSTEM CURRENTLY WELL
WEST OF THE TERMINALS SLOWLY APPROACHES. VFR CEILINGS WILL RETURN
LATE THIS AFTERNOON INTO THE EVENING AS WELL AS
SHOWER/THUNDERSTORM CHANCES. MAINTAINED JUST SHOWERS IN THE TAFS
WITH LOW CONFIDENCE OF TSRA AT THIS TIME...WITH EVEN SOME
POSSIBILITY OF DELAYING THE ONSET OF VCSH/-SHAR WITH LATER
FORECASTS. SOUTHEAST WINDS WILL RAMP UP RATHER QUICKLY LATER THIS
MORNING WITH STRONG GUSTS TO AROUND 30 KT LIKELY BEFORE A SLOW
DOWNWARD TREND OCCURS LATER THIS AFTERNOON. WITH CONFIDENCE LOWER
WITH REGARDS TO OVERALL TIMING OF THIS SYSTEM...HAVE LEFT OUT ANY
MENTION OF WIND SHIFT TO THE NORTHWEST AND POSSIBLE LOW END MVFR
CEILINGS VERY LATE IN THE FORECAST PERIOD FOR ORD.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH RAIN AND VFR CONDITIONS.

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH SHOWERS LATER THIS EVENING...WITH LOW
  MEDIUM CONFIDENCE ON EXACT TIMING AND TSRA.

* LOW CONFIDENCE WITH LOW END MVFR CEILING CHANCES.

RODRIGUEZ

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

* FRIDAY AND SATURDAY...DRY/VFR.
* SUNDAY THROUGH TUESDAY...CHANCE OF SHRA. MVFR POSSIBLE.

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 240455
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1155 PM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 900 PM CDT Wed Apr 23 2014

The initial wave of warm advection rain showers will affect areas
mainly along and north of I-74 the rest of the evening. Precip
amounts will be very light, with a couple hundredths possible.
Most areas that see precip across the north will just see trace
amounts of sprinkles.

Clouds will remain across the area the remainder of the night,
helping to limit the diurnal swing for low temps. Lows should
generally bottom out in the mid to upper 40s, with a few low 40s
possible closer to the Indiana border.

Trends for rain and storms tomorrow appear to be slowing down. We
could see dry conditions for a majority of the day tomorrow, with
areas west of I-55 having the best chances of rain before 6 pm.
Will let the night shift do more complete updates on slowing down
the eastward advance of PoPs on Thursday, but wanted to at least
mention the observed model trends with the evening update.

Minor updates were done to PoP and weather grids for the rest of
the night, along with slightly warmer temps. The latest forecast
info will be available shortly.

Shimon

&&

.AVIATION...
ISSUED 1155 PM CDT Wed Apr 23 2014

A break in the precipitation will occur as a tongue of dry air
follows the initial wave of warm advection precip. The warm front
will develop near the Missouri-Illinois border tomorrow morning,
then progress eastward tomorrow afternoon just ahead of the cold
front. A slower trend is being depicted in the 00z models, and
thunder chances will be focused mainly between 23z and 05z from
west to east. There should be a period of steady rains in the warm
sector ahead of the cold front, with thunder chances highest during
that time as well. A VCTS was included starting at 23z in PIA and
03z at CMI. A tempo for MVFR or possibly IFR may be needed for a
couple hours tomorrow evening.

Winds will increase quickly tomorrow morning, as the nose of an
850mb LLJ advances into western IL. Gusts early in the morning may
actually be a few knots higher than the afternoon based on the
strength of the LLJ as depicted in the HopWRF and RAP. A few gusts
may top out over 30kt for PIA/SPI between 14z-16z. Wind directions
will be SE for the first 12-15 hours of the TAFs, then it will
shift toward the south into the afternoon as wind speeds remain
strong in the 18g28kt range. By evening, wind speeds should
subside a bit as the pressure gradient weakens near the cold
front.

Shimon
&&

.PREV DISCUSSION...
ISSUED 253 PM CDT Wed Apr 23 2014

Plenty of dry air in place over Illinois early this afternoon, on
the periphery of a high pressure ridge, with dew points in the
upper 20s to lower 30s. Across the southeast half of the forecast
area, clouds have been eroding as they move into the drier air. Area
of showers has been advancing eastward from Iowa. Looks impressive
on radar, but surface observations are showing cloud heights well
over 8000 feet in many cases, indicating not much in the way of
measurable rain is reaching the ground. However, this is enough
that a mention of isolated showers across the northern CWA this
evening is warranted.

The first forecast concern is with the timing of rain over the
next day or so, as this storm system pushes eastward. In the
longer term, the duration of the rain is a concern as we get set
in a rainy pattern for the first half of next week.

SHORT TERM...Tonight through Friday:

Water vapor imagery and upper air analysis showing a deep trough
currently pushing east across the Rockies, and is progged to move
across the Mississippi Valley late Thursday. The dry air at the
lower levels will take some time to saturate, with the forecast
soundings still rather parched below 850 mb at mid afternoon. Have
limited Thursday morning PoP`s to areas west of I-55 and still
kept them below 50% during the afternoon east of I-57, otherwise
have maintained the categorical PoP`s over 80% in much of the
forecast area during the afternoon. Best instability looks to be
along and south of I-72 for any thunder, although some low CAPE`s
to around 200 J/kg progged as far north as Peoria, so have kept
some thunder mention that far north. With the system a bit slower,
will mention 80% or higher PoP`s into the evening across the east
half of the forecast area into the evening. Dry weather then on
tap for Friday.

LONG TERM...Friday night through Wednesday:

A cold front will push southward through the region Friday night.
Big question will be where it ends up, as it will likely not be
going anywhere for awhile. Most of the models do have it through
the forecast area by early Saturday, although the ECMWF and GEM
models linger it more toward the I-72 corridor. Saturday should be
dry. However, the main action will be later in the weekend, as all
the models continue to close off an upper low over the central
Rockies. This low will only slowly drift eastward, and will likely
linger in some form into the middle of next week.

Most of Sunday should be fairly decent, with the rain most likely
across the western CWA during the afternoon. After that, rain is
likely on and off, with PoP`s gradually diminishing Tuesday and
Wednesday as the cutoff low slowly weakens. By this point, as the
core of the colder air settles over the Midwest, temperatures will
be a good 15 or so degrees below normal, with highs Tuesday and
especially Wednesday generally in the 50s.

Geelhart


&&

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

$$








000
FXUS63 KLOT 240312
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1012 PM CDT WED APR 23 2014

.DISCUSSION...
931 PM CDT

SHOWERS CONTINUE TO MOVE/DEVELOP EASTWARD ACROSS NORTHERN ILLINOIS
EARLY THIS EVENING WITHIN A ZONE OF INCREASING ISENTROPIC ASCENT
ALONG THE WESTERN PERIPHERY OF A SURFACE RIDGE OF HIGH PRESSURE. THIS
ACTIVITY IS EXPECTED TO CONTINUE MOVING EASTWARD ACROSS NORTHERN
ILLINOIS LATE THIS EVENING...AND LIKELY ENDING PRIOR TO DAYBREAK
THURSDAY AS THE BETTER FORCING AND MOISTENING SHIFTS TO THE NORTH
AND EAST OF THE REGION. THEREFORE...NO BIG CHANGES ARE NEEDED TO THE
GOING FORECAST FOR TONIGHT.

THURSDAY IS SHAPING UP TO BE A BREEZY AND A MILDER DAY ACROSS THE
AREA AS SOUTHEASTERLY FLOW RAMPS UP IN RESPONSE TO AN AREA OF LOW
PRESSURE APPROACHING WESTERN ILLINOIS DURING THE AFTERNOON. IT
APPEARS THAT IN SPITE OF THE SOUTH-SOUTHEASTERLY WIND
COMPONENT...THAT WINDS COULD BE VERY GUSTY...UP IN THE 30 TO 35 KT
RANGE...DURING THE AFTERNOON. ALSO...IT APPEARS THAT THESE
SOUTHEASTERLY WINDS WILL TRANSPORT A DRIER LOWER LEVEL AIR MASS IN
ACROSS THE AREA DURING THE DAY...AND THIS COULD LEAD TO LOWER
SURFACE DEW POINTS THAN CURRENTLY FORECAST...ESPECIALLY ACROSS THE
EASTERN HALF OF THE AREA. WITH THIS IN MIND...I HAVE BACKED OFF ON
POPS DURING THE AFTERNOON THURSDAY...WITH A LIKELY SLOWER EVOLUTION
OF THE PRECIPITATION. IT APPEARS THE MAIN FORCING AND MOISTURE WILL
NOT ARRIVE ACROSS THE AREA UNTIL THURSDAY EVENING. AT THIS TIME I
HAVE LEFT SOME LOW END POPS IN DURING THE AFTERNOON...BUT IF THESE
TRENDS CONTINUE...WE MAY BE ABLE TO GO DRY ALL AFTERNOON ON
THURSDAY...ESPECIALLY ACROSS THE EASTERN HALF OF THE AREA. PERIODS
OF RAIN STILL APPEAR TO BE A GOOD BET THURSDAY NIGHT.

KJB

//PREV DISCUSSION...
310 PM CDT

SYNOPSIS...ANOTHER PLEASANT DAY TODAY...BUT SHOWERS MOVE IN FROM THE
WEST THIS EVENING. SHOWERS AND STORMS ARE EXPECTED TOMORROW
AFTERNOON AND EVENING WITH A DRY AND WARM END TO THE WORK WEEK.
THIS WEEKEND LOOKS TO HAVE BELOW NORMAL TEMPERATURES WITH SHOWERS
AND PERHAPS SOME THUNDERSTORMS ALONG AND SOUTH OF I-80 FOR THE FIRST
HALF OF NEXT WEEK.

REST OF TODAY AND TONIGHT...
A LARGE UPPER LEVEL RIDGE IS OVER THE CENTRAL PLAINS WHILE A SURFACE
HIGH IS CENTERED OVER LAKE MICHIGAN. THE RIDGE PASSES OVERHEAD
TONIGHT WHILE THE SURFACE HIGH PUSHES EAST TO THE NORTHERN OHIO
VALLEY THROUGH EASTERN QUEBEC.

A WEAK SHORTWAVE IS OVER EASTERN NEBRASKA AND WESTERN IOWA WITH
SHOWERS OVER WESTERN IOWA.  THE SHOWERS WILL CONTINUE TO PUSH
EAST...BUT WITH DEWPOINT DEPRESSIONS AT 20+ DEGREES...THINKING THE
SHOWERS WILL DISSIPATE A BIT BEFORE MOVING INTO CENTRAL IL. AS SUCH
THINKING THE FIRST SHOWERS WILL ENTER THE FAR EASTERN CWA AFTER 5PM
CST.  USED THE LOCAL ARW...RAP...AND HRRR TO CREATE THE POPS FOR THE
REST OF TODAY AND TONIGHT. THINKING A BAND OF SCATTERED SHOWERS WILL
SLOWLY CROSS NORTHERN IL THIS EVENING IN ASSOCIATION WITH AN UPPER
LEVEL VORTICITY STREAMER. THE BEST COVERAGE WILL BE BETWEEN MIDNIGHT
AND 4 AM CST WITH A CHANCE OF LIGHT RAIN SHOWERS NORTH OF I-80. THE
BAND THEN LIFTS NORTH EARLY THURSDAY MORNING AS THE RIDGE MOVES
DIRECTLY OVERHEAD. NOT EXPECTING ANY SIGNIFICANT PRECIP
ACCUMULATIONS.

CLOUD COVER WILL INCREASE THROUGH THIS AFTERNOON AND LOOKING AT MIN
TEMPS IN THE UPPER 30S TO MID 40S ACROSS THE CWA.

TOMORROW AND TOMORROW NIGHT...
AN UPPER LEVEL TROUGH MOVES OVER THE PLAINS TOMORROW MORNING AND THE
TROUGH PASSES OVER THE REGION TOMORROW NIGHT. THE UPPER LEVEL LOW
ASSOCIATED WITH THE TROUGH PASSES FARTHER NORTH...ALONG THE
US/CANADA BORDER.  THE SURFACE LOW ALSO BEGINS OVER THE PLAINS
THURSDAY MORNING AND THEN MOVES OVER IL THURSDAY EVENING. GUIDANCE
HAS THE LOW PROGRESSING A BIT SLOWER AND MADE THE NECESSARY
ADJUSTMENTS.

RAIN AND SOME STORMS MOVE IN FROM THE WEST THROUGH THE MORNING AND
EARLY AFTERNOON.  INSTABILITY IS NOT EXTREMELY IMPRESSIVE WITH THE
SYSTEM SO KEPT ONLY A CHANCE OF THUNDER. QPF AMOUNTS ON THE OTHER
HAND COULD BE IMPRESSIVE WITH TOTALS AROUND A HALF INCH OF RAIN.

WINDS WILL ALSO BE SHIFTING FROM SOUTHEAST IN THE MORNING TO OUT OF
THE WEST OVERNIGHT BEHIND THE LOW.  LOOKING AT A BREEZY AFTERNOON
WITH SOUTH WINDS GUSTING TO 35 MPH.  THE AMPLE WAA WILL LEAD TO MAX
TEMPS FROM AROUND 60 ALONG THE IL/WI BORDER TO THE UPPER 60S IF NOT
70 IN THE SOUTHERN CWA.

FRIDAY AND SATURDAY...
THE UPPER LEVEL LOW CONTINUES TO SHIFT EAST REACHING NEW ENGLAND BY
SATURDAY AFTERNOON/EVENING.  THE SURFACE LOW SHIFTS EAST AND
EXPECTING PRECIP TO COME TO AN END EARLY FRIDAY MORNING.  WEST WINDS
WILL BE GUSTING TO ARND 30 MPH FRIDAY AND AM THINKING THERE COULD BE
SOME DRY AIR MIXING DOWN TO THE SURFACE SO LOWERED DEWPOINTS A BIT.

THE AIR BEHIND THE COLD FRONT IS NOT REALLY ALL THAT COLD SINCE MAX
TEMPS ON FRIDAY LOOK TO BE AROUND 70 DEGREES.  A BACK DOOR COLD
FRONT SLIDES DOWN FROM THE NORTH IN THE EVENING. SOME GUIDANCE
MEMBERS FEATURE A BAND OF PRECIP FORMING AHEAD OF THE FRONT OVER FAR
NORTHERN IL AND NW INDIANA. PUT IN A CHANCE OF PRECIP SINCE FORCING
LOOKS GOOD...BUT HAVE LOW CONFIDENCE IN THE BAND OF PRECIP ACTUALLY
FORMING. AS SUCH KEPT POPS IN THE CHANCE RANGE.  WINDS TURN
NORTHEAST BEHIND THE FRONT AND OVERNIGHT LOWS WILL BE IN THE UPPER
30S TO MID 40S.

SOME GUIDANCE MEMBERS KEEP A BAND OF PRECIP OVER THE REGION SATURDAY
MORNING...BUT WITH HIGH PRESSURE MOVING OVER THE REGION HAVE LOW
CONFIDENCE AND WENT WITH A DRY FORECAST SATURDAY.  SKIES WILL CLEAR
BUT THE COOLER AIR OFF THE LAKE WILL RESULT IN HIGHS IN THE UPPER
40S TO MID 50S ALONG THE LAKE...AND THEN IN THE LOW TO MID 60S IN
THE OUTLYING AREAS.

GUIDANCE FEATURES PRECIP MOVING IN AHEAD OF THE NEXT LOW SATURDAY
NIGHT. HAVE LOW CONFIDENCE IN THIS ROUND OF PRECIP AS WELL...BUT
LEFT A CHANCE OF RAIN IN THE FORECAST.  OVERNIGHT LOWS WILL RANGE
FROM THE UPPER 30S TO THE MID 40S.

EXTENDED...SUNDAY THROUGH TUESDAY...
AN UPPER LEVEL CLOSED LOW SHIFTS OVER THE GREAT PLAINS SUNDAY
EVENING/NIGHT. GUIDANCE DIFFERS ON ITS EXACT PATH EARLY NEXT WEEK
BUT DOES HAVE THE UPPER LEVEL LOW OVER THE REGION THROUGH AT LEAST
MID WEEK.  ITS ASSOCIATED SURFACE LOW MOVES OVER THE PLAINS LATE
SUNDAY NIGHT/MONDAY MORNING AND SLIDES SOUTH OF THE CWA MONDAY
NIGHT. THE 12Z GUIDANCE AGREED A BIT MORE ABOUT THE SURFACE LOWS
PATH...AND HAVE IT MOVING THROUGH SOUTHERN IL TUESDAY.

IN TWO WORDS EARLY NEXT WEEK LOOKS CHILLY AND WET.  A BOUNDARY OVER
NORTHERN IL BRINGS THE LIFT FOR THE FIRST WAVE OF PRECIP EARLY ON
SUNDAY...BUT THEN MULTIPLE VORTICITY STREAMERS PASS THROUGH THE
REGION AS THE LOW SLOWLY SHIFTS EAST. THIS WILL RESULT IN A CHANCE
OF PRECIP THROUGHOUT THE EXTENDED. WILL INCLUDE A SLIGHT CHANCE OF
THUNDER ALONG AND SOUTH OF I-80 WHERE THERE WILL BE LIMITED ELEVATED
INSTABILITY BUT ENOUGH TO PERHAPS SUPPORT A COUPLE OF THUNDERSTORMS
SUNDAY NIGHT AND MONDAY. THE UPPER LEVEL JET DIPS FAR SOUTH THROUGH
TEXAS ALLOWING COOL AIR TO SPREAD ACROSS THE REGION. AS SUCH HIGHS
WILL VARY BETWEEN THE LOW 50S NORTH TO MID 60S SOUTH WITH A COOLING
TREND THROUGH TUESDAY.  LUCKILY OVERNIGHT LOWS LOOK LIKE THEY WILL
REMAIN ABOVE FREEZING.

JEE

&&

.AVIATION...

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

* CHANCE OF LIGHT RAIN LATE THIS EVENING/OVERNIGHT.
* STRONG/GUSTY SOUTH/SOUTHEAST WINDS THURSDAY.
* CHANCE OF SHRA LATE THURSDAY AFTERNOON.
* SHOWERS WITH MVFR VIS/CIGS THURSDAY EVENING.
* ISOLATED TSRA THURSDAY EVENING. CMS

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

A LARGE AREA OF VFR LIGHT SHOWERS OVER EASTERN IA AND WESTERN IL
WILL CONTINUE TO DIMINISH AS IT MOVES EAST THIS EVENING WITH VERY
DRY LOW LEVELS AHEAD OF THIS RAIN AIDING ITS EROSION AND THIS
TREND IS HANDLED FAIRLY WELL WITH SHORT TERM/HI RES GUIDANCE.
ADDITIONAL SHOWERS THEN REDEVELOP IN THE VICINITY OF A WARM FRONT
LATE THIS EVENING AND OVERNIGHT...MAINLY OVER NORTHERN IL AND THIS
WILL BE THE BEST TIMING FOR SHOWERS AND MAY NEED A TEMPO BUT
CONFIDENCE IS TOO LOW BOTH COVERAGE AND TIMING TO INCLUDE ANYTHING
WITH THIS FORECAST. CIGS WILL REMAIN VFR LOWERING INTO THE 6-9KFT
RANGE.

EAST/NORTHEAST WINDS AROUND 10KTS WILL DIMINISH THROUGH THE
EVENING AND TURN MORE EAST/SOUTHEASTERLY TOWARD MORNING. SPEEDS
WILL GRADUALLY INCREASE TOWARD SUNRISE AS WELL BUT SHORTLY AFTER
SUNRISE THE GRADIENT WILL TIGHTEN AND COMBINED WITH LOW LEVEL
MIXING...WINDS WILL RAPIDLY INCREASE TO 20KT WITH GUSTS TO 30KT
WITH THE POTENTIAL FOR STRONGER GUSTS ACROSS NORTHWEST IL
INCLUDING RFD. WIND DIRECTION WILL REMAIN MAINLY SOUTHEASTERLY
MUCH OF THE DAY...SLOWLY TURNING MORE SOUTHERLY INTO THE
AFTERNOON. WINDS WILL BEGIN TO DIMINISH BY MID/LATE AFTERNOON...
FIRST AT RFD AND THEN SPREADING EAST ACROSS THE CHICAGO AREA
TERMINALS BY EVENING.

LOW PRESSURE RESPONSIBLE FOR THE STRONGER WINDS WILL MOVE ACROSS
THE AREA THURSDAY EVENING AND THIS APPEARS TO BE THE BEST TIME
PERIOD FOR SHOWERS. HAVE DELAYED SHOWER ARRIVAL UNTIL 20Z AT RFD
AND 01Z AT ORD. ONCE SHOWERS ARRIVE...WINDS WILL LIKELY QUICKLY
DIMINISH AND CIGS COULD QUICKLY LOWER THROUGH MVFR WITH A BRIEF
PERIOD OF IFR POSSIBLE LATE THURSDAY EVENING OR EARLY FRIDAY
MORNING BEFORE WINDS SHIFT WEST/NORTHWEST. THUNDER POTENTIAL ALSO
APPEARS TO BE TIED MORE TO THE COLD FRONT/WIND SHIFT WHICH WILL BE
LATER IN THE EVENING AND WHILE POSSIBLE...CONFIDENCE TOO LOW TO
INCLUDE IN THIS FORECAST. CMS

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

* MEDIUM FOR LIGHT RAIN LATE THIS EVENING/OVERNIGHT.
* HIGH FOR WINDS THROUGH THE PERIOD...MEDIUM FOR TIMING CHANGES.
* MEDIUM FOR SHOWERS THURSDAY EVENING WITH ASSOCIATED CIGS/VIS.
* LOW FOR TSRA THURSDAY EVENING. CMS

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

* FRIDAY AND SATURDAY...DRY/VFR.
* SUNDAY THROUGH TUESDAY...CHANCE OF SHRA. MVFR POSSIBLE.

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 240234
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
934 PM CDT WED APR 23 2014

.DISCUSSION...
931 PM CDT

SHOWERS CONTINUE TO MOVE/DEVELOP EASTWARD ACROSS NORTHERN ILLINOIS
EARLY THIS EVENING WITHIN A ZONE OF INCREASING ISENTROPIC ASCENT
ALONG THE WESTERN PERIPHERY OF A SURFACE RIDGE OF HIGH PRESSURE. THIS
ACTIVITY IS EXPECTED TO CONTINUE MOVING EASTWARD ACROSS NORTHERN
ILLINOIS LATE THIS EVENING...AND LIKELY ENDING PRIOR TO DAYBREAK
THURSDAY AS THE BETTER FORCING AND MOISTENING SHIFTS TO THE NORTH
AND EAST OF THE REGION. THEREFORE...NO BIG CHANGES ARE NEEDED TO THE
GOING FORECAST FOR TONIGHT.

THURSDAY IS SHAPING UP TO BE A BREEZY AND A MILDER DAY ACROSS THE
AREA AS SOUTHEASTERLY FLOW RAMPS UP IN RESPONSE TO AN AREA OF LOW
PRESSURE APPROACHING WESTERN ILLINOIS DURING THE AFTERNOON. IT
APPEARS THAT IN SPITE OF THE SOUTH-SOUTHEASTERLY WIND
COMPONENT...THAT WINDS COULD BE VERY GUSTY...UP IN THE 30 TO 35 KT
RANGE...DURING THE AFTERNOON. ALSO...IT APPEARS THAT THESE
SOUTHEASTERLY WINDS WILL TRANSPORT A DRIER LOWER LEVEL AIR MASS IN
ACROSS THE AREA DURING THE DAY...AND THIS COULD LEAD TO LOWER
SURFACE DEW POINTS THAN CURRENTLY FORECAST...ESPECIALLY ACROSS THE
EASTERN HALF OF THE AREA. WITH THIS IN MIND...I HAVE BACKED OFF ON
POPS DURING THE AFTERNOON THURSDAY...WITH A LIKELY SLOWER EVOLUTION
OF THE PRECIPITATION. IT APPEARS THE MAIN FORCING AND MOISTURE WILL
NOT ARRIVE ACROSS THE AREA UNTIL THURSDAY EVENING. AT THIS TIME I
HAVE LEFT SOME LOW END POPS IN DURING THE AFTERNOON...BUT IF THESE
TRENDS CONTINUE...WE MAY BE ABLE TO GO DRY ALL AFTERNOON ON
THURSDAY...ESPECIALLY ACROSS THE EASTERN HALF OF THE AREA. PERIODS
OF RAIN STILL APPEAR TO BE A GOOD BET THURSDAY NIGHT.

KJB

&&

.PREV DISCUSSION...
310 PM CDT

SYNOPSIS...ANOTHER PLEASANT DAY TODAY...BUT SHOWERS MOVE IN FROM THE
WEST THIS EVENING. SHOWERS AND STORMS ARE EXPECTED TOMORROW
AFTERNOON AND EVENING WITH A DRY AND WARM END TO THE WORK WEEK.
THIS WEEKEND LOOKS TO HAVE BELOW NORMAL TEMPERATURES WITH SHOWERS
AND PERHAPS SOME THUNDERSTORMS ALONG AND SOUTH OF I-80 FOR THE FIRST
HALF OF NEXT WEEK.

REST OF TODAY AND TONIGHT...
A LARGE UPPER LEVEL RIDGE IS OVER THE CENTRAL PLAINS WHILE A SURFACE
HIGH IS CENTERED OVER LAKE MICHIGAN. THE RIDGE PASSES OVERHEAD
TONIGHT WHILE THE SURFACE HIGH PUSHES EAST TO THE NORTHERN OHIO
VALLEY THROUGH EASTERN QUEBEC.

A WEAK SHORTWAVE IS OVER EASTERN NEBRASKA AND WESTERN IOWA WITH
SHOWERS OVER WESTERN IOWA.  THE SHOWERS WILL CONTINUE TO PUSH
EAST...BUT WITH DEWPOINT DEPRESSIONS AT 20+ DEGREES...THINKING THE
SHOWERS WILL DISSIPATE A BIT BEFORE MOVING INTO CENTRAL IL. AS SUCH
THINKING THE FIRST SHOWERS WILL ENTER THE FAR EASTERN CWA AFTER 5PM
CST.  USED THE LOCAL ARW...RAP...AND HRRR TO CREATE THE POPS FOR THE
REST OF TODAY AND TONIGHT. THINKING A BAND OF SCATTERED SHOWERS WILL
SLOWLY CROSS NORTHERN IL THIS EVENING IN ASSOCIATION WITH AN UPPER
LEVEL VORTICITY STREAMER. THE BEST COVERAGE WILL BE BETWEEN MIDNIGHT
AND 4 AM CST WITH A CHANCE OF LIGHT RAIN SHOWERS NORTH OF I-80. THE
BAND THEN LIFTS NORTH EARLY THURSDAY MORNING AS THE RIDGE MOVES
DIRECTLY OVERHEAD. NOT EXPECTING ANY SIGNIFICANT PRECIP
ACCUMULATIONS.

CLOUD COVER WILL INCREASE THROUGH THIS AFTERNOON AND LOOKING AT MIN
TEMPS IN THE UPPER 30S TO MID 40S ACROSS THE CWA.

TOMORROW AND TOMORROW NIGHT...
AN UPPER LEVEL TROUGH MOVES OVER THE PLAINS TOMORROW MORNING AND THE
TROUGH PASSES OVER THE REGION TOMORROW NIGHT. THE UPPER LEVEL LOW
ASSOCIATED WITH THE TROUGH PASSES FARTHER NORTH...ALONG THE
US/CANADA BORDER.  THE SURFACE LOW ALSO BEGINS OVER THE PLAINS
THURSDAY MORNING AND THEN MOVES OVER IL THURSDAY EVENING. GUIDANCE
HAS THE LOW PROGRESSING A BIT SLOWER AND MADE THE NECESSARY
ADJUSTMENTS.

RAIN AND SOME STORMS MOVE IN FROM THE WEST THROUGH THE MORNING AND
EARLY AFTERNOON.  INSTABILITY IS NOT EXTREMELY IMPRESSIVE WITH THE
SYSTEM SO KEPT ONLY A CHANCE OF THUNDER. QPF AMOUNTS ON THE OTHER
HAND COULD BE IMPRESSIVE WITH TOTALS AROUND A HALF INCH OF RAIN.

WINDS WILL ALSO BE SHIFTING FROM SOUTHEAST IN THE MORNING TO OUT OF
THE WEST OVERNIGHT BEHIND THE LOW.  LOOKING AT A BREEZY AFTERNOON
WITH SOUTH WINDS GUSTING TO 35 MPH.  THE AMPLE WAA WILL LEAD TO MAX
TEMPS FROM AROUND 60 ALONG THE IL/WI BORDER TO THE UPPER 60S IF NOT
70 IN THE SOUTHERN CWA.

FRIDAY AND SATURDAY...
THE UPPER LEVEL LOW CONTINUES TO SHIFT EAST REACHING NEW ENGLAND BY
SATURDAY AFTERNOON/EVENING.  THE SURFACE LOW SHIFTS EAST AND
EXPECTING PRECIP TO COME TO AN END EARLY FRIDAY MORNING.  WEST WINDS
WILL BE GUSTING TO ARND 30 MPH FRIDAY AND AM THINKING THERE COULD BE
SOME DRY AIR MIXING DOWN TO THE SURFACE SO LOWERED DEWPOINTS A BIT.

THE AIR BEHIND THE COLD FRONT IS NOT REALLY ALL THAT COLD SINCE MAX
TEMPS ON FRIDAY LOOK TO BE AROUND 70 DEGREES.  A BACK DOOR COLD
FRONT SLIDES DOWN FROM THE NORTH IN THE EVENING. SOME GUIDANCE
MEMBERS FEATURE A BAND OF PRECIP FORMING AHEAD OF THE FRONT OVER FAR
NORTHERN IL AND NW INDIANA. PUT IN A CHANCE OF PRECIP SINCE FORCING
LOOKS GOOD...BUT HAVE LOW CONFIDENCE IN THE BAND OF PRECIP ACTUALLY
FORMING. AS SUCH KEPT POPS IN THE CHANCE RANGE.  WINDS TURN
NORTHEAST BEHIND THE FRONT AND OVERNIGHT LOWS WILL BE IN THE UPPER
30S TO MID 40S.

SOME GUIDANCE MEMBERS KEEP A BAND OF PRECIP OVER THE REGION SATURDAY
MORNING...BUT WITH HIGH PRESSURE MOVING OVER THE REGION HAVE LOW
CONFIDENCE AND WENT WITH A DRY FORECAST SATURDAY.  SKIES WILL CLEAR
BUT THE COOLER AIR OFF THE LAKE WILL RESULT IN HIGHS IN THE UPPER
40S TO MID 50S ALONG THE LAKE...AND THEN IN THE LOW TO MID 60S IN
THE OUTLYING AREAS.

GUIDANCE FEATURES PRECIP MOVING IN AHEAD OF THE NEXT LOW SATURDAY
NIGHT. HAVE LOW CONFIDENCE IN THIS ROUND OF PRECIP AS WELL...BUT
LEFT A CHANCE OF RAIN IN THE FORECAST.  OVERNIGHT LOWS WILL RANGE
FROM THE UPPER 30S TO THE MID 40S.

EXTENDED...SUNDAY THROUGH TUESDAY...
AN UPPER LEVEL CLOSED LOW SHIFTS OVER THE GREAT PLAINS SUNDAY
EVENING/NIGHT. GUIDANCE DIFFERS ON ITS EXACT PATH EARLY NEXT WEEK
BUT DOES HAVE THE UPPER LEVEL LOW OVER THE REGION THROUGH AT LEAST
MID WEEK.  ITS ASSOCIATED SURFACE LOW MOVES OVER THE PLAINS LATE
SUNDAY NIGHT/MONDAY MORNING AND SLIDES SOUTH OF THE CWA MONDAY
NIGHT. THE 12Z GUIDANCE AGREED A BIT MORE ABOUT THE SURFACE LOWS
PATH...AND HAVE IT MOVING THROUGH SOUTHERN IL TUESDAY.

IN TWO WORDS EARLY NEXT WEEK LOOKS CHILLY AND WET.  A BOUNDARY OVER
NORTHERN IL BRINGS THE LIFT FOR THE FIRST WAVE OF PRECIP EARLY ON
SUNDAY...BUT THEN MULTIPLE VORTICITY STREAMERS PASS THROUGH THE
REGION AS THE LOW SLOWLY SHIFTS EAST. THIS WILL RESULT IN A CHANCE
OF PRECIP THROUGHOUT THE EXTENDED. WILL INCLUDE A SLIGHT CHANCE OF
THUNDER ALONG AND SOUTH OF I-80 WHERE THERE WILL BE LIMITED ELEVATED
INSTABILITY BUT ENOUGH TO PERHAPS SUPPORT A COUPLE OF THUNDERSTORMS
SUNDAY NIGHT AND MONDAY. THE UPPER LEVEL JET DIPS FAR SOUTH THROUGH
TEXAS ALLOWING COOL AIR TO SPREAD ACROSS THE REGION. AS SUCH HIGHS
WILL VARY BETWEEN THE LOW 50S NORTH TO MID 60S SOUTH WITH A COOLING
TREND THROUGH TUESDAY.  LUCKILY OVERNIGHT LOWS LOOK LIKE THEY WILL
REMAIN ABOVE FREEZING.

JEE

&&

.AVIATION...

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

* CHANCE OF SHRA LATE THIS EVENING AND OVERNIGHT.
* STRONG/GUSTY SOUTH/SOUTHEAST WINDS THURSDAY.
* CHANCE OF SHRA LATE THURSDAY AFTERNOON.
* SHOWERS WITH MVFR VIS/CIGS THURSDAY EVENING.
* ISOLATED TSRA THURSDAY EVENING. CMS

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

A LARGE AREA OF VFR LIGHT SHOWERS OVER EASTERN IA AND WESTERN IL
WILL CONTINUE TO DIMINISH AS IT MOVES EAST THIS EVENING WITH VERY
DRY LOW LEVELS AHEAD OF THIS RAIN AIDING ITS EROSION AND THIS
TREND IS HANDLED FAIRLY WELL WITH SHORT TERM/HI RES GUIDANCE.
ADDITIONAL SHOWERS THEN REDEVELOP IN THE VICINITY OF A WARM FRONT
LATE THIS EVENING AND OVERNIGHT...MAINLY OVER NORTHERN IL AND THIS
WILL BE THE BEST TIMING FOR SHOWERS AND MAY NEED A TEMPO BUT
CONFIDENCE IS TOO LOW BOTH COVERAGE AND TIMING TO INCLUDE ANYTHING
WITH THIS FORECAST. CIGS WILL REMAIN VFR LOWERING INTO THE 6-9KFT
RANGE.

EAST/NORTHEAST WINDS AROUND 10KTS WILL DIMINISH THROUGH THE
EVENING AND TURN MORE EAST/SOUTHEASTERLY TOWARD MORNING. SPEEDS
WILL GRADUALLY INCREASE TOWARD SUNRISE AS WELL BUT SHORTLY AFTER
SUNRISE THE GRADIENT WILL TIGHTEN AND COMBINED WITH LOW LEVEL
MIXING...WINDS WILL RAPIDLY INCREASE TO 20KT WITH GUSTS TO 30KT
WITH THE POTENTIAL FOR STRONGER GUSTS ACROSS NORTHWEST IL
INCLUDING RFD. WIND DIRECTION WILL REMAIN MAINLY SOUTHEASTERLY
MUCH OF THE DAY...SLOWLY TURNING MORE SOUTHERLY INTO THE
AFTERNOON. WINDS WILL BEGIN TO DIMINISH BY MID/LATE AFTERNOON...
FIRST AT RFD AND THEN SPREADING EAST ACROSS THE CHICAGO AREA
TERMINALS BY EVENING.

LOW PRESSURE RESPONSIBLE FOR THE STRONGER WINDS WILL MOVE ACROSS
THE AREA THURSDAY EVENING AND THIS APPEARS TO BE THE BEST TIME
PERIOD FOR SHOWERS. HAVE DELAYED SHOWER ARRIVAL UNTIL 20Z AT RFD
AND 01Z AT ORD. ONCE SHOWERS ARRIVE...WINDS WILL LIKELY QUICKLY
DIMINISH AND CIGS COULD QUICKLY LOWER THROUGH MVFR WITH A BRIEF
PERIOD OF IFR POSSIBLE LATE THURSDAY EVENING OR EARLY FRIDAY
MORNING BEFORE WINDS SHIFT WEST/NORTHWEST. THUNDER POTENTIAL ALSO
APPEARS TO BE TIED MORE TO THE COLD FRONT/WIND SHIFT WHICH WILL BE
LATER IN THE EVENING AND WHILE POSSIBLE...CONFIDENCE TOO LOW TO
INCLUDE IN THIS FORECAST. CMS

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

* LOW FOR SHOWERS LATE THIS EVENING AND OVERNIGHT.
* HIGH FOR WINDS THROUGH THE PERIOD...MEDIUM FOR TIMING CHANGES.
* MEDIUM FOR SHOWERS THURSDAY EVENING WITH ASSOCIATED CIGS/VIS.
* LOW FOR TSRA THURSDAY EVENING. CMS

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

* FRIDAY AND SATURDAY...DRY/VFR.
* SUNDAY THROUGH TUESDAY...CHANCE OF SHRA. MVFR POSSIBLE.

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

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

&&

$$

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

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






000
FXUS63 KILX 240207
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
907 PM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 900 PM CDT Wed Apr 23 2014

The initial wave of warm advection rain showers will affect areas
mainly along and north of I-74 the rest of the evening. Precip
amounts will be very light, with a couple hundredths possible.
Most areas that see precip across the north will just see trace
amounts of sprinkles.

Clouds will remain across the area the remainder of the night,
helping to limit the diurnal swing for low temps. Lows should
generally bottom out in the mid to upper 40s, with a few low 40s
possible closer to the Indiana border.

Trends for rain and storms tomorrow appear to be slowing down. We
could see dry conditions for a majority of the day tomorrow, with
areas west of I-55 having the best chances of rain before 6 pm.
Will let the night shift do more complete updates on slowing down
the eastward advance of PoPs on Thursday, but wanted to at least
mention the observed model trends with the evening update.

Minor updates were done to PoP and weather grids for the rest of
the night, along with slightly warmer temps. The latest forecast
info will be available shortly.

Shimon
&&

.AVIATION...
ISSUED 654 PM CDT Wed Apr 23 2014

One primary band of light rain will progress eastward across
PIA/BMI/CMI over the first few hours of the TAF period. The dry
air below 7k- 8k feet will preclude much in the way of measurable
rain, with sprinkles the main precipitation this evening. There
will be a chance of sprinkles lingering for PIA the rest of the
evening based on upstream radar and satellite trends.

The next chance of precipitation looks to be later Thursday
morning. Thunderstorm chances will increase as the afternoon
progresses, and a vcts was included at all terminal sites Thursday
afternoon. A tempo for IFR clouds and possibly vis conditions will
most likely be needed, when a better handle on timing develops in
the High Res short term models.

Winds will remain southeast tonight, with speeds in the 08-13kt
range. As the cold front arrives Thursday afternoon, wind speeds
will increase into the 15g30kt range. Wind direction will veer
slightly toward the south as well.

Shimon
&&

.PREV DISCUSSION...
ISSUED 253 PM CDT Wed Apr 23 2014

Plenty of dry air in place over Illinois early this afternoon, on
the periphery of a high pressure ridge, with dew points in the
upper 20s to lower 30s. Across the southeast half of the forecast
area, clouds have been eroding as they move into the drier air. Area
of showers has been advancing eastward from Iowa. Looks impressive
on radar, but surface observations are showing cloud heights well
over 8000 feet in many cases, indicating not much in the way of
measurable rain is reaching the ground. However, this is enough
that a mention of isolated showers across the northern CWA this
evening is warranted.

The first forecast concern is with the timing of rain over the
next day or so, as this storm system pushes eastward. In the
longer term, the duration of the rain is a concern as we get set
in a rainy pattern for the first half of next week.

SHORT TERM...Tonight through Friday:

Water vapor imagery and upper air analysis showing a deep trough
currently pushing east across the Rockies, and is progged to move
across the Mississippi Valley late Thursday. The dry air at the
lower levels will take some time to saturate, with the forecast
soundings still rather parched below 850 mb at mid afternoon. Have
limited Thursday morning PoP`s to areas west of I-55 and still
kept them below 50% during the afternoon east of I-57, otherwise
have maintained the categorical PoP`s over 80% in much of the
forecast area during the afternoon. Best instability looks to be
along and south of I-72 for any thunder, although some low CAPE`s
to around 200 J/kg progged as far north as Peoria, so have kept
some thunder mention that far north. With the system a bit slower,
will mention 80% or higher PoP`s into the evening across the east
half of the forecast area into the evening. Dry weather then on
tap for Friday.

LONG TERM...Friday night through Wednesday:

A cold front will push southward through the region Friday night.
Big question will be where it ends up, as it will likely not be
going anywhere for awhile. Most of the models do have it through
the forecast area by early Saturday, although the ECMWF and GEM
models linger it more toward the I-72 corridor. Saturday should be
dry. However, the main action will be later in the weekend, as all
the models continue to close off an upper low over the central
Rockies. This low will only slowly drift eastward, and will likely
linger in some form into the middle of next week.

Most of Sunday should be fairly decent, with the rain most likely
across the western CWA during the afternoon. After that, rain is
likely on and off, with PoP`s gradually diminishing Tuesday and
Wednesday as the cutoff low slowly weakens. By this point, as the
core of the colder air settles over the Midwest, temperatures will
be a good 15 or so degrees below normal, with highs Tuesday and
especially Wednesday generally in the 50s.

Geelhart

&&

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

$$








000
FXUS63 KLOT 232355
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
655 PM CDT WED APR 23 2014

.DISCUSSION...
310 PM CDT

SYNOPSIS...ANOTHER PLEASANT DAY TODAY...BUT SHOWERS MOVE IN FROM THE
WEST THIS EVENING. SHOWERS AND STORMS ARE EXPECTED TOMORROW
AFTERNOON AND EVENING WITH A DRY AND WARM END TO THE WORK WEEK.
THIS WEEKEND LOOKS TO HAVE BELOW NORMAL TEMPERATURES WITH SHOWERS
AND PERHAPS SOME THUNDERSTORMS ALONG AND SOUTH OF I-80 FOR THE FIRST
HALF OF NEXT WEEK.

REST OF TODAY AND TONIGHT...
A LARGE UPPER LEVEL RIDGE IS OVER THE CENTRAL PLAINS WHILE A SURFACE
HIGH IS CENTERED OVER LAKE MICHIGAN. THE RIDGE PASSES OVERHEAD
TONIGHT WHILE THE SURFACE HIGH PUSHES EAST TO THE NORTHERN OHIO
VALLEY THROUGH EASTERN QUEBEC.

A WEAK SHORTWAVE IS OVER EASTERN NEBRASKA AND WESTERN IOWA WITH
SHOWERS OVER WESTERN IOWA.  THE SHOWERS WILL CONTINUE TO PUSH
EAST...BUT WITH DEWPOINT DEPRESSIONS AT 20+ DEGREES...THINKING THE
SHOWERS WILL DISSIPATE A BIT BEFORE MOVING INTO CENTRAL IL. AS SUCH
THINKING THE FIRST SHOWERS WILL ENTER THE FAR EASTERN CWA AFTER 5PM
CST.  USED THE LOCAL ARW...RAP...AND HRRR TO CREATE THE POPS FOR THE
REST OF TODAY AND TONIGHT. THINKING A BAND OF SCATTERED SHOWERS WILL
SLOWLY CROSS NORTHERN IL THIS EVENING IN ASSOCIATION WITH AN UPPER
LEVEL VORTICITY STREAMER. THE BEST COVERAGE WILL BE BETWEEN MIDNIGHT
AND 4 AM CST WITH A CHANCE OF LIGHT RAIN SHOWERS NORTH OF I-80. THE
BAND THEN LIFTS NORTH EARLY THURSDAY MORNING AS THE RIDGE MOVES
DIRECTLY OVERHEAD. NOT EXPECTING ANY SIGNIFICANT PRECIP
ACCUMULATIONS.

CLOUD COVER WILL INCREASE THROUGH THIS AFTERNOON AND LOOKING AT MIN
TEMPS IN THE UPPER 30S TO MID 40S ACROSS THE CWA.

TOMORROW AND TOMORROW NIGHT...
AN UPPER LEVEL TROUGH MOVES OVER THE PLAINS TOMORROW MORNING AND THE
TROUGH PASSES OVER THE REGION TOMORROW NIGHT. THE UPPER LEVEL LOW
ASSOCIATED WITH THE TROUGH PASSES FARTHER NORTH...ALONG THE
US/CANADA BORDER.  THE SURFACE LOW ALSO BEGINS OVER THE PLAINS
THURSDAY MORNING AND THEN MOVES OVER IL THURSDAY EVENING. GUIDANCE
HAS THE LOW PROGRESSING A BIT SLOWER AND MADE THE NECESSARY
ADJUSTMENTS.

RAIN AND SOME STORMS MOVE IN FROM THE WEST THROUGH THE MORNING AND
EARLY AFTERNOON.  INSTABILITY IS NOT EXTREMELY IMPRESSIVE WITH THE
SYSTEM SO KEPT ONLY A CHANCE OF THUNDER. QPF AMOUNTS ON THE OTHER
HAND COULD BE IMPRESSIVE WITH TOTALS AROUND A HALF INCH OF RAIN.

WINDS WILL ALSO BE SHIFTING FROM SOUTHEAST IN THE MORNING TO OUT OF
THE WEST OVERNIGHT BEHIND THE LOW.  LOOKING AT A BREEZY AFTERNOON
WITH SOUTH WINDS GUSTING TO 35 MPH.  THE AMPLE WAA WILL LEAD TO MAX
TEMPS FROM AROUND 60 ALONG THE IL/WI BORDER TO THE UPPER 60S IF NOT
70 IN THE SOUTHERN CWA.

FRIDAY AND SATURDAY...
THE UPPER LEVEL LOW CONTINUES TO SHIFT EAST REACHING NEW ENGLAND BY
SATURDAY AFTERNOON/EVENING.  THE SURFACE LOW SHIFTS EAST AND
EXPECTING PRECIP TO COME TO AN END EARLY FRIDAY MORNING.  WEST WINDS
WILL BE GUSTING TO ARND 30 MPH FRIDAY AND AM THINKING THERE COULD BE
SOME DRY AIR MIXING DOWN TO THE SURFACE SO LOWERED DEWPOINTS A BIT.

THE AIR BEHIND THE COLD FRONT IS NOT REALLY ALL THAT COLD SINCE MAX
TEMPS ON FRIDAY LOOK TO BE AROUND 70 DEGREES.  A BACK DOOR COLD
FRONT SLIDES DOWN FROM THE NORTH IN THE EVENING. SOME GUIDANCE
MEMBERS FEATURE A BAND OF PRECIP FORMING AHEAD OF THE FRONT OVER FAR
NORTHERN IL AND NW INDIANA. PUT IN A CHANCE OF PRECIP SINCE FORCING
LOOKS GOOD...BUT HAVE LOW CONFIDENCE IN THE BAND OF PRECIP ACTUALLY
FORMING. AS SUCH KEPT POPS IN THE CHANCE RANGE.  WINDS TURN
NORTHEAST BEHIND THE FRONT AND OVERNIGHT LOWS WILL BE IN THE UPPER
30S TO MID 40S.

SOME GUIDANCE MEMBERS KEEP A BAND OF PRECIP OVER THE REGION SATURDAY
MORNING...BUT WITH HIGH PRESSURE MOVING OVER THE REGION HAVE LOW
CONFIDENCE AND WENT WITH A DRY FORECAST SATURDAY.  SKIES WILL CLEAR
BUT THE COOLER AIR OFF THE LAKE WILL RESULT IN HIGHS IN THE UPPER
40S TO MID 50S ALONG THE LAKE...AND THEN IN THE LOW TO MID 60S IN
THE OUTLYING AREAS.

GUIDANCE FEATURES PRECIP MOVING IN AHEAD OF THE NEXT LOW SATURDAY
NIGHT. HAVE LOW CONFIDENCE IN THIS ROUND OF PRECIP AS WELL...BUT
LEFT A CHANCE OF RAIN IN THE FORECAST.  OVERNIGHT LOWS WILL RANGE
FROM THE UPPER 30S TO THE MID 40S.

EXTENDED...SUNDAY THROUGH TUESDAY...
AN UPPER LEVEL CLOSED LOW SHIFTS OVER THE GREAT PLAINS SUNDAY
EVENING/NIGHT. GUIDANCE DIFFERS ON ITS EXACT PATH EARLY NEXT WEEK
BUT DOES HAVE THE UPPER LEVEL LOW OVER THE REGION THROUGH AT LEAST
MID WEEK.  ITS ASSOCIATED SURFACE LOW MOVES OVER THE PLAINS LATE
SUNDAY NIGHT/MONDAY MORNING AND SLIDES SOUTH OF THE CWA MONDAY
NIGHT. THE 12Z GUIDANCE AGREED A BIT MORE ABOUT THE SURFACE LOWS
PATH...AND HAVE IT MOVING THROUGH SOUTHERN IL TUESDAY.

IN TWO WORDS EARLY NEXT WEEK LOOKS CHILLY AND WET.  A BOUNDARY OVER
NORTHERN IL BRINGS THE LIFT FOR THE FIRST WAVE OF PRECIP EARLY ON
SUNDAY...BUT THEN MULTIPLE VORTICITY STREAMERS PASS THROUGH THE
REGION AS THE LOW SLOWLY SHIFTS EAST. THIS WILL RESULT IN A CHANCE
OF PRECIP THROUGHOUT THE EXTENDED. WILL INCLUDE A SLIGHT CHANCE OF
THUNDER ALONG AND SOUTH OF I-80 WHERE THERE WILL BE LIMITED ELEVATED
INSTABILITY BUT ENOUGH TO PERHAPS SUPPORT A COUPLE OF THUNDERSTORMS
SUNDAY NIGHT AND MONDAY. THE UPPER LEVEL JET DIPS FAR SOUTH THROUGH
TEXAS ALLOWING COOL AIR TO SPREAD ACROSS THE REGION. AS SUCH HIGHS
WILL VARY BETWEEN THE LOW 50S NORTH TO MID 60S SOUTH WITH A COOLING
TREND THROUGH TUESDAY.  LUCKILY OVERNIGHT LOWS LOOK LIKE THEY WILL
REMAIN ABOVE FREEZING.

JEE

&&

.AVIATION...

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

* CHANCE OF SHRA LATE THIS EVENING AND OVERNIGHT.
* STRONG/GUSTY SOUTH/SOUTHEAST WINDS THURSDAY.
* CHANCE OF SHRA LATE THURSDAY AFTERNOON.
* SHOWERS WITH MVFR VIS/CIGS THURSDAY EVENING.
* ISOLATED TSRA THURSDAY EVENING. CMS

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

A LARGE AREA OF VFR LIGHT SHOWERS OVER EASTERN IA AND WESTERN IL
WILL CONTINUE TO DIMINISH AS IT MOVES EAST THIS EVENING WITH VERY
DRY LOW LEVELS AHEAD OF THIS RAIN AIDING ITS EROSION AND THIS
TREND IS HANDLED FAIRLY WELL WITH SHORT TERM/HI RES GUIDANCE.
ADDITIONAL SHOWERS THEN REDEVELOP IN THE VICINITY OF A WARM FRONT
LATE THIS EVENING AND OVERNIGHT...MAINLY OVER NORTHERN IL AND THIS
WILL BE THE BEST TIMING FOR SHOWERS AND MAY NEED A TEMPO BUT
CONFIDENCE IS TOO LOW BOTH COVERAGE AND TIMING TO INCLUDE ANYTHING
WITH THIS FORECAST. CIGS WILL REMAIN VFR LOWERING INTO THE 6-9KFT
RANGE.

EAST/NORTHEAST WINDS AROUND 10KTS WILL DIMINISH THROUGH THE
EVENING AND TURN MORE EAST/SOUTHEASTERLY TOWARD MORNING. SPEEDS
WILL GRADUALLY INCREASE TOWARD SUNRISE AS WELL BUT SHORTLY AFTER
SUNRISE THE GRADIENT WILL TIGHTEN AND COMBINED WITH LOW LEVEL
MIXING...WINDS WILL RAPIDLY INCREASE TO 20KT WITH GUSTS TO 30KT
WITH THE POTENTIAL FOR STRONGER GUSTS ACROSS NORTHWEST IL
INCLUDING RFD. WIND DIRECTION WILL REMAIN MAINLY SOUTHEASTERLY
MUCH OF THE DAY...SLOWLY TURNING MORE SOUTHERLY INTO THE
AFTERNOON. WINDS WILL BEGIN TO DIMINISH BY MID/LATE AFTERNOON...
FIRST AT RFD AND THEN SPREADING EAST ACROSS THE CHICAGO AREA
TERMINALS BY EVENING.

LOW PRESSURE RESPONSIBLE FOR THE STRONGER WINDS WILL MOVE ACROSS
THE AREA THURSDAY EVENING AND THIS APPEARS TO BE THE BEST TIME
PERIOD FOR SHOWERS. HAVE DELAYED SHOWER ARRIVAL UNTIL 20Z AT RFD
AND 01Z AT ORD. ONCE SHOWERS ARRIVE...WINDS WILL LIKELY QUICKLY
DIMINISH AND CIGS COULD QUICKLY LOWER THROUGH MVFR WITH A BRIEF
PERIOD OF IFR POSSIBLE LATE THURSDAY EVENING OR EARLY FRIDAY
MORNING BEFORE WINDS SHIFT WEST/NORTHWEST. THUNDER POTENTIAL ALSO
APPEARS TO BE TIED MORE TO THE COLD FRONT/WIND SHIFT WHICH WILL BE
LATER IN THE EVENING AND WHILE POSSIBLE...CONFIDENCE TOO LOW TO
INCLUDE IN THIS FORECAST. CMS

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

* LOW FOR SHOWERS LATE THIS EVENING AND OVERNIGHT.
* HIGH FOR WINDS THROUGH THE PERIOD...MEDIUM FOR TIMING CHANGES.
* MEDIUM FOR SHOWERS THURSDAY EVENING WITH ASSOCIATED CIGS/VIS.
* LOW FOR TSRA THURSDAY EVENING. CMS

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

* FRIDAY AND SATURDAY...DRY/VFR.
* SUNDAY THROUGH TUESDAY...CHANCE OF SHRA. MVFR POSSIBLE.

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 232354
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
654 PM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 253 PM CDT Wed Apr 23 2014

Plenty of dry air in place over Illinois early this afternoon, on
the periphery of a high pressure ridge, with dew points in the
upper 20s to lower 30s. Across the southeast half of the forecast
area, clouds have been eroding as they move into the drier air. Area
of showers has been advancing eastward from Iowa. Looks impressive
on radar, but surface observations are showing cloud heights well
over 8000 feet in many cases, indicating not much in the way of
measurable rain is reaching the ground. However, this is enough
that a mention of isolated showers across the northern CWA this
evening is warranted.

The first forecast concern is with the timing of rain over the
next day or so, as this storm system pushes eastward. In the
longer term, the duration of the rain is a concern as we get set
in a rainy pattern for the first half of next week.

SHORT TERM...Tonight through Friday:

Water vapor imagery and upper air analysis showing a deep trough
currently pushing east across the Rockies, and is progged to move
across the Mississippi Valley late Thursday. The dry air at the
lower levels will take some time to saturate, with the forecast
soundings still rather parched below 850 mb at mid afternoon. Have
limited Thursday morning PoP`s to areas west of I-55 and still
kept them below 50% during the afternoon east of I-57, otherwise
have maintained the categorical PoP`s over 80% in much of the
forecast area during the afternoon. Best instability looks to be
along and south of I-72 for any thunder, although some low CAPE`s
to around 200 J/kg progged as far north as Peoria, so have kept
some thunder mention that far north. With the system a bit slower,
will mention 80% or higher PoP`s into the evening across the east
half of the forecast area into the evening. Dry weather then on
tap for Friday.

LONG TERM...Friday night through Wednesday:

A cold front will push southward through the region Friday night.
Big question will be where it ends up, as it will likely not be
going anywhere for awhile. Most of the models do have it through
the forecast area by early Saturday, although the ECMWF and GEM
models linger it more toward the I-72 corridor. Saturday should be
dry. However, the main action will be later in the weekend, as all
the models continue to close off an upper low over the central
Rockies. This low will only slowly drift eastward, and will likely
linger in some form into the middle of next week.

Most of Sunday should be fairly decent, with the rain most likely
across the western CWA during the afternoon. After that, rain is
likely on and off, with PoP`s gradually diminishing Tuesday and
Wednesday as the cutoff low slowly weakens. By this point, as the
core of the colder air settles over the Midwest, temperatures will
be a good 15 or so degrees below normal, with highs Tuesday and
especially Wednesday generally in the 50s.

Geelhart

&&

.AVIATION...
ISSUED 654 PM CDT Wed Apr 23 2014

One primary band of light rain will progress eastward across
PIA/BMI/CMI over the first few hours of the TAF period. The dry
air below 7k- 8k feet will preclude much in the way of measurable
rain, with sprinkles the main precipitation this evening. There
will be a chance of sprinkles lingering for PIA the rest of the
evening based on upstream radar and satellite trends.

The next chance of precipitation looks to be later Thursday
morning. Thunderstorm chances will increase as the afternoon
progresses, and a vcts was included at all terminal sites Thursday
afternoon. A tempo for IFR clouds and possibly vis conditions will
most likely be needed, when a better handle on timing develops in
the High Res short term models.

Winds will remain southeast tonight, with speeds in the 08-13kt
range. As the cold front arrives Thursday afternoon, wind speeds
will increase into the 15g30kt range. Wind direction will veer
slightly toward the south as well.

Shimon
&&

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

$$








000
FXUS63 KLOT 232207
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
507 PM CDT WED APR 23 2014

.DISCUSSION...
310 PM CDT

SYNOPSIS...ANOTHER PLEASANT DAY TODAY...BUT SHOWERS MOVE IN FROM THE
WEST THIS EVENING. SHOWERS AND STORMS ARE EXPECTED TOMORROW
AFTERNOON AND EVENING WITH A DRY AND WARM END TO THE WORK WEEK.
THIS WEEKEND LOOKS TO HAVE BELOW NORMAL TEMPERATURES WITH SHOWERS
AND PERHAPS SOME THUNDERSTORMS ALONG AND SOUTH OF I-80 FOR THE FIRST
HALF OF NEXT WEEK.

REST OF TODAY AND TONIGHT...
A LARGE UPPER LEVEL RIDGE IS OVER THE CENTRAL PLAINS WHILE A SURFACE
HIGH IS CENTERED OVER LAKE MICHIGAN. THE RIDGE PASSES OVERHEAD
TONIGHT WHILE THE SURFACE HIGH PUSHES EAST TO THE NORTHERN OHIO
VALLEY THROUGH EASTERN QUEBEC.

A WEAK SHORTWAVE IS OVER EASTERN NEBRASKA AND WESTERN IOWA WITH
SHOWERS OVER WESTERN IOWA.  THE SHOWERS WILL CONTINUE TO PUSH
EAST...BUT WITH DEWPOINT DEPRESSIONS AT 20+ DEGREES...THINKING THE
SHOWERS WILL DISSIPATE A BIT BEFORE MOVING INTO CENTRAL IL. AS SUCH
THINKING THE FIRST SHOWERS WILL ENTER THE FAR EASTERN CWA AFTER 5PM
CST.  USED THE LOCAL ARW...RAP...AND HRRR TO CREATE THE POPS FOR THE
REST OF TODAY AND TONIGHT. THINKING A BAND OF SCATTERED SHOWERS WILL
SLOWLY CROSS NORTHERN IL THIS EVENING IN ASSOCIATION WITH AN UPPER
LEVEL VORTICITY STREAMER. THE BEST COVERAGE WILL BE BETWEEN MIDNIGHT
AND 4 AM CST WITH A CHANCE OF LIGHT RAIN SHOWERS NORTH OF I-80. THE
BAND THEN LIFTS NORTH EARLY THURSDAY MORNING AS THE RIDGE MOVES
DIRECTLY OVERHEAD. NOT EXPECTING ANY SIGNIFICANT PRECIP
ACCUMULATIONS.

CLOUD COVER WILL INCREASE THROUGH THIS AFTERNOON AND LOOKING AT MIN
TEMPS IN THE UPPER 30S TO MID 40S ACROSS THE CWA.

TOMORROW AND TOMORROW NIGHT...
AN UPPER LEVEL TROUGH MOVES OVER THE PLAINS TOMORROW MORNING AND THE
TROUGH PASSES OVER THE REGION TOMORROW NIGHT. THE UPPER LEVEL LOW
ASSOCIATED WITH THE TROUGH PASSES FARTHER NORTH...ALONG THE
US/CANADA BORDER.  THE SURFACE LOW ALSO BEGINS OVER THE PLAINS
THURSDAY MORNING AND THEN MOVES OVER IL THURSDAY EVENING. GUIDANCE
HAS THE LOW PROGRESSING A BIT SLOWER AND MADE THE NECESSARY
ADJUSTMENTS.

RAIN AND SOME STORMS MOVE IN FROM THE WEST THROUGH THE MORNING AND
EARLY AFTERNOON.  INSTABILITY IS NOT EXTREMELY IMPRESSIVE WITH THE
SYSTEM SO KEPT ONLY A CHANCE OF THUNDER. QPF AMOUNTS ON THE OTHER
HAND COULD BE IMPRESSIVE WITH TOTALS AROUND A HALF INCH OF RAIN.

WINDS WILL ALSO BE SHIFTING FROM SOUTHEAST IN THE MORNING TO OUT OF
THE WEST OVERNIGHT BEHIND THE LOW.  LOOKING AT A BREEZY AFTERNOON
WITH SOUTH WINDS GUSTING TO 35 MPH.  THE AMPLE WAA WILL LEAD TO MAX
TEMPS FROM AROUND 60 ALONG THE IL/WI BORDER TO THE UPPER 60S IF NOT
70 IN THE SOUTHERN CWA.

FRIDAY AND SATURDAY...
THE UPPER LEVEL LOW CONTINUES TO SHIFT EAST REACHING NEW ENGLAND BY
SATURDAY AFTERNOON/EVENING.  THE SURFACE LOW SHIFTS EAST AND
EXPECTING PRECIP TO COME TO AN END EARLY FRIDAY MORNING.  WEST WINDS
WILL BE GUSTING TO ARND 30 MPH FRIDAY AND AM THINKING THERE COULD BE
SOME DRY AIR MIXING DOWN TO THE SURFACE SO LOWERED DEWPOINTS A BIT.

THE AIR BEHIND THE COLD FRONT IS NOT REALLY ALL THAT COLD SINCE MAX
TEMPS ON FRIDAY LOOK TO BE AROUND 70 DEGREES.  A BACK DOOR COLD
FRONT SLIDES DOWN FROM THE NORTH IN THE EVENING. SOME GUIDANCE
MEMBERS FEATURE A BAND OF PRECIP FORMING AHEAD OF THE FRONT OVER FAR
NORTHERN IL AND NW INDIANA. PUT IN A CHANCE OF PRECIP SINCE FORCING
LOOKS GOOD...BUT HAVE LOW CONFIDENCE IN THE BAND OF PRECIP ACTUALLY
FORMING. AS SUCH KEPT POPS IN THE CHANCE RANGE.  WINDS TURN
NORTHEAST BEHIND THE FRONT AND OVERNIGHT LOWS WILL BE IN THE UPPER
30S TO MID 40S.

SOME GUIDANCE MEMBERS KEEP A BAND OF PRECIP OVER THE REGION SATURDAY
MORNING...BUT WITH HIGH PRESSURE MOVING OVER THE REGION HAVE LOW
CONFIDENCE AND WENT WITH A DRY FORECAST SATURDAY.  SKIES WILL CLEAR
BUT THE COOLER AIR OFF THE LAKE WILL RESULT IN HIGHS IN THE UPPER
40S TO MID 50S ALONG THE LAKE...AND THEN IN THE LOW TO MID 60S IN
THE OUTLYING AREAS.

GUIDANCE FEATURES PRECIP MOVING IN AHEAD OF THE NEXT LOW SATURDAY
NIGHT. HAVE LOW CONFIDENCE IN THIS ROUND OF PRECIP AS WELL...BUT
LEFT A CHANCE OF RAIN IN THE FORECAST.  OVERNIGHT LOWS WILL RANGE
FROM THE UPPER 30S TO THE MID 40S.

EXTENDED...SUNDAY THROUGH TUESDAY...
AN UPPER LEVEL CLOSED LOW SHIFTS OVER THE GREAT PLAINS SUNDAY
EVENING/NIGHT. GUIDANCE DIFFERS ON ITS EXACT PATH EARLY NEXT WEEK
BUT DOES HAVE THE UPPER LEVEL LOW OVER THE REGION THROUGH AT LEAST
MID WEEK.  ITS ASSOCIATED SURFACE LOW MOVES OVER THE PLAINS LATE
SUNDAY NIGHT/MONDAY MORNING AND SLIDES SOUTH OF THE CWA MONDAY
NIGHT. THE 12Z GUIDANCE AGREED A BIT MORE ABOUT THE SURFACE LOWS
PATH...AND HAVE IT MOVING THROUGH SOUTHERN IL TUESDAY.

IN TWO WORDS EARLY NEXT WEEK LOOKS CHILLY AND WET.  A BOUNDARY OVER
NORTHERN IL BRINGS THE LIFT FOR THE FIRST WAVE OF PRECIP EARLY ON
SUNDAY...BUT THEN MULTIPLE VORTICITY STREAMERS PASS THROUGH THE
REGION AS THE LOW SLOWLY SHIFTS EAST. THIS WILL RESULT IN A CHANCE
OF PRECIP THROUGHOUT THE EXTENDED. WILL INCLUDE A SLIGHT CHANCE OF
THUNDER ALONG AND SOUTH OF I-80 WHERE THERE WILL BE LIMITED ELEVATED
INSTABILITY BUT ENOUGH TO PERHAPS SUPPORT A COUPLE OF THUNDERSTORMS
SUNDAY NIGHT AND MONDAY. THE UPPER LEVEL JET DIPS FAR SOUTH THROUGH
TEXAS ALLOWING COOL AIR TO SPREAD ACROSS THE REGION. AS SUCH HIGHS
WILL VARY BETWEEN THE LOW 50S NORTH TO MID 60S SOUTH WITH A COOLING
TREND THROUGH TUESDAY.  LUCKILY OVERNIGHT LOWS LOOK LIKE THEY WILL
REMAIN ABOVE FREEZING.

JEE

&&

.AVIATION...

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

* VARIABILITY IN THE WINDS REST OF THIS AFTERNOON FROM NNE TO ESE.
* CHANCE FOR SHOWERS THIS EVENING...THEN BETTER CHANCES FOR
  SHOWERS LATE THURSDAY AFTERNOON.
* WINDS VEERING TO SSE BY TOMORROW...THEN BECOMING VERY GUSTY LATE
  TOMORROW MORNING INTO THE AFTERNOON.

BMD/CMS

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

HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT EAST AWAY FROM THE
TERMINALS THIS AFTERNOON WITH WINDS CONTINUING TO VEER FROM THE
NORTHEAST EARLY THIS AFTERNOON TO THE SOUTHEAST OVERNIGHT. SHOWERS
CURRENTLY OVER SOUTHERN MINNESOTA AND IOWA MAY SKIRT THE IL/WI STATE
LINE LATE THIS AFTERNOON THROUGH LATE EVENING BRINGING A SMALL CHANCE
FOR SHOWERS. COVERAGE IS STILL UNCERTAIN SO WILL MAINTAIN PROB30 FOR
THE CHICAGO TERMINALS AND VCSH FOR RFD. MEANWHILE...LOW PRESSURE
WILL DEVELOP OVER THE SOUTHERN PLAINS AND LIFT TO THE MID
MISSISSIPPI VALLEY BY MIDDAY THURSDAY. THE GRADIENT WILL TIGHTEN
AHEAD OF THE LOW WITH GUSTS GRADUALLY INCREASING INTO THE UPPER 20
KT RANGE OT OF THE SSE...AND CANNOT RULE OUT SOME GUSTS IN EXCESS OF
30 KT. SHOWERS AND PERHAPS A FEW THUNDERSTORMS WILL THEN OVERSPREAD
THE TERMINALS MID TO LATE THURSDAY AFTERNOON.

BMD

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

* MEDIUM CONFIDENCE IN WIND DIRECTION THIS AFTERNOON...MEDIUM-HIGH
  CONFIDENCE ON WIND DIRECTION/SPEED THURSDAY.
* LOW CONFIDENCE IN PRECIP AT TERMINALS THIS EVENING...MEDIUM
  CONFIDENCE IN PRECIP TIMING THURSDAY AFTERNOON.

BMD/CMS

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 232010
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
310 PM CDT WED APR 23 2014

.DISCUSSION...
310 PM CDT

SYNOPSIS...ANOTHER PLEASANT DAY TODAY...BUT SHOWERS MOVE IN FROM THE
WEST THIS EVENING. SHOWERS AND STORMS ARE EXPECTED TOMORROW
AFTERNOON AND EVENING WITH A DRY AND WARM END TO THE WORK WEEK.
THIS WEEKEND LOOKS TO HAVE BELOW NORMAL TEMPERATURES WITH SHOWERS
AND PERHAPS SOME THUNDERSTORMS ALONG AND SOUTH OF I-80 FOR THE FIRST
HALF OF NEXT WEEK.

REST OF TODAY AND TONIGHT...
A LARGE UPPER LEVEL RIDGE IS OVER THE CENTRAL PLAINS WHILE A SURFACE
HIGH IS CENTERED OVER LAKE MICHIGAN. THE RIDGE PASSES OVERHEAD
TONIGHT WHILE THE SURFACE HIGH PUSHES EAST TO THE NORTHERN OHIO
VALLEY THROUGH EASTERN QUEBEC.

A WEAK SHORTWAVE IS OVER EASTERN NEBRASKA AND WESTERN IOWA WITH
SHOWERS OVER WESTERN IOWA.  THE SHOWERS WILL CONTINUE TO PUSH
EAST...BUT WITH DEWPOINT DEPRESSIONS AT 20+ DEGREES...THINKING THE
SHOWERS WILL DISSIPATE A BIT BEFORE MOVING INTO CENTRAL IL. AS SUCH
THINKING THE FIRST SHOWERS WILL ENTER THE FAR EASTERN CWA AFTER 5PM
CST.  USED THE LOCAL ARW...RAP...AND HRRR TO CREATE THE POPS FOR THE
REST OF TODAY AND TONIGHT. THINKING A BAND OF SCATTERED SHOWERS WILL
SLOWLY CROSS NORTHERN IL THIS EVENING IN ASSOCIATION WITH AN UPPER
LEVEL VORTICITY STREAMER. THE BEST COVERAGE WILL BE BETWEEN MIDNIGHT
AND 4 AM CST WITH A CHANCE OF LIGHT RAIN SHOWERS NORTH OF I-80. THE
BAND THEN LIFTS NORTH EARLY THURSDAY MORNING AS THE RIDGE MOVES
DIRECTLY OVERHEAD. NOT EXPECTING ANY SIGNIFICANT PRECIP
ACCUMULATIONS.

CLOUD COVER WILL INCREASE THROUGH THIS AFTERNOON AND LOOKING AT MIN
TEMPS IN THE UPPER 30S TO MID 40S ACROSS THE CWA.

TOMORROW AND TOMORROW NIGHT...
AN UPPER LEVEL TROUGH MOVES OVER THE PLAINS TOMORROW MORNING AND THE
TROUGH PASSES OVER THE REGION TOMORROW NIGHT. THE UPPER LEVEL LOW
ASSOCIATED WITH THE TROUGH PASSES FARTHER NORTH...ALONG THE
US/CANADA BORDER.  THE SURFACE LOW ALSO BEGINS OVER THE PLAINS
THURSDAY MORNING AND THEN MOVES OVER IL THURSDAY EVENING. GUIDANCE
HAS THE LOW PROGRESSING A BIT SLOWER AND MADE THE NECESSARY
ADJUSTMENTS.

RAIN AND SOME STORMS MOVE IN FROM THE WEST THROUGH THE MORNING AND
EARLY AFTERNOON.  INSTABILITY IS NOT EXTREMELY IMPRESSIVE WITH THE
SYSTEM SO KEPT ONLY A CHANCE OF THUNDER. QPF AMOUNTS ON THE OTHER
HAND COULD BE IMPRESSIVE WITH TOTALS AROUND A HALF INCH OF RAIN.

WINDS WILL ALSO BE SHIFTING FROM SOUTHEAST IN THE MORNING TO OUT OF
THE WEST OVERNIGHT BEHIND THE LOW.  LOOKING AT A BREEZY AFTERNOON
WITH SOUTH WINDS GUSTING TO 35 MPH.  THE AMPLE WAA WILL LEAD TO MAX
TEMPS FROM AROUND 60 ALONG THE IL/WI BORDER TO THE UPPER 60S IF NOT
70 IN THE SOUTHERN CWA.

FRIDAY AND SATURDAY...
THE UPPER LEVEL LOW CONTINUES TO SHIFT EAST REACHING NEW ENGLAND BY
SATURDAY AFTERNOON/EVENING.  THE SURFACE LOW SHIFTS EAST AND
EXPECTING PRECIP TO COME TO AN END EARLY FRIDAY MORNING.  WEST WINDS
WILL BE GUSTING TO ARND 30 MPH FRIDAY AND AM THINKING THERE COULD BE
SOME DRY AIR MIXING DOWN TO THE SURFACE SO LOWERED DEWPOINTS A BIT.

THE AIR BEHIND THE COLD FRONT IS NOT REALLY ALL THAT COLD SINCE MAX
TEMPS ON FRIDAY LOOK TO BE AROUND 70 DEGREES.  A BACK DOOR COLD
FRONT SLIDES DOWN FROM THE NORTH IN THE EVENING. SOME GUIDANCE
MEMBERS FEATURE A BAND OF PRECIP FORMING AHEAD OF THE FRONT OVER FAR
NORTHERN IL AND NW INDIANA. PUT IN A CHANCE OF PRECIP SINCE FORCING
LOOKS GOOD...BUT HAVE LOW CONFIDENCE IN THE BAND OF PRECIP ACTUALLY
FORMING. AS SUCH KEPT POPS IN THE CHANCE RANGE.  WINDS TURN
NORTHEAST BEHIND THE FRONT AND OVERNIGHT LOWS WILL BE IN THE UPPER
30S TO MID 40S.

SOME GUIDANCE MEMBERS KEEP A BAND OF PRECIP OVER THE REGION SATURDAY
MORNING...BUT WITH HIGH PRESSURE MOVING OVER THE REGION HAVE LOW
CONFIDENCE AND WENT WITH A DRY FORECAST SATURDAY.  SKIES WILL CLEAR
BUT THE COOLER AIR OFF THE LAKE WILL RESULT IN HIGHS IN THE UPPER
40S TO MID 50S ALONG THE LAKE...AND THEN IN THE LOW TO MID 60S IN
THE OUTLYING AREAS.

GUIDANCE FEATURES PRECIP MOVING IN AHEAD OF THE NEXT LOW SATURDAY
NIGHT. HAVE LOW CONFIDENCE IN THIS ROUND OF PRECIP AS WELL...BUT
LEFT A CHANCE OF RAIN IN THE FORECAST.  OVERNIGHT LOWS WILL RANGE
FROM THE UPPER 30S TO THE MID 40S.

EXTENDED...SUNDAY THROUGH TUESDAY...
AN UPPER LEVEL CLOSED LOW SHIFTS OVER THE GREAT PLAINS SUNDAY
EVENING/NIGHT. GUIDANCE DIFFERS ON ITS EXACT PATH EARLY NEXT WEEK
BUT DOES HAVE THE UPPER LEVEL LOW OVER THE REGION THROUGH AT LEAST
MID WEEK.  ITS ASSOCIATED SURFACE LOW MOVES OVER THE PLAINS LATE
SUNDAY NIGHT/MONDAY MORNING AND SLIDES SOUTH OF THE CWA MONDAY
NIGHT. THE 12Z GUIDANCE AGREED A BIT MORE ABOUT THE SURFACE LOWS
PATH...AND HAVE IT MOVING THROUGH SOUTHERN IL TUESDAY.

IN TWO WORDS EARLY NEXT WEEK LOOKS CHILLY AND WET.  A BOUNDARY OVER
NORTHERN IL BRINGS THE LIFT FOR THE FIRST WAVE OF PRECIP EARLY ON
SUNDAY...BUT THEN MULTIPLE VORTICITY STREAMERS PASS THROUGH THE
REGION AS THE LOW SLOWLY SHIFTS EAST. THIS WILL RESULT IN A CHANCE
OF PRECIP THROUGHOUT THE EXTENDED. WILL INCLUDE A SLIGHT CHANCE OF
THUNDER ALONG AND SOUTH OF I-80 WHERE THERE WILL BE LIMITED ELEVATED
INSTABILITY BUT ENOUGH TO PERHAPS SUPPORT A COUPLE OF THUNDERSTORMS
SUNDAY NIGHT AND MONDAY. THE UPPER LEVEL JET DIPS FAR SOUTH THROUGH
TEXAS ALLOWING COOL AIR TO SPREAD ACROSS THE REGION. AS SUCH HIGHS
WILL VARY BETWEEN THE LOW 50S NORTH TO MID 60S SOUTH WITH A COOLING
TREND THROUGH TUESDAY.  LUCKILY OVERNIGHT LOWS LOOK LIKE THEY WILL
REMAIN ABOVE FREEZING.

JEE

&&

.AVIATION...

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

* VARIABILITY IN THE WINDS REST OF THIS AFTERNOON FROM NNE TO ESE.
* CHANCE FOR SHOWERS THIS EVENING...THEN BETTER CHANCES FOR
  SHOWERS LATE THURSDAY AFTERNOON.
* WINDS VEERING TO SSE BY TOMORROW...THEN BECOMING VERY GUSTY LATE
  TOMORROW MORNING INTO THE AFTERNOON.

BMD

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

HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT EAST AWAY FROM THE
TERMINALS THIS AFTERNOON WITH WINDS CONTINUING TO VEER FROM THE
NORTHEAST EARLY THIS AFTERNOON TO THE SOUTHEAST OVERNIGHT. SHOWERS
CURRENTLY OVER SOUTHERN MINNESOTA AND IOWA MAY SKIRT THE IL/WI STATE
LINE LATE THIS AFTERNOON THROUGH LATE EVENING BRINGING A SMALL CHANCE
FOR SHOWERS. COVERAGE IS STILL UNCERTAIN SO WILL MAINTAIN PROB30 FOR
THE CHICAGO TERMINALS AND VCSH FOR RFD. MEANWHILE...LOW PRESSURE
WILL DEVELOP OVER THE SOUTHERN PLAINS AND LIFT TO THE MID
MISSISSIPPI VALLEY BY MIDDAY THURSDAY. THE GRADIENT WILL TIGHTEN
AHEAD OF THE LOW WITH GUSTS GRADUALLY INCREASING INTO THE UPPER 20
KT RANGE OT OF THE SSE...AND CANNOT RULE OUT SOME GUSTS IN EXCESS OF
30 KT. SHOWERS AND PERHAPS A FEW THUNDERSTORMS WILL THEN OVERSPREAD
THE TERMINALS MID TO LATE THURSDAY AFTERNOON.

BMD

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

* MEDIUM CONFIDENCE IN WIND DIRECTION THIS AFTERNOON...MEDIUM-HIGH
  CONFIDENCE ON WIND DIRECTION/SPEED THURSDAY.
* LOW CONFIDENCE IN PRECIP AT TERMINALS THIS EVENING...MEDIUM
  CONFIDENCE IN PRECIP TIMING THURSDAY AFTERNOON.

BMD

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 231955
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
255 PM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 253 PM CDT Wed Apr 23 2014

Plenty of dry air in place over Illinois early this afternoon, on
the periphery of a high pressure ridge, with dew points in the
upper 20s to lower 30s. Across the southeast half of the forecast
area, clouds have been eroding as they move into the drier air. Area
of showers has been advancing eastward from Iowa. Looks impressive
on radar, but surface observations are showing cloud heights well
over 8000 feet in many cases, indicating not much in the way of
measurable rain is reaching the ground. However, this is enough
that a mention of isolated showers across the northern CWA this
evening is warranted.

The first forecast concern is with the timing of rain over the
next day or so, as this storm system pushes eastward. In the
longer term, the duration of the rain is a concern as we get set
in a rainy pattern for the first half of next week.


SHORT TERM...Tonight through Friday:

Water vapor imagery and upper air analysis showing a deep trough
currently pushing east across the Rockies, and is progged to move
across the Mississippi Valley late Thursday. The dry air at the
lower levels will take some time to saturate, with the forecast
soundings still rather parched below 850 mb at mid afternoon. Have
limited Thursday morning PoP`s to areas west of I-55 and still
kept them below 50% during the afternoon east of I-57, otherwise
have maintained the categorical PoP`s over 80% in much of the
forecast area during the afternoon. Best instability looks to be
along and south of I-72 for any thunder, although some low CAPE`s
to around 200 J/kg progged as far north as Peoria, so have kept
some thunder mention that far north. With the system a bit slower,
will mention 80% or higher PoP`s into the evening across the east
half of the forecast area into the evening. Dry weather then on
tap for Friday.


LONG TERM...Friday night through Wednesday:

A cold front will push southward through the region Friday night.
Big question will be where it ends up, as it will likely not be
going anywhere for awhile. Most of the models do have it through
the forecast area by early Saturday, although the ECMWF and GEM
models linger it more toward the I-72 corridor. Saturday should be
dry. However, the main action will be later in the weekend, as all
the models continue to close off an upper low over the central
Rockies. This low will only slowly drift eastward, and will likely
linger in some form into the middle of next week.

Most of Sunday should be fairly decent, with the rain most likely
across the western CWA during the afternoon. After that, rain is
likely on and off, with PoP`s gradually diminishing Tuesday and
Wednesday as the cutoff low slowly weakens. By this point, as the
core of the colder air settles over the Midwest, temperatures will
be a good 15 or so degrees below normal, with highs Tuesday and
especially Wednesday generally in the 50s.

Geelhart

&&

.AVIATION...
ISSUED 1236 PM CDT Wed Apr 23 2014

Dry air in place expected to keep the precip out to the west from
working into the TAF sites more than possibly a sprinkle this
afternoon, so keeping from mention at this point. However...will
drop from 10kft cigs to 5kft cigs with the moisture advection
overall by later this evening. VFR through the fcst, but the next
problem is expected tomorrow morning as the wave pushes some
precip towards the FA. Much of the precip is expected to hold off
until mid morning in the west...and a bit later in the east...but
models are not consistent with timing or coverage early.
Mentioning VCSH for the morning to start the trend...and next
issuance will likely see more of a mention and contemplate the
timing/potential for thunder.

HJS

&&

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

$$






000
FXUS63 KLOT 231946
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
246 PM CDT WED APR 23 2014

.DISCUSSION...
402 AM CDT

MAIN FORECAST CONCERNS THIS MORNING ARE WITH RELATIVELY LOW CHANCE
POPS FOR SHOWERS/SPRINKLES LATE THIS AFTERNOON/TONIGHT...THEN BETTER
POTENTIAL FOR RAIN AND A FEW THUNDERSTORMS THURSDAY/THURSDAY
EVENING  WITH APPROACHING SURFACE LOW PRESSURE WAVE PACIFIC COLD
FRONT. TEMPS LOOK MILD FOR FRIDAY BEHIND PACIFIC FRONT...BUT
COOLER/POTENTIALLY WET WEATHER STILL APPEARS TO DOMINATE EXTENDED
PERIODS OF FORECAST FROM THE WEEKEND INTO EARLY NEXT WEEK.

IN THE NEAR TERM...SURFACE HIGH PRESSURE RIDGE WAS OVER WISCONSIN
AND ILLINOIS EARLY THIS MORNING...PROVIDING COOL/DRY AND MAINLY
CLEAR CONDITIONS WITH LIGHT NORTH-NORTHEAST WINDS. A FEW SPOTS
DIPPING TO/BELOW THE FREEZING MARK...ESPECIALLY ACROSS THE FOX AND
ROCK RIVER VALLEY REGIONS THIS MORNING. FROST ADVISORY REMAINS IN
EFFECT THROUGH 7 AM CDT FOR MOST OF FAR NORTHERN/NORTHEAST IL AND
NORTHWEST IND. LOOKING AHEAD...EARLY MORNING GOES IMAGERY ALREADY
SHOWS HIGH CLOUDS INCREASING ACROSS THE PLAINS IN REGION OF WARM
ADVECTION IN ADVANCE OF WESTERN CONUS UPPER TROUGH. SHORT-TERM
MODELS REMAIN CONSISTENT IN BRINGING A WEAK MID-LEVEL SHORT WAVE
FROM THE CENTRAL PLAINS INTO OUR REGION THROUGH THIS EVENING...WITH
MID/UPPER LEVEL MOIST ADVECTION AND CONVERGENCE/FRONTOGENETIC
FORCING ALONG AN ELEVATED WARM FRONTAL ZONE EXPECTED TO PRODUCE SOME
HIGH BASED LIGHT SHOWERS/SPRINKLES INTO NORTH CENTRAL IL BY LATER
THIS AFTERNOON...AND ACROSS MUCH OF THE NORTH/NORTHWEST CWA TONIGHT
AS FORCING CONTINUES AHEAD OF A SECOND WEAK SHORT WAVE. HAVE
GENERALLY MAINTAINED HIGHEST POPS NORTHWEST OF I-88 CORRIDOR ACROSS
IL ALTHOUGH A FEW SHOWERS/SPRINKLES COULD OCCUR JUST ABOUT ANYWHERE
TONIGHT. PRECIP POTENTIAL INCREASES SIGNIFICANTLY THURSDAY AS MAIN
UPPER TROUGH APPROACHES FROM THE WEST...AND LOW LEVEL WINDS SHIFT
MORE SOUTHERLY AS A SURFACE LOW PRESSURE WAVE LIFTS FROM THE
MID-MISSOURI VALLEY NORTHEAST INTO WISCONSIN BY EVENING. NARROW
MOIST AXIS...COMBINED WITH INCREASING DEEP FORCING WITH APPROACH OF
SURFACE COLD FRONT AND LARGE SCALE ASCENT AHEAD OF UPPER TROUGH
SHOULD BE SUFFICIENT TO PRODUCE FAIRLY DECENT COVERAGE OF
RAIN/SHOWERS AND A FEW THUNDERSTORMS ESPECIALLY BY AFTERNOON.
OVERALL TREND OF GUIDANCE HAS BEEN TO SLOW ADVANCE OF COLD FRONT
SLIGHTLY...IN RESPONSE TO SLOWER PROGRESSION OF CLOSED LOW ALONG THE
CANADIAN BORDER. THUS HAVE HELD ONTO HIGHER POPS INTO THURSDAY
EVENING ESPECIALLY ACROSS THE EASTERN CWA...AS COLD FRONT COMPLETES
ITS TRANSIT.

TEMP WISE...EAST-NORTHEAST WINDS TODAY CONTINUE OUR COOLER THAN
NORMAL WEATHER PARTICULARLY ALONG LAKE MICHIGAN. HAVE GENERALLY GONE
WITH/SLIGHTLY ABOVE WARMER MAV NUMBERS WEST/SOUTHWEST WELL AWAY FROM
THE LAKE...THOUGH SHORE LOCATIONS WILL LIKELY NOT GET OUT OF THE 40S
AGAIN TODAY. COOL CONDITIONS CONTINUE TONIGHT ACROSS FAR NORTHEAST
IL WHERE CONTINUED EASTERLY COMPONENT AND LATER ARRIVAL OF THICKER
CLOUD COVER WILL ALLOW MINS TO DIP INTO THE MID-UPPER 30S. GRADUAL
VEERING OF LOW LEVEL WIND TO SOUTHEAST AND SLOW INCREASE IN LOW
LEVEL MOISTURE FROM THE SOUTH WILL HELP KEEP FAR SOUTHERN CWA ABOVE
40. MILDER SOUTHEAST FLOW THURSDAY WILL BE OFFSET BY CLOUDS/PRECIP
AND A CONTINUED SOUTHEAST WIND COMPONENT THROUGH THE MORNING...
THOUGH SHOULD SEE 60S ALL BUT IMMEDIATE NORTH SHORE AND LIKELY CLOSE
TO 70 SOUTH OF I-80. BREEZY/MILD BEHIND PACIFIC COLD FRONT THURSDAY
NIGHT INTO FRIDAY...WITH PERHAPS THE WARMEST TEMPS OF THIS FORECAST
PERIOD WITH GOOD MIXING AND WEST WINDS. LOW LEVEL THERMAL PROGS
SUPPORT GUIDANCE HIGHS FROM MID-UPPER 60S NORTH TO THE LOW 70S
SOUTH.

MODELS HAVE SHOWN SOME VARIATION/ADJUSTMENT WITH HANDLING OF LARGE
SCALE FLOW PATTERN AND RESULTING SYNOPTIC DETAILS FROM FRIDAY NIGHT
ONWARD. OVERALL...SLOWER CANADIAN BORDER SHORT WAVE PASSES NORTH OF
THE REGION FRIDAY...AND TRAILS A SECOND COLD FRONT SOUTH INTO THE
AREA BY EARLY EVENING. SOME POTENTIAL FOR SHOWERS ALONG THE FRONT
FRIDAY NIGHT...THOUGH GUIDANCE INCONSISTENT WITH TIMING/PLACEMENT OF
PRECIP AT THIS TIME AND FEEL SLIGHT CHANCE POPS SUFFICIENT AT THIS
TIME. COOL/DRY HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE LAKES
INTO SATURDAY AS UPPER TROUGH CONTINUES OFF TO THE EAST. HIGHLY
AMPLIFIED TROUGH MOVES ACROSS WESTERN CONUS...WITH CLOSED LOW
DEVELOPING AND EVENTUALLY MOVING OUT ACROSS THE PLAINS
SUNDAY-TUESDAY. GULF MOISTURE IS EVENTUALLY DRAWN NORTH ACROSS LOW
LEVEL BAROCLINIC ZONE ASSOCIATED WITH WEST-EAST STATIONARY FRONT TO
OUR SOUTH...WITH INCREASING POTENTIAL FOR RAIN FROM THE SOUTHWEST
DURING THE PERIOD. COOL/DRY EAST-NORTHEAST FLOW FROM THE RETREATING
HIGH TO OUR NORTHEAST SHOULD SLOW THINGS A BIT...AND KEEP POPS
GRADUATED FROM LOWER NORTHEAST TO HIGHER SOUTHWEST. MODEL
DIFFERENCES IN DETAILS/TIMING OF EVOLUTION OF UPPER AND SURFACE LOWS
LATE IN THE PERIOD DIMINISH CONFIDENCE IN FINER DETAILS AT THIS
TIME.

RATZER

&&

.AVIATION...

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

* VARIABILITY IN THE WINDS REST OF THIS AFTERNOON FROM NNE TO ESE.
* CHANCE FOR SHOWERS THIS EVENING...THEN BETTER CHANCES FOR
  SHOWERS LATE THURSDAY AFTERNOON.
* WINDS VEERING TO SSE BY TOMORROW...THEN BECOMING VERY GUSTY LATE
  TOMORROW MORNING INTO THE AFTERNOON.

BMD

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

HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT EAST AWAY FROM THE
TERMINALS THIS AFTERNOON WITH WINDS CONTINUING TO VEER FROM THE
NORTHEAST EARLY THIS AFTERNOON TO THE SOUTHEAST OVERNIGHT. SHOWERS
CURRENTLY OVER SOUTHERN MINNESOTA AND IOWA MAY SKIRT THE IL/WI STATE
LINE LATE THIS AFTERNOON THROUGH LATE EVENING BRINGING A SMALL CHANCE
FOR SHOWERS. COVERAGE IS STILL UNCERTAIN SO WILL MAINTAIN PROB30 FOR
THE CHICAGO TERMINALS AND VCSH FOR RFD. MEANWHILE...LOW PRESSURE
WILL DEVELOP OVER THE SOUTHERN PLAINS AND LIFT TO THE MID
MISSISSIPPI VALLEY BY MIDDAY THURSDAY. THE GRADIENT WILL TIGHTEN
AHEAD OF THE LOW WITH GUSTS GRADUALLY INCREASING INTO THE UPPER 20
KT RANGE OT OF THE SSE...AND CANNOT RULE OUT SOME GUSTS IN EXCESS OF
30 KT. SHOWERS AND PERHAPS A FEW THUNDERSTORMS WILL THEN OVERSPREAD
THE TERMINALS MID TO LATE THURSDAY AFTERNOON.

BMD

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

* MEDIUM CONFIDENCE IN WIND DIRECTION THIS AFTERNOON...MEDIUM-HIGH
  CONFIDENCE ON WIND DIRECTION/SPEED THURSDAY.
* LOW CONFIDENCE IN PRECIP AT TERMINALS THIS EVENING...MEDIUM
  CONFIDENCE IN PRECIP TIMING THURSDAY AFTERNOON.

BMD

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 AM THURSDAY TO 10 PM 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 231919
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
219 PM CDT WED APR 23 2014

.DISCUSSION...
402 AM CDT

MAIN FORECAST CONCERNS THIS MORNING ARE WITH RELATIVELY LOW CHANCE
POPS FOR SHOWERS/SPRINKLES LATE THIS AFTERNOON/TONIGHT...THEN BETTER
POTENTIAL FOR RAIN AND A FEW THUNDERSTORMS THURSDAY/THURSDAY
EVENING  WITH APPROACHING SURFACE LOW PRESSURE WAVE PACIFIC COLD
FRONT. TEMPS LOOK MILD FOR FRIDAY BEHIND PACIFIC FRONT...BUT
COOLER/POTENTIALLY WET WEATHER STILL APPEARS TO DOMINATE EXTENDED
PERIODS OF FORECAST FROM THE WEEKEND INTO EARLY NEXT WEEK.

IN THE NEAR TERM...SURFACE HIGH PRESSURE RIDGE WAS OVER WISCONSIN
AND ILLINOIS EARLY THIS MORNING...PROVIDING COOL/DRY AND MAINLY
CLEAR CONDITIONS WITH LIGHT NORTH-NORTHEAST WINDS. A FEW SPOTS
DIPPING TO/BELOW THE FREEZING MARK...ESPECIALLY ACROSS THE FOX AND
ROCK RIVER VALLEY REGIONS THIS MORNING. FROST ADVISORY REMAINS IN
EFFECT THROUGH 7 AM CDT FOR MOST OF FAR NORTHERN/NORTHEAST IL AND
NORTHWEST IND. LOOKING AHEAD...EARLY MORNING GOES IMAGERY ALREADY
SHOWS HIGH CLOUDS INCREASING ACROSS THE PLAINS IN REGION OF WARM
ADVECTION IN ADVANCE OF WESTERN CONUS UPPER TROUGH. SHORT-TERM
MODELS REMAIN CONSISTENT IN BRINGING A WEAK MID-LEVEL SHORT WAVE
FROM THE CENTRAL PLAINS INTO OUR REGION THROUGH THIS EVENING...WITH
MID/UPPER LEVEL MOIST ADVECTION AND CONVERGENCE/FRONTOGENETIC
FORCING ALONG AN ELEVATED WARM FRONTAL ZONE EXPECTED TO PRODUCE SOME
HIGH BASED LIGHT SHOWERS/SPRINKLES INTO NORTH CENTRAL IL BY LATER
THIS AFTERNOON...AND ACROSS MUCH OF THE NORTH/NORTHWEST CWA TONIGHT
AS FORCING CONTINUES AHEAD OF A SECOND WEAK SHORT WAVE. HAVE
GENERALLY MAINTAINED HIGHEST POPS NORTHWEST OF I-88 CORRIDOR ACROSS
IL ALTHOUGH A FEW SHOWERS/SPRINKLES COULD OCCUR JUST ABOUT ANYWHERE
TONIGHT. PRECIP POTENTIAL INCREASES SIGNIFICANTLY THURSDAY AS MAIN
UPPER TROUGH APPROACHES FROM THE WEST...AND LOW LEVEL WINDS SHIFT
MORE SOUTHERLY AS A SURFACE LOW PRESSURE WAVE LIFTS FROM THE
MID-MISSOURI VALLEY NORTHEAST INTO WISCONSIN BY EVENING. NARROW
MOIST AXIS...COMBINED WITH INCREASING DEEP FORCING WITH APPROACH OF
SURFACE COLD FRONT AND LARGE SCALE ASCENT AHEAD OF UPPER TROUGH
SHOULD BE SUFFICIENT TO PRODUCE FAIRLY DECENT COVERAGE OF
RAIN/SHOWERS AND A FEW THUNDERSTORMS ESPECIALLY BY AFTERNOON.
OVERALL TREND OF GUIDANCE HAS BEEN TO SLOW ADVANCE OF COLD FRONT
SLIGHTLY...IN RESPONSE TO SLOWER PROGRESSION OF CLOSED LOW ALONG THE
CANADIAN BORDER. THUS HAVE HELD ONTO HIGHER POPS INTO THURSDAY
EVENING ESPECIALLY ACROSS THE EASTERN CWA...AS COLD FRONT COMPLETES
ITS TRANSIT.

TEMP WISE...EAST-NORTHEAST WINDS TODAY CONTINUE OUR COOLER THAN
NORMAL WEATHER PARTICULARLY ALONG LAKE MICHIGAN. HAVE GENERALLY GONE
WITH/SLIGHTLY ABOVE WARMER MAV NUMBERS WEST/SOUTHWEST WELL AWAY FROM
THE LAKE...THOUGH SHORE LOCATIONS WILL LIKELY NOT GET OUT OF THE 40S
AGAIN TODAY. COOL CONDITIONS CONTINUE TONIGHT ACROSS FAR NORTHEAST
IL WHERE CONTINUED EASTERLY COMPONENT AND LATER ARRIVAL OF THICKER
CLOUD COVER WILL ALLOW MINS TO DIP INTO THE MID-UPPER 30S. GRADUAL
VEERING OF LOW LEVEL WIND TO SOUTHEAST AND SLOW INCREASE IN LOW
LEVEL MOISTURE FROM THE SOUTH WILL HELP KEEP FAR SOUTHERN CWA ABOVE
40. MILDER SOUTHEAST FLOW THURSDAY WILL BE OFFSET BY CLOUDS/PRECIP
AND A CONTINUED SOUTHEAST WIND COMPONENT THROUGH THE MORNING...
THOUGH SHOULD SEE 60S ALL BUT IMMEDIATE NORTH SHORE AND LIKELY CLOSE
TO 70 SOUTH OF I-80. BREEZY/MILD BEHIND PACIFIC COLD FRONT THURSDAY
NIGHT INTO FRIDAY...WITH PERHAPS THE WARMEST TEMPS OF THIS FORECAST
PERIOD WITH GOOD MIXING AND WEST WINDS. LOW LEVEL THERMAL PROGS
SUPPORT GUIDANCE HIGHS FROM MID-UPPER 60S NORTH TO THE LOW 70S
SOUTH.

MODELS HAVE SHOWN SOME VARIATION/ADJUSTMENT WITH HANDLING OF LARGE
SCALE FLOW PATTERN AND RESULTING SYNOPTIC DETAILS FROM FRIDAY NIGHT
ONWARD. OVERALL...SLOWER CANADIAN BORDER SHORT WAVE PASSES NORTH OF
THE REGION FRIDAY...AND TRAILS A SECOND COLD FRONT SOUTH INTO THE
AREA BY EARLY EVENING. SOME POTENTIAL FOR SHOWERS ALONG THE FRONT
FRIDAY NIGHT...THOUGH GUIDANCE INCONSISTENT WITH TIMING/PLACEMENT OF
PRECIP AT THIS TIME AND FEEL SLIGHT CHANCE POPS SUFFICIENT AT THIS
TIME. COOL/DRY HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE LAKES
INTO SATURDAY AS UPPER TROUGH CONTINUES OFF TO THE EAST. HIGHLY
AMPLIFIED TROUGH MOVES ACROSS WESTERN CONUS...WITH CLOSED LOW
DEVELOPING AND EVENTUALLY MOVING OUT ACROSS THE PLAINS
SUNDAY-TUESDAY. GULF MOISTURE IS EVENTUALLY DRAWN NORTH ACROSS LOW
LEVEL BAROCLINIC ZONE ASSOCIATED WITH WEST-EAST STATIONARY FRONT TO
OUR SOUTH...WITH INCREASING POTENTIAL FOR RAIN FROM THE SOUTHWEST
DURING THE PERIOD. COOL/DRY EAST-NORTHEAST FLOW FROM THE RETREATING
HIGH TO OUR NORTHEAST SHOULD SLOW THINGS A BIT...AND KEEP POPS
GRADUATED FROM LOWER NORTHEAST TO HIGHER SOUTHWEST. MODEL
DIFFERENCES IN DETAILS/TIMING OF EVOLUTION OF UPPER AND SURFACE LOWS
LATE IN THE PERIOD DIMINISH CONFIDENCE IN FINER DETAILS AT THIS
TIME.

RATZER

&&

.AVIATION...

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

* CHANCE FOR SHOWERS THIS EVENING...THEN BETTER CHANCES FOR
  SHOWERS LATE THURSDAY AFTERNOON.
* WINDS VEERING TO SSE BY TOMORROW...THEN BECOMING VERY GUSTY LATE
  TOMORROW MORNING INTO THE AFTERNOON.

BMD

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

HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT EAST AWAY FROM THE
TERMINALS THIS AFTERNOON WITH WINDS CONTINUING TO VEER FROM THE
NORTHEAST EARLY THIS AFTERNOON TO THE SOUTHEAST OVERNIGHT. SHOWERS
CURRENTLY OVER SOUTHERN MINNESOTA AND IOWA MAY SKIRT THE IL/WI STATE
LINE LATE THIS AFTERNOON THROUGH LATE EVENING BRINGING A SMALL CHANCE
FOR SHOWERS. COVERAGE IS STILL UNCERTAIN SO WILL MAINTAIN PROB30 FOR
THE CHICAGO TERMINALS AND VCSH FOR RFD. MEANWHILE...LOW PRESSURE
WILL DEVELOP OVER THE SOUTHERN PLAINS AND LIFT TO THE MID
MISSISSIPPI VALLEY BY MIDDAY THURSDAY. THE GRADIENT WILL TIGHTEN
AHEAD OF THE LOW WITH GUSTS GRADUALLY INCREASING INTO THE UPPER 20
KT RANGE OT OF THE SSE...AND CANNOT RULE OUT SOME GUSTS IN EXCESS OF
30 KT. SHOWERS AND PERHAPS A FEW THUNDERSTORMS WILL THEN OVERSPREAD
THE TERMINALS MID TO LATE THURSDAY AFTERNOON.

BMD

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

* MEDIUM CONFIDENCE IN WIND DIRECTION THIS AFTERNOON...MEDIUM-HIGH
  CONFIDENCE ON WIND DIRECTION/SPEED THURSDAY.
* LOW CONFIDENCE IN PRECIP AT TERMINALS THIS EVENING...MEDIUM
  CONFIDENCE IN PRECIP TIMING THURSDAY AFTERNOON.

BMD

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
219 PM CDT

PROGRESSIVE FLOW WILL CONTINUE THROUGH FRIDAY BEFORE A MUCH MORE
AMPLIFIED AND LOCKED PATTERN WILL SET UP FOR THE WEEKEND THROUGH THE
MIDDLE OF NEXT WEEK. THE HIGH PRESSURE PRESENTLY OVER THE LAKE WILL
BE SCOOTED EASTWARD EARLY FRIDAY AS LOW PRESSURE FROM THE CENTRAL
PLAINS BOOKS EASTWARD INTO NORTHERN INDIANA. DURING THURSDAY THIS
WILL PROVIDE STRONG SOUTHERLY FLOW. A FAIRLY STOUT INVERSION SHOULD
BE PRESENT OVER THE LAKE...BUT STRONG OFFSHORE WINDS IN NEARSHORE
AREAS SHOULD LEAD TO 25 TO POSSIBLE 30 KT GUSTS. AS A DEEP TROUGH
SETS UP ACROSS THE WESTERN U.S. AND SLOWLY MOVES EAST THROUGH THE
WEEKEND AND EARLY NEXT WEEK...SURFACE HIGH PRESSURE WILL GET
LOCKED OVER THE CENTRAL GREAT LAKES. A TIGHTENING PRESSURE
GRADIENT ON ITS SOUTHERN AND WESTERN SIDES WILL PROVIDE CONTINUOUS
EAST TO NORTHEAST SURFACE WINDS. THIS LOOKS LIKE A POTENTIAL
PROLONGED PERIOD OF SMALL CRAFT ADVISORY CRITERIA.

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 KILX 231741
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1241 PM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 1050 AM CDT Wed Apr 23 2014
Although high pressure is dominating the region this morning, a
brief upper disturbance has produced some rain west of the
Mississippi River Valley. ILX 12z sounding...as well as DVNs
sounding has a lot of dry air below 700mb for the rainfall to work
through before any impact to the ILX area. Most 12z runs of
operational models still very dry... but not picking up on current
activity either. RAPP/RUC reflecting current conditions and
bringing in some version of precip for the afternoon as the rain
to the west drifts and erodes. Considering the amount of dry air
is in place...not a lot of confidence in widespread rainfall...but
will adjust the forecast for some sct sprinkles this evening.
Will continue to monitor...but quick update out momentarily.



&&

.AVIATION...
ISSUED 1236 PM CDT Wed Apr 23 2014
Dry air in place expected to keep the precip out to the west from
working into the TAF sites more than possibly a sprinkle this
afternoon, so keeping from mention at this point. However...will
drop from 10kft cigs to 5kft cigs with the moisture advection
overall by later this evening. VFR through the fcst, but the next problem
is expected tomorrow morning as the wave pushes some precip
towards the FA. Much of the precip is expected to hold off until
mid morning in the west...and a bit later in the east...but models
are not consistent with timing or coverage early. Mentioning VCSH
for the morning to start the trend...and next issuance will likely
see more of a mention and contemplate the timing/potential for thunder.

HJS
&&

.PREV DISCUSSION...
ISSUED 330 AM CDT Wed Apr 23 2014

SHORT TERM...Today through Saturday

Will carry patchy frost over ne counties early this morning as
temps have cooled to 33F at Lacon and Bloomington while Danville
down to 34F. Temps in the upper 30s and lower 40s over rest of
central IL and upper 40s in southeast IL with Mount Carmel airport
at 50F. Band of cirrus clouds spreading se into central IL early
this morning should limit further cooling and think ne counties
will stay above freezing. Cool temps due to 1022 mb high pressure
over WI and ridging southward across IL.

High pressure ridge shifts east of IL today while warm air
advection regime sets up over IL through Thu morning with
increasing mid/high clouds. Isolated convection appears to stay north
and west of central IL today and most of tonight and just have
slight chances of showers over IL river valley overnight. Highs in
the low to mid 60s again today with coolest readings from I-74 ne.
Low tonight in the mid to upper 40s.

Strong storm system over the central Rockies to eject surface low
pressure from CO ne into WI Thu evening and pull a cold front east
across IL later Thu afternoon and evening. A band of showers and
scattered thunderstorms likely along and ahead of cold front Thu
afternoon and in eastern IL Thu evening. SPC has 5% risk of severe
storms in far southeast IL while slight risk is south of IL where
better instability present. Highs Thu range from mid 60s to lower
70s with coolest readings nw over IL river valley.

Mild Pacific air over central and southeast IL with highs in the
low to mid 70s and return of more sunshine. A 2nd cold front drops
se across the region Fri night and could bring a few light rain
showers to mainly ne areas along with cooler temps across the
region by Sat. Highs Sat range from lower 60s from I-74 ne to the
upper 60s to around 70F in southeast IL. Dry conditions expected
to prevail from after midnight Thu night through Saturday with
next chance of showers and isolated thunderstorms returning
during Saturday night and Sunday.

LONG TERM...Saturday night through Wednesday

Extended models continue to advertise a blocky upper level pattern
across the country as a strong/large cutoff upper level low
deepens over the central plains by Sunday and slowly shifts east into
the mid MS river valley by Tue and remains near IL into the middle
of next week. Rather cloudy and unsettled weather pattern to occur
from Sun-Wed as temperatures gradually cool each day as upper
level low settles into the region. Have daily chances of showers
and isolated thunderstorms with best chances from Sunday night through
Tuesday. Large upper level trof/cutoff low will be slow to exit
the eastern states later next week, so temps will also be slow to
modify over IL.

07


&&

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

$$








000
FXUS63 KLOT 231737
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1237 PM CDT WED APR 23 2014

.DISCUSSION...
402 AM CDT

MAIN FORECAST CONCERNS THIS MORNING ARE WITH RELATIVELY LOW CHANCE
POPS FOR SHOWERS/SPRINKLES LATE THIS AFTERNOON/TONIGHT...THEN BETTER
POTENTIAL FOR RAIN AND A FEW THUNDERSTORMS THURSDAY/THURSDAY
EVENING  WITH APPROACHING SURFACE LOW PRESSURE WAVE PACIFIC COLD
FRONT. TEMPS LOOK MILD FOR FRIDAY BEHIND PACIFIC FRONT...BUT
COOLER/POTENTIALLY WET WEATHER STILL APPEARS TO DOMINATE EXTENDED
PERIODS OF FORECAST FROM THE WEEKEND INTO EARLY NEXT WEEK.

IN THE NEAR TERM...SURFACE HIGH PRESSURE RIDGE WAS OVER WISCONSIN
AND ILLINOIS EARLY THIS MORNING...PROVIDING COOL/DRY AND MAINLY
CLEAR CONDITIONS WITH LIGHT NORTH-NORTHEAST WINDS. A FEW SPOTS
DIPPING TO/BELOW THE FREEZING MARK...ESPECIALLY ACROSS THE FOX AND
ROCK RIVER VALLEY REGIONS THIS MORNING. FROST ADVISORY REMAINS IN
EFFECT THROUGH 7 AM CDT FOR MOST OF FAR NORTHERN/NORTHEAST IL AND
NORTHWEST IND. LOOKING AHEAD...EARLY MORNING GOES IMAGERY ALREADY
SHOWS HIGH CLOUDS INCREASING ACROSS THE PLAINS IN REGION OF WARM
ADVECTION IN ADVANCE OF WESTERN CONUS UPPER TROUGH. SHORT-TERM
MODELS REMAIN CONSISTENT IN BRINGING A WEAK MID-LEVEL SHORT WAVE
FROM THE CENTRAL PLAINS INTO OUR REGION THROUGH THIS EVENING...WITH
MID/UPPER LEVEL MOIST ADVECTION AND CONVERGENCE/FRONTOGENETIC
FORCING ALONG AN ELEVATED WARM FRONTAL ZONE EXPECTED TO PRODUCE SOME
HIGH BASED LIGHT SHOWERS/SPRINKLES INTO NORTH CENTRAL IL BY LATER
THIS AFTERNOON...AND ACROSS MUCH OF THE NORTH/NORTHWEST CWA TONIGHT
AS FORCING CONTINUES AHEAD OF A SECOND WEAK SHORT WAVE. HAVE
GENERALLY MAINTAINED HIGHEST POPS NORTHWEST OF I-88 CORRIDOR ACROSS
IL ALTHOUGH A FEW SHOWERS/SPRINKLES COULD OCCUR JUST ABOUT ANYWHERE
TONIGHT. PRECIP POTENTIAL INCREASES SIGNIFICANTLY THURSDAY AS MAIN
UPPER TROUGH APPROACHES FROM THE WEST...AND LOW LEVEL WINDS SHIFT
MORE SOUTHERLY AS A SURFACE LOW PRESSURE WAVE LIFTS FROM THE
MID-MISSOURI VALLEY NORTHEAST INTO WISCONSIN BY EVENING. NARROW
MOIST AXIS...COMBINED WITH INCREASING DEEP FORCING WITH APPROACH OF
SURFACE COLD FRONT AND LARGE SCALE ASCENT AHEAD OF UPPER TROUGH
SHOULD BE SUFFICIENT TO PRODUCE FAIRLY DECENT COVERAGE OF
RAIN/SHOWERS AND A FEW THUNDERSTORMS ESPECIALLY BY AFTERNOON.
OVERALL TREND OF GUIDANCE HAS BEEN TO SLOW ADVANCE OF COLD FRONT
SLIGHTLY...IN RESPONSE TO SLOWER PROGRESSION OF CLOSED LOW ALONG THE
CANADIAN BORDER. THUS HAVE HELD ONTO HIGHER POPS INTO THURSDAY
EVENING ESPECIALLY ACROSS THE EASTERN CWA...AS COLD FRONT COMPLETES
ITS TRANSIT.

TEMP WISE...EAST-NORTHEAST WINDS TODAY CONTINUE OUR COOLER THAN
NORMAL WEATHER PARTICULARLY ALONG LAKE MICHIGAN. HAVE GENERALLY GONE
WITH/SLIGHTLY ABOVE WARMER MAV NUMBERS WEST/SOUTHWEST WELL AWAY FROM
THE LAKE...THOUGH SHORE LOCATIONS WILL LIKELY NOT GET OUT OF THE 40S
AGAIN TODAY. COOL CONDITIONS CONTINUE TONIGHT ACROSS FAR NORTHEAST
IL WHERE CONTINUED EASTERLY COMPONENT AND LATER ARRIVAL OF THICKER
CLOUD COVER WILL ALLOW MINS TO DIP INTO THE MID-UPPER 30S. GRADUAL
VEERING OF LOW LEVEL WIND TO SOUTHEAST AND SLOW INCREASE IN LOW
LEVEL MOISTURE FROM THE SOUTH WILL HELP KEEP FAR SOUTHERN CWA ABOVE
40. MILDER SOUTHEAST FLOW THURSDAY WILL BE OFFSET BY CLOUDS/PRECIP
AND A CONTINUED SOUTHEAST WIND COMPONENT THROUGH THE MORNING...
THOUGH SHOULD SEE 60S ALL BUT IMMEDIATE NORTH SHORE AND LIKELY CLOSE
TO 70 SOUTH OF I-80. BREEZY/MILD BEHIND PACIFIC COLD FRONT THURSDAY
NIGHT INTO FRIDAY...WITH PERHAPS THE WARMEST TEMPS OF THIS FORECAST
PERIOD WITH GOOD MIXING AND WEST WINDS. LOW LEVEL THERMAL PROGS
SUPPORT GUIDANCE HIGHS FROM MID-UPPER 60S NORTH TO THE LOW 70S
SOUTH.

MODELS HAVE SHOWN SOME VARIATION/ADJUSTMENT WITH HANDLING OF LARGE
SCALE FLOW PATTERN AND RESULTING SYNOPTIC DETAILS FROM FRIDAY NIGHT
ONWARD. OVERALL...SLOWER CANADIAN BORDER SHORT WAVE PASSES NORTH OF
THE REGION FRIDAY...AND TRAILS A SECOND COLD FRONT SOUTH INTO THE
AREA BY EARLY EVENING. SOME POTENTIAL FOR SHOWERS ALONG THE FRONT
FRIDAY NIGHT...THOUGH GUIDANCE INCONSISTENT WITH TIMING/PLACEMENT OF
PRECIP AT THIS TIME AND FEEL SLIGHT CHANCE POPS SUFFICIENT AT THIS
TIME. COOL/DRY HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE LAKES
INTO SATURDAY AS UPPER TROUGH CONTINUES OFF TO THE EAST. HIGHLY
AMPLIFIED TROUGH MOVES ACROSS WESTERN CONUS...WITH CLOSED LOW
DEVELOPING AND EVENTUALLY MOVING OUT ACROSS THE PLAINS
SUNDAY-TUESDAY. GULF MOISTURE IS EVENTUALLY DRAWN NORTH ACROSS LOW
LEVEL BAROCLINIC ZONE ASSOCIATED WITH WEST-EAST STATIONARY FRONT TO
OUR SOUTH...WITH INCREASING POTENTIAL FOR RAIN FROM THE SOUTHWEST
DURING THE PERIOD. COOL/DRY EAST-NORTHEAST FLOW FROM THE RETREATING
HIGH TO OUR NORTHEAST SHOULD SLOW THINGS A BIT...AND KEEP POPS
GRADUATED FROM LOWER NORTHEAST TO HIGHER SOUTHWEST. MODEL
DIFFERENCES IN DETAILS/TIMING OF EVOLUTION OF UPPER AND SURFACE LOWS
LATE IN THE PERIOD DIMINISH CONFIDENCE IN FINER DETAILS AT THIS
TIME.

RATZER

&&

.AVIATION...

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

* CHANCE FOR SHOWERS THIS EVENING...THEN BETTER CHANCES FOR
  SHOWERS LATE THURSDAY AFTERNOON.
* WINDS VEERING TO SSE BY TOMORROW...THEN BECOMING VERY GUSTY LATE
  TOMORROW MORNING INTO THE AFTERNOON.

BMD

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

HIGH PRESSURE WILL CONTINUE TO SLOWLY SHIFT EAST AWAY FROM THE
TERMINALS THIS AFTERNOON WITH WINDS CONTINUING TO VEER FROM THE
NORTHEAST EARLY THIS AFTERNOON TO THE SOUTHEAST OVERNIGHT. SHOWERS
CURRENTLY OVER SOUTHERN MINNESOTA AND IOWA MAY SKIRT THE IL/WI STATE
LINE LATE THIS AFTERNOON THROUGH LATE EVENING BRINGING A SMALL CHANCE
FOR SHOWERS. COVERAGE IS STILL UNCERTAIN SO WILL MAINTAIN PROB30 FOR
THE CHICAGO TERMINALS AND VCSH FOR RFD. MEANWHILE...LOW PRESSURE
WILL DEVELOP OVER THE SOUTHERN PLAINS AND LIFT TO THE MID
MISSISSIPPI VALLEY BY MIDDAY THURSDAY. THE GRADIENT WILL TIGHTEN
AHEAD OF THE LOW WITH GUSTS GRADUALLY INCREASING INTO THE UPPER 20
KT RANGE OT OF THE SSE...AND CANNOT RULE OUT SOME GUSTS IN EXCESS OF
30 KT. SHOWERS AND PERHAPS A FEW THUNDERSTORMS WILL THEN OVERSPREAD
THE TERMINALS MID TO LATE THURSDAY AFTERNOON.

BMD


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

* MEDIUM CONFIDENCE IN WIND DIRECTION THIS AFTERNOON...MEDIUM-HIGH
  CONFIDENCE ON WIND DIRECTION/SPEED THURSDAY.
* LOW CONFIDENCE IN PRECIP AT TERMINALS THIS EVENING...MEDIUM
  CONFIDENCE IN PRECIP TIMING THURSDAY AFTERNOON.

BMD

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
310 AM CDT

AS THE LAKE REMAINS ON THE EASTERN FRINGE OF BUILDING HIGH
PRESSURE FROM THE WEST...NORTHWEST TO NORTH WINDS OF 10 TO 20 KT
REMAIN. ALTHOUGH...THIS HIGH WILL MOVE OVER THE LAKE TODAY WITH
SPEEDS DIMINISHING AND WITH WINDS LIKELY BECOMING MORE LIGHT AND
VARIABLE BY THE AFTERNOON. THEN AS THIS HIGH CONTINUES EAST
TONIGHT INTO THURSDAY AND A TROUGH OF LOW PRESSURE OVER THE
CENTRAL AND NORTHERN PLAINS MOVES EAST TOWARDS THE WESTERN GREAT
LAKES...EXPECT EAST TO SOUTHEAST WINDS TO INCREASE. SOUTHEAST
WINDS WILL FURTHER INCREASE ON THURSDAY BEFORE WINDS TURN TO THE
SOUTHWEST THURSDAY NIGHT INTO FRIDAY AS THIS LOW PROGRESSES
THROUGH THE REGION.

RODRIGUEZ

&&

.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 231600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1100 AM CDT WED APR 23 2014

.DISCUSSION...
402 AM CDT

MAIN FORECAST CONCERNS THIS MORNING ARE WITH RELATIVELY LOW CHANCE
POPS FOR SHOWERS/SPRINKLES LATE THIS AFTERNOON/TONIGHT...THEN BETTER
POTENTIAL FOR RAIN AND A FEW THUNDERSTORMS THURSDAY/THURSDAY
EVENING  WITH APPROACHING SURFACE LOW PRESSURE WAVE PACIFIC COLD
FRONT. TEMPS LOOK MILD FOR FRIDAY BEHIND PACIFIC FRONT...BUT
COOLER/POTENTIALLY WET WEATHER STILL APPEARS TO DOMINATE EXTENDED
PERIODS OF FORECAST FROM THE WEEKEND INTO EARLY NEXT WEEK.

IN THE NEAR TERM...SURFACE HIGH PRESSURE RIDGE WAS OVER WISCONSIN
AND ILLINOIS EARLY THIS MORNING...PROVIDING COOL/DRY AND MAINLY
CLEAR CONDITIONS WITH LIGHT NORTH-NORTHEAST WINDS. A FEW SPOTS
DIPPING TO/BELOW THE FREEZING MARK...ESPECIALLY ACROSS THE FOX AND
ROCK RIVER VALLEY REGIONS THIS MORNING. FROST ADVISORY REMAINS IN
EFFECT THROUGH 7 AM CDT FOR MOST OF FAR NORTHERN/NORTHEAST IL AND
NORTHWEST IND. LOOKING AHEAD...EARLY MORNING GOES IMAGERY ALREADY
SHOWS HIGH CLOUDS INCREASING ACROSS THE PLAINS IN REGION OF WARM
ADVECTION IN ADVANCE OF WESTERN CONUS UPPER TROUGH. SHORT-TERM
MODELS REMAIN CONSISTENT IN BRINGING A WEAK MID-LEVEL SHORT WAVE
FROM THE CENTRAL PLAINS INTO OUR REGION THROUGH THIS EVENING...WITH
MID/UPPER LEVEL MOIST ADVECTION AND CONVERGENCE/FRONTOGENETIC
FORCING ALONG AN ELEVATED WARM FRONTAL ZONE EXPECTED TO PRODUCE SOME
HIGH BASED LIGHT SHOWERS/SPRINKLES INTO NORTH CENTRAL IL BY LATER
THIS AFTERNOON...AND ACROSS MUCH OF THE NORTH/NORTHWEST CWA TONIGHT
AS FORCING CONTINUES AHEAD OF A SECOND WEAK SHORT WAVE. HAVE
GENERALLY MAINTAINED HIGHEST POPS NORTHWEST OF I-88 CORRIDOR ACROSS
IL ALTHOUGH A FEW SHOWERS/SPRINKLES COULD OCCUR JUST ABOUT ANYWHERE
TONIGHT. PRECIP POTENTIAL INCREASES SIGNIFICANTLY THURSDAY AS MAIN
UPPER TROUGH APPROACHES FROM THE WEST...AND LOW LEVEL WINDS SHIFT
MORE SOUTHERLY AS A SURFACE LOW PRESSURE WAVE LIFTS FROM THE
MID-MISSOURI VALLEY NORTHEAST INTO WISCONSIN BY EVENING. NARROW
MOIST AXIS...COMBINED WITH INCREASING DEEP FORCING WITH APPROACH OF
SURFACE COLD FRONT AND LARGE SCALE ASCENT AHEAD OF UPPER TROUGH
SHOULD BE SUFFICIENT TO PRODUCE FAIRLY DECENT COVERAGE OF
RAIN/SHOWERS AND A FEW THUNDERSTORMS ESPECIALLY BY AFTERNOON.
OVERALL TREND OF GUIDANCE HAS BEEN TO SLOW ADVANCE OF COLD FRONT
SLIGHTLY...IN RESPONSE TO SLOWER PROGRESSION OF CLOSED LOW ALONG THE
CANADIAN BORDER. THUS HAVE HELD ONTO HIGHER POPS INTO THURSDAY
EVENING ESPECIALLY ACROSS THE EASTERN CWA...AS COLD FRONT COMPLETES
ITS TRANSIT.

TEMP WISE...EAST-NORTHEAST WINDS TODAY CONTINUE OUR COOLER THAN
NORMAL WEATHER PARTICULARLY ALONG LAKE MICHIGAN. HAVE GENERALLY GONE
WITH/SLIGHTLY ABOVE WARMER MAV NUMBERS WEST/SOUTHWEST WELL AWAY FROM
THE LAKE...THOUGH SHORE LOCATIONS WILL LIKELY NOT GET OUT OF THE 40S
AGAIN TODAY. COOL CONDITIONS CONTINUE TONIGHT ACROSS FAR NORTHEAST
IL WHERE CONTINUED EASTERLY COMPONENT AND LATER ARRIVAL OF THICKER
CLOUD COVER WILL ALLOW MINS TO DIP INTO THE MID-UPPER 30S. GRADUAL
VEERING OF LOW LEVEL WIND TO SOUTHEAST AND SLOW INCREASE IN LOW
LEVEL MOISTURE FROM THE SOUTH WILL HELP KEEP FAR SOUTHERN CWA ABOVE
40. MILDER SOUTHEAST FLOW THURSDAY WILL BE OFFSET BY CLOUDS/PRECIP
AND A CONTINUED SOUTHEAST WIND COMPONENT THROUGH THE MORNING...
THOUGH SHOULD SEE 60S ALL BUT IMMEDIATE NORTH SHORE AND LIKELY CLOSE
TO 70 SOUTH OF I-80. BREEZY/MILD BEHIND PACIFIC COLD FRONT THURSDAY
NIGHT INTO FRIDAY...WITH PERHAPS THE WARMEST TEMPS OF THIS FORECAST
PERIOD WITH GOOD MIXING AND WEST WINDS. LOW LEVEL THERMAL PROGS
SUPPORT GUIDANCE HIGHS FROM MID-UPPER 60S NORTH TO THE LOW 70S
SOUTH.

MODELS HAVE SHOWN SOME VARIATION/ADJUSTMENT WITH HANDLING OF LARGE
SCALE FLOW PATTERN AND RESULTING SYNOPTIC DETAILS FROM FRIDAY NIGHT
ONWARD. OVERALL...SLOWER CANADIAN BORDER SHORT WAVE PASSES NORTH OF
THE REGION FRIDAY...AND TRAILS A SECOND COLD FRONT SOUTH INTO THE
AREA BY EARLY EVENING. SOME POTENTIAL FOR SHOWERS ALONG THE FRONT
FRIDAY NIGHT...THOUGH GUIDANCE INCONSISTENT WITH TIMING/PLACEMENT OF
PRECIP AT THIS TIME AND FEEL SLIGHT CHANCE POPS SUFFICIENT AT THIS
TIME. COOL/DRY HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE LAKES
INTO SATURDAY AS UPPER TROUGH CONTINUES OFF TO THE EAST. HIGHLY
AMPLIFIED TROUGH MOVES ACROSS WESTERN CONUS...WITH CLOSED LOW
DEVELOPING AND EVENTUALLY MOVING OUT ACROSS THE PLAINS
SUNDAY-TUESDAY. GULF MOISTURE IS EVENTUALLY DRAWN NORTH ACROSS LOW
LEVEL BAROCLINIC ZONE ASSOCIATED WITH WEST-EAST STATIONARY FRONT TO
OUR SOUTH...WITH INCREASING POTENTIAL FOR RAIN FROM THE SOUTHWEST
DURING THE PERIOD. COOL/DRY EAST-NORTHEAST FLOW FROM THE RETREATING
HIGH TO OUR NORTHEAST SHOULD SLOW THINGS A BIT...AND KEEP POPS
GRADUATED FROM LOWER NORTHEAST TO HIGHER SOUTHWEST. MODEL
DIFFERENCES IN DETAILS/TIMING OF EVOLUTION OF UPPER AND SURFACE LOWS
LATE IN THE PERIOD DIMINISH CONFIDENCE IN FINER DETAILS AT THIS
TIME.

RATZER

&&

.AVIATION...

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

* EAST-NORTHEAST WINDS WITH GUSTS TO AROUND 15 KT THROUGH
  EARLY/MID AFTERNOON.

* SCATTERED LIGHT SHOWERS POSSIBLE LATE TONIGHT.

RODRIGUEZ/DEUBELBEISS

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

WITH HIGH PRESSURE BUILDING OVERHEAD TODAY...EXPECT QUIET WEATHER
TO PERSIST. ALTHOUGH...THE TERMINALS REMAIN ON THE EASTERN FRINGE
OF THIS HIGH WITH SOME STRONGER WINDS STILL IN PLACE. NORTHEAST
WINDS WILL CONTINUE WITH GUSTS AROUND 15 KT LIKELY WITHIN THE NEXT
COUPLE OF HOURS. THESE GUSTS WILL LIKELY BE OBSERVED THROUGH MID
DAY...WITH A DIMINISHING TREND ANTICIPATED THIS AFTERNOON. WINDS
WILL TURN MORE EAST SOUTHEAST TONIGHT INTO THURSDAY WHILE
INCREASING AS THIS HIGH EXITS TO THE EAST AND A TROUGH OF LOW
PRESSURE APPROACHES FROM THE WEST. VFR CEILINGS WILL DEVELOP THIS
EVENING AND OVERNIGHT...WITH SHOWERS DEVELOPING MORE TOWARDS LATE
TONIGHT. ALTHOUGH...EXPECT THESE SHOWERS TO REMAIN RATHER LIGHT
WITH NO VIS RESTRICTION

RODRIGUEZ

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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CONDITIONS.

RODRIGUEZ/DEUBELBEISS

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
310 AM CDT

AS THE LAKE REMAINS ON THE EASTERN FRINGE OF BUILDING HIGH
PRESSURE FROM THE WEST...NORTHWEST TO NORTH WINDS OF 10 TO 20 KT
REMAIN. ALTHOUGH...THIS HIGH WILL MOVE OVER THE LAKE TODAY WITH
SPEEDS DIMINISHING AND WITH WINDS LIKELY BECOMING MORE LIGHT AND
VARIABLE BY THE AFTERNOON. THEN AS THIS HIGH CONTINUES EAST
TONIGHT INTO THURSDAY AND A TROUGH OF LOW PRESSURE OVER THE
CENTRAL AND NORTHERN PLAINS MOVES EAST TOWARDS THE WESTERN GREAT
LAKES...EXPECT EAST TO SOUTHEAST WINDS TO INCREASE. SOUTHEAST
WINDS WILL FURTHER INCREASE ON THURSDAY BEFORE WINDS TURN TO THE
SOUTHWEST THURSDAY NIGHT INTO FRIDAY AS THIS LOW PROGRESSES
THROUGH THE REGION.

RODRIGUEZ

&&

.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 231556
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1056 AM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 1050 AM CDT Wed Apr 23 2014
Although high pressure is dominating the region this morning, a
brief upper disturbance has produced some rain west of the
Mississippi River Valley. ILX 12z sounding...as well as DVNs
sounding has a lot of dry air below 700mb for the rainfall to work
through before any impact to the ILX area. Most 12z runs of
operational models still very dry... but not picking up on current
activity either. RAPP/RUC reflecting current conditions and
bringing in some version of precip for the afternoon as the rain
to the west drifts and erodes. Considering the amount of dry air
is in place...not a lot of confidence in widespread rainfall...but
will adjust the forecast for some sct sprinkles this evening.
Will continue to monitor...but quick update out momentarily.

HJS
&&

.AVIATION...
ISSUED 640 AM CDT Wed Apr 23 2014

VFR conditions are expected through this forecast period (thru
12z Thu). High pressure to our east will continue to push away
from our area today allowing an increase in mid and high level
clouds from the west. Based on current surface observations to
our west it appears the bases on the cigs will range from 8k-12k
feet late this morning into the evening hours. Forecast soundings
continue to suggest the air in the low levels will remain quite
dry but models indicate a weak wave pushing across the area later
this afternoon into the evening hours that may produce some light
showers or sprinkles. At this time, it appears coverage of any
precip will be too limited to include in TAFs for this forecast
cycle. Surface winds will be from the east to southeast today at 8
to 13 kts and then veer more into a southeast direction tonight at
10 to 15 kts.

Smith
&&

.PREV DISCUSSION...
ISSUED 330 AM CDT Wed Apr 23 2014

SHORT TERM...Today through Saturday

Will carry patchy frost over ne counties early this morning as
temps have cooled to 33F at Lacon and Bloomington while Danville
down to 34F. Temps in the upper 30s and lower 40s over rest of
central IL and upper 40s in southeast IL with Mount Carmel airport
at 50F. Band of cirrus clouds spreading se into central IL early
this morning should limit further cooling and think ne counties
will stay above freezing. Cool temps due to 1022 mb high pressure
over WI and ridging southward across IL.

High pressure ridge shifts east of IL today while warm air
advection regime sets up over IL through Thu morning with
increasing mid/high clouds. Isolated convection appears to stay north
and west of central IL today and most of tonight and just have
slight chances of showers over IL river valley overnight. Highs in
the low to mid 60s again today with coolest readings from I-74 ne.
Low tonight in the mid to upper 40s.

Strong storm system over the central Rockies to eject surface low
pressure from CO ne into WI Thu evening and pull a cold front east
across IL later Thu afternoon and evening. A band of showers and
scattered thunderstorms likely along and ahead of cold front Thu
afternoon and in eastern IL Thu evening. SPC has 5% risk of severe
storms in far southeast IL while slight risk is south of IL where
better instability present. Highs Thu range from mid 60s to lower
70s with coolest readings nw over IL river valley.

Mild Pacific air over central and southeast IL with highs in the
low to mid 70s and return of more sunshine. A 2nd cold front drops
se across the region Fri night and could bring a few light rain
showers to mainly ne areas along with cooler temps across the
region by Sat. Highs Sat range from lower 60s from I-74 ne to the
upper 60s to around 70F in southeast IL. Dry conditions expected
to prevail from after midnight Thu night through Saturday with
next chance of showers and isolated thunderstorms returning
during Saturday night and Sunday.

LONG TERM...Saturday night through Wednesday

Extended models continue to advertise a blocky upper level pattern
across the country as a strong/large cutoff upper level low
deepens over the central plains by Sunday and slowly shifts east into
the mid MS river valley by Tue and remains near IL into the middle
of next week. Rather cloudy and unsettled weather pattern to occur
from Sun-Wed as temperatures gradually cool each day as upper
level low settles into the region. Have daily chances of showers
and isolated thunderstorms with best chances from Sunday night through
Tuesday. Large upper level trof/cutoff low will be slow to exit
the eastern states later next week, so temps will also be slow to
modify over IL.

07

&&

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

$$








000
FXUS63 KLOT 231400
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
900 AM CDT WED APR 23 2014

.DISCUSSION...
402 AM CDT

MAIN FORECAST CONCERNS THIS MORNING ARE WITH RELATIVELY LOW CHANCE
POPS FOR SHOWERS/SPRINKLES LATE THIS AFTERNOON/TONIGHT...THEN BETTER
POTENTIAL FOR RAIN AND A FEW THUNDERSTORMS THURSDAY/THURSDAY
EVENING  WITH APPROACHING SURFACE LOW PRESSURE WAVE PACIFIC COLD
FRONT. TEMPS LOOK MILD FOR FRIDAY BEHIND PACIFIC FRONT...BUT
COOLER/POTENTIALLY WET WEATHER STILL APPEARS TO DOMINATE EXTENDED
PERIODS OF FORECAST FROM THE WEEKEND INTO EARLY NEXT WEEK.

IN THE NEAR TERM...SURFACE HIGH PRESSURE RIDGE WAS OVER WISCONSIN
AND ILLINOIS EARLY THIS MORNING...PROVIDING COOL/DRY AND MAINLY
CLEAR CONDITIONS WITH LIGHT NORTH-NORTHEAST WINDS. A FEW SPOTS
DIPPING TO/BELOW THE FREEZING MARK...ESPECIALLY ACROSS THE FOX AND
ROCK RIVER VALLEY REGIONS THIS MORNING. FROST ADVISORY REMAINS IN
EFFECT THROUGH 7 AM CDT FOR MOST OF FAR NORTHERN/NORTHEAST IL AND
NORTHWEST IND. LOOKING AHEAD...EARLY MORNING GOES IMAGERY ALREADY
SHOWS HIGH CLOUDS INCREASING ACROSS THE PLAINS IN REGION OF WARM
ADVECTION IN ADVANCE OF WESTERN CONUS UPPER TROUGH. SHORT-TERM
MODELS REMAIN CONSISTENT IN BRINGING A WEAK MID-LEVEL SHORT WAVE
FROM THE CENTRAL PLAINS INTO OUR REGION THROUGH THIS EVENING...WITH
MID/UPPER LEVEL MOIST ADVECTION AND CONVERGENCE/FRONTOGENETIC
FORCING ALONG AN ELEVATED WARM FRONTAL ZONE EXPECTED TO PRODUCE SOME
HIGH BASED LIGHT SHOWERS/SPRINKLES INTO NORTH CENTRAL IL BY LATER
THIS AFTERNOON...AND ACROSS MUCH OF THE NORTH/NORTHWEST CWA TONIGHT
AS FORCING CONTINUES AHEAD OF A SECOND WEAK SHORT WAVE. HAVE
GENERALLY MAINTAINED HIGHEST POPS NORTHWEST OF I-88 CORRIDOR ACROSS
IL ALTHOUGH A FEW SHOWERS/SPRINKLES COULD OCCUR JUST ABOUT ANYWHERE
TONIGHT. PRECIP POTENTIAL INCREASES SIGNIFICANTLY THURSDAY AS MAIN
UPPER TROUGH APPROACHES FROM THE WEST...AND LOW LEVEL WINDS SHIFT
MORE SOUTHERLY AS A SURFACE LOW PRESSURE WAVE LIFTS FROM THE
MID-MISSOURI VALLEY NORTHEAST INTO WISCONSIN BY EVENING. NARROW
MOIST AXIS...COMBINED WITH INCREASING DEEP FORCING WITH APPROACH OF
SURFACE COLD FRONT AND LARGE SCALE ASCENT AHEAD OF UPPER TROUGH
SHOULD BE SUFFICIENT TO PRODUCE FAIRLY DECENT COVERAGE OF
RAIN/SHOWERS AND A FEW THUNDERSTORMS ESPECIALLY BY AFTERNOON.
OVERALL TREND OF GUIDANCE HAS BEEN TO SLOW ADVANCE OF COLD FRONT
SLIGHTLY...IN RESPONSE TO SLOWER PROGRESSION OF CLOSED LOW ALONG THE
CANADIAN BORDER. THUS HAVE HELD ONTO HIGHER POPS INTO THURSDAY
EVENING ESPECIALLY ACROSS THE EASTERN CWA...AS COLD FRONT COMPLETES
ITS TRANSIT.

TEMP WISE...EAST-NORTHEAST WINDS TODAY CONTINUE OUR COOLER THAN
NORMAL WEATHER PARTICULARLY ALONG LAKE MICHIGAN. HAVE GENERALLY GONE
WITH/SLIGHTLY ABOVE WARMER MAV NUMBERS WEST/SOUTHWEST WELL AWAY FROM
THE LAKE...THOUGH SHORE LOCATIONS WILL LIKELY NOT GET OUT OF THE 40S
AGAIN TODAY. COOL CONDITIONS CONTINUE TONIGHT ACROSS FAR NORTHEAST
IL WHERE CONTINUED EASTERLY COMPONENT AND LATER ARRIVAL OF THICKER
CLOUD COVER WILL ALLOW MINS TO DIP INTO THE MID-UPPER 30S. GRADUAL
VEERING OF LOW LEVEL WIND TO SOUTHEAST AND SLOW INCREASE IN LOW
LEVEL MOISTURE FROM THE SOUTH WILL HELP KEEP FAR SOUTHERN CWA ABOVE
40. MILDER SOUTHEAST FLOW THURSDAY WILL BE OFFSET BY CLOUDS/PRECIP
AND A CONTINUED SOUTHEAST WIND COMPONENT THROUGH THE MORNING...
THOUGH SHOULD SEE 60S ALL BUT IMMEDIATE NORTH SHORE AND LIKELY CLOSE
TO 70 SOUTH OF I-80. BREEZY/MILD BEHIND PACIFIC COLD FRONT THURSDAY
NIGHT INTO FRIDAY...WITH PERHAPS THE WARMEST TEMPS OF THIS FORECAST
PERIOD WITH GOOD MIXING AND WEST WINDS. LOW LEVEL THERMAL PROGS
SUPPORT GUIDANCE HIGHS FROM MID-UPPER 60S NORTH TO THE LOW 70S
SOUTH.

MODELS HAVE SHOWN SOME VARIATION/ADJUSTMENT WITH HANDLING OF LARGE
SCALE FLOW PATTERN AND RESULTING SYNOPTIC DETAILS FROM FRIDAY NIGHT
ONWARD. OVERALL...SLOWER CANADIAN BORDER SHORT WAVE PASSES NORTH OF
THE REGION FRIDAY...AND TRAILS A SECOND COLD FRONT SOUTH INTO THE
AREA BY EARLY EVENING. SOME POTENTIAL FOR SHOWERS ALONG THE FRONT
FRIDAY NIGHT...THOUGH GUIDANCE INCONSISTENT WITH TIMING/PLACEMENT OF
PRECIP AT THIS TIME AND FEEL SLIGHT CHANCE POPS SUFFICIENT AT THIS
TIME. COOL/DRY HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE LAKES
INTO SATURDAY AS UPPER TROUGH CONTINUES OFF TO THE EAST. HIGHLY
AMPLIFIED TROUGH MOVES ACROSS WESTERN CONUS...WITH CLOSED LOW
DEVELOPING AND EVENTUALLY MOVING OUT ACROSS THE PLAINS
SUNDAY-TUESDAY. GULF MOISTURE IS EVENTUALLY DRAWN NORTH ACROSS LOW
LEVEL BAROCLINIC ZONE ASSOCIATED WITH WEST-EAST STATIONARY FRONT TO
OUR SOUTH...WITH INCREASING POTENTIAL FOR RAIN FROM THE SOUTHWEST
DURING THE PERIOD. COOL/DRY EAST-NORTHEAST FLOW FROM THE RETREATING
HIGH TO OUR NORTHEAST SHOULD SLOW THINGS A BIT...AND KEEP POPS
GRADUATED FROM LOWER NORTHEAST TO HIGHER SOUTHWEST. MODEL
DIFFERENCES IN DETAILS/TIMING OF EVOLUTION OF UPPER AND SURFACE LOWS
LATE IN THE PERIOD DIMINISH CONFIDENCE IN FINER DETAILS AT THIS
TIME.

RATZER

&&

.AVIATION...

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

* NORTHEAST WINDS WITH GUSTS TO AROUND 15 KT TODAY.

* SCATTERED LIGHT SHOWERS POSSIBLE LATE TONIGHT.

RODRIGUEZ/DEUBELBEISS

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

WITH HIGH PRESSURE BUILDING OVERHEAD TODAY...EXPECT QUIET WEATHER
TO PERSIST. ALTHOUGH...THE TERMINALS REMAIN ON THE EASTERN FRINGE
OF THIS HIGH WITH SOME STRONGER WINDS STILL IN PLACE. NORTHEAST
WINDS WILL CONTINUE WITH GUSTS AROUND 15 KT LIKELY WITHIN THE NEXT
COUPLE OF HOURS. THESE GUSTS WILL LIKELY BE OBSERVED THROUGH MID
DAY...WITH A DIMINISHING TREND ANTICIPATED THIS AFTERNOON. WINDS
WILL TURN MORE EAST SOUTHEAST TONIGHT INTO THURSDAY WHILE
INCREASING AS THIS HIGH EXITS TO THE EAST AND A TROUGH OF LOW
PRESSURE APPROACHES FROM THE WEST. VFR CEILINGS WILL DEVELOP THIS
EVENING AND OVERNIGHT...WITH SHOWERS DEVELOPING MORE TOWARDS LATE
TONIGHT. ALTHOUGH...EXPECT THESE SHOWERS TO REMAIN RATHER LIGHT
WITH NO VIS RESTRICTION

RODRIGUEZ

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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CONDITIONS.

RODRIGUEZ/DEUBELBEISS

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
310 AM CDT

AS THE LAKE REMAINS ON THE EASTERN FRINGE OF BUILDING HIGH
PRESSURE FROM THE WEST...NORTHWEST TO NORTH WINDS OF 10 TO 20 KT
REMAIN. ALTHOUGH...THIS HIGH WILL MOVE OVER THE LAKE TODAY WITH
SPEEDS DIMINISHING AND WITH WINDS LIKELY BECOMING MORE LIGHT AND
VARIABLE BY THE AFTERNOON. THEN AS THIS HIGH CONTINUES EAST
TONIGHT INTO THURSDAY AND A TROUGH OF LOW PRESSURE OVER THE
CENTRAL AND NORTHERN PLAINS MOVES EAST TOWARDS THE WESTERN GREAT
LAKES...EXPECT EAST TO SOUTHEAST WINDS TO INCREASE. SOUTHEAST
WINDS WILL FURTHER INCREASE ON THURSDAY BEFORE WINDS TURN TO THE
SOUTHWEST THURSDAY NIGHT INTO FRIDAY AS THIS LOW PROGRESSES
THROUGH THE REGION.

RODRIGUEZ

&&

.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 231145
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
645 AM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 330 AM CDT Wed Apr 23 2014

SHORT TERM...Today through Saturday

Will carry patchy frost over ne counties early this morning as
temps have cooled to 33F at Lacon and Bloomington while Danville
down to 34F. Temps in the upper 30s and lower 40s over rest of
central IL and upper 40s in southeast IL with Mount Carmel airport
at 50F. Band of cirrus clouds spreading se into central IL early
this morning should limit further cooling and think ne counties
will stay above freezing. Cool temps due to 1022 mb high pressure
over WI and ridging southward across IL.

High pressure ridge shifts east of IL today while warm air
advection regime sets up over IL through Thu morning with
increasing mid/high clouds. Isolated convection appears to stay north
and west of central IL today and most of tonight and just have
slight chances of showers over IL river valley overnight. Highs in
the low to mid 60s again today with coolest readings from I-74 ne.
Low tonight in the mid to upper 40s.

Strong storm system over the central Rockies to eject surface low
pressure from CO ne into WI Thu evening and pull a cold front east
across IL later Thu afternoon and evening. A band of showers and
scattered thunderstorms likely along and ahead of cold front Thu
afternoon and in eastern IL Thu evening. SPC has 5% risk of severe
storms in far southeast IL while slight risk is south of IL where
better instability present. Highs Thu range from mid 60s to lower
70s with coolest readings nw over IL river valley.

Mild Pacific air over central and southeast IL with highs in the
low to mid 70s and return of more sunshine. A 2nd cold front drops
se across the region Fri night and could bring a few light rain
showers to mainly ne areas along with cooler temps across the
region by Sat. Highs Sat range from lower 60s from I-74 ne to the
upper 60s to around 70F in southeast IL. Dry conditions expected
to prevail from after midnight Thu night through Saturday with
next chance of showers and iosolated thunderstorms returning
during Saturday night and Sunday.

LONG TERM...Saturday night through Wednesday

Extended models continue to advertise a blocky upper level pattern
across the country as a strong/large cutoff upper level low
deepens over the central plains by Sunday and slowly shifts east into
the mid MS river valley by Tue and remains near IL into the middle
of next week. Rather cloudy and unsettled weather pattern to occur
from Sun-Wed as temperatures gradually cool each day as upper
level low settles into the region. Have daily chances of showers
and isolated thunderstorms with best chances from Sunday night through
Tuesday. Large upper level trof/cutoff low will be slow to exit
the eastern states later next week, so temps will also be slow to
modify over IL.

07

&&

.AVIATION...
ISSUED 640 AM CDT Wed Apr 23 2014

VFR conditions are expected through this forecast period (thru
12z Thu). High pressure to our east will continue to push away
from our area today allowing an increase in mid and high level
clouds from the west. Based on current surface observations to
our west it appears the bases on the cigs will range from 8k-12k
feet late this morning into the evening hours. Forecast soundings
continue to suggest the air in the low levels will remain quite
dry but models indicate a weak wave pushing acorss the area later
this afternoon into the evening hours that may produce some light
showers or sprinkles. At this time, it appears coverage of any
precip will be too limited to include in TAFs for this forecast
cycle. Surface winds will be from the east to southeast today at 8
to 13 kts and then veer more into a southeast direction tonight at
10 to 15 kts.

Smith
&&

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

$$





000
FXUS63 KLOT 231132
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
632 AM CDT WED APR 23 2014

.DISCUSSION...
402 AM CDT

MAIN FORECAST CONCERNS THIS MORNING ARE WITH RELATIVELY LOW CHANCE
POPS FOR SHOWERS/SPRINKLES LATE THIS AFTERNOON/TONIGHT...THEN BETTER
POTENTIAL FOR RAIN AND A FEW THUNDERSTORMS THURSDAY/THURSDAY
EVENING  WITH APPROACHING SURFACE LOW PRESSURE WAVE PACIFIC COLD
FRONT. TEMPS LOOK MILD FOR FRIDAY BEHIND PACIFIC FRONT...BUT
COOLER/POTENTIALLY WET WEATHER STILL APPEARS TO DOMINATE EXTENDED
PERIODS OF FORECAST FROM THE WEEKEND INTO EARLY NEXT WEEK.

IN THE NEAR TERM...SURFACE HIGH PRESSURE RIDGE WAS OVER WISCONSIN
AND ILLINOIS EARLY THIS MORNING...PROVIDING COOL/DRY AND MAINLY
CLEAR CONDITIONS WITH LIGHT NORTH-NORTHEAST WINDS. A FEW SPOTS
DIPPING TO/BELOW THE FREEZING MARK...ESPECIALLY ACROSS THE FOX AND
ROCK RIVER VALLEY REGIONS THIS MORNING. FROST ADVISORY REMAINS IN
EFFECT THROUGH 7 AM CDT FOR MOST OF FAR NORTHERN/NORTHEAST IL AND
NORTHWEST IND. LOOKING AHEAD...EARLY MORNING GOES IMAGERY ALREADY
SHOWS HIGH CLOUDS INCREASING ACROSS THE PLAINS IN REGION OF WARM
ADVECTION IN ADVANCE OF WESTERN CONUS UPPER TROUGH. SHORT-TERM
MODELS REMAIN CONSISTENT IN BRINGING A WEAK MID-LEVEL SHORT WAVE
FROM THE CENTRAL PLAINS INTO OUR REGION THROUGH THIS EVENING...WITH
MID/UPPER LEVEL MOIST ADVECTION AND CONVERGENCE/FRONTOGENETIC
FORCING ALONG AN ELEVATED WARM FRONTAL ZONE EXPECTED TO PRODUCE SOME
HIGH BASED LIGHT SHOWERS/SPRINKLES INTO NORTH CENTRAL IL BY LATER
THIS AFTERNOON...AND ACROSS MUCH OF THE NORTH/NORTHWEST CWA TONIGHT
AS FORCING CONTINUES AHEAD OF A SECOND WEAK SHORT WAVE. HAVE
GENERALLY MAINTAINED HIGHEST POPS NORTHWEST OF I-88 CORRIDOR ACROSS
IL ALTHOUGH A FEW SHOWERS/SPRINKLES COULD OCCUR JUST ABOUT ANYWHERE
TONIGHT. PRECIP POTENTIAL INCREASES SIGNIFICANTLY THURSDAY AS MAIN
UPPER TROUGH APPROACHES FROM THE WEST...AND LOW LEVEL WINDS SHIFT
MORE SOUTHERLY AS A SURFACE LOW PRESSURE WAVE LIFTS FROM THE
MID-MISSOURI VALLEY NORTHEAST INTO WISCONSIN BY EVENING. NARROW
MOIST AXIS...COMBINED WITH INCREASING DEEP FORCING WITH APPROACH OF
SURFACE COLD FRONT AND LARGE SCALE ASCENT AHEAD OF UPPER TROUGH
SHOULD BE SUFFICIENT TO PRODUCE FAIRLY DECENT COVERAGE OF
RAIN/SHOWERS AND A FEW THUNDERSTORMS ESPECIALLY BY AFTERNOON.
OVERALL TREND OF GUIDANCE HAS BEEN TO SLOW ADVANCE OF COLD FRONT
SLIGHTLY...IN RESPONSE TO SLOWER PROGRESSION OF CLOSED LOW ALONG THE
CANADIAN BORDER. THUS HAVE HELD ONTO HIGHER POPS INTO THURSDAY
EVENING ESPECIALLY ACROSS THE EASTERN CWA...AS COLD FRONT COMPLETES
ITS TRANSIT.

TEMP WISE...EAST-NORTHEAST WINDS TODAY CONTINUE OUR COOLER THAN
NORMAL WEATHER PARTICULARLY ALONG LAKE MICHIGAN. HAVE GENERALLY GONE
WITH/SLIGHTLY ABOVE WARMER MAV NUMBERS WEST/SOUTHWEST WELL AWAY FROM
THE LAKE...THOUGH SHORE LOCATIONS WILL LIKELY NOT GET OUT OF THE 40S
AGAIN TODAY. COOL CONDITIONS CONTINUE TONIGHT ACROSS FAR NORTHEAST
IL WHERE CONTINUED EASTERLY COMPONENT AND LATER ARRIVAL OF THICKER
CLOUD COVER WILL ALLOW MINS TO DIP INTO THE MID-UPPER 30S. GRADUAL
VEERING OF LOW LEVEL WIND TO SOUTHEAST AND SLOW INCREASE IN LOW
LEVEL MOISTURE FROM THE SOUTH WILL HELP KEEP FAR SOUTHERN CWA ABOVE
40. MILDER SOUTHEAST FLOW THURSDAY WILL BE OFFSET BY CLOUDS/PRECIP
AND A CONTINUED SOUTHEAST WIND COMPONENT THROUGH THE MORNING...
THOUGH SHOULD SEE 60S ALL BUT IMMEDIATE NORTH SHORE AND LIKELY CLOSE
TO 70 SOUTH OF I-80. BREEZY/MILD BEHIND PACIFIC COLD FRONT THURSDAY
NIGHT INTO FRIDAY...WITH PERHAPS THE WARMEST TEMPS OF THIS FORECAST
PERIOD WITH GOOD MIXING AND WEST WINDS. LOW LEVEL THERMAL PROGS
SUPPORT GUIDANCE HIGHS FROM MID-UPPER 60S NORTH TO THE LOW 70S
SOUTH.

MODELS HAVE SHOWN SOME VARIATION/ADJUSTMENT WITH HANDLING OF LARGE
SCALE FLOW PATTERN AND RESULTING SYNOPTIC DETAILS FROM FRIDAY NIGHT
ONWARD. OVERALL...SLOWER CANADIAN BORDER SHORT WAVE PASSES NORTH OF
THE REGION FRIDAY...AND TRAILS A SECOND COLD FRONT SOUTH INTO THE
AREA BY EARLY EVENING. SOME POTENTIAL FOR SHOWERS ALONG THE FRONT
FRIDAY NIGHT...THOUGH GUIDANCE INCONSISTENT WITH TIMING/PLACEMENT OF
PRECIP AT THIS TIME AND FEEL SLIGHT CHANCE POPS SUFFICIENT AT THIS
TIME. COOL/DRY HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE LAKES
INTO SATURDAY AS UPPER TROUGH CONTINUES OFF TO THE EAST. HIGHLY
AMPLIFIED TROUGH MOVES ACROSS WESTERN CONUS...WITH CLOSED LOW
DEVELOPING AND EVENTUALLY MOVING OUT ACROSS THE PLAINS
SUNDAY-TUESDAY. GULF MOISTURE IS EVENTUALLY DRAWN NORTH ACROSS LOW
LEVEL BAROCLINIC ZONE ASSOCIATED WITH WEST-EAST STATIONARY FRONT TO
OUR SOUTH...WITH INCREASING POTENTIAL FOR RAIN FROM THE SOUTHWEST
DURING THE PERIOD. COOL/DRY EAST-NORTHEAST FLOW FROM THE RETREATING
HIGH TO OUR NORTHEAST SHOULD SLOW THINGS A BIT...AND KEEP POPS
GRADUATED FROM LOWER NORTHEAST TO HIGHER SOUTHWEST. MODEL
DIFFERENCES IN DETAILS/TIMING OF EVOLUTION OF UPPER AND SURFACE LOWS
LATE IN THE PERIOD DIMINISH CONFIDENCE IN FINER DETAILS AT THIS
TIME.

RATZER

&&

.AVIATION...

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

* NORTHEAST WINDS WITH GUSTS TO AROUND 15 KT TODAY.

* SCATTERED LIGHT SHOWERS POSSIBLE LATE TONIGHT.

RODRIGUEZ

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

WITH HIGH PRESSURE BUILDING OVERHEAD TODAY...EXPECT QUIET WEATHER
TO PERSIST. ALTHOUGH...THE TERMINALS REMAIN ON THE EASTERN FRINGE
OF THIS HIGH WITH SOME STRONGER WINDS STILL IN PLACE. NORTHEAST
WINDS WILL CONTINUE WITH GUSTS AROUND 15 KT LIKELY WITHIN THE NEXT
COUPLE OF HOURS. THESE GUSTS WILL LIKELY BE OBSERVED THROUGH MID
DAY...WITH A DIMINISHING TREND ANTICIPATED THIS AFTERNOON. WINDS
WILL TURN MORE EAST SOUTHEAST TONIGHT INTO THURSDAY WHILE
INCREASING AS THIS HIGH EXITS TO THE EAST AND A TROUGH OF LOW
PRESSURE APPROACHES FROM THE WEST. VFR CEILINGS WILL DEVELOP THIS
EVENING AND OVERNIGHT...WITH SHOWERS DEVELOPING MORE TOWARDS LATE
TONIGHT. ALTHOUGH...EXPECT THESE SHOWERS TO REMAIN RATHER LIGHT
WITH NO VIS RESTRICTION

RODRIGUEZ


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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CONDITIONS.

RODRIGUEZ

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

THURSDAY NIGHT...SHRA/MVFR LIKELY WITH A CHANCE OF TSRA.

FRIDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SATURDAY...SLIGHT CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

TUESDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
310 AM CDT

AS THE LAKE REMAINS ON THE EASTERN FRINGE OF BUILDING HIGH
PRESSURE FROM THE WEST...NORTHWEST TO NORTH WINDS OF 10 TO 20 KT
REMAIN. ALTHOUGH...THIS HIGH WILL MOVE OVER THE LAKE TODAY WITH
SPEEDS DIMINISHING AND WITH WINDS LIKELY BECOMING MORE LIGHT AND
VARIABLE BY THE AFTERNOON. THEN AS THIS HIGH CONTINUES EAST
TONIGHT INTO THURSDAY AND A TROUGH OF LOW PRESSURE OVER THE
CENTRAL AND NORTHERN PLAINS MOVES EAST TOWARDS THE WESTERN GREAT
LAKES...EXPECT EAST TO SOUTHEAST WINDS TO INCREASE. SOUTHEAST
WINDS WILL FURTHER INCREASE ON THURSDAY BEFORE WINDS TURN TO THE
SOUTHWEST THURSDAY NIGHT INTO FRIDAY AS THIS LOW PROGRESSES
THROUGH THE REGION.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023 UNTIL 7 AM
     WEDNESDAY.

IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 7 AM
     WEDNESDAY.

LM...NONE.
&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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000
FXUS63 KLOT 230903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
403 AM CDT WED APR 23 2014

.DISCUSSION...
402 AM CDT

MAIN FORECAST CONCERNS THIS MORNING ARE WITH RELATIVELY LOW CHANCE
POPS FOR SHOWERS/SPRINKLES LATE THIS AFTERNOON/TONIGHT...THEN BETTER
POTENTIAL FOR RAIN AND A FEW THUNDERSTORMS THURSDAY/THURSDAY
EVENING  WITH APPROACHING SURFACE LOW PRESSURE WAVE PACIFIC COLD
FRONT. TEMPS LOOK MILD FOR FRIDAY BEHIND PACIFIC FRONT...BUT
COOLER/POTENTIALLY WET WEATHER STILL APPEARS TO DOMINATE EXTENDED
PERIODS OF FORECAST FROM THE WEEKEND INTO EARLY NEXT WEEK.

IN THE NEAR TERM...SURFACE HIGH PRESSURE RIDGE WAS OVER WISCONSIN
AND ILLINOIS EARLY THIS MORNING...PROVIDING COOL/DRY AND MAINLY
CLEAR CONDITIONS WITH LIGHT NORTH-NORTHEAST WINDS. A FEW SPOTS
DIPPING TO/BELOW THE FREEZING MARK...ESPECIALLY ACROSS THE FOX AND
ROCK RIVER VALLEY REGIONS THIS MORNING. FROST ADVISORY REMAINS IN
EFFECT THROUGH 7 AM CDT FOR MOST OF FAR NORTHERN/NORTHEAST IL AND
NORTHWEST IND. LOOKING AHEAD...EARLY MORNING GOES IMAGERY ALREADY
SHOWS HIGH CLOUDS INCREASING ACROSS THE PLAINS IN REGION OF WARM
ADVECTION IN ADVANCE OF WESTERN CONUS UPPER TROUGH. SHORT-TERM
MODELS REMAIN CONSISTENT IN BRINGING A WEAK MID-LEVEL SHORT WAVE
FROM THE CENTRAL PLAINS INTO OUR REGION THROUGH THIS EVENING...WITH
MID/UPPER LEVEL MOIST ADVECTION AND CONVERGENCE/FRONTOGENETIC
FORCING ALONG AN ELEVATED WARM FRONTAL ZONE EXPECTED TO PRODUCE SOME
HIGH BASED LIGHT SHOWERS/SPRINKLES INTO NORTH CENTRAL IL BY LATER
THIS AFTERNOON...AND ACROSS MUCH OF THE NORTH/NORTHWEST CWA TONIGHT
AS FORCING CONTINUES AHEAD OF A SECOND WEAK SHORT WAVE. HAVE
GENERALLY MAINTAINED HIGHEST POPS NORTHWEST OF I-88 CORRIDOR ACROSS
IL ALTHOUGH A FEW SHOWERS/SPRINKLES COULD OCCUR JUST ABOUT ANYWHERE
TONIGHT. PRECIP POTENTIAL INCREASES SIGNIFICANTLY THURSDAY AS MAIN
UPPER TROUGH APPROACHES FROM THE WEST...AND LOW LEVEL WINDS SHIFT
MORE SOUTHERLY AS A SURFACE LOW PRESSURE WAVE LIFTS FROM THE
MID-MISSOURI VALLEY NORTHEAST INTO WISCONSIN BY EVENING. NARROW
MOIST AXIS...COMBINED WITH INCREASING DEEP FORCING WITH APPROACH OF
SURFACE COLD FRONT AND LARGE SCALE ASCENT AHEAD OF UPPER TROUGH
SHOULD BE SUFFICIENT TO PRODUCE FAIRLY DECENT COVERAGE OF
RAIN/SHOWERS AND A FEW THUNDERSTORMS ESPECIALLY BY AFTERNOON.
OVERALL TREND OF GUIDANCE HAS BEEN TO SLOW ADVANCE OF COLD FRONT
SLIGHTLY...IN RESPONSE TO SLOWER PROGRESSION OF CLOSED LOW ALONG THE
CANADIAN BORDER. THUS HAVE HELD ONTO HIGHER POPS INTO THURSDAY
EVENING ESPECIALLY ACROSS THE EASTERN CWA...AS COLD FRONT COMPLETES
ITS TRANSIT.

TEMP WISE...EAST-NORTHEAST WINDS TODAY CONTINUE OUR COOLER THAN
NORMAL WEATHER PARTICULARLY ALONG LAKE MICHIGAN. HAVE GENERALLY GONE
WITH/SLIGHTLY ABOVE WARMER MAV NUMBERS WEST/SOUTHWEST WELL AWAY FROM
THE LAKE...THOUGH SHORE LOCATIONS WILL LIKELY NOT GET OUT OF THE 40S
AGAIN TODAY. COOL CONDITIONS CONTINUE TONIGHT ACROSS FAR NORTHEAST
IL WHERE CONTINUED EASTERLY COMPONENT AND LATER ARRIVAL OF THICKER
CLOUD COVER WILL ALLOW MINS TO DIP INTO THE MID-UPPER 30S. GRADUAL
VEERING OF LOW LEVEL WIND TO SOUTHEAST AND SLOW INCREASE IN LOW
LEVEL MOISTURE FROM THE SOUTH WILL HELP KEEP FAR SOUTHERN CWA ABOVE
40. MILDER SOUTHEAST FLOW THURSDAY WILL BE OFFSET BY CLOUDS/PRECIP
AND A CONTINUED SOUTHEAST WIND COMPONENT THROUGH THE MORNING...
THOUGH SHOULD SEE 60S ALL BUT IMMEDIATE NORTH SHORE AND LIKELY CLOSE
TO 70 SOUTH OF I-80. BREEZY/MILD BEHIND PACIFIC COLD FRONT THURSDAY
NIGHT INTO FRIDAY...WITH PERHAPS THE WARMEST TEMPS OF THIS FORECAST
PERIOD WITH GOOD MIXING AND WEST WINDS. LOW LEVEL THERMAL PROGS
SUPPORT GUIDANCE HIGHS FROM MID-UPPER 60S NORTH TO THE LOW 70S
SOUTH.

MODELS HAVE SHOWN SOME VARIATION/ADJUSTMENT WITH HANDLING OF LARGE
SCALE FLOW PATTERN AND RESULTING SYNOPTIC DETAILS FROM FRIDAY NIGHT
ONWARD. OVERALL...SLOWER CANADIAN BORDER SHORT WAVE PASSES NORTH OF
THE REGION FRIDAY...AND TRAILS A SECOND COLD FRONT SOUTH INTO THE
AREA BY EARLY EVENING. SOME POTENTIAL FOR SHOWERS ALONG THE FRONT
FRIDAY NIGHT...THOUGH GUIDANCE INCONSISTENT WITH TIMING/PLACEMENT OF
PRECIP AT THIS TIME AND FEEL SLIGHT CHANCE POPS SUFFICIENT AT THIS
TIME. COOL/DRY HIGH PRESSURE BUILDS ACROSS ONTARIO AND THE LAKES
INTO SATURDAY AS UPPER TROUGH CONTINUES OFF TO THE EAST. HIGHLY
AMPLIFIED TROUGH MOVES ACROSS WESTERN CONUS...WITH CLOSED LOW
DEVELOPING AND EVENTUALLY MOVING OUT ACROSS THE PLAINS
SUNDAY-TUESDAY. GULF MOISTURE IS EVENTUALLY DRAWN NORTH ACROSS LOW
LEVEL BAROCLINIC ZONE ASSOCIATED WITH WEST-EAST STATIONARY FRONT TO
OUR SOUTH...WITH INCREASING POTENTIAL FOR RAIN FROM THE SOUTHWEST
DURING THE PERIOD. COOL/DRY EAST-NORTHEAST FLOW FROM THE RETREATING
HIGH TO OUR NORTHEAST SHOULD SLOW THINGS A BIT...AND KEEP POPS
GRADUATED FROM LOWER NORTHEAST TO HIGHER SOUTHWEST. MODEL
DIFFERENCES IN DETAILS/TIMING OF EVOLUTION OF UPPER AND SURFACE LOWS
LATE IN THE PERIOD DIMINISH CONFIDENCE IN FINER DETAILS AT THIS
TIME.

RATZER

&&

.AVIATION...

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

* SCATTERED LIGHT SHOWERS POSSIBLE TOWARDS THE END OF THE FORECAST
  PERIOD.

RODRIGUEZ

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

LIGHT NORTHEAST WINDS WITH CLEAR SKIES IN PLACE...AND EXPECT WINDS
TO REMAIN NORTHEAST THROUGH MOST OF TODAY BEFORE TURNING MORE
EASTERLY LATER THIS EVENING AS VFR CEILINGS MOVE OVERHEAD.
SCATTERED LIGHT SHOWER DEVELOPMENT WILL MOVE ACROSS THE RFD AREA
LATE THIS AFTERNOON AND EARLY EVENING WITH THE REMAINING TERMINALS
LIKELY NOT OBSERVING THIS DEVELOPMENT UNTIL LATE IN THE EVENING.
ALTHOUGH...THESE SHOWERS WILL REMAIN RATHER LIGHT WITH NO VIS
RESTRICTION EXPECTED AT THIS TIME.

RODRIGUEZ

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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CONDITIONS.

RODRIGUEZ

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

THURSDAY...SHRA/MVFR LIKELY IN EVENING WITH A CHANCE OF TSRA.

FRIDAY AND SATURDAY...GENERALLY VFR.

SUNDAY...CHANCE OF SHRA/TSRA...MAINLY AT NIGHT.

MONDAY...SHRA/TSRA POSSIBLE.

IZZI

&&

.MARINE...
310 AM CDT

AS THE LAKE REMAINS ON THE EASTERN FRINGE OF BUILDING HIGH
PRESSURE FROM THE WEST...NORTHWEST TO NORTH WINDS OF 10 TO 20 KT
REMAIN. ALTHOUGH...THIS HIGH WILL MOVE OVER THE LAKE TODAY WITH
SPEEDS DIMINISHING AND WITH WINDS LIKELY BECOMING MORE LIGHT AND
VARIABLE BY THE AFTERNOON. THEN AS THIS HIGH CONTINUES EAST
TONIGHT INTO THURSDAY AND A TROUGH OF LOW PRESSURE OVER THE
CENTRAL AND NORTHERN PLAINS MOVES EAST TOWARDS THE WESTERN GREAT
LAKES...EXPECT EAST TO SOUTHEAST WINDS TO INCREASE. SOUTHEAST
WINDS WILL FURTHER INCREASE ON THURSDAY BEFORE WINDS TURN TO THE
SOUTHWEST THURSDAY NIGHT INTO FRIDAY AS THIS LOW PROGRESSES
THROUGH THE REGION.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023 UNTIL 7 AM
     WEDNESDAY.

IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 7 AM
     WEDNESDAY.

LM...NONE.
&&

$$

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 230832
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
332 AM CDT Wed Apr 23 2014

.DISCUSSION...
ISSUED 330 AM CDT Wed Apr 23 2014

SHORT TERM...Today through Saturday

Will carry patchy frost over ne counties early this morning as
temps have cooled to 33F at Lacon and Bloomington while Danville
down to 34F. Temps in the upper 30s and lower 40s over rest of
central IL and upper 40s in southeast IL with Mount Carmel airport
at 50F. Band of cirrus clouds spreading se into central IL early
this morning should limit further cooling and think ne counties
will stay above freezing. Cool temps due to 1022 mb high pressure
over WI and ridging southward across IL.

High pressure ridge shifts east of IL today while warm air
advection regime sets up over IL through Thu morning with
increasing mid/high clouds. Isolated convection appears to stay north
and west of central IL today and most of tonight and just have
slight chances of showers over IL river valley overnight. Highs in
the low to mid 60s again today with coolest readings from I-74 ne.
Low tonight in the mid to upper 40s.

Strong storm system over the central Rockies to eject surface low
pressure from CO ne into WI Thu evening and pull a cold front east
across IL later Thu afternoon and evening. A band of showers and
scattered thunderstorms likely along and ahead of cold front Thu
afternoon and in eastern IL Thu evening. SPC has 5% risk of severe
storms in far southeast IL while slight risk is south of IL where
better instability present. Highs Thu range from mid 60s to lower
70s with coolest readings nw over IL river valley.

Mild Pacific air over central and southeast IL with highs in the
low to mid 70s and return of more sunshine. A 2nd cold front drops
se across the region Fri night and could bring a few light rain
showers to mainly ne areas along with cooler temps across the
region by Sat. Highs Sat range from lower 60s from I-74 ne to the
upper 60s to around 70F in southeast IL. Dry conditions expected
to prevail from after midnight Thu night through Saturday with
next chance of showers and iosolated thunderstorms returning
during Saturday night and Sunday.

LONG TERM...Saturday night through Wednesday

Extended models continue to advertise a blocky upper level pattern
across the country as a strong/large cutoff upper level low
deepens over the central plains by Sunday and slowly shifts east into
the mid MS river valley by Tue and remains near IL into the middle
of next week. Rather cloudy and unsettled weather pattern to occur
from Sun-Wed as temperatures gradually cool each day as upper
level low settles into the region. Have daily chances of showers
and isolated thunderstorms with best chances from Sunday night through
Tuesday. Large upper level trof/cutoff low will be slow to exit
the eastern states later next week, so temps will also be slow to
modify over IL.

07

&&

.AVIATION...
ISSUED 1147 PM CDT Tue Apr 22 2014

The surface high will keep skies mostly clear through Wed morning
with some cirrus the only clouds of note. By mid-day, increasing
mid clouds will begin to overspread PIA and SPI as warm advection
clouds progress into NW IL. Guidance is showing potential for a
few rain showers for PIA between 18z/1pm and 00z/7pm. Forecast
soundings show plenty of dry air below the cloud bases to preclude
measurable rain from occurring. A few sprinkles may reach the
ground toward 00z, but we kept vcsh out of the TAFs for now.

Winds will be light north or variable the rest of the night under
the surface ridge axis. Wind direction will become east-southeast
by mid-day on Wed, and remain that direction as low pressure
develops in the Plains through Wed evening.

Shimon

&&

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

&&

$$








000
FXUS63 KLOT 230811
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
311 AM CDT WED APR 23 2014

.DISCUSSION...
852 PM CDT

HAVE UPDATED HOURLY TEMPS TO ACCOUNT FOR A QUICKER FALL THIS
EVENING AND LOWERED MIN TEMPS A FEW DEGREES IN THE TYPICALLY
COLDER VALLEYS AND LOW LYING AREAS. ALSO...GIVEN THE CLEAR
SKIES...LIGHT WINDS...AND RECENT GREEN UP AND WARMTH...HAVE
THROWN OUT A FROST ADVISORY AWAY FROM THE URBANIZED AREAS OF
CHICAGO.

IZZI

//PREV DISCUSSION...
330 PM CDT

THE GENERAL TREND FOR THE NEXT SEVERAL DAYS SHOULD BE FOR A PERIOD
OF COOL AND DRY...FOLLOWED BY WARM AND WET...AND THEN COOL AND WET.

FOR THE REMAINDER OF THE AFTERNOON...SUNNY SKIES WITH SEASONABLE
TEMPERATURES WILL PREVAIL.  HOWEVER...A A VERY WEAK PRESSURE
GRADIENT OVER THE REGION AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES...COMBINED WITH
DIFFERENTIAL HEATING BETWEEN THE WARMER LAND AND COLDER LAKE
MICHIGAN WATER...HAS GENERATED A LAKE BREEZE BOUNDARY...WHICH HAS
MOVED INLAND INTO NERN IL/NWRN IN.  TEMPERATURES ALONG THE LAKEFRONT
HAVE DROPPED INTO THE MIDDLE 40S...COMPARED WITH UPPER 50S TO LOWER
60S WELL INLAND.  FOR THE OVERNIGHT HOURS...THE CONCERN WILL BE
OVERNIGHT LOW TEMPERATURES AND A CHANCE FOR FROST.  SKIES SHOULD
REMAIN MOSTLY CLEAR WITH VERY LIGHT WINDS.  ALSO...THE AIRMASS WILL
CONTINUE TO DRY OUT WITH SFC DEWPOINTS DROPPING INTO THE UPPER 20S
TO LOWER 30S.  SINCE ABUNDANT SUNSHINE TODAY HAS WARMED THE
GROUND...DO NOT EXPECT THAT SFC TEMPS WILL RADIATE DOWN TO THE
DEWPOINT...BUT DO EXPECT TEMPS SHOULD DROP INTO THE LOWER 30S AWAY
FROM THE LAKEFRONT AND THE HEAVILY URBANIZED AREAS OF THE CHICAGO
METRO AREA.  ALSO...THE PONTIAC AREA SHOULD SEE TEMPS ONLY DROPPING
DOWN TO ARND 35F...SO WILL CONTINUE TO MENTION THE POSSIBILITY OF
AREAS OF FROST FOR LOCATIONS WHERE THE OVERNIGHT LOW TEMPERATURE
WILL DROP BELOW 35F.

WEDNESDAY SHOULD START OUT COOL AND DRY...BUT THE NEXT UPSTREAM
SYSTEM WILL BRING INCREASING CHANCES FOR RAIN DURG THE AFTERNOON
HOURS.  THE LATEST GUIDANCE TRENDS HAVE BEEN FOR A SLIGHTLY DELAYED
ONSET OF PCPN...LARGELY DUE TO THE VERY DRY LOW LEVELS WHICH WILL BE
SLOW TO SATURATE AND THE SLOW MOVEMENT OF THE HIGH PRESSURE PUSHING
OFF TO THE EAST.  INITIALLY...PCPN SHOULD START OUT AS OVERRUNNING
SHOWERS IN ADVANCE OF A DEVELOPING WARM FRONT LIFTING NEWD THROUGH
THE REGION.  THERE COULD BE A MINIMA IN PCPN WEDNESDAY NIGHT AS THE
WARM SECTOR AIR OVERSPREADS NRN IL/NWRN IN...BUT THERE WILL STILL BE
A LOW CHANCE FOR SOME SHOWERS...AND ANY PCPN WOULD LIKELY BE
ISOLD/SCT.  THE GREATER CHANCES FOR MORE WIDESPREAD AND HEAVIER PCPN
WILL COME BY THURSDAY.  THIS WILL BE THE WARM/WET PERIOD PREVIOUSLY
MENTIONED AS GENERALLY SOUTHERLY FLOW PREVAILS AHEAD OF AN
APPROACHING COLD FRONT WITH FLOW OFF OF A WIDE OPEN GULF OF MEXICO.
EXPECT THAT TEMPERATURES WILL REACH INTO THE LOWER TO MIDDLE 60S
WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S.  THE EXCEPTION TO THIS
MAY BE THE LAKE COUNTY ILLINOIS LAKEFRONT...INCLUDING THE WAUKEGAN
AREA...WHERE A WINDS SHOULD BE SLIGHTLY EAST OF SOUTH AND BRING SOME
LAKE COOLED AIR INLAND...KEEPING TEMPS IN THE LOWER 50S.  DOWNTOWN
CHICAGO COULD ALSO SEE SOME LAKE INFLUENCE...WITH TEMPERATURES
DROPPING OFF AFTER REACHING AN EARLY AFTERNOON HIGH AROUND 60F.  THE
MODELS HAVE TRENDED TOWARD A RELATIVELY CONSISTENT SOLUTION WITH
THIS SYSTEM WITH ONLY SOME SLIGHT TIMING ISSUES WITH THE SPEED OF
THE FRONT.  HAVE GONE WITH A FAIRLY BROAD BAND OF CATEGORICAL POPS
ALONG AND JUST AHEAD OF THE FRONT.  THE LATEST GUIDANCE ALSO
INDICATES INCREASING SFC BASED INSTABILITY AHEAD OF THE FRONT...SO
WILL CARRY AND CHANCE OF THUNDERSTORMS WITH THE PCPN.  SINCE THE
GREATEST INSTABILITY SHOULD BE SOUTH OF THE CWA...HAVE KEPT THE
PROBABILITY OF THUNDER LOWER THAN THE PROBABILITY OF PCPN...THOUGH
EXPECT THAT MUCH OF THE AREA SHOULD SEE AT LEAST SOME THUNDER AS THE
FRONT SWEEPS ACROSS THE REGION.  AS FOR THE SEVERE POTENTIAL...THE
DAY 3 SPC OUTLOOK COVERS THE CWA IN A "SEE TEXT" AREA.  A STRONG
SWLY LOW LEVEL JET OF 45-50 KT ABOVE 10-15KT SELY WINDS COMBINED
WITH MODEST CAPE COULD BRING A CHANCE FOR SOME STRONGER
STORMS...ESPECIALLY FOR THE SOUTHERN PORTIONS OF THE CWA.  THE TIME
OF GREATEST OPPORTUNITY FOR THUNDERSTORMS WILL BE FROM LATE MORNING
THROUGH EARLY EVENING THURSDAY.

FOLLOWING THE FRONTAL PASSAGE...FLOW ACROSS THE REGION WILL BECOME
MORE ZONAL AND THE REAL COLD ADVECTION WILL NOT SET UP UNTIL
SATURDAY.  WITH WLY FLOW SETTING UP AS THE MAIN SFC LOW MOVES
THROUGH WISCONSIN AND CENTRAL LAKE MICHIGAN EARLY FRIDAY...THERE
WILL STILL BE AN OPPORTUNITY FOR TEMPS IN THE UPPER 60S TO AROUND
70S.  A SECONDARY COLD FRONT SHOULD PUSH SOUTH ACROSS THE REGION
FRIDAY EVENING AND THE UPPER LOW CENTER PUSHED OVER THE ERN GREAT
LAKES.

THE EXTENDED FORECAST PERIOD...SATURDAY THROUGH TUESDAY...SHOULD BE
THE AFOREMENTIONED COOL/WET PERIOD.  BY SATURDAY...CANADIAN HIGH
PRESSURE WILL NOSE SOUTH ACROSS THE UPPER MIDWEST...SETTING UP AN
EXTENDED PERIOD OF SELY TO ELY FLOW OFF OF THE COLD WATERS OF LAKE
MICHIGAN.  ANOTHER DEVELOPING LOW PRESSURE SYSTEM IS EXPECTED TO
DEVELOP OVER THE PLAINS OVER THE WEEKEND WITH A MAIN LOW OVER THE
DAKOTAS AND A TRIPLE POINT LOW OVER THE CNTRL PLAINS.  A WARM FRONT
EXTENDING EAST OF THE TRIPLE POINT WILL BE KEPT SOUTH OF THE LOCAL
AREA BY THE CANADIAN HIGH PRESSURE...SO THERE WILL BE LITTLE
OPPORTUNITY FOR SIGNIFICANT WARMING THROUGH THE WEEKEND.  WHEN THE
SYSTEM FINALLY REACHES THE MIDWEST BY EARLY NEXT WEEK...THE MAIN LOW
WILL DISSIPATE AND THE TRIPLE POINT LOW WILL DEEPEN...BUT THERE IS
DECENT AGREEMENT AMONG THE LONGER RANGE GUIDANCE THAT THIS SFC LOW
SHOULD SLIDE SOUTH OF THE CWA...THROUGH SRN IL AND INTO THE OHIO
VALLEY.  SO...WARM SECTOR AIR WILL LIKELY NEVER REACH THIS FAR
NORTH...SO TEMPERATURES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN WELL BELOW NORMAL...MIDDLE 40S TO MIDDLE 50S...WITH
PERIODIC CHANCES FOR RAIN.

KREIN

&&

.AVIATION...

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

* SCATTERED LIGHT SHOWERS POSSIBLE TOWARDS THE END OF THE FORECAST
  PERIOD.

RODRIGUEZ

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

LIGHT NORTHEAST WINDS WITH CLEAR SKIES IN PLACE...AND EXPECT WINDS
TO REMAIN NORTHEAST THROUGH MOST OF TODAY BEFORE TURNING MORE
EASTERLY LATER THIS EVENING AS VFR CEILINGS MOVE OVERHEAD.
SCATTERED LIGHT SHOWER DEVELOPMENT WILL MOVE ACROSS THE RFD AREA
LATE THIS AFTERNOON AND EARLY EVENING WITH THE REMAINING TERMINALS
LIKELY NOT OBSERVING THIS DEVELOPMENT UNTIL LATE IN THE EVENING.
ALTHOUGH...THESE SHOWERS WILL REMAIN RATHER LIGHT WITH NO VIS
RESTRICTION EXPECTED AT THIS TIME.

RODRIGUEZ

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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CONDITIONS.

RODRIGUEZ

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

THURSDAY...SHRA/MVFR LIKELY IN EVENING WITH A CHANCE OF TSRA.

FRIDAY AND SATURDAY...GENERALLY VFR.

SUNDAY...CHANCE OF SHRA/TSRA...MAINLY AT NIGHT.

MONDAY...SHRA/TSRA POSSIBLE.

IZZI

&&

.MARINE...
310 AM CDT

AS THE LAKE REMAINS ON THE EASTERN FRINGE OF BUILDING HIGH
PRESSURE FROM THE WEST...NORTHWEST TO NORTH WINDS OF 10 TO 20 KT
REMAIN. ALTHOUGH...THIS HIGH WILL MOVE OVER THE LAKE TODAY WITH
SPEEDS DIMINISHING AND WITH WINDS LIKELY BECOMING MORE LIGHT AND
VARIABLE BY THE AFTERNOON. THEN AS THIS HIGH CONTINUES EAST
TONIGHT INTO THURSDAY AND A TROUGH OF LOW PRESSURE OVER THE
CENTRAL AND NORTHERN PLAINS MOVES EAST TOWARDS THE WESTERN GREAT
LAKES...EXPECT EAST TO SOUTHEAST WINDS TO INCREASE. SOUTHEAST
WINDS WILL FURTHER INCREASE ON THURSDAY BEFORE WINDS TURN TO THE
SOUTHWEST THURSDAY NIGHT INTO FRIDAY AS THIS LOW PROGRESSES
THROUGH THE REGION.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023 UNTIL 7 AM
     WEDNESDAY.

IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 7 AM
     WEDNESDAY.

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 230535
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1235 AM CDT WED APR 23 2014

.DISCUSSION...
852 PM CDT

HAVE UPDATED HOURLY TEMPS TO ACCOUNT FOR A QUICKER FALL THIS
EVENING AND LOWERED MIN TEMPS A FEW DEGREES IN THE TYPICALLY
COLDER VALLEYS AND LOW LYING AREAS. ALSO...GIVEN THE CLEAR
SKIES...LIGHT WINDS...AND RECENT GREEN UP AND WARMTH...HAVE
THROWN OUT A FROST ADVISORY AWAY FROM THE URBANIZED AREAS OF
CHICAGO.

IZZI

//PREV DISCUSSION...
330 PM CDT

THE GENERAL TREND FOR THE NEXT SEVERAL DAYS SHOULD BE FOR A PERIOD
OF COOL AND DRY...FOLLOWED BY WARM AND WET...AND THEN COOL AND WET.

FOR THE REMAINDER OF THE AFTERNOON...SUNNY SKIES WITH SEASONABLE
TEMPERATURES WILL PREVAIL.  HOWEVER...A A VERY WEAK PRESSURE
GRADIENT OVER THE REGION AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES...COMBINED WITH
DIFFERENTIAL HEATING BETWEEN THE WARMER LAND AND COLDER LAKE
MICHIGAN WATER...HAS GENERATED A LAKE BREEZE BOUNDARY...WHICH HAS
MOVED INLAND INTO NERN IL/NWRN IN.  TEMPERATURES ALONG THE LAKEFRONT
HAVE DROPPED INTO THE MIDDLE 40S...COMPARED WITH UPPER 50S TO LOWER
60S WELL INLAND.  FOR THE OVERNIGHT HOURS...THE CONCERN WILL BE
OVERNIGHT LOW TEMPERATURES AND A CHANCE FOR FROST.  SKIES SHOULD
REMAIN MOSTLY CLEAR WITH VERY LIGHT WINDS.  ALSO...THE AIRMASS WILL
CONTINUE TO DRY OUT WITH SFC DEWPOINTS DROPPING INTO THE UPPER 20S
TO LOWER 30S.  SINCE ABUNDANT SUNSHINE TODAY HAS WARMED THE
GROUND...DO NOT EXPECT THAT SFC TEMPS WILL RADIATE DOWN TO THE
DEWPOINT...BUT DO EXPECT TEMPS SHOULD DROP INTO THE LOWER 30S AWAY
FROM THE LAKEFRONT AND THE HEAVILY URBANIZED AREAS OF THE CHICAGO
METRO AREA.  ALSO...THE PONTIAC AREA SHOULD SEE TEMPS ONLY DROPPING
DOWN TO ARND 35F...SO WILL CONTINUE TO MENTION THE POSSIBILITY OF
AREAS OF FROST FOR LOCATIONS WHERE THE OVERNIGHT LOW TEMPERATURE
WILL DROP BELOW 35F.

WEDNESDAY SHOULD START OUT COOL AND DRY...BUT THE NEXT UPSTREAM
SYSTEM WILL BRING INCREASING CHANCES FOR RAIN DURG THE AFTERNOON
HOURS.  THE LATEST GUIDANCE TRENDS HAVE BEEN FOR A SLIGHTLY DELAYED
ONSET OF PCPN...LARGELY DUE TO THE VERY DRY LOW LEVELS WHICH WILL BE
SLOW TO SATURATE AND THE SLOW MOVEMENT OF THE HIGH PRESSURE PUSHING
OFF TO THE EAST.  INITIALLY...PCPN SHOULD START OUT AS OVERRUNNING
SHOWERS IN ADVANCE OF A DEVELOPING WARM FRONT LIFTING NEWD THROUGH
THE REGION.  THERE COULD BE A MINIMA IN PCPN WEDNESDAY NIGHT AS THE
WARM SECTOR AIR OVERSPREADS NRN IL/NWRN IN...BUT THERE WILL STILL BE
A LOW CHANCE FOR SOME SHOWERS...AND ANY PCPN WOULD LIKELY BE
ISOLD/SCT.  THE GREATER CHANCES FOR MORE WIDESPREAD AND HEAVIER PCPN
WILL COME BY THURSDAY.  THIS WILL BE THE WARM/WET PERIOD PREVIOUSLY
MENTIONED AS GENERALLY SOUTHERLY FLOW PREVAILS AHEAD OF AN
APPROACHING COLD FRONT WITH FLOW OFF OF A WIDE OPEN GULF OF MEXICO.
EXPECT THAT TEMPERATURES WILL REACH INTO THE LOWER TO MIDDLE 60S
WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S.  THE EXCEPTION TO THIS
MAY BE THE LAKE COUNTY ILLINOIS LAKEFRONT...INCLUDING THE WAUKEGAN
AREA...WHERE A WINDS SHOULD BE SLIGHTLY EAST OF SOUTH AND BRING SOME
LAKE COOLED AIR INLAND...KEEPING TEMPS IN THE LOWER 50S.  DOWNTOWN
CHICAGO COULD ALSO SEE SOME LAKE INFLUENCE...WITH TEMPERATURES
DROPPING OFF AFTER REACHING AN EARLY AFTERNOON HIGH AROUND 60F.  THE
MODELS HAVE TRENDED TOWARD A RELATIVELY CONSISTENT SOLUTION WITH
THIS SYSTEM WITH ONLY SOME SLIGHT TIMING ISSUES WITH THE SPEED OF
THE FRONT.  HAVE GONE WITH A FAIRLY BROAD BAND OF CATEGORICAL POPS
ALONG AND JUST AHEAD OF THE FRONT.  THE LATEST GUIDANCE ALSO
INDICATES INCREASING SFC BASED INSTABILITY AHEAD OF THE FRONT...SO
WILL CARRY AND CHANCE OF THUNDERSTORMS WITH THE PCPN.  SINCE THE
GREATEST INSTABILITY SHOULD BE SOUTH OF THE CWA...HAVE KEPT THE
PROBABILITY OF THUNDER LOWER THAN THE PROBABILITY OF PCPN...THOUGH
EXPECT THAT MUCH OF THE AREA SHOULD SEE AT LEAST SOME THUNDER AS THE
FRONT SWEEPS ACROSS THE REGION.  AS FOR THE SEVERE POTENTIAL...THE
DAY 3 SPC OUTLOOK COVERS THE CWA IN A "SEE TEXT" AREA.  A STRONG
SWLY LOW LEVEL JET OF 45-50 KT ABOVE 10-15KT SELY WINDS COMBINED
WITH MODEST CAPE COULD BRING A CHANCE FOR SOME STRONGER
STORMS...ESPECIALLY FOR THE SOUTHERN PORTIONS OF THE CWA.  THE TIME
OF GREATEST OPPORTUNITY FOR THUNDERSTORMS WILL BE FROM LATE MORNING
THROUGH EARLY EVENING THURSDAY.

FOLLOWING THE FRONTAL PASSAGE...FLOW ACROSS THE REGION WILL BECOME
MORE ZONAL AND THE REAL COLD ADVECTION WILL NOT SET UP UNTIL
SATURDAY.  WITH WLY FLOW SETTING UP AS THE MAIN SFC LOW MOVES
THROUGH WISCONSIN AND CENTRAL LAKE MICHIGAN EARLY FRIDAY...THERE
WILL STILL BE AN OPPORTUNITY FOR TEMPS IN THE UPPER 60S TO AROUND
70S.  A SECONDARY COLD FRONT SHOULD PUSH SOUTH ACROSS THE REGION
FRIDAY EVENING AND THE UPPER LOW CENTER PUSHED OVER THE ERN GREAT
LAKES.

THE EXTENDED FORECAST PERIOD...SATURDAY THROUGH TUESDAY...SHOULD BE
THE AFOREMENTIONED COOL/WET PERIOD.  BY SATURDAY...CANADIAN HIGH
PRESSURE WILL NOSE SOUTH ACROSS THE UPPER MIDWEST...SETTING UP AN
EXTENDED PERIOD OF SELY TO ELY FLOW OFF OF THE COLD WATERS OF LAKE
MICHIGAN.  ANOTHER DEVELOPING LOW PRESSURE SYSTEM IS EXPECTED TO
DEVELOP OVER THE PLAINS OVER THE WEEKEND WITH A MAIN LOW OVER THE
DAKOTAS AND A TRIPLE POINT LOW OVER THE CNTRL PLAINS.  A WARM FRONT
EXTENDING EAST OF THE TRIPLE POINT WILL BE KEPT SOUTH OF THE LOCAL
AREA BY THE CANADIAN HIGH PRESSURE...SO THERE WILL BE LITTLE
OPPORTUNITY FOR SIGNIFICANT WARMING THROUGH THE WEEKEND.  WHEN THE
SYSTEM FINALLY REACHES THE MIDWEST BY EARLY NEXT WEEK...THE MAIN LOW
WILL DISSIPATE AND THE TRIPLE POINT LOW WILL DEEPEN...BUT THERE IS
DECENT AGREEMENT AMONG THE LONGER RANGE GUIDANCE THAT THIS SFC LOW
SHOULD SLIDE SOUTH OF THE CWA...THROUGH SRN IL AND INTO THE OHIO
VALLEY.  SO...WARM SECTOR AIR WILL LIKELY NEVER REACH THIS FAR
NORTH...SO TEMPERATURES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN WELL BELOW NORMAL...MIDDLE 40S TO MIDDLE 50S...WITH
PERIODIC CHANCES FOR RAIN.

KREIN

&&

.AVIATION...

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

* SCATTERED LIGHT SHOWERS POSSIBLE TOWARDS THE END OF THE FORECAST
  PERIOD.

RODRIGUEZ

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

LIGHT NORTHEAST WINDS WITH CLEAR SKIES IN PLACE...AND EXPECT WINDS
TO REMAIN NORTHEAST THROUGH MOST OF TODAY BEFORE TURNING MORE
EASTERLY LATER THIS EVENING AS VFR CEILINGS MOVE OVERHEAD.
SCATTERED LIGHT SHOWER DEVELOPMENT WILL MOVE ACROSS THE RFD AREA
LATE THIS AFTERNOON AND EARLY EVENING WITH THE REMAINING TERMINALS
LIKELY NOT OBSERVING THIS DEVELOPMENT UNTIL LATE IN THE EVENING.
ALTHOUGH...THESE SHOWERS WILL REMAIN RATHER LIGHT WITH NO VIS
RESTRICTION EXPECTED AT THIS TIME.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CONDITIONS.

RODRIGUEZ

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

THURSDAY...SHRA/MVFR LIKELY IN EVENING WITH A CHANCE OF TSRA.

FRIDAY AND SATURDAY...GENERALLY VFR.

SUNDAY...CHANCE OF SHRA/TSRA...MAINLY AT NIGHT.

MONDAY...SHRA/TSRA POSSIBLE.

IZZI

&&

.MARINE...
253 PM CDT

HIGH PRESSURE STRETCHES FROM THE UPPER MIDWEST INTO THE CENTRAL
PLAINS AND WILL BECOME CENTERED OVER LAKE MICHIGAN BY MIDDAY
WEDNESDAY. AS THIS OCCURS...WINDS WILL CONTINUE TO SLOWLY
DIMINISH...WITH LAKE BREEZES DEVELOPING THIS AFTERNOON AND AGAIN
WEDNESDAY AFTERNOON. LOW PRESSURE WILL MOVE ACROSS THE PLAINS
WEDNESDAY NIGHT WITH SOUTHEAST FLOW BEGINNING TO RAMP UP.
SOUTHEAST FLOW WILL INCREASE WITH SUSTAINED WINDS TO AROUND 25
KT...BUT STABLE CONDITIONS WILL HELP KEEP GUSTS TO AROUND 30 KT.
WINDS TURN SOUTHWEST THURSDAY NIGHT INTO EARLY FRIDAY AS THE LOW
LIFTS ACROSS LAKE MICHIGAN...THEN TURN NORTHWEST BY LATER IN THE
DAY FRIDAY AS A COLD FRONT SWEEPS ACROSS THE LAKE.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023 UNTIL 7 AM
     WEDNESDAY.

IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 7 AM
     WEDNESDAY.

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 230447
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1147 PM CDT Tue Apr 22 2014

.DISCUSSION...
ISSUED 900 PM CDT Tue Apr 22 2014

Quiet weather is expected the rest of the night as high pressure
has progressed far enough into Illinois to create much lighter
winds and clear skies.

Dewpoints have dipped into the mid 20s from Peoria to Bloomington.
They should rebound upward later tonight as higher upstream
dewpoints advect into the area. The higher moisture levels should
help to keep our lows from dipping too close to freezing. Frost
could develop if air temps dip into the mid 30s. Our coldest lows
look to be in the northeast, where the lower dewpoints and light
winds will linger the longest. Low temps may reach 36-37F, so we will
continue to leave out any mention of patchy frost with the evening
update.

Overall, the forecast grids are on track with expected trends, and
no formal update will be needed this evening.

Shimon

&&

.AVIATION...
ISSUED 1147 PM CDT Tue Apr 22 2014

The surface high will keep skies mostly clear through Wed morning
with some cirrus the only clouds of note. By mid-day, increasing
mid clouds will begin to overspread PIA and SPI as warm advection
clouds progress into NW IL. Guidance is showing potential for a
few rain showers for PIA between 18z/1pm and 00z/7pm. Forecast
soundings show plenty of dry air below the cloud bases to preclude
measurable rain from occurring. A few sprinkles may reach the
ground toward 00z, but we kept vcsh out of the TAFs for now.

Winds will be light north or variable the rest of the night under
the surface ridge axis. Wind direction will become east-southeast
by mid-day on Wed, and remain that direction as low pressure
develops in the Plains through Wed evening.

Shimon
&&

.PREV DISCUSSION...
ISSUED 259 PM CDT Tue Apr 22 2014

Breezy conditions persist across central and southeast Illinois
this afternoon between yesterday`s departing cold front and an
approaching ridge of high pressure. The ridge will continue to
dominate the weather for Wednesday, keeping quiet conditions in
place. The next storm system is still on track for Thursday, with
an associated risk of showers/thunderstorms. The precipitation
threat for the end of the weekend into early next week remains
murky as a slow moving system, part of a developing Rex block,
moves through our vicinity. Main forecast problems today remain
trying to pin point precipitation chances/timing with these two
systems.

SHORT TERM...Tonight through Friday:

The ridge of high pressure to our west will push into the forecast
area overnight. The main concern with the arrival of the ridge is
if temperatures will fall enough to pose a threat of frost. At
this point, forecast lows are only marginal for frost in most
areas. Also, winds appear as though they may stay up enough to
mitigate the frost threat. If winds die off quickly this evening,
the frost threat will need to be looked at more closely.

Return flow on the back side of the ridge increases on Wednesday,
with a warm frontal zone setting up to the east of a developing
storm system in the plains. Many model solutions persist in trying
to produce some precipitation in this warm advection regime,
Wednesday afternoon/evening, mainly across northern portions of
the forecast area. Still feel there is likely to be too much dry
air to overcome initially and that models are a little too
bullish. With this thinking in mind, plan to keep forecast dry
until overnight Wednesday night when some precipitation may begin
to slip in ahead of Thursday`s system.

Showers/storms still expected to spread from west to east on
Thursday as storm system crosses the forecast area. Severe threat
expected to be low overall due to low instability (CAPE values
below 1000 j/kg for the most part), and modest shear profiles
(bulk shear values no better than 35-40 kts). Drier conditions
quickly filter in behind the cold front associated with the system
overnight Thursday into Friday, although the post frontal airmass
is not especially cool.

LONG TERM...Saturday through Tuesday:

Attention turns to the Rex block expected to develop during the
period as we head into the extended range of the forecast. The
ECMWF has been the most aggressive by far with the return of
precipitation chances over the weekend, but it has backed off a
bit in its 12Z run. In any event, once the upper low with the Rex
block is in the vicinity, period of showers and some thunderstorms
are likely for at least a few days. However, due to the model
spread, run-to-run inconsistency, and intra-model ensemble spread,
confidence remains quite low in the details. Unfortunately, this
results in several periods of chance PoPs, starting Saturday
night. Hopefully, a clear consensus with the ultimate forecast
solution will emerge soon. However, considering the trouble models
have entering (and leaving) blocky patterns, we may be waiting a
while.

BAK


&&

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

$$








000
FXUS63 KLOT 230259
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
959 PM CDT TUE APR 22 2014

.DISCUSSION...
852 PM CDT

HAVE UPDATED HOURLY TEMPS TO ACCOUNT FOR A QUICKER FALL THIS
EVENING AND LOWERED MIN TEMPS A FEW DEGREES IN THE TYPICALLY
COLDER VALLEYS AND LOW LYING AREAS. ALSO...GIVEN THE CLEAR
SKIES...LIGHT WINDS...AND RECENT GREEN UP AND WARMTH...HAVE
THROWN OUT A FROST ADVISORY AWAY FROM THE URBANIZED AREAS OF
CHICAGO.

IZZI

//PREV DISCUSSION...
330 PM CDT

THE GENERAL TREND FOR THE NEXT SEVERAL DAYS SHOULD BE FOR A PERIOD
OF COOL AND DRY...FOLLOWED BY WARM AND WET...AND THEN COOL AND WET.

FOR THE REMAINDER OF THE AFTERNOON...SUNNY SKIES WITH SEASONABLE
TEMPERATURES WILL PREVAIL.  HOWEVER...A A VERY WEAK PRESSURE
GRADIENT OVER THE REGION AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES...COMBINED WITH
DIFFERENTIAL HEATING BETWEEN THE WARMER LAND AND COLDER LAKE
MICHIGAN WATER...HAS GENERATED A LAKE BREEZE BOUNDARY...WHICH HAS
MOVED INLAND INTO NERN IL/NWRN IN.  TEMPERATURES ALONG THE LAKEFRONT
HAVE DROPPED INTO THE MIDDLE 40S...COMPARED WITH UPPER 50S TO LOWER
60S WELL INLAND.  FOR THE OVERNIGHT HOURS...THE CONCERN WILL BE
OVERNIGHT LOW TEMPERATURES AND A CHANCE FOR FROST.  SKIES SHOULD
REMAIN MOSTLY CLEAR WITH VERY LIGHT WINDS.  ALSO...THE AIRMASS WILL
CONTINUE TO DRY OUT WITH SFC DEWPOINTS DROPPING INTO THE UPPER 20S
TO LOWER 30S.  SINCE ABUNDANT SUNSHINE TODAY HAS WARMED THE
GROUND...DO NOT EXPECT THAT SFC TEMPS WILL RADIATE DOWN TO THE
DEWPOINT...BUT DO EXPECT TEMPS SHOULD DROP INTO THE LOWER 30S AWAY
FROM THE LAKEFRONT AND THE HEAVILY URBANIZED AREAS OF THE CHICAGO
METRO AREA.  ALSO...THE PONTIAC AREA SHOULD SEE TEMPS ONLY DROPPING
DOWN TO ARND 35F...SO WILL CONTINUE TO MENTION THE POSSIBILITY OF
AREAS OF FROST FOR LOCATIONS WHERE THE OVERNIGHT LOW TEMPERATURE
WILL DROP BELOW 35F.

WEDNESDAY SHOULD START OUT COOL AND DRY...BUT THE NEXT UPSTREAM
SYSTEM WILL BRING INCREASING CHANCES FOR RAIN DURG THE AFTERNOON
HOURS.  THE LATEST GUIDANCE TRENDS HAVE BEEN FOR A SLIGHTLY DELAYED
ONSET OF PCPN...LARGELY DUE TO THE VERY DRY LOW LEVELS WHICH WILL BE
SLOW TO SATURATE AND THE SLOW MOVEMENT OF THE HIGH PRESSURE PUSHING
OFF TO THE EAST.  INITIALLY...PCPN SHOULD START OUT AS OVERRUNNING
SHOWERS IN ADVANCE OF A DEVELOPING WARM FRONT LIFTING NEWD THROUGH
THE REGION.  THERE COULD BE A MINIMA IN PCPN WEDNESDAY NIGHT AS THE
WARM SECTOR AIR OVERSPREADS NRN IL/NWRN IN...BUT THERE WILL STILL BE
A LOW CHANCE FOR SOME SHOWERS...AND ANY PCPN WOULD LIKELY BE
ISOLD/SCT.  THE GREATER CHANCES FOR MORE WIDESPREAD AND HEAVIER PCPN
WILL COME BY THURSDAY.  THIS WILL BE THE WARM/WET PERIOD PREVIOUSLY
MENTIONED AS GENERALLY SOUTHERLY FLOW PREVAILS AHEAD OF AN
APPROACHING COLD FRONT WITH FLOW OFF OF A WIDE OPEN GULF OF MEXICO.
EXPECT THAT TEMPERATURES WILL REACH INTO THE LOWER TO MIDDLE 60S
WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S.  THE EXCEPTION TO THIS
MAY BE THE LAKE COUNTY ILLINOIS LAKEFRONT...INCLUDING THE WAUKEGAN
AREA...WHERE A WINDS SHOULD BE SLIGHTLY EAST OF SOUTH AND BRING SOME
LAKE COOLED AIR INLAND...KEEPING TEMPS IN THE LOWER 50S.  DOWNTOWN
CHICAGO COULD ALSO SEE SOME LAKE INFLUENCE...WITH TEMPERATURES
DROPPING OFF AFTER REACHING AN EARLY AFTERNOON HIGH AROUND 60F.  THE
MODELS HAVE TRENDED TOWARD A RELATIVELY CONSISTENT SOLUTION WITH
THIS SYSTEM WITH ONLY SOME SLIGHT TIMING ISSUES WITH THE SPEED OF
THE FRONT.  HAVE GONE WITH A FAIRLY BROAD BAND OF CATEGORICAL POPS
ALONG AND JUST AHEAD OF THE FRONT.  THE LATEST GUIDANCE ALSO
INDICATES INCREASING SFC BASED INSTABILITY AHEAD OF THE FRONT...SO
WILL CARRY AND CHANCE OF THUNDERSTORMS WITH THE PCPN.  SINCE THE
GREATEST INSTABILITY SHOULD BE SOUTH OF THE CWA...HAVE KEPT THE
PROBABILITY OF THUNDER LOWER THAN THE PROBABILITY OF PCPN...THOUGH
EXPECT THAT MUCH OF THE AREA SHOULD SEE AT LEAST SOME THUNDER AS THE
FRONT SWEEPS ACROSS THE REGION.  AS FOR THE SEVERE POTENTIAL...THE
DAY 3 SPC OUTLOOK COVERS THE CWA IN A "SEE TEXT" AREA.  A STRONG
SWLY LOW LEVEL JET OF 45-50 KT ABOVE 10-15KT SELY WINDS COMBINED
WITH MODEST CAPE COULD BRING A CHANCE FOR SOME STRONGER
STORMS...ESPECIALLY FOR THE SOUTHERN PORTIONS OF THE CWA.  THE TIME
OF GREATEST OPPORTUNITY FOR THUNDERSTORMS WILL BE FROM LATE MORNING
THROUGH EARLY EVENING THURSDAY.

FOLLOWING THE FRONTAL PASSAGE...FLOW ACROSS THE REGION WILL BECOME
MORE ZONAL AND THE REAL COLD ADVECTION WILL NOT SET UP UNTIL
SATURDAY.  WITH WLY FLOW SETTING UP AS THE MAIN SFC LOW MOVES
THROUGH WISCONSIN AND CENTRAL LAKE MICHIGAN EARLY FRIDAY...THERE
WILL STILL BE AN OPPORTUNITY FOR TEMPS IN THE UPPER 60S TO AROUND
70S.  A SECONDARY COLD FRONT SHOULD PUSH SOUTH ACROSS THE REGION
FRIDAY EVENING AND THE UPPER LOW CENTER PUSHED OVER THE ERN GREAT
LAKES.

THE EXTENDED FORECAST PERIOD...SATURDAY THROUGH TUESDAY...SHOULD BE
THE AFOREMENTIONED COOL/WET PERIOD.  BY SATURDAY...CANADIAN HIGH
PRESSURE WILL NOSE SOUTH ACROSS THE UPPER MIDWEST...SETTING UP AN
EXTENDED PERIOD OF SELY TO ELY FLOW OFF OF THE COLD WATERS OF LAKE
MICHIGAN.  ANOTHER DEVELOPING LOW PRESSURE SYSTEM IS EXPECTED TO
DEVELOP OVER THE PLAINS OVER THE WEEKEND WITH A MAIN LOW OVER THE
DAKOTAS AND A TRIPLE POINT LOW OVER THE CNTRL PLAINS.  A WARM FRONT
EXTENDING EAST OF THE TRIPLE POINT WILL BE KEPT SOUTH OF THE LOCAL
AREA BY THE CANADIAN HIGH PRESSURE...SO THERE WILL BE LITTLE
OPPORTUNITY FOR SIGNIFICANT WARMING THROUGH THE WEEKEND.  WHEN THE
SYSTEM FINALLY REACHES THE MIDWEST BY EARLY NEXT WEEK...THE MAIN LOW
WILL DISSIPATE AND THE TRIPLE POINT LOW WILL DEEPEN...BUT THERE IS
DECENT AGREEMENT AMONG THE LONGER RANGE GUIDANCE THAT THIS SFC LOW
SHOULD SLIDE SOUTH OF THE CWA...THROUGH SRN IL AND INTO THE OHIO
VALLEY.  SO...WARM SECTOR AIR WILL LIKELY NEVER REACH THIS FAR
NORTH...SO TEMPERATURES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN WELL BELOW NORMAL...MIDDLE 40S TO MIDDLE 50S...WITH
PERIODIC CHANCES FOR RAIN.

KREIN

&&

.AVIATION...

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

* NONE

IZZI

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

VFR CIGS LIKELY TO DEVELOP AT OR ABOVE FL200 WEDNESDAY WITH
GRADUALLY LOWERING CIGS DURING AFTERNOON/EVENING. SOME SPOTTY
LIGHT SHRA OR VIRGA ARE POSSIBLE WEDNESDAY EVENING BUT KEPT OUT OF
TAFS SINCE CHANCES ARE LOW AND POTENTIAL IMPACT WOULD LIKELY BE
LOWER.

IZZI

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS

IZZI

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

THURSDAY...SHRA/MVFR LIKELY IN EVENING WITH A CHANCE OF TSRA.

FRIDAY AND SATURDAY...GENERALLY VFR.

SUNDAY...CHANCE OF SHRA/TSRA...MAINLY AT NIGHT.

MONDAY...SHRA/TSRA POSSIBLE.

IZZI

&&

.MARINE...
253 PM CDT

HIGH PRESSURE STRETCHES FROM THE UPPER MIDWEST INTO THE CENTRAL
PLAINS AND WILL BECOME CENTERED OVER LAKE MICHIGAN BY MIDDAY
WEDNESDAY. AS THIS OCCURS...WINDS WILL CONTINUE TO SLOWLY
DIMINISH...WITH LAKE BREEZES DEVELOPING THIS AFTERNOON AND AGAIN
WEDNESDAY AFTERNOON. LOW PRESSURE WILL MOVE ACROSS THE PLAINS
WEDNESDAY NIGHT WITH SOUTHEAST FLOW BEGINNING TO RAMP UP.
SOUTHEAST FLOW WILL INCREASE WITH SUSTAINED WINDS TO AROUND 25
KT...BUT STABLE CONDITIONS WILL HELP KEEP GUSTS TO AROUND 30 KT.
WINDS TURN SOUTHWEST THURSDAY NIGHT INTO EARLY FRIDAY AS THE LOW
LIFTS ACROSS LAKE MICHIGAN...THEN TURN NORTHWEST BY LATER IN THE
DAY FRIDAY AS A COLD FRONT SWEEPS ACROSS THE LAKE.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023...3 AM
     WEDNESDAY TO 7 AM WEDNESDAY.

IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011...3 AM WEDNESDAY TO
     7 AM WEDNESDAY.

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 230206
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
906 PM CDT Tue Apr 22 2014

.DISCUSSION...
ISSUED 900 PM CDT Tue Apr 22 2014

Quiet weather is expected the rest of the night as high pressure
has progressed far enough into Illinois to create much lighter
winds and clear skies.

Dewpoints have dipped into the mid 20s from Peoria to Bloomington.
They should rebound upward later tonight as higher upstream
dewpoints advect into the area. The higher moisture levels should
help to keep our lows from dipping too close to freezing. Frost
could develop if air temps dip into the mid 30s. Our coldest lows
look to be in the northeast, where the lower dewpoints and light
winds will linger the longest. Low temps may reach 36-37F, so we will
continue to leave out any mention of patchy frost with the evening
update.

Overall, the forecast grids are on track with expected trends, and
no formal update will be needed this evening.

Shimon
&&

.AVIATION...
ISSUED 659 PM CDT Tue Apr 22 2014

High pressure at the surface will advance into IL tonight,
bringing dry air and mostly clear skies. Some thin cirrus will
progress over the top of the ridge in the northern horizon, but
little to no mid to low clouds are expected over the next 24
hours. Gust NW winds to 18-20kt will diminish with sunset. Winds
will also diminish in response to a weakening pressure gradient as the
surface ridge axis approaches from the west.

Winds will shift to the southeast Wed morning as the surface high
passes to the east and return flow develops.

Shimon
&&

.PREV DISCUSSION...
ISSUED 259 PM CDT Tue Apr 22 2014

Breezy conditions persist across central and southeast Illinois
this afternoon between yesterday`s departing cold front and an
approaching ridge of high pressure. The ridge will continue to
dominate the weather for Wednesday, keeping quiet conditions in
place. The next storm system is still on track for Thursday, with
an associated risk of showers/thunderstorms. The precipitation
threat for the end of the weekend into early next week remains
murky as a slow moving system, part of a developing Rex block,
moves through our vicinity. Main forecast problems today remain
trying to pin point precipitation chances/timing with these two
systems.

SHORT TERM...Tonight through Friday:

The ridge of high pressure to our west will push into the forecast
area overnight. The main concern with the arrival of the ridge is
if temperatures will fall enough to pose a threat of frost. At
this point, forecast lows are only marginal for frost in most
areas. Also, winds appear as though they may stay up enough to
mitigate the frost threat. If winds die off quickly this evening,
the frost threat will need to be looked at more closely.

Return flow on the back side of the ridge increases on Wednesday,
with a warm frontal zone setting up to the east of a developing
storm system in the plains. Many model solutions persist in trying
to produce some precipitation in this warm advection regime,
Wednesday afternoon/evening, mainly across northern portions of
the forecast area. Still feel there is likely to be too much dry
air to overcome initially and that models are a little too
bullish. With this thinking in mind, plan to keep forecast dry
until overnight Wednesday night when some precipitation may begin
to slip in ahead of Thursday`s system.

Showers/storms still expected to spread from west to east on
Thursday as storm system crosses the forecast area. Severe threat
expected to be low overall due to low instability (CAPE values
below 1000 j/kg for the most part), and modest shear profiles
(bulk shear values no better than 35-40 kts). Drier conditions
quickly filter in behind the cold front associated with the system
overnight Thursday into Friday, although the post frontal airmass
is not especially cool.

LONG TERM...Saturday through Tuesday:

Attention turns to the Rex block expected to develop during the
period as we head into the extended range of the forecast. The
ECMWF has been the most aggressive by far with the return of
precipitation chances over the weekend, but it has backed off a
bit in its 12Z run. In any event, once the upper low with the Rex
block is in the vicinity, period of showers and some thunderstorms
are likely for at least a few days. However, due to the model
spread, run-to-run inconsistency, and intra-model ensemble spread,
confidence remains quite low in the details. Unfortunately, this
results in several periods of chance PoPs, starting Saturday
night. Hopefully, a clear consensus with the ultimate forecast
solution will emerge soon. However, considering the trouble models
have entering (and leaving) blocky patterns, we may be waiting a
while.

BAK

&&

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

$$








000
FXUS63 KLOT 230152
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
852 PM CDT TUE APR 22 2014

.DISCUSSION...
852 PM CDT

HAVE UPDATED HOURLY TEMPS TO ACCOUNT FOR A QUICKER FALL THIS
EVENING AND LOWERED MIN TEMPS A FEW DEGREES IN THE TYPICALLY
COLDER VALLEYS AND LOW LYING AREAS. ALSO...GIVEN THE CLEAR
SKIES...LIGHT WINDS...AND RECENT GREEN UP AND WARMTH...HAVE
THROWN OUT A FROST ADVISORY AWAY FROM THE URBANIZED AREAS OF
CHICAGO.

IZZI

&&

.PREV DISCUSSION...
330 PM CDT

THE GENERAL TREND FOR THE NEXT SEVERAL DAYS SHOULD BE FOR A PERIOD
OF COOL AND DRY...FOLLOWED BY WARM AND WET...AND THEN COOL AND WET.

FOR THE REMAINDER OF THE AFTERNOON...SUNNY SKIES WITH SEASONABLE
TEMPERATURES WILL PREVAIL.  HOWEVER...A A VERY WEAK PRESSURE
GRADIENT OVER THE REGION AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES...COMBINED WITH
DIFFERENTIAL HEATING BETWEEN THE WARMER LAND AND COLDER LAKE
MICHIGAN WATER...HAS GENERATED A LAKE BREEZE BOUNDARY...WHICH HAS
MOVED INLAND INTO NERN IL/NWRN IN.  TEMPERATURES ALONG THE LAKEFRONT
HAVE DROPPED INTO THE MIDDLE 40S...COMPARED WITH UPPER 50S TO LOWER
60S WELL INLAND.  FOR THE OVERNIGHT HOURS...THE CONCERN WILL BE
OVERNIGHT LOW TEMPERATURES AND A CHANCE FOR FROST.  SKIES SHOULD
REMAIN MOSTLY CLEAR WITH VERY LIGHT WINDS.  ALSO...THE AIRMASS WILL
CONTINUE TO DRY OUT WITH SFC DEWPOINTS DROPPING INTO THE UPPER 20S
TO LOWER 30S.  SINCE ABUNDANT SUNSHINE TODAY HAS WARMED THE
GROUND...DO NOT EXPECT THAT SFC TEMPS WILL RADIATE DOWN TO THE
DEWPOINT...BUT DO EXPECT TEMPS SHOULD DROP INTO THE LOWER 30S AWAY
FROM THE LAKEFRONT AND THE HEAVILY URBANIZED AREAS OF THE CHICAGO
METRO AREA.  ALSO...THE PONTIAC AREA SHOULD SEE TEMPS ONLY DROPPING
DOWN TO ARND 35F...SO WILL CONTINUE TO MENTION THE POSSIBILITY OF
AREAS OF FROST FOR LOCATIONS WHERE THE OVERNIGHT LOW TEMPERATURE
WILL DROP BELOW 35F.

WEDNESDAY SHOULD START OUT COOL AND DRY...BUT THE NEXT UPSTREAM
SYSTEM WILL BRING INCREASING CHANCES FOR RAIN DURG THE AFTERNOON
HOURS.  THE LATEST GUIDANCE TRENDS HAVE BEEN FOR A SLIGHTLY DELAYED
ONSET OF PCPN...LARGELY DUE TO THE VERY DRY LOW LEVELS WHICH WILL BE
SLOW TO SATURATE AND THE SLOW MOVEMENT OF THE HIGH PRESSURE PUSHING
OFF TO THE EAST.  INITIALLY...PCPN SHOULD START OUT AS OVERRUNNING
SHOWERS IN ADVANCE OF A DEVELOPING WARM FRONT LIFTING NEWD THROUGH
THE REGION.  THERE COULD BE A MINIMA IN PCPN WEDNESDAY NIGHT AS THE
WARM SECTOR AIR OVERSPREADS NRN IL/NWRN IN...BUT THERE WILL STILL BE
A LOW CHANCE FOR SOME SHOWERS...AND ANY PCPN WOULD LIKELY BE
ISOLD/SCT.  THE GREATER CHANCES FOR MORE WIDESPREAD AND HEAVIER PCPN
WILL COME BY THURSDAY.  THIS WILL BE THE WARM/WET PERIOD PREVIOUSLY
MENTIONED AS GENERALLY SOUTHERLY FLOW PREVAILS AHEAD OF AN
APPROACHING COLD FRONT WITH FLOW OFF OF A WIDE OPEN GULF OF MEXICO.
EXPECT THAT TEMPERATURES WILL REACH INTO THE LOWER TO MIDDLE 60S
WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S.  THE EXCEPTION TO THIS
MAY BE THE LAKE COUNTY ILLINOIS LAKEFRONT...INCLUDING THE WAUKEGAN
AREA...WHERE A WINDS SHOULD BE SLIGHTLY EAST OF SOUTH AND BRING SOME
LAKE COOLED AIR INLAND...KEEPING TEMPS IN THE LOWER 50S.  DOWNTOWN
CHICAGO COULD ALSO SEE SOME LAKE INFLUENCE...WITH TEMPERATURES
DROPPING OFF AFTER REACHING AN EARLY AFTERNOON HIGH AROUND 60F.  THE
MODELS HAVE TRENDED TOWARD A RELATIVELY CONSISTENT SOLUTION WITH
THIS SYSTEM WITH ONLY SOME SLIGHT TIMING ISSUES WITH THE SPEED OF
THE FRONT.  HAVE GONE WITH A FAIRLY BROAD BAND OF CATEGORICAL POPS
ALONG AND JUST AHEAD OF THE FRONT.  THE LATEST GUIDANCE ALSO
INDICATES INCREASING SFC BASED INSTABILITY AHEAD OF THE FRONT...SO
WILL CARRY AND CHANCE OF THUNDERSTORMS WITH THE PCPN.  SINCE THE
GREATEST INSTABILITY SHOULD BE SOUTH OF THE CWA...HAVE KEPT THE
PROBABILITY OF THUNDER LOWER THAN THE PROBABILITY OF PCPN...THOUGH
EXPECT THAT MUCH OF THE AREA SHOULD SEE AT LEAST SOME THUNDER AS THE
FRONT SWEEPS ACROSS THE REGION.  AS FOR THE SEVERE POTENTIAL...THE
DAY 3 SPC OUTLOOK COVERS THE CWA IN A "SEE TEXT" AREA.  A STRONG
SWLY LOW LEVEL JET OF 45-50 KT ABOVE 10-15KT SELY WINDS COMBINED
WITH MODEST CAPE COULD BRING A CHANCE FOR SOME STRONGER
STORMS...ESPECIALLY FOR THE SOUTHERN PORTIONS OF THE CWA.  THE TIME
OF GREATEST OPPORTUNITY FOR THUNDERSTORMS WILL BE FROM LATE MORNING
THROUGH EARLY EVENING THURSDAY.

FOLLOWING THE FRONTAL PASSAGE...FLOW ACROSS THE REGION WILL BECOME
MORE ZONAL AND THE REAL COLD ADVECTION WILL NOT SET UP UNTIL
SATURDAY.  WITH WLY FLOW SETTING UP AS THE MAIN SFC LOW MOVES
THROUGH WISCONSIN AND CENTRAL LAKE MICHIGAN EARLY FRIDAY...THERE
WILL STILL BE AN OPPORTUNITY FOR TEMPS IN THE UPPER 60S TO AROUND
70S.  A SECONDARY COLD FRONT SHOULD PUSH SOUTH ACROSS THE REGION
FRIDAY EVENING AND THE UPPER LOW CENTER PUSHED OVER THE ERN GREAT
LAKES.

THE EXTENDED FORECAST PERIOD...SATURDAY THROUGH TUESDAY...SHOULD BE
THE AFOREMENTIONED COOL/WET PERIOD.  BY SATURDAY...CANADIAN HIGH
PRESSURE WILL NOSE SOUTH ACROSS THE UPPER MIDWEST...SETTING UP AN
EXTENDED PERIOD OF SELY TO ELY FLOW OFF OF THE COLD WATERS OF LAKE
MICHIGAN.  ANOTHER DEVELOPING LOW PRESSURE SYSTEM IS EXPECTED TO
DEVELOP OVER THE PLAINS OVER THE WEEKEND WITH A MAIN LOW OVER THE
DAKOTAS AND A TRIPLE POINT LOW OVER THE CNTRL PLAINS.  A WARM FRONT
EXTENDING EAST OF THE TRIPLE POINT WILL BE KEPT SOUTH OF THE LOCAL
AREA BY THE CANADIAN HIGH PRESSURE...SO THERE WILL BE LITTLE
OPPORTUNITY FOR SIGNIFICANT WARMING THROUGH THE WEEKEND.  WHEN THE
SYSTEM FINALLY REACHES THE MIDWEST BY EARLY NEXT WEEK...THE MAIN LOW
WILL DISSIPATE AND THE TRIPLE POINT LOW WILL DEEPEN...BUT THERE IS
DECENT AGREEMENT AMONG THE LONGER RANGE GUIDANCE THAT THIS SFC LOW
SHOULD SLIDE SOUTH OF THE CWA...THROUGH SRN IL AND INTO THE OHIO
VALLEY.  SO...WARM SECTOR AIR WILL LIKELY NEVER REACH THIS FAR
NORTH...SO TEMPERATURES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN WELL BELOW NORMAL...MIDDLE 40S TO MIDDLE 50S...WITH
PERIODIC CHANCES FOR RAIN.

KREIN

&&

.AVIATION...

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

* NONE

IZZI

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

VFR CIGS LIKELY TO DEVELOP AT OR ABOVE FL200 WEDNESDAY WITH
GRADUALLY LOWERING CIGS DURING AFTERNOON/EVENING. SOME SPOTTY
LIGHT SHRA OR VIRGA ARE POSSIBLE WEDNESDAY EVENING BUT KEPT OUT OF
TAFS SINCE CHANCES ARE LOW AND POTENTIAL IMPACT WOULD LIKELY BE
LOWER.

IZZI

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS

IZZI

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

THURSDAY...SHRA/MVFR LIKELY IN EVENING WITH A CHANCE OF TSRA.

FRIDAY AND SATURDAY...GENERALLY VFR.

SUNDAY...CHANCE OF SHRA/TSRA...MAINLY AT NIGHT.

MONDAY...SHRA/TSRA POSSIBLE.

IZZI

&&

.MARINE...
253 PM CDT

HIGH PRESSURE STRETCHES FROM THE UPPER MIDWEST INTO THE CENTRAL
PLAINS AND WILL BECOME CENTERED OVER LAKE MICHIGAN BY MIDDAY
WEDNESDAY. AS THIS OCCURS...WINDS WILL CONTINUE TO SLOWLY
DIMINISH...WITH LAKE BREEZES DEVELOPING THIS AFTERNOON AND AGAIN
WEDNESDAY AFTERNOON. LOW PRESSURE WILL MOVE ACROSS THE PLAINS
WEDNESDAY NIGHT WITH SOUTHEAST FLOW BEGINNING TO RAMP UP.
SOUTHEAST FLOW WILL INCREASE WITH SUSTAINED WINDS TO AROUND 25
KT...BUT STABLE CONDITIONS WILL HELP KEEP GUSTS TO AROUND 30 KT.
WINDS TURN SOUTHWEST THURSDAY NIGHT INTO EARLY FRIDAY AS THE LOW
LIFTS ACROSS LAKE MICHIGAN...THEN TURN NORTHWEST BY LATER IN THE
DAY FRIDAY AS A COLD FRONT SWEEPS ACROSS THE LAKE.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023...3 AM
     WEDNESDAY TO 7 AM WEDNESDAY.

IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011...3 AM WEDNESDAY TO
     7 AM WEDNESDAY.

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 222359
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
659 PM CDT Tue Apr 22 2014

.DISCUSSION...
ISSUED 259 PM CDT Tue Apr 22 2014

Breezy conditions persist across central and southeast Illinois
this afternoon between yesterday`s departing cold front and an
approaching ridge of high pressure. The ridge will continue to
dominate the weather for Wednesday, keeping quiet conditions in
place. The next storm system is still on track for Thursday, with
an associated risk of showers/thunderstorms. The precipitation
threat for the end of the weekend into early next week remains
murky as a slow moving system, part of a developing Rex block,
moves through our vicinity. Main forecast problems today remain
trying to pin point precipitation chances/timing with these two
systems.

SHORT TERM...Tonight through Friday:

The ridge of high pressure to our west will push into the forecast
area overnight. The main concern with the arrival of the ridge is
if temperatures will fall enough to pose a threat of frost. At
this point, forecast lows are only marginal for frost in most
areas. Also, winds appear as though they may stay up enough to
mitigate the frost threat. If winds die off quickly this evening,
the frost threat will need to be looked at more closely.

Return flow on the back side of the ridge increases on Wednesday,
with a warm frontal zone setting up to the east of a developing
storm system in the plains. Many model solutions persist in trying
to produce some precipitation in this warm advection regime,
Wednesday afternoon/evening, mainly across northern portions of
the forecast area. Still feel there is likely to be too much dry
air to overcome initially and that models are a little too
bullish. With this thinking in mind, plan to keep forecast dry
until overnight Wednesday night when some precipitation may begin
to slip in ahead of Thursday`s system.

Showers/storms still expected to spread from west to east on
Thursday as storm system crosses the forecast area. Severe threat
expected to be low overall due to low instability (CAPE values
below 1000 j/kg for the most part), and modest shear profiles
(bulk shear values no better than 35-40 kts). Drier conditions
quickly filter in behind the cold front associated with the system
overnight Thursday into Friday, although the post frontal airmass
is not especially cool.

LONG TERM...Saturday through Tuesday:

Attention turns to the Rex block expected to develop during the
period as we head into the extended range of the forecast. The
ECMWF has been the most aggressive by far with the return of
precipitation chances over the weekend, but it has backed off a
bit in its 12Z run. In any event, once the upper low with the Rex
block is in the vicinity, period of showers and some thunderstorms
are likely for at least a few days. However, due to the model
spread, run-to-run inconsistency, and intra-model ensemble spread,
confidence remains quite low in the details. Unfortunately, this
results in several periods of chance PoPs, starting Saturday
night. Hopefully, a clear consensus with the ultimate forecast
solution will emerge soon. However, considering the trouble models
have entering (and leaving) blocky patterns, we may be waiting a
while.

BAK

&&

.AVIATION...
ISSUED 659 PM CDT Tue Apr 22 2014

High pressure at the surface will advance into IL tonight,
bringing dry air and mostly clear skies. Some thin cirrus will
progress over the top of the ridge in the northern horizon, but
little to no mid to low clouds are expected over the next 24
hours. Gust NW winds to 18-20kt will diminish with sunset. Winds
will also diminish in response to a weakening pressure gradient as the
surface ridge axis approaches from the west.

Winds will shift to the southeast Wed morning as the surface high
passes to the east and return flow develops.

Shimon
&&

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

$$








000
FXUS63 KLOT 222301
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
601 PM CDT TUE APR 22 2014

.DISCUSSION...
330 PM CDT

THE GENERAL TREND FOR THE NEXT SEVERAL DAYS SHOULD BE FOR A PERIOD
OF COOL AND DRY...FOLLOWED BY WARM AND WET...AND THEN COOL AND WET.

FOR THE REMAINDER OF THE AFTERNOON...SUNNY SKIES WITH SEASONABLE
TEMPERATURES WILL PREVAIL.  HOWEVER...A A VERY WEAK PRESSURE
GRADIENT OVER THE REGION AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES...COMBINED WITH
DIFFERENTIAL HEATING BETWEEN THE WARMER LAND AND COLDER LAKE
MICHIGAN WATER...HAS GENERATED A LAKE BREEZE BOUNDARY...WHICH HAS
MOVED INLAND INTO NERN IL/NWRN IN.  TEMPERATURES ALONG THE LAKEFRONT
HAVE DROPPED INTO THE MIDDLE 40S...COMPARED WITH UPPER 50S TO LOWER
60S WELL INLAND.  FOR THE OVERNIGHT HOURS...THE CONCERN WILL BE
OVERNIGHT LOW TEMPERATURES AND A CHANCE FOR FROST.  SKIES SHOULD
REMAIN MOSTLY CLEAR WITH VERY LIGHT WINDS.  ALSO...THE AIRMASS WILL
CONTINUE TO DRY OUT WITH SFC DEWPOINTS DROPPING INTO THE UPPER 20S
TO LOWER 30S.  SINCE ABUNDANT SUNSHINE TODAY HAS WARMED THE
GROUND...DO NOT EXPECT THAT SFC TEMPS WILL RADIATE DOWN TO THE
DEWPOINT...BUT DO EXPECT TEMPS SHOULD DROP INTO THE LOWER 30S AWAY
FROM THE LAKEFRONT AND THE HEAVILY URBANIZED AREAS OF THE CHICAGO
METRO AREA.  ALSO...THE PONTIAC AREA SHOULD SEE TEMPS ONLY DROPPING
DOWN TO ARND 35F...SO WILL CONTINUE TO MENTION THE POSSIBILITY OF
AREAS OF FROST FOR LOCATIONS WHERE THE OVERNIGHT LOW TEMPERATURE
WILL DROP BELOW 35F.

WEDNESDAY SHOULD START OUT COOL AND DRY...BUT THE NEXT UPSTREAM
SYSTEM WILL BRING INCREASING CHANCES FOR RAIN DURG THE AFTERNOON
HOURS.  THE LATEST GUIDANCE TRENDS HAVE BEEN FOR A SLIGHTLY DELAYED
ONSET OF PCPN...LARGELY DUE TO THE VERY DRY LOW LEVELS WHICH WILL BE
SLOW TO SATURATE AND THE SLOW MOVEMENT OF THE HIGH PRESSURE PUSHING
OFF TO THE EAST.  INITIALLY...PCPN SHOULD START OUT AS OVERRUNNING
SHOWERS IN ADVANCE OF A DEVELOPING WARM FRONT LIFTING NEWD THROUGH
THE REGION.  THERE COULD BE A MINIMA IN PCPN WEDNESDAY NIGHT AS THE
WARM SECTOR AIR OVERSPREADS NRN IL/NWRN IN...BUT THERE WILL STILL BE
A LOW CHANCE FOR SOME SHOWERS...AND ANY PCPN WOULD LIKELY BE
ISOLD/SCT.  THE GREATER CHANCES FOR MORE WIDESPREAD AND HEAVIER PCPN
WILL COME BY THURSDAY.  THIS WILL BE THE WARM/WET PERIOD PREVIOUSLY
MENTIONED AS GENERALLY SOUTHERLY FLOW PREVAILS AHEAD OF AN
APPROACHING COLD FRONT WITH FLOW OFF OF A WIDE OPEN GULF OF MEXICO.
EXPECT THAT TEMPERATURES WILL REACH INTO THE LOWER TO MIDDLE 60S
WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S.  THE EXCEPTION TO THIS
MAY BE THE LAKE COUNTY ILLINOIS LAKEFRONT...INCLUDING THE WAUKEGAN
AREA...WHERE A WINDS SHOULD BE SLIGHTLY EAST OF SOUTH AND BRING SOME
LAKE COOLED AIR INLAND...KEEPING TEMPS IN THE LOWER 50S.  DOWNTOWN
CHICAGO COULD ALSO SEE SOME LAKE INFLUENCE...WITH TEMPERATURES
DROPPING OFF AFTER REACHING AN EARLY AFTERNOON HIGH AROUND 60F.  THE
MODELS HAVE TRENDED TOWARD A RELATIVELY CONSISTENT SOLUTION WITH
THIS SYSTEM WITH ONLY SOME SLIGHT TIMING ISSUES WITH THE SPEED OF
THE FRONT.  HAVE GONE WITH A FAIRLY BROAD BAND OF CATEGORICAL POPS
ALONG AND JUST AHEAD OF THE FRONT.  THE LATEST GUIDANCE ALSO
INDICATES INCREASING SFC BASED INSTABILITY AHEAD OF THE FRONT...SO
WILL CARRY AND CHANCE OF THUNDERSTORMS WITH THE PCPN.  SINCE THE
GREATEST INSTABILITY SHOULD BE SOUTH OF THE CWA...HAVE KEPT THE
PROBABILITY OF THUNDER LOWER THAN THE PROBABILITY OF PCPN...THOUGH
EXPECT THAT MUCH OF THE AREA SHOULD SEE AT LEAST SOME THUNDER AS THE
FRONT SWEEPS ACROSS THE REGION.  AS FOR THE SEVERE POTENTIAL...THE
DAY 3 SPC OUTLOOK COVERS THE CWA IN A "SEE TEXT" AREA.  A STRONG
SWLY LOW LEVEL JET OF 45-50 KT ABOVE 10-15KT SELY WINDS COMBINED
WITH MODEST CAPE COULD BRING A CHANCE FOR SOME STRONGER
STORMS...ESPECIALLY FOR THE SOUTHERN PORTIONS OF THE CWA.  THE TIME
OF GREATEST OPPORTUNITY FOR THUNDERSTORMS WILL BE FROM LATE MORNING
THROUGH EARLY EVENING THURSDAY.

FOLLOWING THE FRONTAL PASSAGE...FLOW ACROSS THE REGION WILL BECOME
MORE ZONAL AND THE REAL COLD ADVECTION WILL NOT SET UP UNTIL
SATURDAY.  WITH WLY FLOW SETTING UP AS THE MAIN SFC LOW MOVES
THROUGH WISCONSIN AND CENTRAL LAKE MICHIGAN EARLY FRIDAY...THERE
WILL STILL BE AN OPPORTUNITY FOR TEMPS IN THE UPPER 60S TO AROUND
70S.  A SECONDARY COLD FRONT SHOULD PUSH SOUTH ACROSS THE REGION
FRIDAY EVENING AND THE UPPER LOW CENTER PUSHED OVER THE ERN GREAT
LAKES.

THE EXTENDED FORECAST PERIOD...SATURDAY THROUGH TUESDAY...SHOULD BE
THE AFOREMENTIONED COOL/WET PERIOD.  BY SATURDAY...CANADIAN HIGH
PRESSURE WILL NOSE SOUTH ACROSS THE UPPER MIDWEST...SETTING UP AN
EXTENDED PERIOD OF SELY TO ELY FLOW OFF OF THE COLD WATERS OF LAKE
MICHIGAN.  ANOTHER DEVELOPING LOW PRESSURE SYSTEM IS EXPECTED TO
DEVELOP OVER THE PLAINS OVER THE WEEKEND WITH A MAIN LOW OVER THE
DAKOTAS AND A TRIPLE POINT LOW OVER THE CNTRL PLAINS.  A WARM FRONT
EXTENDING EAST OF THE TRIPLE POINT WILL BE KEPT SOUTH OF THE LOCAL
AREA BY THE CANADIAN HIGH PRESSURE...SO THERE WILL BE LITTLE
OPPORTUNITY FOR SIGNIFICANT WARMING THROUGH THE WEEKEND.  WHEN THE
SYSTEM FINALLY REACHES THE MIDWEST BY EARLY NEXT WEEK...THE MAIN LOW
WILL DISSIPATE AND THE TRIPLE POINT LOW WILL DEEPEN...BUT THERE IS
DECENT AGREEMENT AMONG THE LONGER RANGE GUIDANCE THAT THIS SFC LOW
SHOULD SLIDE SOUTH OF THE CWA...THROUGH SRN IL AND INTO THE OHIO
VALLEY.  SO...WARM SECTOR AIR WILL LIKELY NEVER REACH THIS FAR
NORTH...SO TEMPERATURES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN WELL BELOW NORMAL...MIDDLE 40S TO MIDDLE 50S...WITH
PERIODIC CHANCES FOR RAIN.

KREIN

&&

.AVIATION...

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

* NONE

IZZI

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

VFR CIGS LIKELY TO DEVELOP AT OR ABOVE FL200 WEDNESDAY WITH
GRADUALLY LOWERING CIGS DURING AFTERNOON/EVENING. SOME SPOTTY
LIGHT SHRA OR VIRGA ARE POSSIBLE WEDNESDAY EVENING BUT KEPT OUT OF
TAFS SINCE CHANCES ARE LOW AND POTENTIAL IMPACT WOULD LIKELY BE
LOWER.

IZZI


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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS

IZZI

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

THURSDAY...SHRA/MVFR LIKELY IN EVENING WITH A CHANCE OF TSRA.

FRIDAY AND SATURDAY...GENERALLY VFR.

SUNDAY...CHANCE OF SHRA/TSRA...MAINLY AT NIGHT.

MONDAY...SHRA/TSRA POSSIBLE.

IZZI

&&

.MARINE...
253 PM CDT

HIGH PRESSURE STRETCHES FROM THE UPPER MIDWEST INTO THE CENTRAL
PLAINS AND WILL BECOME CENTERED OVER LAKE MICHIGAN BY MIDDAY
WEDNESDAY. AS THIS OCCURS...WINDS WILL CONTINUE TO SLOWLY
DIMINISH...WITH LAKE BREEZES DEVELOPING THIS AFTERNOON AND AGAIN
WEDNESDAY AFTERNOON. LOW PRESSURE WILL MOVE ACROSS THE PLAINS
WEDNESDAY NIGHT WITH SOUTHEAST FLOW BEGINNING TO RAMP UP.
SOUTHEAST FLOW WILL INCREASE WITH SUSTAINED WINDS TO AROUND 25
KT...BUT STABLE CONDITIONS WILL HELP KEEP GUSTS TO AROUND 30 KT.
WINDS TURN SOUTHWEST THURSDAY NIGHT INTO EARLY FRIDAY AS THE LOW
LIFTS ACROSS LAKE MICHIGAN...THEN TURN NORTHWEST BY LATER IN THE
DAY FRIDAY AS A COLD FRONT SWEEPS ACROSS THE LAKE.

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 222208
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
508 PM CDT TUE APR 22 2014

.DISCUSSION...
330 PM CDT

THE GENERAL TREND FOR THE NEXT SEVERAL DAYS SHOULD BE FOR A PERIOD
OF COOL AND DRY...FOLLOWED BY WARM AND WET...AND THEN COOL AND WET.

FOR THE REMAINDER OF THE AFTERNOON...SUNNY SKIES WITH SEASONABLE
TEMPERATURES WILL PREVAIL.  HOWEVER...A A VERY WEAK PRESSURE
GRADIENT OVER THE REGION AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES...COMBINED WITH
DIFFERENTIAL HEATING BETWEEN THE WARMER LAND AND COLDER LAKE
MICHIGAN WATER...HAS GENERATED A LAKE BREEZE BOUNDARY...WHICH HAS
MOVED INLAND INTO NERN IL/NWRN IN.  TEMPERATURES ALONG THE LAKEFRONT
HAVE DROPPED INTO THE MIDDLE 40S...COMPARED WITH UPPER 50S TO LOWER
60S WELL INLAND.  FOR THE OVERNIGHT HOURS...THE CONCERN WILL BE
OVERNIGHT LOW TEMPERATURES AND A CHANCE FOR FROST.  SKIES SHOULD
REMAIN MOSTLY CLEAR WITH VERY LIGHT WINDS.  ALSO...THE AIRMASS WILL
CONTINUE TO DRY OUT WITH SFC DEWPOINTS DROPPING INTO THE UPPER 20S
TO LOWER 30S.  SINCE ABUNDANT SUNSHINE TODAY HAS WARMED THE
GROUND...DO NOT EXPECT THAT SFC TEMPS WILL RADIATE DOWN TO THE
DEWPOINT...BUT DO EXPECT TEMPS SHOULD DROP INTO THE LOWER 30S AWAY
FROM THE LAKEFRONT AND THE HEAVILY URBANIZED AREAS OF THE CHICAGO
METRO AREA.  ALSO...THE PONTIAC AREA SHOULD SEE TEMPS ONLY DROPPING
DOWN TO ARND 35F...SO WILL CONTINUE TO MENTION THE POSSIBILITY OF
AREAS OF FROST FOR LOCATIONS WHERE THE OVERNIGHT LOW TEMPERATURE
WILL DROP BELOW 35F.

WEDNESDAY SHOULD START OUT COOL AND DRY...BUT THE NEXT UPSTREAM
SYSTEM WILL BRING INCREASING CHANCES FOR RAIN DURG THE AFTERNOON
HOURS.  THE LATEST GUIDANCE TRENDS HAVE BEEN FOR A SLIGHTLY DELAYED
ONSET OF PCPN...LARGELY DUE TO THE VERY DRY LOW LEVELS WHICH WILL BE
SLOW TO SATURATE AND THE SLOW MOVEMENT OF THE HIGH PRESSURE PUSHING
OFF TO THE EAST.  INITIALLY...PCPN SHOULD START OUT AS OVERRUNNING
SHOWERS IN ADVANCE OF A DEVELOPING WARM FRONT LIFTING NEWD THROUGH
THE REGION.  THERE COULD BE A MINIMA IN PCPN WEDNESDAY NIGHT AS THE
WARM SECTOR AIR OVERSPREADS NRN IL/NWRN IN...BUT THERE WILL STILL BE
A LOW CHANCE FOR SOME SHOWERS...AND ANY PCPN WOULD LIKELY BE
ISOLD/SCT.  THE GREATER CHANCES FOR MORE WIDESPREAD AND HEAVIER PCPN
WILL COME BY THURSDAY.  THIS WILL BE THE WARM/WET PERIOD PREVIOUSLY
MENTIONED AS GENERALLY SOUTHERLY FLOW PREVAILS AHEAD OF AN
APPROACHING COLD FRONT WITH FLOW OFF OF A WIDE OPEN GULF OF MEXICO.
EXPECT THAT TEMPERATURES WILL REACH INTO THE LOWER TO MIDDLE 60S
WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S.  THE EXCEPTION TO THIS
MAY BE THE LAKE COUNTY ILLINOIS LAKEFRONT...INCLUDING THE WAUKEGAN
AREA...WHERE A WINDS SHOULD BE SLIGHTLY EAST OF SOUTH AND BRING SOME
LAKE COOLED AIR INLAND...KEEPING TEMPS IN THE LOWER 50S.  DOWNTOWN
CHICAGO COULD ALSO SEE SOME LAKE INFLUENCE...WITH TEMPERATURES
DROPPING OFF AFTER REACHING AN EARLY AFTERNOON HIGH AROUND 60F.  THE
MODELS HAVE TRENDED TOWARD A RELATIVELY CONSISTENT SOLUTION WITH
THIS SYSTEM WITH ONLY SOME SLIGHT TIMING ISSUES WITH THE SPEED OF
THE FRONT.  HAVE GONE WITH A FAIRLY BROAD BAND OF CATEGORICAL POPS
ALONG AND JUST AHEAD OF THE FRONT.  THE LATEST GUIDANCE ALSO
INDICATES INCREASING SFC BASED INSTABILITY AHEAD OF THE FRONT...SO
WILL CARRY AND CHANCE OF THUNDERSTORMS WITH THE PCPN.  SINCE THE
GREATEST INSTABILITY SHOULD BE SOUTH OF THE CWA...HAVE KEPT THE
PROBABILITY OF THUNDER LOWER THAN THE PROBABILITY OF PCPN...THOUGH
EXPECT THAT MUCH OF THE AREA SHOULD SEE AT LEAST SOME THUNDER AS THE
FRONT SWEEPS ACROSS THE REGION.  AS FOR THE SEVERE POTENTIAL...THE
DAY 3 SPC OUTLOOK COVERS THE CWA IN A "SEE TEXT" AREA.  A STRONG
SWLY LOW LEVEL JET OF 45-50 KT ABOVE 10-15KT SELY WINDS COMBINED
WITH MODEST CAPE COULD BRING A CHANCE FOR SOME STRONGER
STORMS...ESPECIALLY FOR THE SOUTHERN PORTIONS OF THE CWA.  THE TIME
OF GREATEST OPPORTUNITY FOR THUNDERSTORMS WILL BE FROM LATE MORNING
THROUGH EARLY EVENING THURSDAY.

FOLLOWING THE FRONTAL PASSAGE...FLOW ACROSS THE REGION WILL BECOME
MORE ZONAL AND THE REAL COLD ADVECTION WILL NOT SET UP UNTIL
SATURDAY.  WITH WLY FLOW SETTING UP AS THE MAIN SFC LOW MOVES
THROUGH WISCONSIN AND CENTRAL LAKE MICHIGAN EARLY FRIDAY...THERE
WILL STILL BE AN OPPORTUNITY FOR TEMPS IN THE UPPER 60S TO AROUND
70S.  A SECONDARY COLD FRONT SHOULD PUSH SOUTH ACROSS THE REGION
FRIDAY EVENING AND THE UPPER LOW CENTER PUSHED OVER THE ERN GREAT
LAKES.

THE EXTENDED FORECAST PERIOD...SATURDAY THROUGH TUESDAY...SHOULD BE
THE AFOREMENTIONED COOL/WET PERIOD.  BY SATURDAY...CANADIAN HIGH
PRESSURE WILL NOSE SOUTH ACROSS THE UPPER MIDWEST...SETTING UP AN
EXTENDED PERIOD OF SELY TO ELY FLOW OFF OF THE COLD WATERS OF LAKE
MICHIGAN.  ANOTHER DEVELOPING LOW PRESSURE SYSTEM IS EXPECTED TO
DEVELOP OVER THE PLAINS OVER THE WEEKEND WITH A MAIN LOW OVER THE
DAKOTAS AND A TRIPLE POINT LOW OVER THE CNTRL PLAINS.  A WARM FRONT
EXTENDING EAST OF THE TRIPLE POINT WILL BE KEPT SOUTH OF THE LOCAL
AREA BY THE CANADIAN HIGH PRESSURE...SO THERE WILL BE LITTLE
OPPORTUNITY FOR SIGNIFICANT WARMING THROUGH THE WEEKEND.  WHEN THE
SYSTEM FINALLY REACHES THE MIDWEST BY EARLY NEXT WEEK...THE MAIN LOW
WILL DISSIPATE AND THE TRIPLE POINT LOW WILL DEEPEN...BUT THERE IS
DECENT AGREEMENT AMONG THE LONGER RANGE GUIDANCE THAT THIS SFC LOW
SHOULD SLIDE SOUTH OF THE CWA...THROUGH SRN IL AND INTO THE OHIO
VALLEY.  SO...WARM SECTOR AIR WILL LIKELY NEVER REACH THIS FAR
NORTH...SO TEMPERATURES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN WELL BELOW NORMAL...MIDDLE 40S TO MIDDLE 50S...WITH
PERIODIC CHANCES FOR RAIN.

KREIN

&&

.AVIATION...

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

* NONE

IZZI

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

HIGH PRESSURE IS TO OUR WEST WITH NORTHWEST FLOW OVER MUCH OF THE
REGION. A LAKE BREEZE IS NOW VISIBLE ON RADAR AND RIGHT NOW IT
DOES NOT APPEAR TO BE MOVING VERY MUCH. WINDS WILL TURN EAST AT
MDW ARND 1830Z AND EXPECTING THE LAKE BREEZE TO REACH ORD BY 20Z.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
WEAKENING BUT REMAINING NE ACROSS THE REGION. THE NEXT LOW
PRESSURE SYSTEM MOVES OVER THE CENTRAL PLAINS TOMORROW AND VFR CIGS
WILL THICKEN FROM THE LATE MORNING THROUGH THE AFTN. WENT ON THE
SLOW SLIDE OF PRECIP AND THINK IT WILL MOVE INTO NORTH CENTRAL IL
AFTER 18Z AND THEN IMPACT THE EASTERN TERMINALS AFTER 00Z. WINDS
REMAIN E TO SE AT 5-9 KT TOMORROW.

JEE

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

* MEDIUM-HIGH CONFIDENCE THAT PRECIP WILL REMAIN EAST OF THE
  TERMINALS THROUGH 00Z THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/IZZI

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

WEDNESDAY NIGHT...CHANCE OF SHOWERS...OTHERWISE VFR.

THURSDAY...SHRA/TSRA LIKELY WITH PERIODS OF MVFR CIGS/VSBYS IN
THUNDERSTORMS.

FRIDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
253 PM CDT

HIGH PRESSURE STRETCHES FROM THE UPPER MIDWEST INTO THE CENTRAL
PLAINS AND WILL BECOME CENTERED OVER LAKE MICHIGAN BY MIDDAY
WEDNESDAY. AS THIS OCCURS...WINDS WILL CONTINUE TO SLOWLY
DIMINISH...WITH LAKE BREEZES DEVELOPING THIS AFTERNOON AND AGAIN
WEDNESDAY AFTERNOON. LOW PRESSURE WILL MOVE ACROSS THE PLAINS
WEDNESDAY NIGHT WITH SOUTHEAST FLOW BEGINNING TO RAMP UP.
SOUTHEAST FLOW WILL INCREASE WITH SUSTAINED WINDS TO AROUND 25
KT...BUT STABLE CONDITIONS WILL HELP KEEP GUSTS TO AROUND 30 KT.
WINDS TURN SOUTHWEST THURSDAY NIGHT INTO EARLY FRIDAY AS THE LOW
LIFTS ACROSS LAKE MICHIGAN...THEN TURN NORTHWEST BY LATER IN THE
DAY FRIDAY AS A COLD FRONT SWEEPS ACROSS THE LAKE.

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 222031
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
331 PM CDT TUE APR 22 2014

.DISCUSSION...
330 PM CDT

THE GENERAL TREND FOR THE NEXT SEVERAL DAYS SHOULD BE FOR A PERIOD
OF COOL AND DRY...FOLLOWED BY WARM AND WET...AND THEN COOL AND WET.

FOR THE REMAINDER OF THE AFTERNOON...SUNNY SKIES WITH SEASONABLE
TEMPERATURES WILL PREVAIL.  HOWEVER...A A VERY WEAK PRESSURE
GRADIENT OVER THE REGION AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES...COMBINED WITH
DIFFERENTIAL HEATING BETWEEN THE WARMER LAND AND COLDER LAKE
MICHIGAN WATER...HAS GENERATED A LAKE BREEZE BOUNDARY...WHICH HAS
MOVED INLAND INTO NERN IL/NWRN IN.  TEMPERATURES ALONG THE LAKEFRONT
HAVE DROPPED INTO THE MIDDLE 40S...COMPARED WITH UPPER 50S TO LOWER
60S WELL INLAND.  FOR THE OVERNIGHT HOURS...THE CONCERN WILL BE
OVERNIGHT LOW TEMPERATURES AND A CHANCE FOR FROST.  SKIES SHOULD
REMAIN MOSTLY CLEAR WITH VERY LIGHT WINDS.  ALSO...THE AIRMASS WILL
CONTINUE TO DRY OUT WITH SFC DEWPOINTS DROPPING INTO THE UPPER 20S
TO LOWER 30S.  SINCE ABUNDANT SUNSHINE TODAY HAS WARMED THE
GROUND...DO NOT EXPECT THAT SFC TEMPS WILL RADIATE DOWN TO THE
DEWPOINT...BUT DO EXPECT TEMPS SHOULD DROP INTO THE LOWER 30S AWAY
FROM THE LAKEFRONT AND THE HEAVILY URBANIZED AREAS OF THE CHICAGO
METRO AREA.  ALSO...THE PONTIAC AREA SHOULD SEE TEMPS ONLY DROPPING
DOWN TO ARND 35F...SO WILL CONTINUE TO MENTION THE POSSIBILITY OF
AREAS OF FROST FOR LOCATIONS WHERE THE OVERNIGHT LOW TEMPERATURE
WILL DROP BELOW 35F.

WEDNESDAY SHOULD START OUT COOL AND DRY...BUT THE NEXT UPSTREAM
SYSTEM WILL BRING INCREASING CHANCES FOR RAIN DURG THE AFTERNOON
HOURS.  THE LATEST GUIDANCE TRENDS HAVE BEEN FOR A SLIGHTLY DELAYED
ONSET OF PCPN...LARGELY DUE TO THE VERY DRY LOW LEVELS WHICH WILL BE
SLOW TO SATURATE AND THE SLOW MOVEMENT OF THE HIGH PRESSURE PUSHING
OFF TO THE EAST.  INITIALLY...PCPN SHOULD START OUT AS OVERRUNNING
SHOWERS IN ADVANCE OF A DEVELOPING WARM FRONT LIFTING NEWD THROUGH
THE REGION.  THERE COULD BE A MINIMA IN PCPN WEDNESDAY NIGHT AS THE
WARM SECTOR AIR OVERSPREADS NRN IL/NWRN IN...BUT THERE WILL STILL BE
A LOW CHANCE FOR SOME SHOWERS...AND ANY PCPN WOULD LIKELY BE
ISOLD/SCT.  THE GREATER CHANCES FOR MORE WIDESPREAD AND HEAVIER PCPN
WILL COME BY THURSDAY.  THIS WILL BE THE WARM/WET PERIOD PREVIOUSLY
MENTIONED AS GENERALLY SOUTHERLY FLOW PREVAILS AHEAD OF AN
APPROACHING COLD FRONT WITH FLOW OFF OF A WIDE OPEN GULF OF MEXICO.
EXPECT THAT TEMPERATURES WILL REACH INTO THE LOWER TO MIDDLE 60S
WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S.  THE EXCEPTION TO THIS
MAY BE THE LAKE COUNTY ILLINOIS LAKEFRONT...INCLUDING THE WAUKEGAN
AREA...WHERE A WINDS SHOULD BE SLIGHTLY EAST OF SOUTH AND BRING SOME
LAKE COOLED AIR INLAND...KEEPING TEMPS IN THE LOWER 50S.  DOWNTOWN
CHICAGO COULD ALSO SEE SOME LAKE INFLUENCE...WITH TEMPERATURES
DROPPING OFF AFTER REACHING AN EARLY AFTERNOON HIGH AROUND 60F.  THE
MODELS HAVE TRENDED TOWARD A RELATIVELY CONSISTENT SOLUTION WITH
THIS SYSTEM WITH ONLY SOME SLIGHT TIMING ISSUES WITH THE SPEED OF
THE FRONT.  HAVE GONE WITH A FAIRLY BROAD BAND OF CATEGORICAL POPS
ALONG AND JUST AHEAD OF THE FRONT.  THE LATEST GUIDANCE ALSO
INDICATES INCREASING SFC BASED INSTABILITY AHEAD OF THE FRONT...SO
WILL CARRY AND CHANCE OF THUNDERSTORMS WITH THE PCPN.  SINCE THE
GREATEST INSTABILITY SHOULD BE SOUTH OF THE CWA...HAVE KEPT THE
PROBABILITY OF THUNDER LOWER THAN THE PROBABILITY OF PCPN...THOUGH
EXPECT THAT MUCH OF THE AREA SHOULD SEE AT LEAST SOME THUNDER AS THE
FRONT SWEEPS ACROSS THE REGION.  AS FOR THE SEVERE POTENTIAL...THE
DAY 3 SPC OUTLOOK COVERS THE CWA IN A "SEE TEXT" AREA.  A STRONG
SWLY LOW LEVEL JET OF 45-50 KT ABOVE 10-15KT SELY WINDS COMBINED
WITH MODEST CAPE COULD BRING A CHANCE FOR SOME STRONGER
STORMS...ESPECIALLY FOR THE SOUTHERN PORTIONS OF THE CWA.  THE TIME
OF GREATEST OPPORTUNITY FOR THUNDERSTORMS WILL BE FROM LATE MORNING
THROUGH EARLY EVENING THURSDAY.

FOLLOWING THE FRONTAL PASSAGE...FLOW ACROSS THE REGION WILL BECOME
MORE ZONAL AND THE REAL COLD ADVECTION WILL NOT SET UP UNTIL
SATURDAY.  WITH WLY FLOW SETTING UP AS THE MAIN SFC LOW MOVES
THROUGH WISCONSIN AND CENTRAL LAKE MICHIGAN EARLY FRIDAY...THERE
WILL STILL BE AN OPPORTUNITY FOR TEMPS IN THE UPPER 60S TO AROUND
70S.  A SECONDARY COLD FRONT SHOULD PUSH SOUTH ACROSS THE REGION
FRIDAY EVENING AND THE UPPER LOW CENTER PUSHED OVER THE ERN GREAT
LAKES.

THE EXTENDED FORECAST PERIOD...SATURDAY THROUGH TUESDAY...SHOULD BE
THE AFOREMENTIONED COOL/WET PERIOD.  BY SATURDAY...CANADIAN HIGH
PRESSURE WILL NOSE SOUTH ACROSS THE UPPER MIDWEST...SETTING UP AN
EXTENDED PERIOD OF SELY TO ELY FLOW OFF OF THE COLD WATERS OF LAKE
MICHIGAN.  ANOTHER DEVELOPING LOW PRESSURE SYSTEM IS EXPECTED TO
DEVELOP OVER THE PLAINS OVER THE WEEKEND WITH A MAIN LOW OVER THE
DAKOTAS AND A TRIPLE POINT LOW OVER THE CNTRL PLAINS.  A WARM FRONT
EXTENDING EAST OF THE TRIPLE POINT WILL BE KEPT SOUTH OF THE LOCAL
AREA BY THE CANADIAN HIGH PRESSURE...SO THERE WILL BE LITTLE
OPPORTUNITY FOR SIGNIFICANT WARMING THROUGH THE WEEKEND.  WHEN THE
SYSTEM FINALLY REACHES THE MIDWEST BY EARLY NEXT WEEK...THE MAIN LOW
WILL DISSIPATE AND THE TRIPLE POINT LOW WILL DEEPEN...BUT THERE IS
DECENT AGREEMENT AMONG THE LONGER RANGE GUIDANCE THAT THIS SFC LOW
SHOULD SLIDE SOUTH OF THE CWA...THROUGH SRN IL AND INTO THE OHIO
VALLEY.  SO...WARM SECTOR AIR WILL LIKELY NEVER REACH THIS FAR
NORTH...SO TEMPERATURES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN WELL BELOW NORMAL...MIDDLE 40S TO MIDDLE 50S...WITH
PERIODIC CHANCES FOR RAIN.


KREIN

&&

.AVIATION...

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

* NE ARND 10 KT WITH GUSTS ARND 15 KT THIS AFTN.

* GUSTS DIMINISH THIS EVENING BUT WINDS REMAIN EAST THROUGH
  TOMORROW 5-9 KT.

JEE

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

HIGH PRESSURE IS TO OUR WEST WITH NORTHWEST FLOW OVER MUCH OF THE
REGION. A LAKE BREEZE IS NOW VISIBLE ON RADAR AND RIGHT NOW IT
DOES NOT APPEAR TO BE MOVING VERY MUCH. WINDS WILL TURN EAST AT
MDW ARND 1830Z AND EXPECTING THE LAKE BREEZE TO REACH ORD BY 20Z.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
WEAKENING BUT REMAINING NE ACROSS THE REGION. THE NEXT LOW
PRESSURE SYSTEM MOVES OVER THE CENTRAL PLAINS TOMORROW AND VFR CIGS
WILL THICKEN FROM THE LATE MORNING THROUGH THE AFTN. WENT ON THE
SLOW SLIDE OF PRECIP AND THINK IT WILL MOVE INTO NORTH CENTRAL IL
AFTER 18Z AND THEN IMPACT THE EASTERN TERMINALS AFTER 00Z. WINDS
REMAIN E TO SE AT 5-9 KT TOMORROW.

JEE

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

* MEDIUM-HIGH CONFIDENCE THAT PRECIP WILL REMAIN EAST OF THE
  TERMINALS THROUGH 00Z THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

WEDNESDAY NIGHT...CHANCE OF SHOWERS...OTHERWISE VFR.

THURSDAY...SHRA/TSRA LIKELY WITH PERIODS OF MVFR CIGS/VSBYS IN
THUNDERSTORMS.

FRIDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
253 PM CDT

HIGH PRESSURE STRETCHES FROM THE UPPER MIDWEST INTO THE CENTRAL
PLAINS AND WILL BECOME CENTERED OVER LAKE MICHIGAN BY MIDDAY
WEDNESDAY. AS THIS OCCURS...WINDS WILL CONTINUE TO SLOWLY
DIMINISH...WITH LAKE BREEZES DEVELOPING THIS AFTERNOON AND AGAIN
WEDNESDAY AFTERNOON. LOW PRESSURE WILL MOVE ACROSS THE PLAINS
WEDNESDAY NIGHT WITH SOUTHEAST FLOW BEGINNING TO RAMP UP.
SOUTHEAST FLOW WILL INCREASE WITH SUSTAINED WINDS TO AROUND 25
KT...BUT STABLE CONDITIONS WILL HELP KEEP GUSTS TO AROUND 30 KT.
WINDS TURN SOUTHWEST THURSDAY NIGHT INTO EARLY FRIDAY AS THE LOW
LIFTS ACROSS LAKE MICHIGAN...THEN TURN NORTHWEST BY LATER IN THE
DAY FRIDAY AS A COLD FRONT SWEEPS ACROSS THE LAKE.

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 222000
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
300 PM CDT Tue Apr 22 2014

.DISCUSSION...
ISSUED 259 PM CDT Tue Apr 22 2014

Breezy conditions persist across central and southeast Illinois
this afternoon between yesterday`s departing cold front and an
approaching ridge of high pressure. The ridge will continue to
dominate the weather for Wednesday, keeping quiet conditions in
place. The next storm system is still on track for Thursday, with
an associated risk of showers/thunderstorms. The precipitation
threat for the end of the weekend into early next week remains
murky as a slow moving system, part of a developing Rex block,
moves through our vicinity. Main forecast problems today remain
trying to pin point precipitation chances/timing with these two
systems.

SHORT TERM...Tonight through Friday:

The ridge of high pressure to our west will push into the forecast
area overnight. The main concern with the arrival of the ridge is
if temperatures will fall enough to pose a threat of frost. At
this point, forecast lows are only marginal for frost in most
areas. Also, winds appear as though they may stay up enough to
mitigate the frost threat. If winds die off quickly this evening,
the frost threat will need to be looked at more closely.

Return flow on the back side of the ridge increases on Wednesday,
with a warm frontal zone setting up to the east of a developing
storm system in the plains. Many model solutions persist in trying
to produce some precipitation in this warm advection regime,
Wednesday afternoon/evening, mainly across northern portions of
the forecast area. Still feel there is likely to be too much dry
air to overcome initially and that models are a little too
bullish. With this thinking in mind, plan to keep forecast dry
until overnight Wednesday night when some precipitation may begin
to slip in ahead of Thursday`s system.

Showers/storms still expected to spread from west to east on
Thursday as storm system crosses the forecast area. Severe threat
expected to be low overall due to low instability (CAPE values
below 1000 j/kg for the most part), and modest shear profiles
(bulk shear values no better than 35-40 kts). Drier conditions
quickly filter in behind the cold front associated with the system
overnight Thursday into Friday, although the post frontal airmass
is not especially cool.

LONG TERM...Saturday through Tuesday:

Attention turns to the Rex block expected to develop during the
period as we head into the extended range of the forecast. The
ECMWF has been the most aggressive by far with the return of
precipitation chances over the weekend, but it has backed off a
bit in its 12Z run. In any event, once the upper low with the Rex
block is in the vicinity, period of showers and some thunderstorms
are likely for at least a few days. However, due to the model
spread, run-to-run inconsistency, and intra-model ensemble spread,
confidence remains quite low in the details. Unfortunately, this
results in several periods of chance PoPs, starting Saturday
night. Hopefully, a clear consensus with the ultimate forecast
solution will emerge soon. However, considering the trouble models
have entering (and leaving) blocky patterns, we may be waiting a
while.

Bak
&&

.AVIATION...
ISSUED 1225 PM CDT Tue Apr 22 2014
High pressure dominating the forecast. SKC and breezy northerly
winds with gusts 20-24kts today. Will slowly see the gusts dwindle
after sunset and the winds decouple again. High level moisture
will stream some cirrus into the region and winds will become more
east/northeasterly later tonight, and lighter under the ridge as
the high shifts east. Though model time heights indicate some
moisture working into 850-700mb layer...clouds not in guidance...high
pressure still in place...and will avoid any additional mention
at this time.

HJS
&&

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

$$








000
FXUS63 KLOT 221954
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
254 PM CDT TUE APR 22 2014

.DISCUSSION...
343 AM CDT

HIGHLIGHTS INCLUDE COOL/DRY CONDITIONS TODAY INTO WEDNESDAY...THEN
PRECIP POTENTIAL WITH NEXT LOW PRESSURE AND FRONTAL SYSTEM MOVING
THROUGH THE AREA THURSDAY. BRIEFLY MILD CONDITIONS FRIDAY...THEN
MUCH COOLER WEATHER AHEAD IN THE EXTENDED.

EARLY MORNING SURFACE ANALYSIS INDICATES COLD FRONT JUST CLEARING
FAR SOUTHEAST COUNTIES AT 08Z...WITH COOLER AND DRIER AIR PUSHING IN
ON NORTH-NORTHWEST WINDS BEHIND THE FRONT. SHOWERS HAVE MOVED EAST
OF THE CWA...WITH CLEARING SKIES FROM THE NORTHWEST PER GOES 11-3.9
MICRON IMAGERY. MOSTLY SUNNY...BREEZY AND COOLER CONDITIONS IN STORE
FOR TODAY IN POST-FRONTAL AIR MASS...WITH ONSHORE WINDS ALONG THE
LAKE KEEPING TEMPS EVEN COOLER NEAR THE LAKE. WHILE FAR
WEST/SOUTHWEST PARTS OF THE FORECAST AREA WILL LIKELY TOUCH THE 60
DEGREE MARK PER GUIDANCE...MID-40S TO MID-50S EXPECTED CLOSER TO THE
LAKE. SURFACE HIGH PRESSURE RIDGE MOVES INTO THE REGION TONIGHT AND
SETS THE STAGE FOR SOME CHILLY LATE APRIL MINS...AND HAVE MENTIONED
SOME PATCHY FROST ACROSS PARTS OF NORTHERN IL/NORTHWEST IND AWAY
FROM THE CITY. PATCHY FROST NOT AS LIKELY FAR WEST WHERE AN INCREASE
IN HIGH CLOUDS IS EXPECTED FROM THE WEST TOWARD MORNING.

SURFACE RIDGE MOVES OFF TO THE EAST ON WEDNESDAY...AS
SOUTH-SOUTHEAST WINDS INCREASE ACROSS THE PLAINS AND MISSISSIPPI
VALLEY AHEAD OF AFOREMENTIONED TROUGH AND ASSOCIATED SURFACE LOW
PRESSURE DEVELOPING ACROSS THE PLAINS. EASTERLY COMPONENT OF LOW
LEVEL FLOW MAINTAINS DRY AIR ACROSS THE WESTERN LAKES WEDNESDAY AS
INDICATED BY DRY TIME/HEIGHT SECTIONS. SHALLOW MIXING AND EAST
SURFACE WINDS DO NOT SUPPORT MUCH WARMING OVER TODAYS TEMPS...AND
LOOKS EVEN A FEW DEGREES COOLER ACROSS PARTS OF NORTH/NORTHEAST IL.
MODELS STEADFAST IN DEVELOPING PRECIP ACROSS AREA BY WEDNESDAY
AFTERNOON...THOUGH APPEARS QPF IS OVERDONE AND SUSPECT MAINLY JUST
SOME LIGHT SHOWERS/SPRINKLES FROM MID-LEVEL CLOUD BASES WEDNESDAY
AFTERNOON INTO WEDNESDAY NIGHT WITH ELEVATED WARM FRONT. MUCH BETTER
RAIN CHANCES ARRIVE ON THURSDAY AS UPPER TROUGH APPROACHES AND LOW
LEVEL WINDS TURN SOUTHERLY AND SPREAD PRE-COLD FRONTAL MOISTURE AXIS
INTO THE FORECAST AREA. WRF/SREF ARE QUICKER TO MOVE FRONT THROUGH
THURSDAY AFTERNOON...BUT PREFER THE CONSISTENTLY SLOWER SOLUTION
FROM THE GLOBAL ECMWF/GFS/GEM WHICH BRING THE FRONT THROUGH A FEW
HOURS SLOWER. IN ANY CASE...BEST PRECIP POTENTIAL SHOULD BE
ASSOCIATED WITH LOW LEVEL MOISTURE POOL ALONG AND AHEAD OF THE FRONT
AND MAINTAINED HIGHEST POPS THURSDAY/THURSDAY EVENING WITH THE ITS
PASSAGE. MODEST LAPSE RATES 6.5-7.0 C/KM ABOVE BOUNDARY LAYER WILL
LIKELY SUPPORT AT LEAST SCATTERED THUNDERSTORMS DURING PERIOD OF
BEST FORCING AHEAD OF THE FRONT. SOUTH-SOUTHEAST WINDS DO PRODUCE
SOME WARMING IN THE TEMP DEPARTMENT...THOUGH SLIGHT EAST COMPONENT
FOR PART OF THE DAY COMBINED WITH CLOUDS/PRECIP AND FAIRLY SHALLOW
BOUNDARY LAYER PER MODEL SOUNDINGS SUGGEST A REPEAT OF THIS
WEEKEND/S 70S/80 IS UNLIKELY. THERMAL FIELDS INDICATE 65-70 FOR
HIGHS ACROSS MUCH OF THE AREA...WITH LOWER 60S CLOSER TO THE IL/WI
BORDER.

LONGER RANGE GUIDANCE SOLUTIONS IN GENERAL AGREEMENT THAT UPPER
TROUGH WILL CLOSE OFF OVER THE NORTHERN LAKES THURSDAY NIGHT INTO
FRIDAY...WITH ANOTHER STRONG VORT WRAPPING AROUND THE SOUTHERN
PERIPHERY OF THE CLOSED UPPER LOW FRIDAY. INITIAL FRONTAL PASSAGE
LATER THURSDAY IS OF PACIFIC NATURE...WITH MILD WESTERLY FLOW FRIDAY
ALLOWING TEMPS BACK INTO THE MID 60S-LOW 70S RANGE. SECONDARY VORT
BRINGS ABOUT PASSAGE OF STRONGER COLD FRONT FROM THE NORTH WITH THE
POTENTIAL FOR A FEW SHOWERS BY LATE FRIDAY HOWEVER...STARTING THE
TRANSITION TO A COOLER REGIME WHICH LOOKS TO LINGER THROUGH THE
WEEKEND AND EARLY NEXT WEEK. EXTENDED GUIDANCE IN CLOSE AGREEMENT IN
DEVELOPING SLOW-MOVING CLOSED LOW OVER THE PLAINS AND SLOWING OUR
PREVIOUSLY PROGRESSIVE FLOW. COLD FRONT BECOMES STATIONARY ACROSS
THE OHIO VALLEY TO OUR SOUTH...WITH COOL HIGH PRESSURE ANCHORED
NORTH OF THE LAKES. COOL/DRY EASTERLY FLOW PREVAILS SATURDAY THROUGH
MONDAY...THOUGH SOME POTENTIAL FOR PRECIP DOES EXIST BENEATH
ELEVATED BAROCLINIC ZONE ASSOCIATED WITH STALLED FRONT TO OUR
SOUTH...ESPECIALLY LATER IN THE PERIOD (SUN-MON). EAST-NORTHEAST LOW
LEVEL WIND REGIME SUPPORTS WELL BELOW NORMAL TEMPS WITH HIGHS IN THE
40S/50S AND LOWS IN THE 30S. REMAINDER OF WEEK LOOKS SIMILARLY COOL
AS UPPER LOW VERY SLOWLY TRANSITS THE MIDWEST.

RATZER

&&

.AVIATION...

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

* NE ARND 10 KT WITH GUSTS ARND 15 KT THIS AFTN.

* GUSTS DIMINISH THIS EVENING BUT WINDS REMAIN EAST THROUGH
  TOMORROW 5-9 KT.

JEE

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

HIGH PRESSURE IS TO OUR WEST WITH NORTHWEST FLOW OVER MUCH OF THE
REGION. A LAKE BREEZE IS NOW VISIBLE ON RADAR AND RIGHT NOW IT
DOES NOT APPEAR TO BE MOVING VERY MUCH. WINDS WILL TURN EAST AT
MDW ARND 1830Z AND EXPECTING THE LAKE BREEZE TO REACH ORD BY 20Z.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
WEAKENING BUT REMAINING NE ACROSS THE REGION. THE NEXT LOW
PRESSURE SYSTEM MOVES OVER THE CENTRAL PLAINS TOMORROW AND VFR CIGS
WILL THICKEN FROM THE LATE MORNING THROUGH THE AFTN. WENT ON THE
SLOW SLIDE OF PRECIP AND THINK IT WILL MOVE INTO NORTH CENTRAL IL
AFTER 18Z AND THEN IMPACT THE EASTERN TERMINALS AFTER 00Z. WINDS
REMAIN E TO SE AT 5-9 KT TOMORROW.

JEE

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

* MEDIUM-HIGH CONFIDENCE THAT PRECIP WILL REMAIN EAST OF THE
  TERMINALS THROUGH 00Z THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

WEDNESDAY NIGHT...CHANCE OF SHOWERS...OTHERWISE VFR.

THURSDAY...SHRA/TSRA LIKELY WITH PERIODS OF MVFR CIGS/VSBYS IN
THUNDERSTORMS.

FRIDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
253 PM CDT

HIGH PRESSURE STRETCHES FROM THE UPPER MIDWEST INTO THE CENTRAL
PLAINS AND WILL BECOME CENTERED OVER LAKE MICHIGAN BY MIDDAY
WEDNESDAY. AS THIS OCCURS...WINDS WILL CONTINUE TO SLOWLY
DIMINISH...WITH LAKE BREEZES DEVELOPING THIS AFTERNOON AND AGAIN
WEDNESDAY AFTERNOON. LOW PRESSURE WILL MOVE ACROSS THE PLAINS
WEDNESDAY NIGHT WITH SOUTHEAST FLOW BEGINNING TO RAMP UP.
SOUTHEAST FLOW WILL INCREASE WITH SUSTAINED WINDS TO AROUND 25
KT...BUT STABLE CONDITIONS WILL HELP KEEP GUSTS TO AROUND 30 KT.
WINDS TURN SOUTHWEST THURSDAY NIGHT INTO EARLY FRIDAY AS THE LOW
LIFTS ACROSS LAKE MICHIGAN...THEN TURN NORTHWEST BY LATER IN THE
DAY FRIDAY AS A COLD FRONT SWEEPS ACROSS THE LAKE.

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:
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000
FXUS63 KLOT 221942
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
242 PM CDT TUE APR 22 2014

.DISCUSSION...
343 AM CDT

HIGHLIGHTS INCLUDE COOL/DRY CONDITIONS TODAY INTO WEDNESDAY...THEN
PRECIP POTENTIAL WITH NEXT LOW PRESSURE AND FRONTAL SYSTEM MOVING
THROUGH THE AREA THURSDAY. BRIEFLY MILD CONDITIONS FRIDAY...THEN
MUCH COOLER WEATHER AHEAD IN THE EXTENDED.

EARLY MORNING SURFACE ANALYSIS INDICATES COLD FRONT JUST CLEARING
FAR SOUTHEAST COUNTIES AT 08Z...WITH COOLER AND DRIER AIR PUSHING IN
ON NORTH-NORTHWEST WINDS BEHIND THE FRONT. SHOWERS HAVE MOVED EAST
OF THE CWA...WITH CLEARING SKIES FROM THE NORTHWEST PER GOES 11-3.9
MICRON IMAGERY. MOSTLY SUNNY...BREEZY AND COOLER CONDITIONS IN STORE
FOR TODAY IN POST-FRONTAL AIR MASS...WITH ONSHORE WINDS ALONG THE
LAKE KEEPING TEMPS EVEN COOLER NEAR THE LAKE. WHILE FAR
WEST/SOUTHWEST PARTS OF THE FORECAST AREA WILL LIKELY TOUCH THE 60
DEGREE MARK PER GUIDANCE...MID-40S TO MID-50S EXPECTED CLOSER TO THE
LAKE. SURFACE HIGH PRESSURE RIDGE MOVES INTO THE REGION TONIGHT AND
SETS THE STAGE FOR SOME CHILLY LATE APRIL MINS...AND HAVE MENTIONED
SOME PATCHY FROST ACROSS PARTS OF NORTHERN IL/NORTHWEST IND AWAY
FROM THE CITY. PATCHY FROST NOT AS LIKELY FAR WEST WHERE AN INCREASE
IN HIGH CLOUDS IS EXPECTED FROM THE WEST TOWARD MORNING.

SURFACE RIDGE MOVES OFF TO THE EAST ON WEDNESDAY...AS
SOUTH-SOUTHEAST WINDS INCREASE ACROSS THE PLAINS AND MISSISSIPPI
VALLEY AHEAD OF AFOREMENTIONED TROUGH AND ASSOCIATED SURFACE LOW
PRESSURE DEVELOPING ACROSS THE PLAINS. EASTERLY COMPONENT OF LOW
LEVEL FLOW MAINTAINS DRY AIR ACROSS THE WESTERN LAKES WEDNESDAY AS
INDICATED BY DRY TIME/HEIGHT SECTIONS. SHALLOW MIXING AND EAST
SURFACE WINDS DO NOT SUPPORT MUCH WARMING OVER TODAYS TEMPS...AND
LOOKS EVEN A FEW DEGREES COOLER ACROSS PARTS OF NORTH/NORTHEAST IL.
MODELS STEADFAST IN DEVELOPING PRECIP ACROSS AREA BY WEDNESDAY
AFTERNOON...THOUGH APPEARS QPF IS OVERDONE AND SUSPECT MAINLY JUST
SOME LIGHT SHOWERS/SPRINKLES FROM MID-LEVEL CLOUD BASES WEDNESDAY
AFTERNOON INTO WEDNESDAY NIGHT WITH ELEVATED WARM FRONT. MUCH BETTER
RAIN CHANCES ARRIVE ON THURSDAY AS UPPER TROUGH APPROACHES AND LOW
LEVEL WINDS TURN SOUTHERLY AND SPREAD PRE-COLD FRONTAL MOISTURE AXIS
INTO THE FORECAST AREA. WRF/SREF ARE QUICKER TO MOVE FRONT THROUGH
THURSDAY AFTERNOON...BUT PREFER THE CONSISTENTLY SLOWER SOLUTION
FROM THE GLOBAL ECMWF/GFS/GEM WHICH BRING THE FRONT THROUGH A FEW
HOURS SLOWER. IN ANY CASE...BEST PRECIP POTENTIAL SHOULD BE
ASSOCIATED WITH LOW LEVEL MOISTURE POOL ALONG AND AHEAD OF THE FRONT
AND MAINTAINED HIGHEST POPS THURSDAY/THURSDAY EVENING WITH THE ITS
PASSAGE. MODEST LAPSE RATES 6.5-7.0 C/KM ABOVE BOUNDARY LAYER WILL
LIKELY SUPPORT AT LEAST SCATTERED THUNDERSTORMS DURING PERIOD OF
BEST FORCING AHEAD OF THE FRONT. SOUTH-SOUTHEAST WINDS DO PRODUCE
SOME WARMING IN THE TEMP DEPARTMENT...THOUGH SLIGHT EAST COMPONENT
FOR PART OF THE DAY COMBINED WITH CLOUDS/PRECIP AND FAIRLY SHALLOW
BOUNDARY LAYER PER MODEL SOUNDINGS SUGGEST A REPEAT OF THIS
WEEKEND/S 70S/80 IS UNLIKELY. THERMAL FIELDS INDICATE 65-70 FOR
HIGHS ACROSS MUCH OF THE AREA...WITH LOWER 60S CLOSER TO THE IL/WI
BORDER.

LONGER RANGE GUIDANCE SOLUTIONS IN GENERAL AGREEMENT THAT UPPER
TROUGH WILL CLOSE OFF OVER THE NORTHERN LAKES THURSDAY NIGHT INTO
FRIDAY...WITH ANOTHER STRONG VORT WRAPPING AROUND THE SOUTHERN
PERIPHERY OF THE CLOSED UPPER LOW FRIDAY. INITIAL FRONTAL PASSAGE
LATER THURSDAY IS OF PACIFIC NATURE...WITH MILD WESTERLY FLOW FRIDAY
ALLOWING TEMPS BACK INTO THE MID 60S-LOW 70S RANGE. SECONDARY VORT
BRINGS ABOUT PASSAGE OF STRONGER COLD FRONT FROM THE NORTH WITH THE
POTENTIAL FOR A FEW SHOWERS BY LATE FRIDAY HOWEVER...STARTING THE
TRANSITION TO A COOLER REGIME WHICH LOOKS TO LINGER THROUGH THE
WEEKEND AND EARLY NEXT WEEK. EXTENDED GUIDANCE IN CLOSE AGREEMENT IN
DEVELOPING SLOW-MOVING CLOSED LOW OVER THE PLAINS AND SLOWING OUR
PREVIOUSLY PROGRESSIVE FLOW. COLD FRONT BECOMES STATIONARY ACROSS
THE OHIO VALLEY TO OUR SOUTH...WITH COOL HIGH PRESSURE ANCHORED
NORTH OF THE LAKES. COOL/DRY EASTERLY FLOW PREVAILS SATURDAY THROUGH
MONDAY...THOUGH SOME POTENTIAL FOR PRECIP DOES EXIST BENEATH
ELEVATED BAROCLINIC ZONE ASSOCIATED WITH STALLED FRONT TO OUR
SOUTH...ESPECIALLY LATER IN THE PERIOD (SUN-MON). EAST-NORTHEAST LOW
LEVEL WIND REGIME SUPPORTS WELL BELOW NORMAL TEMPS WITH HIGHS IN THE
40S/50S AND LOWS IN THE 30S. REMAINDER OF WEEK LOOKS SIMILARLY COOL
AS UPPER LOW VERY SLOWLY TRANSITS THE MIDWEST.

RATZER

&&

.AVIATION...

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

* NE ARND 10 KT WITH GUSTS ARND 15 KT THIS AFTN.

* GUSTS DIMINISH THIS EVENING BUT WINDS REMAIN EAST THROUGH
  TOMORROW 5-9 KT.

JEE

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

HIGH PRESSURE IS TO OUR WEST WITH NORTHWEST FLOW OVER MUCH OF THE
REGION. A LAKE BREEZE IS NOW VISIBLE ON RADAR AND RIGHT NOW IT
DOES NOT APPEAR TO BE MOVING VERY MUCH. WINDS WILL TURN EAST AT
MDW ARND 1830Z AND EXPECTING THE LAKE BREEZE TO REACH ORD BY 20Z.

HIGH PRESSURE SPREADS OVER THE REGION THIS EVENING WITH WINDS
WEAKENING BUT REMAINING NE ACROSS THE REGION. THE NEXT LOW
PRESSURE SYSTEM MOVES OVER THE CENTRAL PLAINS TOMORROW AND VFR CIGS
WILL THICKEN FROM THE LATE MORNING THROUGH THE AFTN. WENT ON THE
SLOW SLIDE OF PRECIP AND THINK IT WILL MOVE INTO NORTH CENTRAL IL
AFTER 18Z AND THEN IMPACT THE EASTERN TERMINALS AFTER 00Z. WINDS
REMAIN E TO SE AT 5-9 KT TOMORROW.

JEE

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

* MEDIUM-HIGH CONFIDENCE THAT PRECIP WILL REMAIN EAST OF THE
  TERMINALS THROUGH 00Z THURSDAY.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

WEDNESDAY NIGHT...CHANCE OF SHOWERS...OTHERWISE VFR.

THURSDAY...SHRA/TSRA LIKELY WITH PERIODS OF MVFR CIGS/VSBYS IN
THUNDERSTORMS.

FRIDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.

SATURDAY...CHANCE OF SHOWERS LATE...OTHERWISE VFR.

SUNDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

MONDAY...CHANCE OF SHOWERS...OTHERWISE VFR.

RODRIGUEZ

&&

.MARINE...
427 AM CDT

AS LOW PRESSURE EXITED TO THE EAST OF THE LAKE OVERNIGHT...A FRONT
ON THE BACKSIDE PUSHED DOWN THE LAKE. THIS RESULTED IN WINDS
QUICKLY TURNING TO THE NORTHWEST/NORTH WHILE ALSO RAPIDLY
INCREASING. NORTHWEST WINDS TO 30 KT ARE STILL ONGOING AT THIS
TIME BUT EXPECT THEM TO DIMINISH THIS MORNING AND THROUGHOUT THE
DAY AS HIGH PRESSURE WELL TO THE WEST OF THE LAKE MOVES EAST TODAY
INTO WEDNESDAY. WITH THIS STRONGER NORTHERLY FLOW IN
PLACE...EXPECT BUILDING WAVES THIS MORNING TO RESULT IN HAZARDOUS
CONDITIONS FOR SMALL CRAFT IN THE NEARSHORE THROUGH THIS
AFTERNOON...BEFORE WAVES SUBSIDE INTO THE EVENING. DIMINISHING
WIND TREND WILL CONTINUE INTO WEDNESDAY AS THIS HIGH PRESSURE
MOVES OVERHEAD. A SLOW INCREASING TREND OUT OF THE SOUTHEAST WILL
ONCE AGAIN OCCUR WEDNESDAY NIGHT INTO THURSDAY AS NEW LOW PRESSURE
APPROACHES FROM THE WEST.

RODRIGUEZ

&&

.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






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