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000
FXUS63 KLOT 251543
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1043 AM CDT SAT OCT 25 2014

.DISCUSSION...
314 AM CDT

SHORT TERM...THROUGH SATURDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO SATURDAY MORNING...THE INITIAL
CONCERNS WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  A WEAK
MID LEVEL IMPULSE THAT TRACKED ACROSS THE REGION FRIDAY EVENING
BROUGHT SOME SCT SPRINKLES.  AS THE MID AND HIGH CLOUD PUSHES AWAY
FROM THE AREA...FOG AND LOW STRATUS ARE BLOOMING.  NWRN IL AND ERN
IA HAVE ALREADY SEEN DENSE FOG AND LOW STRATUS FORM...AND IN THE
MOIST AIRMASS IN PLACE...WITH DEWPOINTS IN THE LOW 50S...EXPECT THAT
THE AREA OF FOG/STRATUS SHOULD INCREASE...THOUGH THE LOWEST
CONDITIONS SHOULD BE ALONG AND WEST OF THE I-39 CORRIDOR.  EAST OF
I-39...ANY DENSE FOG SHOULD BE LIMITED TO SHELTERED...LOW-LYING
AREAS.

THROUGH THE MORNING HOURS...A WEAK FRONTAL BOUNDARY WILL CROSS THE
AREA...WITH SFC HIGH PRESSURE BUILDING ACROSS THE CNTRL PLAINS WHILE
UPPER LEVEL RIDGING ALSO BUILDS OUT OF THE ROCKIES AND ACROSS THE
CENTRAL PLAINS.  THE UPPER RIDGING WILL SET UP A SUBSIDENCE PATTERN
ACROSS THE AREA...LEADING TO MOSTLY SUNNY SKIES.  LOW PRESSURE
MOVING THROUGH SERN CANADA...COMBINED WITH THE HIGH PRESSURE OVER
THE PLAINS WILL SET UP A GENERALLY NWLY GRADIENT ACROSS NRN IL/IN.
DAYTIME WARMING SHOULD ALLOW ANY RESIDUAL FOG/STRATUS TO DISSIPATE
BY LATE MORNING...WHILE THE AMPLE SUNSHINE AND LARGER SCALE
SUBSIDENCE SHOULD ALLOW TEMPERATURES TO QUICKLY RISE INTO THE LOWER
70S ACROSS THE SRN PORTIONS OF THE CWA...WHILE LOCATION CLOSER TO
THE WI BORDER WILL BE A BIT COOLER...BUT STILL SIGNIFICANTLY WARMER
THAN NORMAL...WITH HIGHS IN THE UPPER 60S.  STEADY NWLY WINDS AT THE
SFC AND ALOFT SHOULD PREVENT ANY KIND OF LAKE BREEZE FROM FORMING
AND THE WARMER AIR SHOULD COVER THE AREA UP TO THE LAKEFRONT.  WHILE
DEWPOINTS WILL BE IN THE 50S FOR THE MORNING HOURS...DEEP MIXING
SHOULD DRAW MUCH DRIER AIR TO THE SFC...WITH DEWPOINTS DROPPING INTO
THE UPPER 30S FOR THE AFTERNOON HOURS.  SO...OVERALL...SATURDAY IS
SHAPING UP TO A VERY PLEASANT DAY...WITH TEMPERATURES AROUND 10
DEGREES ABOVE NORMAL.  THE SFC HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI VALLEY AND INTO THE MIDWEST OVERNIGHT TONIGHT WHILE THE
UPPER RIDGE SLOWLY PROGRESSES AS WELL.  WITH A DRIER AIRMASS IN
PLACE TONIGHT...THE CHANCES FOR ANOTHER ROUND OF FOG AND STRATUS IS
UNLIKELY...THROUGH THE CLEAR SKIES...LIGHT WINDS AND LOWER DEWPOINTS
SHOULD ALLOW TEMPERATURES TO RADIATE DOWN INTO THE UPPER 30S TO
LOWER 40S.  THE CHICAGO AREA URBAN HEAT ISLAND SHOULD REMAIN A
LITTLE WARMER...WITH LOWS IN THE MIDDLE 40S.

KREIN

SUNDAY THROUGH TUESDAY...
GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN THE MEDIUM TERM FEATURING
MID-LVL RIDGING OVER THE UPPER MIDWEST/GREAT LAKES REGION WITH A SFC
RIDGE PROVIDING ABUNDANT SUNSHINE AND DRY CONDS FOR THE SECOND HALF
OF THE WEEKEND. HOWEVER THIS RIDGE WILL ONLY BE TEMPORARY AS THE
MID-LVL HEIGHTS BEGIN TO FALL AND A QUASI-ZONAL FLOW BEGINS TO SETUP
FOR EARLY NEXT WEEK. FORTUNATELY IT REMAINS LIKELY THAT MON WILL
REMAIN DRY...WITH VERY MILD TEMPS EXPECTED. THE SFC RIDGE WILL BE
SHIFTING EAST OF THE FORECAST AREA...BUT SHOULD CONTINUE TO KEEP
CLOUDS TO A MINIMUM AND PRECIP WEST OF THE AREA. THE COMBINATION OF
THIS AND AN ANOMALOUS THERMAL RIDGE WILL ALLOW TEMPS TO SOAR INTO
THE MID/UPR 70S...WITH A FEW 80 DEGREE READINGS IN THE SOUTHERN CWFA
MON AFTN.

BROAD SFC TROUGH OVER THE CENTRAL/NORTHERN PLAINS WILL SLOWLY
CONSOLIDATE AS THIS FEATURE NEARS THE GREAT LAKES MON EVE. THERE IS
A SMALL CHANCE THAT A FEW SHOWERS/THUNDERSTORMS COULD SKIRT THE
NORTHERN CWFA MON AFTN...BUT EXPECT THE BULK OF THE PRECIP TO OCCUR
POST SUNSET. MID-LVL TROUGH WILL AMPLIFY ACROSS THE CENTRAL PLAINS
TUE MORNING...AS THE SFC LOW DEEPENS ACROSS LOWER MICHIGAN. HAVE
HELD ONTO THE MENTION OF THUNDER INTO TUE MORNING...AS IT APPEARS
SOME INSTABILITY/FORCING WILL CONTINUE. MON NGT TEMPS WILL LIKELY
NOT FALL MUCH...PRODUCING A MILD OVERNIGHT. THEN FOR TUE WITH
CONTINUED CLOUD COVER/PRECIP...EXPECT TEMPS TO REMAIN IN THE UPR
50S/LOW 60S. DEPENDING ON THE TIMING OF THE FROPA TUE...TEMPS COULD
BEGIN TO FALL TUE AFTN INTO THE LOW 50S.

WEDNESDAY THROUGH FRIDAY...
FOR THE SECOND HALF OF THE WEEK IT APPEARS THE PATTERN WILL BE
TRANSITIONING TOWARDS A COOLER AND SOMEWHAT ACTIVE SETUP. ENSEMBLES
CONTINUE TO PROG MID-LVL RIDGING DEVELOPING ACROSS THE WESTERN
CONUS...ALLOWING BROAD TROUGHING DOWNSTREAM FOR THE GREAT LAKES
REGION WED/THUR. THEN FRI THE 500MB RIDGE MAY BEGIN TO FURTHER
AMPLIFY AS A POTENT SHORTWAVE IS PROGGED TO APPROACH THE PAC-NW AND
RIDGING REMAINS ACROSS THE NORTH ATLANTIC. TROUGHING WILL LINGER
ACROSS THE GREAT LAKES FRI. TEMPS WILL TREND BACK TOWARDS
SEASONAL...WITH PERHAPS FRI BEING SUB-SEASONAL WITH HIGHS IN THE UPR
40S/LOW 50S. PERIODIC CHANCES FOR SHOWERS THROUGHOUT THE EXTENDED
TIMEFRAME.

BEACHLER

&&

.AVIATION...

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

* GUSTY NW WINDS WITH GUSTS 20-24 KT.

JEE

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE HAVE PASSED EAST OF THE
REGION...CLEARING OUT THE MID AND HIGH CLOUD. RESIDUAL MOISTURE
HAS ALLOWED FOG AND LOW STRATUS TO DEVELOP...DROPPING CIGS/VIS
INTO IFR RANGES...WITH THE LOWEST CONDITIONS OVER THE RFD AREA
WHICH CLEARED FIRST. THE STRATUS AND FOG WILL BURN OFF BY ARND 14Z
AS DRIER AIR FILTERS INTO THE REGION. THE MAIN ISSUE FOR THE
REMAINDER OF THE DAY WILL BE WINDS. FOLLOWING THE PASSAGE OF THE
WEAK SFC TROUGH...HIGH PRESSURE BUILDING OVER THE NRN PLAINS WILL
SET UP A STRENGTHENING WNWLY-NWLY GRADIENT OVER THE AREA. WITH
AMPLE MIXING THROUGH THE AFTERNOON...WINDS SHOULD BECOME MORE
GUSTY...WITH GUSTS TO OR SLIGHTLY IN EXCESS OF 20KT THROUGH SUNSET.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

JEE

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

MONDAY...VFR/WX NIL BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA EARLY. MVFR POSSIBLE EARLY. WEST WINDS.

WEDNESDAY...VFR/WX NIL. WEST WINDS DAYTIME...BECMG SLY WEDNESDAY
NIGHT.

THURSDAY...SLIGHT CHANCE SHRA DAYTIME. VFR. SOUTHWEST WINDS
VEERING TO NLY BY EARLY EVENING AND OVERNIGHT.

FRIDAY...VFR/WX NIL. NORTH WINDS.

KREIN

&&

.MARINE...
229 AM CDT

LOW PRESSURE OVER JAMES BAY ALONG WITH A SFC RIDGE CENTERED OVER
THE NORTHERN PLAINS HAS CREATED A TIGHT PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS...WHICH IS POSITIONED OVER THE LAKE. THIS HAS
RESULTED IN BREEZY SOUTHWEST WINDS OVER THE LAKE WITH SPEEDS
GENERALLY BETWEEN 20-25KT. ACROSS THE NORTHERN HALF OF THE LAKE
THE GUSTS MAY NEAR 30 KT THIS MORNING. AS HIGH PRESSURE SLOWLY
BUILDS IN FROM THE WEST ACROSS THE LAKE...WIND WILL TURN
WEST/NORTHWEST AND GRADUALLY DIMINISH LATE TONIGHT/EARLY SUN. HIGH
PRESSURE WILL BECOME CENTERED OVER THE LAKE SUN...THEN CONTINUE TO
SLIDE EAST BY LATE SUN NIGHT. THIS WILL ALLOW ONLY A TEMPORARY
LULL IN THE WINDS...BEFORE WINDS TURN SOUTH/SOUTHWEST AND BEGIN TO
INCREASE. ANOTHER LOW PRESSURE IS POISED TO DEVELOP ACROSS THE
CENTRAL PLAINS MONDAY AFTERNOON...AND SLOWLY LIFT NORTHEAST
TOWARDS LAKE MICHIGAN MONDAY NIGHT/EARLY TUE. THIS LOW WILL THEN
DEEPEN TUE AFTERNOON AS IT LIFTS NORTHEAST ACROSS LOWER MICHIGAN.
THIS COULD PRODUCE A PERIOD OF WEST GALES TUE NGT/EARLY WED...THEN
ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE WESTERN LAKES
TOWARDS THE MIDDLE OF THE WEEK.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...4 PM SATURDAY TO
     10 AM SUNDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 5 PM SATURDAY.

&&

$$

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

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





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000
FXUS63 KILX 251415
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
915 AM CDT Sat Oct 25 2014

.UPDATE...
ISSUED AT 915 AM CDT SAT OCT 25 2014

Dense fog has once again developed across west-central Illinois
this morning, with 14z/9am obs showing visibilities of 1/4 mile or
less along/northwest of a Jacksonville to Bloomington line. Weak
cold front is approaching the I-55 corridor: however, the drier
airmass lags well behind the boundary across central/northern
Iowa. Dry advection will eventually help erode the northern edge
of the fog area, while the rising sun will help get rid of the fog
as well. With dry air only slowly trickling in, think fog will
stick around until mid to late morning, much like what happened
yesterday morning. As a result, have extended the Dense Fog
Advisory until midday. Have also expanded it southeastward to
include Bloomington-Normal and Jacksonville. Once drier air
arrives and sun angle gets higher, fog/low clouds will rapidly
dissipate between 16z and 17z, followed by sunny skies for the
balance of the day. Further east, mostly sunny conditions will
prevail for the entire day across east-central and southeast
Illinois. High temperatures will climb well into the 70s across
the board.  Forecast update has already been issued.


&&

.SHORT TERM...(Today)
ISSUED AT 319 AM CDT SAT OCT 25 2014

Main concern in the short term will be the dense fog again early
this morning, mainly in the northwestern parts of the CWA. Unlike
last night, the dense fog has not developed yet in the CWA and is
still located along and west of the Mississippi River. However, HRRR
model still forecast dense fog to move into the area. So will
continue the dense fog advisory as is, and will not extend in time or
area. Fog will be in areas east of the Illinois river, but not
dense. After the fog dissipates this morning, mostly clear skies
will be the rule for the area. Should be lots of sunshine to allow
temps to rise into the lower to middle 70s by this afternoon, which
is well above normal for the later part of October. Northwest winds
will only bring in a drier airmass for the day and beyond.

&&

.LONG TERM...(Tonight through Friday)
ISSUED AT 319 AM CDT SAT OCT 25 2014

1020 mb high pressure over over the northern High Plains, near the
eastern MT and western Dakotas border, to settle into IL by
sunrise Sunday and weaken a bit to 1018 mb, then drift into
eastern KY by sunset Sunday. This will continue fair weather
through Sunday night. 850 mb temps cool to 12-14C tonight into
Sunday morning before rising back up to 14-16C by sunset Sunday.
Lows mostly in the middle 40s tonight (fog limited overnight
tonight over central IL with drier air advecting in). Highs
Sunday mostly 70-75F, except upper 60s to near 70F from I-74
northeast.

Strong low pressure of 1000 mb to eject ne from western KS Sunday
evening into Lake MI Monday night and bring a cold front east across
IL overnight Monday night and across the Wabash river valley in
eastern IL Tue morning. Breezy ssw winds Monday ahead of this storm
system to bring in warm air with highs approaching 80F. Have a
slight chance of showers and thunderstorms late Monday afternoon
far NW CWA by Galesburg. Best chances of showers and isolated
thunderstorms spread east across IL during Monday night (mainly
after midnight Monday night in eastern IL) and Tue morning, then
diminish Tue afternoon from the west. Highs Tue range from lower 60s
from I-55 nw to upper 60s to around 70F from I-70 se. Temperatures
steady or slowly falling Tue afternoon behind the cold front. Slight
chance of showers early Tue evening near the Wabash river, otherwise
dry weather returns Tue night through Wed night as another high
pressure system settles over IL by Wed afternoon. Near normal highs
Wed/Thu in the upper 50s/lower 60s.

A weak northern stream short wave to dive se into upper level trof
over the eastern states and bring another cold front into IL by Thu
afternoon/evening. Have just slight chance of showers Thu due to
limited moisture. ECMWF model shows strong cutoff upper level low
near IL on Halloween along with showers, but other models like GFS
are drier. Models due agree that even colder air arrives on
Halloween with highs in the lower 50s central IL and mid 50s se of
I-70, while low temperatures near freezing next Friday night over
central IL and mid 30s in southeast IL.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 638 AM CDT SAT OCT 25 2014

Difficult part of the forecast will be dense fog and lower IFR
clouds this morning and what time it will dissipate. HRRR keeps
the lower vis along the IL river and to the northwest. So, PIA
will be the only site effected by dense fog. However, other sites
will also have some light fog during the first 2-3hrs of the
morning. IFR and MVFR clouds are also advecting into the area from
the northwest and will effect the other sites early this morning,
before the sunshine burns them off. HRRR is keeps lower clouds in
the area til later this morning. Not sure if I agree with this
forecast, so have skies scattering out and then clearing at all
sites between 15 and 17z. Then clear skies will prevail for
remainder of TAF period, as high pressure builds into the area
with lower dewpoints and northwest winds at 5-10kts.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until Noon CDT today FOR ILZ027>031-036>038-
040-041-047>050.

&&

$$

UPDATE...Barnes
SHORT TERM...Auten
LONG TERM...07
AVIATION...Auten







000
FXUS63 KLOT 251405
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
905 AM CDT SAT OCT 25 2014

.DISCUSSION...
314 AM CDT

SHORT TERM...THROUGH SATURDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO SATURDAY MORNING...THE INITIAL
CONCERNS WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  A WEAK
MID LEVEL IMPULSE THAT TRACKED ACROSS THE REGION FRIDAY EVENING
BROUGHT SOME SCT SPRINKLES.  AS THE MID AND HIGH CLOUD PUSHES AWAY
FROM THE AREA...FOG AND LOW STRATUS ARE BLOOMING.  NWRN IL AND ERN
IA HAVE ALREADY SEEN DENSE FOG AND LOW STRATUS FORM...AND IN THE
MOIST AIRMASS IN PLACE...WITH DEWPOINTS IN THE LOW 50S...EXPECT THAT
THE AREA OF FOG/STRATUS SHOULD INCREASE...THOUGH THE LOWEST
CONDITIONS SHOULD BE ALONG AND WEST OF THE I-39 CORRIDOR.  EAST OF
I-39...ANY DENSE FOG SHOULD BE LIMITED TO SHELTERED...LOW-LYING
AREAS.

THROUGH THE MORNING HOURS...A WEAK FRONTAL BOUNDARY WILL CROSS THE
AREA...WITH SFC HIGH PRESSURE BUILDING ACROSS THE CNTRL PLAINS WHILE
UPPER LEVEL RIDGING ALSO BUILDS OUT OF THE ROCKIES AND ACROSS THE
CENTRAL PLAINS.  THE UPPER RIDGING WILL SET UP A SUBSIDENCE PATTERN
ACROSS THE AREA...LEADING TO MOSTLY SUNNY SKIES.  LOW PRESSURE
MOVING THROUGH SERN CANADA...COMBINED WITH THE HIGH PRESSURE OVER
THE PLAINS WILL SET UP A GENERALLY NWLY GRADIENT ACROSS NRN IL/IN.
DAYTIME WARMING SHOULD ALLOW ANY RESIDUAL FOG/STRATUS TO DISSIPATE
BY LATE MORNING...WHILE THE AMPLE SUNSHINE AND LARGER SCALE
SUBSIDENCE SHOULD ALLOW TEMPERATURES TO QUICKLY RISE INTO THE LOWER
70S ACROSS THE SRN PORTIONS OF THE CWA...WHILE LOCATION CLOSER TO
THE WI BORDER WILL BE A BIT COOLER...BUT STILL SIGNIFICANTLY WARMER
THAN NORMAL...WITH HIGHS IN THE UPPER 60S.  STEADY NWLY WINDS AT THE
SFC AND ALOFT SHOULD PREVENT ANY KIND OF LAKE BREEZE FROM FORMING
AND THE WARMER AIR SHOULD COVER THE AREA UP TO THE LAKEFRONT.  WHILE
DEWPOINTS WILL BE IN THE 50S FOR THE MORNING HOURS...DEEP MIXING
SHOULD DRAW MUCH DRIER AIR TO THE SFC...WITH DEWPOINTS DROPPING INTO
THE UPPER 30S FOR THE AFTERNOON HOURS.  SO...OVERALL...SATURDAY IS
SHAPING UP TO A VERY PLEASANT DAY...WITH TEMPERATURES AROUND 10
DEGREES ABOVE NORMAL.  THE SFC HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI VALLEY AND INTO THE MIDWEST OVERNIGHT TONIGHT WHILE THE
UPPER RIDGE SLOWLY PROGRESSES AS WELL.  WITH A DRIER AIRMASS IN
PLACE TONIGHT...THE CHANCES FOR ANOTHER ROUND OF FOG AND STRATUS IS
UNLIKELY...THROUGH THE CLEAR SKIES...LIGHT WINDS AND LOWER DEWPOINTS
SHOULD ALLOW TEMPERATURES TO RADIATE DOWN INTO THE UPPER 30S TO
LOWER 40S.  THE CHICAGO AREA URBAN HEAT ISLAND SHOULD REMAIN A
LITTLE WARMER...WITH LOWS IN THE MIDDLE 40S.

KREIN

SUNDAY THROUGH TUESDAY...
GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN THE MEDIUM TERM FEATURING
MID-LVL RIDGING OVER THE UPPER MIDWEST/GREAT LAKES REGION WITH A SFC
RIDGE PROVIDING ABUNDANT SUNSHINE AND DRY CONDS FOR THE SECOND HALF
OF THE WEEKEND. HOWEVER THIS RIDGE WILL ONLY BE TEMPORARY AS THE
MID-LVL HEIGHTS BEGIN TO FALL AND A QUASI-ZONAL FLOW BEGINS TO SETUP
FOR EARLY NEXT WEEK. FORTUNATELY IT REMAINS LIKELY THAT MON WILL
REMAIN DRY...WITH VERY MILD TEMPS EXPECTED. THE SFC RIDGE WILL BE
SHIFTING EAST OF THE FORECAST AREA...BUT SHOULD CONTINUE TO KEEP
CLOUDS TO A MINIMUM AND PRECIP WEST OF THE AREA. THE COMBINATION OF
THIS AND AN ANOMALOUS THERMAL RIDGE WILL ALLOW TEMPS TO SOAR INTO
THE MID/UPR 70S...WITH A FEW 80 DEGREE READINGS IN THE SOUTHERN CWFA
MON AFTN.

BROAD SFC TROUGH OVER THE CENTRAL/NORTHERN PLAINS WILL SLOWLY
CONSOLIDATE AS THIS FEATURE NEARS THE GREAT LAKES MON EVE. THERE IS
A SMALL CHANCE THAT A FEW SHOWERS/THUNDERSTORMS COULD SKIRT THE
NORTHERN CWFA MON AFTN...BUT EXPECT THE BULK OF THE PRECIP TO OCCUR
POST SUNSET. MID-LVL TROUGH WILL AMPLIFY ACROSS THE CENTRAL PLAINS
TUE MORNING...AS THE SFC LOW DEEPENS ACROSS LOWER MICHIGAN. HAVE
HELD ONTO THE MENTION OF THUNDER INTO TUE MORNING...AS IT APPEARS
SOME INSTABILITY/FORCING WILL CONTINUE. MON NGT TEMPS WILL LIKELY
NOT FALL MUCH...PRODUCING A MILD OVERNIGHT. THEN FOR TUE WITH
CONTINUED CLOUD COVER/PRECIP...EXPECT TEMPS TO REMAIN IN THE UPR
50S/LOW 60S. DEPENDING ON THE TIMING OF THE FROPA TUE...TEMPS COULD
BEGIN TO FALL TUE AFTN INTO THE LOW 50S.

WEDNESDAY THROUGH FRIDAY...
FOR THE SECOND HALF OF THE WEEK IT APPEARS THE PATTERN WILL BE
TRANSITIONING TOWARDS A COOLER AND SOMEWHAT ACTIVE SETUP. ENSEMBLES
CONTINUE TO PROG MID-LVL RIDGING DEVELOPING ACROSS THE WESTERN
CONUS...ALLOWING BROAD TROUGHING DOWNSTREAM FOR THE GREAT LAKES
REGION WED/THUR. THEN FRI THE 500MB RIDGE MAY BEGIN TO FURTHER
AMPLIFY AS A POTENT SHORTWAVE IS PROGGED TO APPROACH THE PAC-NW AND
RIDGING REMAINS ACROSS THE NORTH ATLANTIC. TROUGHING WILL LINGER
ACROSS THE GREAT LAKES FRI. TEMPS WILL TREND BACK TOWARDS
SEASONAL...WITH PERHAPS FRI BEING SUB-SEASONAL WITH HIGHS IN THE UPR
40S/LOW 50S. PERIODIC CHANCES FOR SHOWERS THROUGHOUT THE EXTENDED
TIMEFRAME.

BEACHLER

&&

.AVIATION...

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

* GUSTY NW WINDS WITH GUSTS 20-24 KT.

JEE

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE HAVE PASSED EAST OF THE
REGION...CLEARING OUT THE MID AND HIGH CLOUD. RESIDUAL MOISTURE
HAS ALLOWED FOG AND LOW STRATUS TO DEVELOP...DROPPING CIGS/VIS
INTO IFR RANGES...WITH THE LOWEST CONDITIONS OVER THE RFD AREA
WHICH CLEARED FIRST. THE STRATUS AND FOG WILL BURN OFF BY ARND 14Z
AS DRIER AIR FILTERS INTO THE REGION. THE MAIN ISSUE FOR THE
REMAINDER OF THE DAY WILL BE WINDS. FOLLOWING THE PASSAGE OF THE
WEAK SFC TROUGH...HIGH PRESSURE BUILDING OVER THE NRN PLAINS WILL
SET UP A STRENGTHENING WNWLY-NWLY GRADIENT OVER THE AREA. WITH
AMPLE MIXING THROUGH THE AFTERNOON...WINDS SHOULD BECOME MORE
GUSTY...WITH GUSTS TO OR SLIGHTLY IN EXCESS OF 20KT THROUGH SUNSET.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

JEE

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

MONDAY...VFR/WX NIL BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA EARLY. MVFR POSSIBLE EARLY. WEST WINDS.

WEDNESDAY...VFR/WX NIL. WEST WINDS DAYTIME...BECMG SLY WEDNESDAY
NIGHT.

THURSDAY...SLIGHT CHANCE SHRA DAYTIME. VFR. SOUTHWEST WINDS
VEERING TO NLY BY EARLY EVENING AND OVERNIGHT.

FRIDAY...VFR/WX NIL. NORTH WINDS.

KREIN

&&

.MARINE...
229 AM CDT

LOW PRESSURE OVER JAMES BAY ALONG WITH A SFC RIDGE CENTERED OVER
THE NORTHERN PLAINS HAS CREATED A TIGHT PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS...WHICH IS POSITIONED OVER THE LAKE. THIS HAS
RESULTED IN BREEZY SOUTHWEST WINDS OVER THE LAKE WITH SPEEDS
GENERALLY BETWEEN 20-25KT. ACROSS THE NORTHERN HALF OF THE LAKE
THE GUSTS MAY NEAR 30 KT THIS MORNING. AS HIGH PRESSURE SLOWLY
BUILDS IN FROM THE WEST ACROSS THE LAKE...WIND WILL TURN
WEST/NORTHWEST AND GRADUALLY DIMINISH LATE TONIGHT/EARLY SUN. HIGH
PRESSURE WILL BECOME CENTERED OVER THE LAKE SUN...THEN CONTINUE TO
SLIDE EAST BY LATE SUN NIGHT. THIS WILL ALLOW ONLY A TEMPORARY
LULL IN THE WINDS...BEFORE WINDS TURN SOUTH/SOUTHWEST AND BEGIN TO
INCREASE. ANOTHER LOW PRESSURE IS POISED TO DEVELOP ACROSS THE
CENTRAL PLAINS MONDAY AFTERNOON...AND SLOWLY LIFT NORTHEAST
TOWARDS LAKE MICHIGAN MONDAY NIGHT/EARLY TUE. THIS LOW WILL THEN
DEEPEN TUE AFTERNOON AS IT LIFTS NORTHEAST ACROSS LOWER MICHIGAN.
THIS COULD PRODUCE A PERIOD OF WEST GALES TUE NGT/EARLY WED...THEN
ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE WESTERN LAKES
TOWARDS THE MIDDLE OF THE WEEK.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 251151
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
651 AM CDT SAT OCT 25 2014

.DISCUSSION...
314 AM CDT

SHORT TERM...THROUGH SATURDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO SATURDAY MORNING...THE INITIAL
CONCERNS WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  A WEAK
MID LEVEL IMPULSE THAT TRACKED ACROSS THE REGION FRIDAY EVENING
BROUGHT SOME SCT SPRINKLES.  AS THE MID AND HIGH CLOUD PUSHES AWAY
FROM THE AREA...FOG AND LOW STRATUS ARE BLOOMING.  NWRN IL AND ERN
IA HAVE ALREADY SEEN DENSE FOG AND LOW STRATUS FORM...AND IN THE
MOIST AIRMASS IN PLACE...WITH DEWPOINTS IN THE LOW 50S...EXPECT THAT
THE AREA OF FOG/STRATUS SHOULD INCREASE...THOUGH THE LOWEST
CONDITIONS SHOULD BE ALONG AND WEST OF THE I-39 CORRIDOR.  EAST OF
I-39...ANY DENSE FOG SHOULD BE LIMITED TO SHELTERED...LOW-LYING
AREAS.

THROUGH THE MORNING HOURS...A WEAK FRONTAL BOUNDARY WILL CROSS THE
AREA...WITH SFC HIGH PRESSURE BUILDING ACROSS THE CNTRL PLAINS WHILE
UPPER LEVEL RIDGING ALSO BUILDS OUT OF THE ROCKIES AND ACROSS THE
CENTRAL PLAINS.  THE UPPER RIDGING WILL SET UP A SUBSIDENCE PATTERN
ACROSS THE AREA...LEADING TO MOSTLY SUNNY SKIES.  LOW PRESSURE
MOVING THROUGH SERN CANADA...COMBINED WITH THE HIGH PRESSURE OVER
THE PLAINS WILL SET UP A GENERALLY NWLY GRADIENT ACROSS NRN IL/IN.
DAYTIME WARMING SHOULD ALLOW ANY RESIDUAL FOG/STRATUS TO DISSIPATE
BY LATE MORNING...WHILE THE AMPLE SUNSHINE AND LARGER SCALE
SUBSIDENCE SHOULD ALLOW TEMPERATURES TO QUICKLY RISE INTO THE LOWER
70S ACROSS THE SRN PORTIONS OF THE CWA...WHILE LOCATION CLOSER TO
THE WI BORDER WILL BE A BIT COOLER...BUT STILL SIGNIFICANTLY WARMER
THAN NORMAL...WITH HIGHS IN THE UPPER 60S.  STEADY NWLY WINDS AT THE
SFC AND ALOFT SHOULD PREVENT ANY KIND OF LAKE BREEZE FROM FORMING
AND THE WARMER AIR SHOULD COVER THE AREA UP TO THE LAKEFRONT.  WHILE
DEWPOINTS WILL BE IN THE 50S FOR THE MORNING HOURS...DEEP MIXING
SHOULD DRAW MUCH DRIER AIR TO THE SFC...WITH DEWPOINTS DROPPING INTO
THE UPPER 30S FOR THE AFTERNOON HOURS.  SO...OVERALL...SATURDAY IS
SHAPING UP TO A VERY PLEASANT DAY...WITH TEMPERATURES AROUND 10
DEGREES ABOVE NORMAL.  THE SFC HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI VALLEY AND INTO THE MIDWEST OVERNIGHT TONIGHT WHILE THE
UPPER RIDGE SLOWLY PROGRESSES AS WELL.  WITH A DRIER AIRMASS IN
PLACE TONIGHT...THE CHANCES FOR ANOTHER ROUND OF FOG AND STRATUS IS
UNLIKELY...THROUGH THE CLEAR SKIES...LIGHT WINDS AND LOWER DEWPOINTS
SHOULD ALLOW TEMPERATURES TO RADIATE DOWN INTO THE UPPER 30S TO
LOWER 40S.  THE CHICAGO AREA URBAN HEAT ISLAND SHOULD REMAIN A
LITTLE WARMER...WITH LOWS IN THE MIDDLE 40S.

KREIN

SUNDAY THROUGH TUESDAY...
GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN THE MEDIUM TERM FEATURING
MID-LVL RIDGING OVER THE UPPER MIDWEST/GREAT LAKES REGION WITH A SFC
RIDGE PROVIDING ABUNDANT SUNSHINE AND DRY CONDS FOR THE SECOND HALF
OF THE WEEKEND. HOWEVER THIS RIDGE WILL ONLY BE TEMPORARY AS THE
MID-LVL HEIGHTS BEGIN TO FALL AND A QUASI-ZONAL FLOW BEGINS TO SETUP
FOR EARLY NEXT WEEK. FORTUNATELY IT REMAINS LIKELY THAT MON WILL
REMAIN DRY...WITH VERY MILD TEMPS EXPECTED. THE SFC RIDGE WILL BE
SHIFTING EAST OF THE FORECAST AREA...BUT SHOULD CONTINUE TO KEEP
CLOUDS TO A MINIMUM AND PRECIP WEST OF THE AREA. THE COMBINATION OF
THIS AND AN ANOMALOUS THERMAL RIDGE WILL ALLOW TEMPS TO SOAR INTO
THE MID/UPR 70S...WITH A FEW 80 DEGREE READINGS IN THE SOUTHERN CWFA
MON AFTN.

BROAD SFC TROUGH OVER THE CENTRAL/NORTHERN PLAINS WILL SLOWLY
CONSOLIDATE AS THIS FEATURE NEARS THE GREAT LAKES MON EVE. THERE IS
A SMALL CHANCE THAT A FEW SHOWERS/THUNDERSTORMS COULD SKIRT THE
NORTHERN CWFA MON AFTN...BUT EXPECT THE BULK OF THE PRECIP TO OCCUR
POST SUNSET. MID-LVL TROUGH WILL AMPLIFY ACROSS THE CENTRAL PLAINS
TUE MORNING...AS THE SFC LOW DEEPENS ACROSS LOWER MICHIGAN. HAVE
HELD ONTO THE MENTION OF THUNDER INTO TUE MORNING...AS IT APPEARS
SOME INSTABILITY/FORCING WILL CONTINUE. MON NGT TEMPS WILL LIKELY
NOT FALL MUCH...PRODUCING A MILD OVERNIGHT. THEN FOR TUE WITH
CONTINUED CLOUD COVER/PRECIP...EXPECT TEMPS TO REMAIN IN THE UPR
50S/LOW 60S. DEPENDING ON THE TIMING OF THE FROPA TUE...TEMPS COULD
BEGIN TO FALL TUE AFTN INTO THE LOW 50S.

WEDNESDAY THROUGH FRIDAY...
FOR THE SECOND HALF OF THE WEEK IT APPEARS THE PATTERN WILL BE
TRANSITIONING TOWARDS A COOLER AND SOMEWHAT ACTIVE SETUP. ENSEMBLES
CONTINUE TO PROG MID-LVL RIDGING DEVELOPING ACROSS THE WESTERN
CONUS...ALLOWING BROAD TROUGHING DOWNSTREAM FOR THE GREAT LAKES
REGION WED/THUR. THEN FRI THE 500MB RIDGE MAY BEGIN TO FURTHER
AMPLIFY AS A POTENT SHORTWAVE IS PROGGED TO APPROACH THE PAC-NW AND
RIDGING REMAINS ACROSS THE NORTH ATLANTIC. TROUGHING WILL LINGER
ACROSS THE GREAT LAKES FRI. TEMPS WILL TREND BACK TOWARDS
SEASONAL...WITH PERHAPS FRI BEING SUB-SEASONAL WITH HIGHS IN THE UPR
40S/LOW 50S. PERIODIC CHANCES FOR SHOWERS THROUGHOUT THE EXTENDED
TIMEFRAME.

BEACHLER

&&

.AVIATION...

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

* IFR CIGS/MVFR VIS THIS MORNING.

* BREEZY WEST-NORTHWEST WINDS...WITH GUSTS TO ARND 20KT.

KREIN

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE HAVE PASSED EAST OF THE
REGION...CLEARING OUT THE MID AND HIGH CLOUD. RESIDUAL MOISTURE
HAS ALLOWED FOG AND LOW STRATUS TO DEVELOP...DROPPING CIGS/VIS
INTO IFR RANGES...WITH THE LOWEST CONDITIONS OVER THE RFD AREA
WHICH CLEARED FIRST. THE STRATUS AND FOG WILL BURN OFF BY ARND 14Z
AS DRIER AIR FILTERS INTO THE REGION. THE MAIN ISSUE FOR THE
REMAINDER OF THE DAY WILL BE WINDS. FOLLOWING THE PASSAGE OF THE
WEAK SFC TROUGH...HIGH PRESSURE BUILDING OVER THE NRN PLAINS WILL
SET UP A STRENGTHENING WNWLY-NWLY GRADIENT OVER THE AREA. WITH
AMPLE MIXING THROUGH THE AFTERNOON...WINDS SHOULD BECOME MORE
GUSTY...WITH GUSTS TO OR SLIGHTLY IN EXCESS OF 20KT THROUGH SUNSET.

KREIN

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

* MEDIUM CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO VFR.

* HIGH CONFIDENCE WIND TRENDS WITH WNWLY-NWLY WINDS GUSTING TO
  ARND 20KT.

KREIN

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

MONDAY...VFR/WX NIL BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA EARLY. MVFR POSSIBLE EARLY. WEST WINDS.

WEDNESDAY...VFR/WX NIL. WEST WINDS DAYTIME...BECMG SLY WEDNESDAY
NIGHT.

THURSDAY...SLIGHT CHANCE SHRA DAYTIME. VFR. SOUTHWEST WINDS
VEERING TO NLY BY EARLY EVENING AND OVERNIGHT.

FRIDAY...VFR/WX NIL. NORTH WINDS.

KREIN

&&

.MARINE...
229 AM CDT

LOW PRESSURE OVER JAMES BAY ALONG WITH A SFC RIDGE CENTERED OVER
THE NORTHERN PLAINS HAS CREATED A TIGHT PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS...WHICH IS POSITIONED OVER THE LAKE. THIS HAS
RESULTED IN BREEZY SOUTHWEST WINDS OVER THE LAKE WITH SPEEDS
GENERALLY BETWEEN 20-25KT. ACROSS THE NORTHERN HALF OF THE LAKE
THE GUSTS MAY NEAR 30 KT THIS MORNING. AS HIGH PRESSURE SLOWLY
BUILDS IN FROM THE WEST ACROSS THE LAKE...WIND WILL TURN
WEST/NORTHWEST AND GRADUALLY DIMINISH LATE TONIGHT/EARLY SUN. HIGH
PRESSURE WILL BECOME CENTERED OVER THE LAKE SUN...THEN CONTINUE TO
SLIDE EAST BY LATE SUN NIGHT. THIS WILL ALLOW ONLY A TEMPORARY
LULL IN THE WINDS...BEFORE WINDS TURN SOUTH/SOUTHWEST AND BEGIN TO
INCREASE. ANOTHER LOW PRESSURE IS POISED TO DEVELOP ACROSS THE
CENTRAL PLAINS MONDAY AFTERNOON...AND SLOWLY LIFT NORTHEAST
TOWARDS LAKE MICHIGAN MONDAY NIGHT/EARLY TUE. THIS LOW WILL THEN
DEEPEN TUE AFTERNOON AS IT LIFTS NORTHEAST ACROSS LOWER MICHIGAN.
THIS COULD PRODUCE A PERIOD OF WEST GALES TUE NGT/EARLY WED...THEN
ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE WESTERN LAKES
TOWARDS THE MIDDLE OF THE WEEK.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 251151
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
651 AM CDT SAT OCT 25 2014

.DISCUSSION...
314 AM CDT

SHORT TERM...THROUGH SATURDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO SATURDAY MORNING...THE INITIAL
CONCERNS WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  A WEAK
MID LEVEL IMPULSE THAT TRACKED ACROSS THE REGION FRIDAY EVENING
BROUGHT SOME SCT SPRINKLES.  AS THE MID AND HIGH CLOUD PUSHES AWAY
FROM THE AREA...FOG AND LOW STRATUS ARE BLOOMING.  NWRN IL AND ERN
IA HAVE ALREADY SEEN DENSE FOG AND LOW STRATUS FORM...AND IN THE
MOIST AIRMASS IN PLACE...WITH DEWPOINTS IN THE LOW 50S...EXPECT THAT
THE AREA OF FOG/STRATUS SHOULD INCREASE...THOUGH THE LOWEST
CONDITIONS SHOULD BE ALONG AND WEST OF THE I-39 CORRIDOR.  EAST OF
I-39...ANY DENSE FOG SHOULD BE LIMITED TO SHELTERED...LOW-LYING
AREAS.

THROUGH THE MORNING HOURS...A WEAK FRONTAL BOUNDARY WILL CROSS THE
AREA...WITH SFC HIGH PRESSURE BUILDING ACROSS THE CNTRL PLAINS WHILE
UPPER LEVEL RIDGING ALSO BUILDS OUT OF THE ROCKIES AND ACROSS THE
CENTRAL PLAINS.  THE UPPER RIDGING WILL SET UP A SUBSIDENCE PATTERN
ACROSS THE AREA...LEADING TO MOSTLY SUNNY SKIES.  LOW PRESSURE
MOVING THROUGH SERN CANADA...COMBINED WITH THE HIGH PRESSURE OVER
THE PLAINS WILL SET UP A GENERALLY NWLY GRADIENT ACROSS NRN IL/IN.
DAYTIME WARMING SHOULD ALLOW ANY RESIDUAL FOG/STRATUS TO DISSIPATE
BY LATE MORNING...WHILE THE AMPLE SUNSHINE AND LARGER SCALE
SUBSIDENCE SHOULD ALLOW TEMPERATURES TO QUICKLY RISE INTO THE LOWER
70S ACROSS THE SRN PORTIONS OF THE CWA...WHILE LOCATION CLOSER TO
THE WI BORDER WILL BE A BIT COOLER...BUT STILL SIGNIFICANTLY WARMER
THAN NORMAL...WITH HIGHS IN THE UPPER 60S.  STEADY NWLY WINDS AT THE
SFC AND ALOFT SHOULD PREVENT ANY KIND OF LAKE BREEZE FROM FORMING
AND THE WARMER AIR SHOULD COVER THE AREA UP TO THE LAKEFRONT.  WHILE
DEWPOINTS WILL BE IN THE 50S FOR THE MORNING HOURS...DEEP MIXING
SHOULD DRAW MUCH DRIER AIR TO THE SFC...WITH DEWPOINTS DROPPING INTO
THE UPPER 30S FOR THE AFTERNOON HOURS.  SO...OVERALL...SATURDAY IS
SHAPING UP TO A VERY PLEASANT DAY...WITH TEMPERATURES AROUND 10
DEGREES ABOVE NORMAL.  THE SFC HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI VALLEY AND INTO THE MIDWEST OVERNIGHT TONIGHT WHILE THE
UPPER RIDGE SLOWLY PROGRESSES AS WELL.  WITH A DRIER AIRMASS IN
PLACE TONIGHT...THE CHANCES FOR ANOTHER ROUND OF FOG AND STRATUS IS
UNLIKELY...THROUGH THE CLEAR SKIES...LIGHT WINDS AND LOWER DEWPOINTS
SHOULD ALLOW TEMPERATURES TO RADIATE DOWN INTO THE UPPER 30S TO
LOWER 40S.  THE CHICAGO AREA URBAN HEAT ISLAND SHOULD REMAIN A
LITTLE WARMER...WITH LOWS IN THE MIDDLE 40S.

KREIN

SUNDAY THROUGH TUESDAY...
GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN THE MEDIUM TERM FEATURING
MID-LVL RIDGING OVER THE UPPER MIDWEST/GREAT LAKES REGION WITH A SFC
RIDGE PROVIDING ABUNDANT SUNSHINE AND DRY CONDS FOR THE SECOND HALF
OF THE WEEKEND. HOWEVER THIS RIDGE WILL ONLY BE TEMPORARY AS THE
MID-LVL HEIGHTS BEGIN TO FALL AND A QUASI-ZONAL FLOW BEGINS TO SETUP
FOR EARLY NEXT WEEK. FORTUNATELY IT REMAINS LIKELY THAT MON WILL
REMAIN DRY...WITH VERY MILD TEMPS EXPECTED. THE SFC RIDGE WILL BE
SHIFTING EAST OF THE FORECAST AREA...BUT SHOULD CONTINUE TO KEEP
CLOUDS TO A MINIMUM AND PRECIP WEST OF THE AREA. THE COMBINATION OF
THIS AND AN ANOMALOUS THERMAL RIDGE WILL ALLOW TEMPS TO SOAR INTO
THE MID/UPR 70S...WITH A FEW 80 DEGREE READINGS IN THE SOUTHERN CWFA
MON AFTN.

BROAD SFC TROUGH OVER THE CENTRAL/NORTHERN PLAINS WILL SLOWLY
CONSOLIDATE AS THIS FEATURE NEARS THE GREAT LAKES MON EVE. THERE IS
A SMALL CHANCE THAT A FEW SHOWERS/THUNDERSTORMS COULD SKIRT THE
NORTHERN CWFA MON AFTN...BUT EXPECT THE BULK OF THE PRECIP TO OCCUR
POST SUNSET. MID-LVL TROUGH WILL AMPLIFY ACROSS THE CENTRAL PLAINS
TUE MORNING...AS THE SFC LOW DEEPENS ACROSS LOWER MICHIGAN. HAVE
HELD ONTO THE MENTION OF THUNDER INTO TUE MORNING...AS IT APPEARS
SOME INSTABILITY/FORCING WILL CONTINUE. MON NGT TEMPS WILL LIKELY
NOT FALL MUCH...PRODUCING A MILD OVERNIGHT. THEN FOR TUE WITH
CONTINUED CLOUD COVER/PRECIP...EXPECT TEMPS TO REMAIN IN THE UPR
50S/LOW 60S. DEPENDING ON THE TIMING OF THE FROPA TUE...TEMPS COULD
BEGIN TO FALL TUE AFTN INTO THE LOW 50S.

WEDNESDAY THROUGH FRIDAY...
FOR THE SECOND HALF OF THE WEEK IT APPEARS THE PATTERN WILL BE
TRANSITIONING TOWARDS A COOLER AND SOMEWHAT ACTIVE SETUP. ENSEMBLES
CONTINUE TO PROG MID-LVL RIDGING DEVELOPING ACROSS THE WESTERN
CONUS...ALLOWING BROAD TROUGHING DOWNSTREAM FOR THE GREAT LAKES
REGION WED/THUR. THEN FRI THE 500MB RIDGE MAY BEGIN TO FURTHER
AMPLIFY AS A POTENT SHORTWAVE IS PROGGED TO APPROACH THE PAC-NW AND
RIDGING REMAINS ACROSS THE NORTH ATLANTIC. TROUGHING WILL LINGER
ACROSS THE GREAT LAKES FRI. TEMPS WILL TREND BACK TOWARDS
SEASONAL...WITH PERHAPS FRI BEING SUB-SEASONAL WITH HIGHS IN THE UPR
40S/LOW 50S. PERIODIC CHANCES FOR SHOWERS THROUGHOUT THE EXTENDED
TIMEFRAME.

BEACHLER

&&

.AVIATION...

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

* IFR CIGS/MVFR VIS THIS MORNING.

* BREEZY WEST-NORTHWEST WINDS...WITH GUSTS TO ARND 20KT.

KREIN

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE HAVE PASSED EAST OF THE
REGION...CLEARING OUT THE MID AND HIGH CLOUD. RESIDUAL MOISTURE
HAS ALLOWED FOG AND LOW STRATUS TO DEVELOP...DROPPING CIGS/VIS
INTO IFR RANGES...WITH THE LOWEST CONDITIONS OVER THE RFD AREA
WHICH CLEARED FIRST. THE STRATUS AND FOG WILL BURN OFF BY ARND 14Z
AS DRIER AIR FILTERS INTO THE REGION. THE MAIN ISSUE FOR THE
REMAINDER OF THE DAY WILL BE WINDS. FOLLOWING THE PASSAGE OF THE
WEAK SFC TROUGH...HIGH PRESSURE BUILDING OVER THE NRN PLAINS WILL
SET UP A STRENGTHENING WNWLY-NWLY GRADIENT OVER THE AREA. WITH
AMPLE MIXING THROUGH THE AFTERNOON...WINDS SHOULD BECOME MORE
GUSTY...WITH GUSTS TO OR SLIGHTLY IN EXCESS OF 20KT THROUGH SUNSET.

KREIN

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

* MEDIUM CONFIDENCE IN TIMING OF CIGS/VIS IMPROVING TO VFR.

* HIGH CONFIDENCE WIND TRENDS WITH WNWLY-NWLY WINDS GUSTING TO
  ARND 20KT.

KREIN

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

MONDAY...VFR/WX NIL BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA EARLY. MVFR POSSIBLE EARLY. WEST WINDS.

WEDNESDAY...VFR/WX NIL. WEST WINDS DAYTIME...BECMG SLY WEDNESDAY
NIGHT.

THURSDAY...SLIGHT CHANCE SHRA DAYTIME. VFR. SOUTHWEST WINDS
VEERING TO NLY BY EARLY EVENING AND OVERNIGHT.

FRIDAY...VFR/WX NIL. NORTH WINDS.

KREIN

&&

.MARINE...
229 AM CDT

LOW PRESSURE OVER JAMES BAY ALONG WITH A SFC RIDGE CENTERED OVER
THE NORTHERN PLAINS HAS CREATED A TIGHT PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS...WHICH IS POSITIONED OVER THE LAKE. THIS HAS
RESULTED IN BREEZY SOUTHWEST WINDS OVER THE LAKE WITH SPEEDS
GENERALLY BETWEEN 20-25KT. ACROSS THE NORTHERN HALF OF THE LAKE
THE GUSTS MAY NEAR 30 KT THIS MORNING. AS HIGH PRESSURE SLOWLY
BUILDS IN FROM THE WEST ACROSS THE LAKE...WIND WILL TURN
WEST/NORTHWEST AND GRADUALLY DIMINISH LATE TONIGHT/EARLY SUN. HIGH
PRESSURE WILL BECOME CENTERED OVER THE LAKE SUN...THEN CONTINUE TO
SLIDE EAST BY LATE SUN NIGHT. THIS WILL ALLOW ONLY A TEMPORARY
LULL IN THE WINDS...BEFORE WINDS TURN SOUTH/SOUTHWEST AND BEGIN TO
INCREASE. ANOTHER LOW PRESSURE IS POISED TO DEVELOP ACROSS THE
CENTRAL PLAINS MONDAY AFTERNOON...AND SLOWLY LIFT NORTHEAST
TOWARDS LAKE MICHIGAN MONDAY NIGHT/EARLY TUE. THIS LOW WILL THEN
DEEPEN TUE AFTERNOON AS IT LIFTS NORTHEAST ACROSS LOWER MICHIGAN.
THIS COULD PRODUCE A PERIOD OF WEST GALES TUE NGT/EARLY WED...THEN
ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE WESTERN LAKES
TOWARDS THE MIDDLE OF THE WEEK.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KILX 251138
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
638 AM CDT Sat Oct 25 2014

.SHORT TERM...(Today)
ISSUED AT 319 AM CDT SAT OCT 25 2014

Main concern in the short term will be the dense fog again early
this morning, mainly in the northwestern parts of the CWA. Unlike
last night, the dense fog has not developed yet in the CWA and is
still located along and west of the Mississippi River. However, HRRR
model still forecast dense fog to move into the area. So will
continue the dense fog advisory as is, and will not extend in time or
area. Fog will be in areas east of the Illinois river, but not
dense. After the fog dissipates this morning, mostly clear skies
will be the rule for the area. Should be lots of sunshine to allow
temps to rise into the lower to middle 70s by this afternoon, which
is well above normal for the later part of October. Northwest winds
will only bring in a drier airmass for the day and beyond.

&&

.LONG TERM...(Tonight through Friday)
ISSUED AT 319 AM CDT SAT OCT 25 2014

1020 mb high pressure over over the northern High Plains, near the
eastern MT and western Dakotas border, to settle into IL by
sunrise Sunday and weaken a bit to 1018 mb, then drift into
eastern KY by sunset Sunday. This will continue fair weather
through Sunday night. 850 mb temps cool to 12-14C tonight into
Sunday morning before rising back up to 14-16C by sunset Sunday.
Lows mostly in the middle 40s tonight (fog limited overnight
tonight over central IL with drier air advecting in). Highs
Sunday mostly 70-75F, except upper 60s to near 70F from I-74
northeast.

Strong low pressure of 1000 mb to eject ne from western KS Sunday
evening into Lake MI Monday night and bring a cold front east across
IL overnight Monday night and across the Wabash river valley in
eastern IL Tue morning. Breezy ssw winds Monday ahead of this storm
system to bring in warm air with highs approaching 80F. Have a
slight chance of showers and thunderstorms late Monday afternoon
far NW CWA by Galesburg. Best chances of showers and isolated
thunderstorms spread east across IL during Monday night (mainly
after midnight Monday night in eastern IL) and Tue morning, then
diminish Tue afternoon from the west. Highs Tue range from lower 60s
from I-55 nw to upper 60s to around 70F from I-70 se. Temperatures
steady or slowly falling Tue afternoon behind the cold front. Slight
chance of showers early Tue evening near the Wabash river, otherwise
dry weather returns Tue night through Wed night as another high
pressure system settles over IL by Wed afternoon. Near normal highs
Wed/Thu in the upper 50s/lower 60s.

A weak northern stream short wave to dive se into upper level trof
over the eastern states and bring another cold front into IL by Thu
afternoon/evening. Have just slight chance of showers Thu due to
limited moisture. ECMWF model shows strong cutoff upper level low
near IL on Halloween along with showers, but other models like GFS
are drier. Models due agree that even colder air arrives on
Halloween with highs in the lower 50s central IL and mid 50s se of
I-70, while low temperatures near freezing next Friday night over
central IL and mid 30s in southeast IL.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 638 AM CDT SAT OCT 25 2014

Difficult part of the forecast will be dense fog and lower IFR
clouds this morning and what time it will dissipate. HRRR keeps
the lower vis along the IL river and to the northwest. So, PIA
will be the only site effected by dense fog. However, other sites
will also have some light fog during the first 2-3hrs of the
morning. IFR and MVFR clouds are also advecting into the area from
the northwest and will effect the other sites early this morning,
before the sunshine burns them off. HRRR is keeps lower clouds in
the area til later this morning. Not sure if I agree with this
forecast, so have skies scattering out and then clearing at all
sites between 15 and 17z. Then clear skies will prevail for
remainder of TAF period, as high pressure builds into the area
with lower dewpoints and northwest winds at 5-10kts.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 9 AM CDT this morning FOR ILZ027>029-
036-040.

&&

$$

SHORT TERM...Auten
LONG TERM...07
AVIATION...Auten







000
FXUS63 KILX 251138
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
638 AM CDT Sat Oct 25 2014

.SHORT TERM...(Today)
ISSUED AT 319 AM CDT SAT OCT 25 2014

Main concern in the short term will be the dense fog again early
this morning, mainly in the northwestern parts of the CWA. Unlike
last night, the dense fog has not developed yet in the CWA and is
still located along and west of the Mississippi River. However, HRRR
model still forecast dense fog to move into the area. So will
continue the dense fog advisory as is, and will not extend in time or
area. Fog will be in areas east of the Illinois river, but not
dense. After the fog dissipates this morning, mostly clear skies
will be the rule for the area. Should be lots of sunshine to allow
temps to rise into the lower to middle 70s by this afternoon, which
is well above normal for the later part of October. Northwest winds
will only bring in a drier airmass for the day and beyond.

&&

.LONG TERM...(Tonight through Friday)
ISSUED AT 319 AM CDT SAT OCT 25 2014

1020 mb high pressure over over the northern High Plains, near the
eastern MT and western Dakotas border, to settle into IL by
sunrise Sunday and weaken a bit to 1018 mb, then drift into
eastern KY by sunset Sunday. This will continue fair weather
through Sunday night. 850 mb temps cool to 12-14C tonight into
Sunday morning before rising back up to 14-16C by sunset Sunday.
Lows mostly in the middle 40s tonight (fog limited overnight
tonight over central IL with drier air advecting in). Highs
Sunday mostly 70-75F, except upper 60s to near 70F from I-74
northeast.

Strong low pressure of 1000 mb to eject ne from western KS Sunday
evening into Lake MI Monday night and bring a cold front east across
IL overnight Monday night and across the Wabash river valley in
eastern IL Tue morning. Breezy ssw winds Monday ahead of this storm
system to bring in warm air with highs approaching 80F. Have a
slight chance of showers and thunderstorms late Monday afternoon
far NW CWA by Galesburg. Best chances of showers and isolated
thunderstorms spread east across IL during Monday night (mainly
after midnight Monday night in eastern IL) and Tue morning, then
diminish Tue afternoon from the west. Highs Tue range from lower 60s
from I-55 nw to upper 60s to around 70F from I-70 se. Temperatures
steady or slowly falling Tue afternoon behind the cold front. Slight
chance of showers early Tue evening near the Wabash river, otherwise
dry weather returns Tue night through Wed night as another high
pressure system settles over IL by Wed afternoon. Near normal highs
Wed/Thu in the upper 50s/lower 60s.

A weak northern stream short wave to dive se into upper level trof
over the eastern states and bring another cold front into IL by Thu
afternoon/evening. Have just slight chance of showers Thu due to
limited moisture. ECMWF model shows strong cutoff upper level low
near IL on Halloween along with showers, but other models like GFS
are drier. Models due agree that even colder air arrives on
Halloween with highs in the lower 50s central IL and mid 50s se of
I-70, while low temperatures near freezing next Friday night over
central IL and mid 30s in southeast IL.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 638 AM CDT SAT OCT 25 2014

Difficult part of the forecast will be dense fog and lower IFR
clouds this morning and what time it will dissipate. HRRR keeps
the lower vis along the IL river and to the northwest. So, PIA
will be the only site effected by dense fog. However, other sites
will also have some light fog during the first 2-3hrs of the
morning. IFR and MVFR clouds are also advecting into the area from
the northwest and will effect the other sites early this morning,
before the sunshine burns them off. HRRR is keeps lower clouds in
the area til later this morning. Not sure if I agree with this
forecast, so have skies scattering out and then clearing at all
sites between 15 and 17z. Then clear skies will prevail for
remainder of TAF period, as high pressure builds into the area
with lower dewpoints and northwest winds at 5-10kts.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 9 AM CDT this morning FOR ILZ027>029-
036-040.

&&

$$

SHORT TERM...Auten
LONG TERM...07
AVIATION...Auten







000
FXUS63 KLOT 250903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
403 AM CDT SAT OCT 25 2014

.DISCUSSION...
314 AM CDT

SHORT TERM...THROUGH SATURDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO SATURDAY MORNING...THE INITIAL
CONCERNS WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  A WEAK
MID LEVEL IMPULSE THAT TRACKED ACROSS THE REGION FRIDAY EVENING
BROUGHT SOME SCT SPRINKLES.  AS THE MID AND HIGH CLOUD PUSHES AWAY
FROM THE AREA...FOG AND LOW STRATUS ARE BLOOMING.  NWRN IL AND ERN
IA HAVE ALREADY SEEN DENSE FOG AND LOW STRATUS FORM...AND IN THE
MOIST AIRMASS IN PLACE...WITH DEWPOINTS IN THE LOW 50S...EXPECT THAT
THE AREA OF FOG/STRATUS SHOULD INCREASE...THOUGH THE LOWEST
CONDITIONS SHOULD BE ALONG AND WEST OF THE I-39 CORRIDOR.  EAST OF
I-39...ANY DENSE FOG SHOULD BE LIMITED TO SHELTERED...LOW-LYING
AREAS.

THROUGH THE MORNING HOURS...A WEAK FRONTAL BOUNDARY WILL CROSS THE
AREA...WITH SFC HIGH PRESSURE BUILDING ACROSS THE CNTRL PLAINS WHILE
UPPER LEVEL RIDGING ALSO BUILDS OUT OF THE ROCKIES AND ACROSS THE
CENTRAL PLAINS.  THE UPPER RIDGING WILL SET UP A SUBSIDENCE PATTERN
ACROSS THE AREA...LEADING TO MOSTLY SUNNY SKIES.  LOW PRESSURE
MOVING THROUGH SERN CANADA...COMBINED WITH THE HIGH PRESSURE OVER
THE PLAINS WILL SET UP A GENERALLY NWLY GRADIENT ACROSS NRN IL/IN.
DAYTIME WARMING SHOULD ALLOW ANY RESIDUAL FOG/STRATUS TO DISSIPATE
BY LATE MORNING...WHILE THE AMPLE SUNSHINE AND LARGER SCALE
SUBSIDENCE SHOULD ALLOW TEMPERATURES TO QUICKLY RISE INTO THE LOWER
70S ACROSS THE SRN PORTIONS OF THE CWA...WHILE LOCATION CLOSER TO
THE WI BORDER WILL BE A BIT COOLER...BUT STILL SIGNIFICANTLY WARMER
THAN NORMAL...WITH HIGHS IN THE UPPER 60S.  STEADY NWLY WINDS AT THE
SFC AND ALOFT SHOULD PREVENT ANY KIND OF LAKE BREEZE FROM FORMING
AND THE WARMER AIR SHOULD COVER THE AREA UP TO THE LAKEFRONT.  WHILE
DEWPOINTS WILL BE IN THE 50S FOR THE MORNING HOURS...DEEP MIXING
SHOULD DRAW MUCH DRIER AIR TO THE SFC...WITH DEWPOINTS DROPPING INTO
THE UPPER 30S FOR THE AFTERNOON HOURS.  SO...OVERALL...SATURDAY IS
SHAPING UP TO A VERY PLEASANT DAY...WITH TEMPERATURES AROUND 10
DEGREES ABOVE NORMAL.  THE SFC HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI VALLEY AND INTO THE MIDWEST OVERNIGHT TONIGHT WHILE THE
UPPER RIDGE SLOWLY PROGRESSES AS WELL.  WITH A DRIER AIRMASS IN
PLACE TONIGHT...THE CHANCES FOR ANOTHER ROUND OF FOG AND STRATUS IS
UNLIKELY...THROUGH THE CLEAR SKIES...LIGHT WINDS AND LOWER DEWPOINTS
SHOULD ALLOW TEMPERATURES TO RADIATE DOWN INTO THE UPPER 30S TO
LOWER 40S.  THE CHICAGO AREA URBAN HEAT ISLAND SHOULD REMAIN A
LITTLE WARMER...WITH LOWS IN THE MIDDLE 40S.

KREIN

SUNDAY THROUGH TUESDAY...
GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN THE MEDIUM TERM FEATURING
MID-LVL RIDGING OVER THE UPPER MIDWEST/GREAT LAKES REGION WITH A SFC
RIDGE PROVIDING ABUNDANT SUNSHINE AND DRY CONDS FOR THE SECOND HALF
OF THE WEEKEND. HOWEVER THIS RIDGE WILL ONLY BE TEMPORARY AS THE
MID-LVL HEIGHTS BEGIN TO FALL AND A QUASI-ZONAL FLOW BEGINS TO SETUP
FOR EARLY NEXT WEEK. FORTUNATELY IT REMAINS LIKELY THAT MON WILL
REMAIN DRY...WITH VERY MILD TEMPS EXPECTED. THE SFC RIDGE WILL BE
SHIFTING EAST OF THE FORECAST AREA...BUT SHOULD CONTINUE TO KEEP
CLOUDS TO A MINIMUM AND PRECIP WEST OF THE AREA. THE COMBINATION OF
THIS AND AN ANOMALOUS THERMAL RIDGE WILL ALLOW TEMPS TO SOAR INTO
THE MID/UPR 70S...WITH A FEW 80 DEGREE READINGS IN THE SOUTHERN CWFA
MON AFTN.

BROAD SFC TROUGH OVER THE CENTRAL/NORTHERN PLAINS WILL SLOWLY
CONSOLIDATE AS THIS FEATURE NEARS THE GREAT LAKES MON EVE. THERE IS
A SMALL CHANCE THAT A FEW SHOWERS/THUNDERSTORMS COULD SKIRT THE
NORTHERN CWFA MON AFTN...BUT EXPECT THE BULK OF THE PRECIP TO OCCUR
POST SUNSET. MID-LVL TROUGH WILL AMPLIFY ACROSS THE CENTRAL PLAINS
TUE MORNING...AS THE SFC LOW DEEPENS ACROSS LOWER MICHIGAN. HAVE
HELD ONTO THE MENTION OF THUNDER INTO TUE MORNING...AS IT APPEARS
SOME INSTABILITY/FORCING WILL CONTINUE. MON NGT TEMPS WILL LIKELY
NOT FALL MUCH...PRODUCING A MILD OVERNIGHT. THEN FOR TUE WITH
CONTINUED CLOUD COVER/PRECIP...EXPECT TEMPS TO REMAIN IN THE UPR
50S/LOW 60S. DEPENDING ON THE TIMING OF THE FROPA TUE...TEMPS COULD
BEGIN TO FALL TUE AFTN INTO THE LOW 50S.

WEDNESDAY THROUGH FRIDAY...
FOR THE SECOND HALF OF THE WEEK IT APPEARS THE PATTERN WILL BE
TRANSITIONING TOWARDS A COOLER AND SOMEWHAT ACTIVE SETUP. ENSEMBLES
CONTINUE TO PROG MID-LVL RIDGING DEVELOPING ACROSS THE WESTERN
CONUS...ALLOWING BROAD TROUGHING DOWNSTREAM FOR THE GREAT LAKES
REGION WED/THUR. THEN FRI THE 500MB RIDGE MAY BEGIN TO FURTHER
AMPLIFY AS A POTENT SHORTWAVE IS PROGGED TO APPROACH THE PAC-NW AND
RIDGING REMAINS ACROSS THE NORTH ATLANTIC. TROUGHING WILL LINGER
ACROSS THE GREAT LAKES FRI. TEMPS WILL TREND BACK TOWARDS
SEASONAL...WITH PERHAPS FRI BEING SUB-SEASONAL WITH HIGHS IN THE UPR
40S/LOW 50S. PERIODIC CHANCES FOR SHOWERS THROUGHOUT THE EXTENDED
TIMEFRAME.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS LIKELY OVERNIGHT...IFR CIGS A POSSIBILITY.

* MVFR VSBY POSSIBLE OVERNIGHT.

* IMPROVING CIG/VIS SATURDAY MORNING.

* BREEZY WEST-NORTHWEST WINDS...WITH GUSTS TO ARND 20KT.

KREIN

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE WILL CROSS THE REGION
OVERNIGHT. LATEST SATELLITE IMAGERY INDICATES JET CIRRUS AND SOME
MID LEVEL CLOUDINESS OVER THE AREA...BUT THE HIGHER LEVEL CLOUD IS
PUSHING EAST OF THE REGION...AND LOCATIONS THAT HAVE LOST THE
HIGHER LEVEL CLOUD COVER ARE ALREADY SEEING LOWERING STRATUS AND
FOG. ANTICIPATE THAT CIGS WILL GRADUALLY LOWER WITH THE WRN
TERMINALS...RFD/DPA LOWERING FIRST AND THEN ORD/MDW/GYY A LITTLE
LATER. STILL HAVE SOME CONCERNS FOR IFR CIGS DEVELOPING...WITH
HIGHER CONFIDENCE IN IFR CONDITIONS AT RFD/DPA...BUT HAVE ENOUGH
CONFIDENCE IN IFR CIGS AT ORD/MDW/GYY TO AT LEAST INCLUDE IN A
TEMPO GROUP. THERE IS SOME CONCERN FOR LIFR CIGS/VIS...ESPECIALLY
AT RFD...WHICH WILL HAVE THE LONGEST PERIOD OF TIME WITHOUT THE
HIGHER LEVEL CLOUD. ALSO...AS THE WEAK SFC TROUGH AXIS CROSSES THE
AREA...WINDS DECREASING TO BLW 5KT COULD ALSO HELP WITH DENSER FOG
DEVELOPMENT AWAY FROM THE CHICAGO AREA URBAN HEAT ISLAND.

WITH AMPLE SUNSHINE EXPECTED...CONDITIONS SHOULD QUICKLY IMPROVE
AFTER SUNRISE AND THE REMAINDER OF THE DAY SHOULD SEE VFR
CONDITIONS. THE MAIN ISSUE FOR THE REMAINDER OF THE DAY WILL BE
WINDS. FOLLOWING THE PASSAGE OF THE WEAK SFC TROUGH...HIGH
PRESSURE BUILDING OVER THE NRN PLAINS WILL SET UP A STRENGTHENING
WNWLY-NWLY GRADIENT OVER THE AREA. WITH AMPLE MIXING THROUGH THE
AFTERNOON...WINDS SHOULD BECOME MORE GUSTY...WITH GUSTS TO ARND
20KT THROUGH SUNSET.

KREIN

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

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR OVERNIGHT. MEDIUM
  CONFIDENCE IN IFR CIGS DEVELOPING.

* LOW TO MEDIUM CONFIDENCE IN MVFR VIS OVERNIGHT.

* HIGH CONFIDENCE IN IMPROVEMENT TO VFR AND WNWLY-NWLY WINDS
  SATURDAY...WITH GUSTS TO ARND 20KT IN THE AFTERNOON.

KREIN

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

SUNDAY...VFR. SLGT CHC SHRA/TSRA SUNDAY NIGHT. SE WINDS.

MONDAY...VFR BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST-WEST WINDS.

WEDNESDAY AND THURSDAY...VFR. WEST-SOUTHWEST WINDS.

RATZER

&&

.MARINE...
229 AM CDT

LOW PRESSURE OVER JAMES BAY ALONG WITH A SFC RIDGE CENTERED OVER
THE NORTHERN PLAINS HAS CREATED A TIGHT PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS...WHICH IS POSITIONED OVER THE LAKE. THIS HAS
RESULTED IN BREEZY SOUTHWEST WINDS OVER THE LAKE WITH SPEEDS
GENERALLY BETWEEN 20-25KT. ACROSS THE NORTHERN HALF OF THE LAKE
THE GUSTS MAY NEAR 30 KT THIS MORNING. AS HIGH PRESSURE SLOWLY
BUILDS IN FROM THE WEST ACROSS THE LAKE...WIND WILL TURN
WEST/NORTHWEST AND GRADUALLY DIMINISH LATE TONIGHT/EARLY SUN. HIGH
PRESSURE WILL BECOME CENTERED OVER THE LAKE SUN...THEN CONTINUE TO
SLIDE EAST BY LATE SUN NIGHT. THIS WILL ALLOW ONLY A TEMPORARY
LULL IN THE WINDS...BEFORE WINDS TURN SOUTH/SOUTHWEST AND BEGIN TO
INCREASE. ANOTHER LOW PRESSURE IS POISED TO DEVELOP ACROSS THE
CENTRAL PLAINS MONDAY AFTERNOON...AND SLOWLY LIFT NORTHEAST
TOWARDS LAKE MICHIGAN MONDAY NIGHT/EARLY TUE. THIS LOW WILL THEN
DEEPEN TUE AFTERNOON AS IT LIFTS NORTHEAST ACROSS LOWER MICHIGAN.
THIS COULD PRODUCE A PERIOD OF WEST GALES TUE NGT/EARLY WED...THEN
ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE WESTERN LAKES
TOWARDS THE MIDDLE OF THE WEEK.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KILX 250821
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
321 AM CDT Sat Oct 25 2014

.SHORT TERM...(Today)
ISSUED AT 319 AM CDT SAT OCT 25 2014

Main concern in the short term will be the dense fog again early
this morning, mainly in the northwestern parts of the CWA. Unlike
last night, the dense fog has not developed yet in the CWA and is
still located along and west of the Mississippi River. However, HRRR
model still forecast dense fog to move into the area. So will
continue the dense fog advisory as is, and will not extend in time or
area. Fog will be in areas east of the Illinois river, but not
dense. After the fog dissipates this morning, mostly clear skies
will be the rule for the area. Should be lots of sunshine to allow
temps to rise into the lower to middle 70s by this afternoon, which
is well above normal for the later part of October. Northwest winds
will only bring in a drier airmass for the day and beyond.

&&

.LONG TERM...(Tonight through Friday)
ISSUED AT 319 AM CDT SAT OCT 25 2014

1020 mb high pressure over over the northern High Plains, near the
eastern MT and western Dakotas border, to settle into IL by
sunrise Sunday and weaken a bit to 1018 mb, then drift into
eastern KY by sunset Sunday. This will continue fair weather
through Sunday night. 850 mb temps cool to 12-14C tonight into
Sunday morning before rising back up to 14-16C by sunset Sunday.
Lows mostly in the middle 40s tonight (fog limited overnight
tonight over central IL with drier air advecting in). Highs
Sunday mostly 70-75F, except upper 60s to near 70F from I-74
northeast.

Strong low pressure of 1000 mb to eject ne from western KS Sunday
evening into Lake MI Monday night and bring a cold front east across
IL overnight Monday night and across the Wabash river valley in
eastern IL Tue morning. Breezy ssw winds Monday ahead of this storm
system to bring in warm air with highs approaching 80F. Have a
slight chance of showers and thunderstorms late Monday afternoon
far NW CWA by Galesburg. Best chances of showers and isolated
thunderstorms spread east across IL during Monday night (mainly
after midnight monday night in eastern IL) and Tue morning, then
diminish Tue afternoon from the west. Highs Tue range from lower 60s
from I-55 nw to upper 60s to around 70F from I-70 se. Temperatures
steady or slowly falling tue afternoon behind the cold front. Slight
chance of showers early Tue evening near the Wabash river, otherwise
dry weather returns Tue night through Wed night as another high
pressure system settles over IL by Wed afternoon. Near normal highs
Wed/Thu in the upper 50s/lower 60s.

A weak northern stream short wave to dive se into upper level trof
over the eastern states and bring another cold front into IL by Thu
afternoon/evening. Have just slight chance of showers Thu due to
limited moisture. ECMWF model shows strong cutoff upper level low
near IL on Halloween along with showers, but other models like GFS
are drier. Models due agree that even colder air arrives on
Halloween with highs in the lower 50s central IL and mid 50s se of
I-70, while low temperatures near freezing next Friday night over
central IL and mid 30s in southeast IL.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1150 PM CDT FRI OCT 24 2014

Mainly VFR conditions continue across central/SE Illinois late
this evening as a shortwave trough and weak cold front moves
across the region, bringing cigs just above 3 kft AGL. This
feature will move off to the east overnight, then clearing of the
cloud cover will allow fog to develop overnight. Given a similar
air mass to last night and winds expected to become light/variable
in the vicinity of the trough, vsbys between 1 and 3 miles
included for most central Illinois TAF locations, with LIFR
category included for KPIA. Gradual clearing with winds NW 8-10
kts expected after 14Z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 9 AM CDT this morning FOR ILZ027>029-
036-040.

&&

$$

SHORT TERM...Auten
LONG TERM...07
AVIATION...Onton







000
FXUS63 KLOT 250815
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
315 AM CDT SAT OCT 25 2014

.DISCUSSION...
314 AM CDT

SHORT TERM...THROUGH SATURDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO SATURDAY MORNING...THE INITIAL
CONCERNS WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  A WEAK
MID LEVEL IMPULSE THAT TRACKED ACROSS THE REGION FRIDAY EVENING
BROUGHT SOME SCT SPRINKLES.  AS THE MID AND HIGH CLOUD PUSHES AWAY
FROM THE AREA...FOG AND LOW STRATUS ARE BLOOMING.  NWRN IL AND ERN
IA HAVE ALREADY SEEN DENSE FOG AND LOW STRATUS FORM...AND IN THE
MOIST AIRMASS IN PLACE...WITH DEWPOINTS IN THE LOW 50S...EXPECT THAT
THE AREA OF FOG/STRATUS SHOULD INCREASE...THOUGH THE LOWEST
CONDITIONS SHOULD BE ALONG AND WEST OF THE I-39 CORRIDOR.  EAST OF
I-39...ANY DENSE FOG SHOULD BE LIMITED TO SHELTERED...LOW-LYING
AREAS.

THROUGH THE MORNING HOURS...A WEAK FRONTAL BOUNDARY WILL CROSS THE
AREA...WITH SFC HIGH PRESSURE BUILDING ACROSS THE CNTRL PLAINS WHILE
UPPER LEVEL RIDGING ALSO BUILDS OUT OF THE ROCKIES AND ACROSS THE
CENTRAL PLAINS.  THE UPPER RIDGING WILL SET UP A SUBSIDENCE PATTERN
ACROSS THE AREA...LEADING TO MOSTLY SUNNY SKIES.  LOW PRESSURE
MOVING THROUGH SERN CANADA...COMBINED WITH THE HIGH PRESSURE OVER
THE PLAINS WILL SET UP A GENERALLY NWLY GRADIENT ACROSS NRN IL/IN.
DAYTIME WARMING SHOULD ALLOW ANY RESIDUAL FOG/STRATUS TO DISSIPATE
BY LATE MORNING...WHILE THE AMPLE SUNSHINE AND LARGER SCALE
SUBSIDENCE SHOULD ALLOW TEMPERATURES TO QUICKLY RISE INTO THE LOWER
70S ACROSS THE SRN PORTIONS OF THE CWA...WHILE LOCATION CLOSER TO
THE WI BORDER WILL BE A BIT COOLER...BUT STILL SIGNIFICANTLY WARMER
THAN NORMAL...WITH HIGHS IN THE UPPER 60S.  STEADY NWLY WINDS AT THE
SFC AND ALOFT SHOULD PREVENT ANY KIND OF LAKE BREEZE FROM FORMING
AND THE WARMER AIR SHOULD COVER THE AREA UP TO THE LAKEFRONT.  WHILE
DEWPOINTS WILL BE IN THE 50S FOR THE MORNING HOURS...DEEP MIXING
SHOULD DRAW MUCH DRIER AIR TO THE SFC...WITH DEWPOINTS DROPPING INTO
THE UPPER 30S FOR THE AFTERNOON HOURS.  SO...OVERALL...SATURDAY IS
SHAPING UP TO A VERY PLEASANT DAY...WITH TEMPERATURES AROUND 10
DEGREES ABOVE NORMAL.  THE SFC HIGH PRESSURE WILL BUILD ACROSS THE
MISSISSIPPI VALLEY AND INTO THE MIDWEST OVERNIGHT TONIGHT WHILE THE
UPPER RIDGE SLOWLY PROGRESSES AS WELL.  WITH A DRIER AIRMASS IN
PLACE TONIGHT...THE CHANCES FOR ANOTHER ROUND OF FOG AND STRATUS IS
UNLIKELY...THROUGH THE CLEAR SKIES...LIGHT WINDS AND LOWER DEWPOINTS
SHOULD ALLOW TEMPERATURES TO RADIATE DOWN INTO THE UPPER 30S TO
LOWER 40S.  THE CHICAGO AREA URBAN HEAT ISLAND SHOULD REMAIN A
LITTLE WARMER...WITH LOWS IN THE MIDDLE 40S.

KREIN

SUNDAY THROUGH TUESDAY...
GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN THE MEDIUM TERM FEATURING
MID-LVL RIDGING OVER THE UPPER MIDWEST/GREAT LAKES REGION WITH A SFC
RIDGE PROVIDING ABUNDANT SUNSHINE AND DRY CONDS FOR THE SECOND HALF
OF THE WEEKEND. HOWEVER THIS RIDGE WILL ONLY BE TEMPORARY AS THE
MID-LVL HEIGHTS BEGIN TO FALL AND A QUASI-ZONAL FLOW BEGINS TO SETUP
FOR EARLY NEXT WEEK. FORTUNATELY IT REMAINS LIKELY THAT MON WILL
REMAIN DRY...WITH VERY MILD TEMPS EXPECTED. THE SFC RIDGE WILL BE
SHIFTING EAST OF THE FORECAST AREA...BUT SHOULD CONTINUE TO KEEP
CLOUDS TO A MINIMUM AND PRECIP WEST OF THE AREA. THE COMBINATION OF
THIS AND AN ANOMALOUS THERMAL RIDGE WILL ALLOW TEMPS TO SOAR INTO
THE MID/UPR 70S...WITH A FEW 80 DEGREE READINGS IN THE SOUTHERN CWFA
MON AFTN.

BROAD SFC TROUGH OVER THE CENTRAL/NORTHERN PLAINS WILL SLOWLY
CONSOLIDATE AS THIS FEATURE NEARS THE GREAT LAKES MON EVE. THERE IS
A SMALL CHANCE THAT A FEW SHOWERS/THUNDERSTORMS COULD SKIRT THE
NORTHERN CWFA MON AFTN...BUT EXPECT THE BULK OF THE PRECIP TO OCCUR
POST SUNSET. MID-LVL TROUGH WILL AMPLIFY ACROSS THE CENTRAL PLAINS
TUE MORNING...AS THE SFC LOW DEEPENS ACROSS LOWER MICHIGAN. HAVE
HELD ONTO THE MENTION OF THUNDER INTO TUE MORNING...AS IT APPEARS
SOME INSTABILITY/FORCING WILL CONTINUE. MON NGT TEMPS WILL LIKELY
NOT FALL MUCH...PRODUCING A MILD OVERNIGHT. THEN FOR TUE WITH
CONTINUED CLOUD COVER/PRECIP...EXPECT TEMPS TO REMAIN IN THE UPR
50S/LOW 60S. DEPENDING ON THE TIMING OF THE FROPA TUE...TEMPS COULD
BEGIN TO FALL TUE AFTN INTO THE LOW 50S.

WEDNESDAY THROUGH FRIDAY...
FOR THE SECOND HALF OF THE WEEK IT APPEARS THE PATTERN WILL BE
TRANSITIONING TOWARDS A COOLER AND SOMEWHAT ACTIVE SETUP. ENSEMBLES
CONTINUE TO PROG MID-LVL RIDGING DEVELOPING ACROSS THE WESTERN
CONUS...ALLOWING BROAD TROUGHING DOWNSTREAM FOR THE GREAT LAKES
REGION WED/THUR. THEN FRI THE 500MB RIDGE MAY BEGIN TO FURTHER
AMPLIFY AS A POTENT SHORTWAVE IS PROGGED TO APPROACH THE PAC-NW AND
RIDGING REMAINS ACROSS THE NORTH ATLANTIC. TROUGHING WILL LINGER
ACROSS THE GREAT LAKES FRI. TEMPS WILL TREND BACK TOWARDS
SEASONAL...WITH PERHAPS FRI BEING SUB-SEASONAL WITH HIGHS IN THE UPR
40S/LOW 50S. PERIODIC CHANCES FOR SHOWERS THROUGHOUT THE EXTENDED
TIMEFRAME.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS LIKELY OVERNIGHT...IFR CIGS A POSSIBILITY.

* MVFR VSBY POSSIBLE OVERNIGHT.

* IMPROVING CIG/VIS SATURDAY MORNING.

* BREEZY WEST-NORTHWEST WINDS...WITH GUSTS TO ARND 20KT.

KREIN

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE WILL CROSS THE REGION
OVERNIGHT. LATEST SATELLITE IMAGERY INDICATES JET CIRRUS AND SOME
MID LEVEL CLOUDINESS OVER THE AREA...BUT THE HIGHER LEVEL CLOUD IS
PUSHING EAST OF THE REGION...AND LOCATIONS THAT HAVE LOST THE
HIGHER LEVEL CLOUD COVER ARE ALREADY SEEING LOWERING STRATUS AND
FOG. ANTICIPATE THAT CIGS WILL GRADUALLY LOWER WITH THE WRN
TERMINALS...RFD/DPA LOWERING FIRST AND THEN ORD/MDW/GYY A LITTLE
LATER. STILL HAVE SOME CONCERNS FOR IFR CIGS DEVELOPING...WITH
HIGHER CONFIDENCE IN IFR CONDITIONS AT RFD/DPA...BUT HAVE ENOUGH
CONFIDENCE IN IFR CIGS AT ORD/MDW/GYY TO AT LEAST INCLUDE IN A
TEMPO GROUP. THERE IS SOME CONCERN FOR LIFR CIGS/VIS...ESPECIALLY
AT RFD...WHICH WILL HAVE THE LONGEST PERIOD OF TIME WITHOUT THE
HIGHER LEVEL CLOUD. ALSO...AS THE WEAK SFC TROUGH AXIS CROSSES THE
AREA...WINDS DECREASING TO BLW 5KT COULD ALSO HELP WITH DENSER FOG
DEVELOPMENT AWAY FROM THE CHICAGO AREA URBAN HEAT ISLAND.

WITH AMPLE SUNSHINE EXPECTED...CONDITIONS SHOULD QUICKLY IMPROVE
AFTER SUNRISE AND THE REMAINDER OF THE DAY SHOULD SEE VFR
CONDITIONS. THE MAIN ISSUE FOR THE REMAINDER OF THE DAY WILL BE
WINDS. FOLLOWING THE PASSAGE OF THE WEAK SFC TROUGH...HIGH
PRESSURE BUILDING OVER THE NRN PLAINS WILL SET UP A STRENGTHENING
WNWLY-NWLY GRADIENT OVER THE AREA. WITH AMPLE MIXING THROUGH THE
AFTERNOON...WINDS SHOULD BECOME MORE GUSTY...WITH GUSTS TO ARND
20KT THROUGH SUNSET.

KREIN

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

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR OVERNIGHT. MEDIUM
  CONFIDENCE IN IFR CIGS DEVELOPING.

* MEDIUM CONFIDENCE IN MVFR VIS OVERNIGHT.

* HIGH CONFIDENCE IN IMPROVEMENT TO VFR AND WNWLY-NWLY WINDS
  SATURDAY...WITH GUSTS TO ARND 20KT IN THE AFTERNOON.

KREIN

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

SUNDAY...VFR. SLGT CHC SHRA/TSRA SUNDAY NIGHT. SE WINDS.

MONDAY...VFR BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST-WEST WINDS.

WEDNESDAY AND THURSDAY...VFR. WEST-SOUTHWEST WINDS.

RATZER

&&

.MARINE...
229 AM CDT

LOW PRESSURE OVER JAMES BAY ALONG WITH A SFC RIDGE CENTERED OVER
THE NORTHERN PLAINS HAS CREATED A TIGHT PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS...WHICH IS POSITIONED OVER THE LAKE. THIS HAS
RESULTED IN BREEZY SOUTHWEST WINDS OVER THE LAKE WITH SPEEDS
GENERALLY BETWEEN 20-25KT. ACROSS THE NORTHERN HALF OF THE LAKE
THE GUSTS MAY NEAR 30 KT THIS MORNING. AS HIGH PRESSURE SLOWLY
BUILDS IN FROM THE WEST ACROSS THE LAKE...WIND WILL TURN
WEST/NORTHWEST AND GRADUALLY DIMINISH LATE TONIGHT/EARLY SUN. HIGH
PRESSURE WILL BECOME CENTERED OVER THE LAKE SUN...THEN CONTINUE TO
SLIDE EAST BY LATE SUN NIGHT. THIS WILL ALLOW ONLY A TEMPORARY
LULL IN THE WINDS...BEFORE WINDS TURN SOUTH/SOUTHWEST AND BEGIN TO
INCREASE. ANOTHER LOW PRESSURE IS POISED TO DEVELOP ACROSS THE
CENTRAL PLAINS MONDAY AFTERNOON...AND SLOWLY LIFT NORTHEAST
TOWARDS LAKE MICHIGAN MONDAY NIGHT/EARLY TUE. THIS LOW WILL THEN
DEEPEN TUE AFTERNOON AS IT LIFTS NORTHEAST ACROSS LOWER MICHIGAN.
THIS COULD PRODUCE A PERIOD OF WEST GALES TUE NGT/EARLY WED...THEN
ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE WESTERN LAKES
TOWARDS THE MIDDLE OF THE WEEK.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 250745
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
245 AM CDT SAT OCT 25 2014

.DISCUSSION...
947 PM CDT

ISOLATED SHOWERS ARE MOVING THROUGH THIS EVENING. MOST AREAS WILL
REMAIN DRY...AND EXPECT SHOWERS TO BE INTO NW INDIANA AFTER
MIDNIGHT...AND EAST OF THE AREA SHORTLY THEREAFTER.
OTHERWISE...EXPECT SOME FOG TO REFORM AGAIN TONIGHT...WITH WESTERN
AREAS FAVORED DUE TO A THINNING AND LOWERING OF CLOUDS.

KMD

//PREV DISCUSSION...
304 PM CDT

THIS EVENING AND TONIGHT...
BROAD SURFACE HIGH STRETCHES FROM THE LOWER MISSISSIPPI VALLEY INTO
THE UPPER OHIO VALLEY AND EASTERN GREAT LAKES THIS AFTERNOON WHILE
LOW PRESSURE LIES OVER ONTARIO WITH A COLD FRONT STRETCHING INTO THE
CENTRAL PLAINS. A NARROW RIBBON OF MOISTURE IS ANALYZED OUT AHEAD OF
THE COLD FRONT WITH 60 DEGREE DEWPOINTS STRETCHING NORTH INTO
NORTHERN IOWA THIS AFTERNOON...AND JUST OFF THE DECK A CORRIDOR OF
LOW/MID LEVEL THETA-E ADVECTION IS DRIVING AT LEAST A FEW VERY WEAK
RADAR RETURNS OVER FAR SE MN AND NE IA. RAP/HRRR GUIDANCE SHOWS THIS
AREA PERSISTING ACROSS NORTHERN ILLINOIS THIS EVENING WITH THE
CHANCE FOR A FEW SHOWERS. GIVEN THE VERY SPARSE COVERAGE SO FAR
UPSTREAM AND THE DRY SOUNDINGS/LIMITED DURATION OF FORCING...NOT
BITING OFF ON PRECIP MOVING ACROSS THE FORECAST AREA...BUT WILL
MAINTAIN SOME LOW END SLIGHT CHANCE POPS SINCE THERE ARE SOME
INGREDIENTS IN PLACE.

SATURDAY THROUGH SUNDAY...
WEAK FRONT WILL PASS ACROSS THE AREA EARLY ON SATURDAY WITH DRY AIR
FILTERING BACK INTO THE REGION AS AN UPPER RIDGE BUILDS OVER THE
AREA AND SUBSIDENCE SETS IN OVERHEAD. EXPECT DEW POINTS TO MIX OUT
NICELY TOMORROW AFTERNOON...ESPECIALLY IN NORTH CENTRAL ILLINOIS
WHERE DEW POINTS MAY DROP INTO THE LOW TO MID 30S. THE DRY
CONDITIONS SHOULD ALLOW FOR A NICE RESPONSE FROM DIABATIC HEATING
WHICH WILL RESULT IN TEMPS A FEW DEGREES WARMER TOMORROW.
MEANWHILE...SURFACE HIGH WILL BUILD FROM THE NORTHERN PLAINS
SATURDAY DIRECTLY OVERHEAD EARLY TUESDAY MORNING WHICH WILL ALLOW
FAVORABLE RADIATIONAL COOLING SUNDAY MORNING WITH LOWS DIPPING INTO
THE 30S IN OUTLYING AREAS AND SOME OF THE TYPICAL COLD SPOTS.
ELSEWHERE EXPECT LOW 40S WITH DOWNTOWN CHICAGO STAYING PROPPED UP IN
THE MID 40S. TEMPERATURES MAY BE A BIT TRICKY SUNDAY WITH WARM
ADVECTION ALOFT INCREASING THROUGH THE DAY ON THE BACKSIDE OF THE
SURFACE HIGH. A COOL STARTING POINT AND INCREASING CLOUD COVER
THROUGH THE DAY WILL KEEP HIGHS ONLY INTO THE 60S SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY...
UPPER RIDGE BEGINS TO BUCKLE SUNDAY NIGHT INTO MONDAY AS SHORTWAVE
TROUGH DIGS FROM THE PAC NW INTO THE CENTRAL PLAINS. BROAD SURFACE
LOW PRESSURE OVER THE PLAINS WILL SHIFT EAST TOWARDS THE MIDWEST
EARLY MONDAY WITH SOUTHWEST FLOW INCREASING OUT AHEAD AND A CORRIDOR
OF MODERATE TO STRONG MID LEVEL THETA-E ADVECTION LIFTING ACROSS THE
LOCAL FORECAST AREA ON THE NOSE OF A 40KT OR SO LOW LEVEL JET.
COLUMN IS FAIRLY DRY OUT AHEAD OF THE BAROCLINIC ZONE BUT A NARROW
LAYER OF SATURATION COULD TAP INTO SOME MODEST INSTABILITY ROOTED
BETWEEN H7-H9. THIS DOES POINT TO SOME CHANCES FOR THUNDERSTORMS
THOUGH CHANCES ARE BETTER TO OUR NORTH WHERE THE MUCAPE ALIGNS
BETTER WITH THE FORCING FROM THE LOW LEVEL JET. EXPECT LOWERING
CLOUDS IN THE PREDAWN HOURS AS THE SURFACE WARM FRONT APPROACHES.
THE MID LEVELS DRY OUT AGAIN AND THE MOISTURE IS FAIRLY SHALLOW SO
ANY ADDITIONAL PRECIP EARLY ON MONDAY MAY JUST BE DRIZZLE. SURFACE
WARM FRONT LIFTS ACROSS THE AREA MID MORNING MONDAY AND EXPECT DRY
CONDITIONS ONCE IN THE WARM SECTOR WITH LOW CLOUD COVER EVENTUALLY
SCATTERING. H85 TEMPS WARM TO 15-16C WITH 17C BEING THE 99TH
PERCENTILE OF UPPER AIR CLIMO FOR THE END OF OCTOBER. SURFACE HIGHS
WILL BE WELL ABOVE NORMAL...POSSIBLY PUSHING 20F ABOVE
NORMAL...THOUGH THE RECORD HIGH SHOULD BE SAFE. LEANED HEAVILY ON
EC/ECBC FOR AFTERNOON HIGHS MONDAY FORECASTING MID 70S...WITH UPPER
70S SOUTH OF I-80. THE WARMER CONDITIONS WILL BE ACCOMPANIED BY
STRONGER WINDS HOWEVER WITH SOUTHWEST WINDS GUSTING 20 TO 25 MPH AND
POSSIBLY 30 MPH AT TIMES.

TUESDAY THROUGH FRIDAY...
MODELS ARE INDICATING A STRONG LOW PRESSURE SYSTEM WILL BEGIN TO
DEVELOP OVER THE REGION EARLY NEXT WEEK WITH A COLD FRONT SWEEPING
ACROSS THE ARE MONDAY NIGHT INTO EARLY TUESDAY BRINGING CHANCES FOR
SHOWER AND THUNDERSTORMS. THE LOW REALLY BEGINS TO DEEPEN IN EARNEST
AS IT LIFTS ACROSS THE GREAT LAKES INTO CANADA TUESDAY INTO
WEDNESDAY WITH DRIVING POLAR AIR SOUTH INTO THE CANADIAN PRAIRIES
AND A COLD POLAR HIGH GRAZING THE LOCAL AREA LATE NEXT WEEK. DETAILS
STILL MURKY THIS FAR OUT BUT DOES APPEAR WE COULD BE IN FOR A BIG
COOL DOWN LATE NEXT WEEK IN TIME FOR HALLOWEEN IF CURRENT GFS/ECMWF
RUNS PAN OUT.

DEUBELBEISS

&&

.AVIATION...

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

* MVFR CIGS LIKELY OVERNIGHT...IFR CIGS A POSSIBILITY.

* MVFR VSBY POSSIBLE OVERNIGHT.

* IMPROVING CIG/VIS SATURDAY MORNING.

* BREEZY WEST-NORTHWEST WINDS...WITH GUSTS TO ARND 20KT.

KREIN

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE WILL CROSS THE REGION
OVERNIGHT. LATEST SATELLITE IMAGERY INDICATES JET CIRRUS AND SOME
MID LEVEL CLOUDINESS OVER THE AREA...BUT THE HIGHER LEVEL CLOUD IS
PUSHING EAST OF THE REGION...AND LOCATIONS THAT HAVE LOST THE
HIGHER LEVEL CLOUD COVER ARE ALREADY SEEING LOWERING STRATUS AND
FOG. ANTICIPATE THAT CIGS WILL GRADUALLY LOWER WITH THE WRN
TERMINALS...RFD/DPA LOWERING FIRST AND THEN ORD/MDW/GYY A LITTLE
LATER. STILL HAVE SOME CONCERNS FOR IFR CIGS DEVELOPING...WITH
HIGHER CONFIDENCE IN IFR CONDITIONS AT RFD/DPA...BUT HAVE ENOUGH
CONFIDENCE IN IFR CIGS AT ORD/MDW/GYY TO AT LEAST INCLUDE IN A
TEMPO GROUP. THERE IS SOME CONCERN FOR LIFR CIGS/VIS...ESPECIALLY
AT RFD...WHICH WILL HAVE THE LONGEST PERIOD OF TIME WITHOUT THE
HIGHER LEVEL CLOUD. ALSO...AS THE WEAK SFC TROUGH AXIS CROSSES THE
AREA...WINDS DECREASING TO BLW 5KT COULD ALSO HELP WITH DENSER FOG
DEVELOPMENT AWAY FROM THE CHICAGO AREA URBAN HEAT ISLAND.

WITH AMPLE SUNSHINE EXPECTED...CONDITIONS SHOULD QUICKLY IMPROVE
AFTER SUNRISE AND THE REMAINDER OF THE DAY SHOULD SEE VFR
CONDITIONS. THE MAIN ISSUE FOR THE REMAINDER OF THE DAY WILL BE
WINDS. FOLLOWING THE PASSAGE OF THE WEAK SFC TROUGH...HIGH
PRESSURE BUILDING OVER THE NRN PLAINS WILL SET UP A STRENGTHENING
WNWLY-NWLY GRADIENT OVER THE AREA. WITH AMPLE MIXING THROUGH THE
AFTERNOON...WINDS SHOULD BECOME MORE GUSTY...WITH GUSTS TO ARND
20KT THROUGH SUNSET.

KREIN

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

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR OVERNIGHT. MEDIUM
  CONFIDENCE IN IFR CIGS DEVELOPING.

* MEDIUM CONFIDENCE IN MVFR VIS OVERNIGHT.

* HIGH CONFIDENCE IN IMPROVEMENT TO VFR AND WNWLY-NWLY WINDS
  SATURDAY...WITH GUSTS TO ARND 20KT IN THE AFTERNOON.

KREIN

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

SUNDAY...VFR. SLGT CHC SHRA/TSRA SUNDAY NIGHT. SE WINDS.

MONDAY...VFR BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST-WEST WINDS.

WEDNESDAY AND THURSDAY...VFR. WEST-SOUTHWEST WINDS.

RATZER

&&

.MARINE...
229 AM CDT

LOW PRESSURE OVER JAMES BAY ALONG WITH A SFC RIDGE CENTERED OVER
THE NORTHERN PLAINS HAS CREATED A TIGHT PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS...WHICH IS POSITIONED OVER THE LAKE. THIS HAS
RESULTED IN BREEZY SOUTHWEST WINDS OVER THE LAKE WITH SPEEDS
GENERALLY BETWEEN 20-25KT. ACROSS THE NORTHERN HALF OF THE LAKE
THE GUSTS MAY NEAR 30 KT THIS MORNING. AS HIGH PRESSURE SLOWLY
BUILDS IN FROM THE WEST ACROSS THE LAKE...WIND WILL TURN
WEST/NORTHWEST AND GRADUALLY DIMINISH LATE TONIGHT/EARLY SUN. HIGH
PRESSURE WILL BECOME CENTERED OVER THE LAKE SUN...THEN CONTINUE TO
SLIDE EAST BY LATE SUN NIGHT. THIS WILL ALLOW ONLY A TEMPORARY
LULL IN THE WINDS...BEFORE WINDS TURN SOUTH/SOUTHWEST AND BEGIN TO
INCREASE. ANOTHER LOW PRESSURE IS POISED TO DEVELOP ACROSS THE
CENTRAL PLAINS MONDAY AFTERNOON...AND SLOWLY LIFT NORTHEAST
TOWARDS LAKE MICHIGAN MONDAY NIGHT/EARLY TUE. THIS LOW WILL THEN
DEEPEN TUE AFTERNOON AS IT LIFTS NORTHEAST ACROSS LOWER MICHIGAN.
THIS COULD PRODUCE A PERIOD OF WEST GALES TUE NGT/EARLY WED...THEN
ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE WESTERN LAKES
TOWARDS THE MIDDLE OF THE WEEK.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 250558
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1258 AM CDT SAT OCT 25 2014

.DISCUSSION...
947 PM CDT

ISOLATED SHOWERS ARE MOVING THROUGH THIS EVENING. MOST AREAS WILL
REMAIN DRY...AND EXPECT SHOWERS TO BE INTO NW INDIANA AFTER
MIDNIGHT...AND EAST OF THE AREA SHORTLY THEREAFTER.
OTHERWISE...EXPECT SOME FOG TO REFORM AGAIN TONIGHT...WITH WESTERN
AREAS FAVORED DUE TO A THINNING AND LOWERING OF CLOUDS.

KMD

//PREV DISCUSSION...
304 PM CDT

THIS EVENING AND TONIGHT...
BROAD SURFACE HIGH STRETCHES FROM THE LOWER MISSISSIPPI VALLEY INTO
THE UPPER OHIO VALLEY AND EASTERN GREAT LAKES THIS AFTERNOON WHILE
LOW PRESSURE LIES OVER ONTARIO WITH A COLD FRONT STRETCHING INTO THE
CENTRAL PLAINS. A NARROW RIBBON OF MOISTURE IS ANALYZED OUT AHEAD OF
THE COLD FRONT WITH 60 DEGREE DEWPOINTS STRETCHING NORTH INTO
NORTHERN IOWA THIS AFTERNOON...AND JUST OFF THE DECK A CORRIDOR OF
LOW/MID LEVEL THETA-E ADVECTION IS DRIVING AT LEAST A FEW VERY WEAK
RADAR RETURNS OVER FAR SE MN AND NE IA. RAP/HRRR GUIDANCE SHOWS THIS
AREA PERSISTING ACROSS NORTHERN ILLINOIS THIS EVENING WITH THE
CHANCE FOR A FEW SHOWERS. GIVEN THE VERY SPARSE COVERAGE SO FAR
UPSTREAM AND THE DRY SOUNDINGS/LIMITED DURATION OF FORCING...NOT
BITING OFF ON PRECIP MOVING ACROSS THE FORECAST AREA...BUT WILL
MAINTAIN SOME LOW END SLIGHT CHANCE POPS SINCE THERE ARE SOME
INGREDIENTS IN PLACE.

SATURDAY THROUGH SUNDAY...
WEAK FRONT WILL PASS ACROSS THE AREA EARLY ON SATURDAY WITH DRY AIR
FILTERING BACK INTO THE REGION AS AN UPPER RIDGE BUILDS OVER THE
AREA AND SUBSIDENCE SETS IN OVERHEAD. EXPECT DEW POINTS TO MIX OUT
NICELY TOMORROW AFTERNOON...ESPECIALLY IN NORTH CENTRAL ILLINOIS
WHERE DEW POINTS MAY DROP INTO THE LOW TO MID 30S. THE DRY
CONDITIONS SHOULD ALLOW FOR A NICE RESPONSE FROM DIABATIC HEATING
WHICH WILL RESULT IN TEMPS A FEW DEGREES WARMER TOMORROW.
MEANWHILE...SURFACE HIGH WILL BUILD FROM THE NORTHERN PLAINS
SATURDAY DIRECTLY OVERHEAD EARLY TUESDAY MORNING WHICH WILL ALLOW
FAVORABLE RADIATIONAL COOLING SUNDAY MORNING WITH LOWS DIPPING INTO
THE 30S IN OUTLYING AREAS AND SOME OF THE TYPICAL COLD SPOTS.
ELSEWHERE EXPECT LOW 40S WITH DOWNTOWN CHICAGO STAYING PROPPED UP IN
THE MID 40S. TEMPERATURES MAY BE A BIT TRICKY SUNDAY WITH WARM
ADVECTION ALOFT INCREASING THROUGH THE DAY ON THE BACKSIDE OF THE
SURFACE HIGH. A COOL STARTING POINT AND INCREASING CLOUD COVER
THROUGH THE DAY WILL KEEP HIGHS ONLY INTO THE 60S SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY...
UPPER RIDGE BEGINS TO BUCKLE SUNDAY NIGHT INTO MONDAY AS SHORTWAVE
TROUGH DIGS FROM THE PAC NW INTO THE CENTRAL PLAINS. BROAD SURFACE
LOW PRESSURE OVER THE PLAINS WILL SHIFT EAST TOWARDS THE MIDWEST
EARLY MONDAY WITH SOUTHWEST FLOW INCREASING OUT AHEAD AND A CORRIDOR
OF MODERATE TO STRONG MID LEVEL THETA-E ADVECTION LIFTING ACROSS THE
LOCAL FORECAST AREA ON THE NOSE OF A 40KT OR SO LOW LEVEL JET.
COLUMN IS FAIRLY DRY OUT AHEAD OF THE BAROCLINIC ZONE BUT A NARROW
LAYER OF SATURATION COULD TAP INTO SOME MODEST INSTABILITY ROOTED
BETWEEN H7-H9. THIS DOES POINT TO SOME CHANCES FOR THUNDERSTORMS
THOUGH CHANCES ARE BETTER TO OUR NORTH WHERE THE MUCAPE ALIGNS
BETTER WITH THE FORCING FROM THE LOW LEVEL JET. EXPECT LOWERING
CLOUDS IN THE PREDAWN HOURS AS THE SURFACE WARM FRONT APPROACHES.
THE MID LEVELS DRY OUT AGAIN AND THE MOISTURE IS FAIRLY SHALLOW SO
ANY ADDITIONAL PRECIP EARLY ON MONDAY MAY JUST BE DRIZZLE. SURFACE
WARM FRONT LIFTS ACROSS THE AREA MID MORNING MONDAY AND EXPECT DRY
CONDITIONS ONCE IN THE WARM SECTOR WITH LOW CLOUD COVER EVENTUALLY
SCATTERING. H85 TEMPS WARM TO 15-16C WITH 17C BEING THE 99TH
PERCENTILE OF UPPER AIR CLIMO FOR THE END OF OCTOBER. SURFACE HIGHS
WILL BE WELL ABOVE NORMAL...POSSIBLY PUSHING 20F ABOVE
NORMAL...THOUGH THE RECORD HIGH SHOULD BE SAFE. LEANED HEAVILY ON
EC/ECBC FOR AFTERNOON HIGHS MONDAY FORECASTING MID 70S...WITH UPPER
70S SOUTH OF I-80. THE WARMER CONDITIONS WILL BE ACCOMPANIED BY
STRONGER WINDS HOWEVER WITH SOUTHWEST WINDS GUSTING 20 TO 25 MPH AND
POSSIBLY 30 MPH AT TIMES.

TUESDAY THROUGH FRIDAY...
MODELS ARE INDICATING A STRONG LOW PRESSURE SYSTEM WILL BEGIN TO
DEVELOP OVER THE REGION EARLY NEXT WEEK WITH A COLD FRONT SWEEPING
ACROSS THE ARE MONDAY NIGHT INTO EARLY TUESDAY BRINGING CHANCES FOR
SHOWER AND THUNDERSTORMS. THE LOW REALLY BEGINS TO DEEPEN IN EARNEST
AS IT LIFTS ACROSS THE GREAT LAKES INTO CANADA TUESDAY INTO
WEDNESDAY WITH DRIVING POLAR AIR SOUTH INTO THE CANADIAN PRAIRIES
AND A COLD POLAR HIGH GRAZING THE LOCAL AREA LATE NEXT WEEK. DETAILS
STILL MURKY THIS FAR OUT BUT DOES APPEAR WE COULD BE IN FOR A BIG
COOL DOWN LATE NEXT WEEK IN TIME FOR HALLOWEEN IF CURRENT GFS/ECMWF
RUNS PAN OUT.

DEUBELBEISS

&&

.AVIATION...

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

* MVFR CIGS LIKELY OVERNIGHT...IFR CIGS A POSSIBILITY.

* MVFR VSBY POSSIBLE OVERNIGHT.

* IMPROVING CIG/VIS SATURDAY MORNING.

* BREEZY WEST-NORTHWEST WINDS...WITH GUSTS TO ARND 20KT.

KREIN

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

A WEAK SFC TROUGH AND MID LEVEL IMPULSE WILL CROSS THE REGION
OVERNIGHT. LATEST SATELLITE IMAGERY INDICATES JET CIRRUS AND SOME
MID LEVEL CLOUDINESS OVER THE AREA...BUT THE HIGHER LEVEL CLOUD IS
PUSHING EAST OF THE REGION...AND LOCATIONS THAT HAVE LOST THE
HIGHER LEVEL CLOUD COVER ARE ALREADY SEEING LOWERING STRATUS AND
FOG. ANTICIPATE THAT CIGS WILL GRADUALLY LOWER WITH THE WRN
TERMINALS...RFD/DPA LOWERING FIRST AND THEN ORD/MDW/GYY A LITTLE
LATER. STILL HAVE SOME CONCERNS FOR IFR CIGS DEVELOPING...WITH
HIGHER CONFIDENCE IN IFR CONDITIONS AT RFD/DPA...BUT HAVE ENOUGH
CONFIDENCE IN IFR CIGS AT ORD/MDW/GYY TO AT LEAST INCLUDE IN A
TEMPO GROUP. THERE IS SOME CONCERN FOR LIFR CIGS/VIS...ESPECIALLY
AT RFD...WHICH WILL HAVE THE LONGEST PERIOD OF TIME WITHOUT THE
HIGHER LEVEL CLOUD. ALSO...AS THE WEAK SFC TROUGH AXIS CROSSES THE
AREA...WINDS DECREASING TO BLW 5KT COULD ALSO HELP WITH DENSER FOG
DEVELOPMENT AWAY FROM THE CHICAGO AREA URBAN HEAT ISLAND.

WITH AMPLE SUNSHINE EXPECTED...CONDITIONS SHOULD QUICKLY IMPROVE
AFTER SUNRISE AND THE REMAINDER OF THE DAY SHOULD SEE VFR
CONDITIONS. THE MAIN ISSUE FOR THE REMAINDER OF THE DAY WILL BE
WINDS. FOLLOWING THE PASSAGE OF THE WEAK SFC TROUGH...HIGH
PRESSURE BUILDING OVER THE NRN PLAINS WILL SET UP A STRENGTHENING
WNWLY-NWLY GRADIENT OVER THE AREA. WITH AMPLE MIXING THROUGH THE
AFTERNOON...WINDS SHOULD BECOME MORE GUSTY...WITH GUSTS TO ARND
20KT THROUGH SUNSET.

KREIN

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

* HIGH CONFIDENCE IN CIGS LOWERING TO MVFR OVERNIGHT. MEDIUM
  CONFIDENCE IN IFR CIGS DEVELOPING.

* MEDIUM CONFIDENCE IN MVFR VIS OVERNIGHT.

* HIGH CONFIDENCE IN IMPROVEMENT TO VFR AND WNWLY-NWLY WINDS
  SATURDAY...WITH GUSTS TO ARND 20KT IN THE AFTERNOON.

KREIN

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

SUNDAY...VFR. SLGT CHC SHRA/TSRA SUNDAY NIGHT. SE WINDS.

MONDAY...VFR BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST-WEST WINDS.

WEDNESDAY AND THURSDAY...VFR. WEST-SOUTHWEST WINDS.

RATZER

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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






000
FXUS63 KILX 250450
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1150 PM CDT Fri Oct 24 2014

.UPDATE...
ISSUED AT 1150 PM CDT FRI OCT 24 2014

Dense fog advisory issued for areas west of the Illinois River. As
a shortwave trough moves off to the southeast late tonight,
clearing skies should allow good radiational cooling to resume in
a slightly moister air mass, bringing a good scenario for fog
formation. Observations of very low visibilities in fog over
eastern Iowa indicate west central Illinois should develop dense
fog overnight as the clearing sets in. Later updates may be
needed to adjust for fog coverage.

&&

.SHORT TERM...(Tonight)
ISSUED AT 309 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 309 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder than the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1150 PM CDT FRI OCT 24 2014

Mainly VFR conditions continue across central/SE Illinois late
this evening as a shortwave trough and weak cold front moves
across the region, bringing cigs just above 3 kft AGL. This
feature will move off to the east overnight, then clearing of the
cloud cover will allow fog to develop overnight. Given a similar
air mass to last night and winds expected to become light/variable
in the vicinity of the trough, vsbys between 1 and 3 miles
included for most central Illinois TAF locations, with LIFR
category included for KPIA. Gradual clearing with winds NW 8-10
kts expected after 14Z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY from 3 AM to 9 AM CDT Saturday FOR ILZ027>029-
036-040.

&&

$$

UPDATE...Onton
SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Onton







000
FXUS63 KLOT 250302
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1002 PM CDT FRI OCT 24 2014

.DISCUSSION...
947 PM CDT

ISOLATED SHOWERS ARE MOVING THROUGH THIS EVENING. MOST AREAS WILL
REMAIN DRY...AND EXPECT SHOWERS TO BE INTO NW INDIANA AFTER
MIDNIGHT...AND EAST OF THE AREA SHORTLY THEREAFTER.
OTHERWISE...EXPECT SOME FOG TO REFORM AGAIN TONIGHT...WITH WESTERN
AREAS FAVORED DUE TO A THINNING AND LOWERING OF CLOUDS.

KMD

//PREV DISCUSSION...
304 PM CDT

THIS EVENING AND TONIGHT...
BROAD SURFACE HIGH STRETCHES FROM THE LOWER MISSISSIPPI VALLEY INTO
THE UPPER OHIO VALLEY AND EASTERN GREAT LAKES THIS AFTERNOON WHILE
LOW PRESSURE LIES OVER ONTARIO WITH A COLD FRONT STRETCHING INTO THE
CENTRAL PLAINS. A NARROW RIBBON OF MOISTURE IS ANALYZED OUT AHEAD OF
THE COLD FRONT WITH 60 DEGREE DEWPOINTS STRETCHING NORTH INTO
NORTHERN IOWA THIS AFTERNOON...AND JUST OFF THE DECK A CORRIDOR OF
LOW/MID LEVEL THETA-E ADVECTION IS DRIVING AT LEAST A FEW VERY WEAK
RADAR RETURNS OVER FAR SE MN AND NE IA. RAP/HRRR GUIDANCE SHOWS THIS
AREA PERSISTING ACROSS NORTHERN ILLINOIS THIS EVENING WITH THE
CHANCE FOR A FEW SHOWERS. GIVEN THE VERY SPARSE COVERAGE SO FAR
UPSTREAM AND THE DRY SOUNDINGS/LIMITED DURATION OF FORCING...NOT
BITING OFF ON PRECIP MOVING ACROSS THE FORECAST AREA...BUT WILL
MAINTAIN SOME LOW END SLIGHT CHANCE POPS SINCE THERE ARE SOME
INGREDIENTS IN PLACE.

SATURDAY THROUGH SUNDAY...
WEAK FRONT WILL PASS ACROSS THE AREA EARLY ON SATURDAY WITH DRY AIR
FILTERING BACK INTO THE REGION AS AN UPPER RIDGE BUILDS OVER THE
AREA AND SUBSIDENCE SETS IN OVERHEAD. EXPECT DEW POINTS TO MIX OUT
NICELY TOMORROW AFTERNOON...ESPECIALLY IN NORTH CENTRAL ILLINOIS
WHERE DEW POINTS MAY DROP INTO THE LOW TO MID 30S. THE DRY
CONDITIONS SHOULD ALLOW FOR A NICE RESPONSE FROM DIABATIC HEATING
WHICH WILL RESULT IN TEMPS A FEW DEGREES WARMER TOMORROW.
MEANWHILE...SURFACE HIGH WILL BUILD FROM THE NORTHERN PLAINS
SATURDAY DIRECTLY OVERHEAD EARLY TUESDAY MORNING WHICH WILL ALLOW
FAVORABLE RADIATIONAL COOLING SUNDAY MORNING WITH LOWS DIPPING INTO
THE 30S IN OUTLYING AREAS AND SOME OF THE TYPICAL COLD SPOTS.
ELSEWHERE EXPECT LOW 40S WITH DOWNTOWN CHICAGO STAYING PROPPED UP IN
THE MID 40S. TEMPERATURES MAY BE A BIT TRICKY SUNDAY WITH WARM
ADVECTION ALOFT INCREASING THROUGH THE DAY ON THE BACKSIDE OF THE
SURFACE HIGH. A COOL STARTING POINT AND INCREASING CLOUD COVER
THROUGH THE DAY WILL KEEP HIGHS ONLY INTO THE 60S SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY...
UPPER RIDGE BEGINS TO BUCKLE SUNDAY NIGHT INTO MONDAY AS SHORTWAVE
TROUGH DIGS FROM THE PAC NW INTO THE CENTRAL PLAINS. BROAD SURFACE
LOW PRESSURE OVER THE PLAINS WILL SHIFT EAST TOWARDS THE MIDWEST
EARLY MONDAY WITH SOUTHWEST FLOW INCREASING OUT AHEAD AND A CORRIDOR
OF MODERATE TO STRONG MID LEVEL THETA-E ADVECTION LIFTING ACROSS THE
LOCAL FORECAST AREA ON THE NOSE OF A 40KT OR SO LOW LEVEL JET.
COLUMN IS FAIRLY DRY OUT AHEAD OF THE BAROCLINIC ZONE BUT A NARROW
LAYER OF SATURATION COULD TAP INTO SOME MODEST INSTABILITY ROOTED
BETWEEN H7-H9. THIS DOES POINT TO SOME CHANCES FOR THUNDERSTORMS
THOUGH CHANCES ARE BETTER TO OUR NORTH WHERE THE MUCAPE ALIGNS
BETTER WITH THE FORCING FROM THE LOW LEVEL JET. EXPECT LOWERING
CLOUDS IN THE PREDAWN HOURS AS THE SURFACE WARM FRONT APPROACHES.
THE MID LEVELS DRY OUT AGAIN AND THE MOISTURE IS FAIRLY SHALLOW SO
ANY ADDITIONAL PRECIP EARLY ON MONDAY MAY JUST BE DRIZZLE. SURFACE
WARM FRONT LIFTS ACROSS THE AREA MID MORNING MONDAY AND EXPECT DRY
CONDITIONS ONCE IN THE WARM SECTOR WITH LOW CLOUD COVER EVENTUALLY
SCATTERING. H85 TEMPS WARM TO 15-16C WITH 17C BEING THE 99TH
PERCENTILE OF UPPER AIR CLIMO FOR THE END OF OCTOBER. SURFACE HIGHS
WILL BE WELL ABOVE NORMAL...POSSIBLY PUSHING 20F ABOVE
NORMAL...THOUGH THE RECORD HIGH SHOULD BE SAFE. LEANED HEAVILY ON
EC/ECBC FOR AFTERNOON HIGHS MONDAY FORECASTING MID 70S...WITH UPPER
70S SOUTH OF I-80. THE WARMER CONDITIONS WILL BE ACCOMPANIED BY
STRONGER WINDS HOWEVER WITH SOUTHWEST WINDS GUSTING 20 TO 25 MPH AND
POSSIBLY 30 MPH AT TIMES.

TUESDAY THROUGH FRIDAY...
MODELS ARE INDICATING A STRONG LOW PRESSURE SYSTEM WILL BEGIN TO
DEVELOP OVER THE REGION EARLY NEXT WEEK WITH A COLD FRONT SWEEPING
ACROSS THE ARE MONDAY NIGHT INTO EARLY TUESDAY BRINGING CHANCES FOR
SHOWER AND THUNDERSTORMS. THE LOW REALLY BEGINS TO DEEPEN IN EARNEST
AS IT LIFTS ACROSS THE GREAT LAKES INTO CANADA TUESDAY INTO
WEDNESDAY WITH DRIVING POLAR AIR SOUTH INTO THE CANADIAN PRAIRIES
AND A COLD POLAR HIGH GRAZING THE LOCAL AREA LATE NEXT WEEK. DETAILS
STILL MURKY THIS FAR OUT BUT DOES APPEAR WE COULD BE IN FOR A BIG
COOL DOWN LATE NEXT WEEK IN TIME FOR HALLOWEEN IF CURRENT GFS/ECMWF
RUNS PAN OUT.

DEUBELBEISS

&&

.AVIATION...

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

* LOWERING CIGS LATE EVENING/OVERNIGHT...MVFR PROBABLE WITH
  IFR/LIFR A LOW POSSIBILITY.

* MVFR VSBY POSSIBLE OVERNIGHT.

* IMPROVING CIG/VIS SATURDAY MORNING WITH BREEZY WEST-NORTHWEST
  WINDS.

RATZER

//DISCUSSION...UPDATED 03Z...

IFR/LIFR CIGS AND VIS EXPANDING ACROSS PARTS OF CENTRAL AND
EASTERN IOWA THIS EVENING...EXPECTED TO SPREAD INTO PARTS OF
NORTHWEST AND WESTERN/CENTRAL IL LATE TONIGHT. LATEST MODEL
GUIDANCE CONTINUES TO INDICATE POTENTIAL FOR LOW CIGS/VIS MAINLY
WEST AND SOUTHWEST OF THE CHICAGO TERMINALS. HAVE INDICATED A
PERIOD OF IFR CONDITIONS AT RFD DURING THE EARLY SATURDAY MORNING
PERIOD...WITH LOWER MVFR CONDITIONS LIKELY FARTHER EAST ACROSS
ORD/MDW/GYY/DPA.

RATZER

PREVIOUS DISCUSSION FROM 00Z...

SUBTLE SURFACE LOW PRESSURE WAVE WAS OVER EASTERN IOWA EARLY THIS
EVENING...AND WILL MOVE EAST ACROSS THE TERMINALS OVERNIGHT. AN
AREA OF IFR/LIFR CIGS AND FOG WAS LOCATED JUST AHEAD OF THIS WAVE
ACROSS EASTERN IOWA/SOUTHWEST MINNESOTA...AND IS EXPECTED TO
ADVANCE INTO PARTS OF SOUTHWEST WISCONSIN AND WESTERN ILLINOIS
OVERNIGHT...AS LIGHT SOUTH-SOUTHWEST WINDS CONTINUE TO ADVECT LOW
LEVEL MOISTURE AHEAD OF THE WAVE. A FASTER MOVING COLD FRONT WITH
A STRONG PUSH OF DRIER AIR WILL OVERTAKE THE WEAKER WAVE
OVERNIGHT. A FEW SPRINKLES WILL BE POSSIBLE LATER THIS EVENING AS
AN ASSOCIATED UPPER LEVEL DISTURBANCE ENHANCES LIFT...THOUGH THESE
SHOULD BE VERY LIGHT AND FAIRLY ISOLATED.

LOW END VFR AND MVFR CIGS ARE EXPECTED TO SPREAD EAST AS FAR AS
THE CHICAGO TERMINALS DURING THE LATE EVENING/OVERNIGHT HOURS...
THOUGH CONFIDENCE IS LOW THAT THE LOWER IFR/LIFR CIGS OVER IOWA
WILL MAKE IT THIS FAR EAST AS THE LOW LEVEL MOIST AXIS GETS
PINCHED OFF BY THE FASTER COLD FRONT. THE SECOND FRONT WILL CLEAR
THE TERMINALS SATURDAY MORNING...WITH MUCH DRIER AIR SCOURING OUT
ANY LOW CLOUDS THAT DO FORM OVERNIGHT.

SOUTH-SOUTHWEST WINDS LESS THAN 10 KT THIS EVENING WILL SHIFT TO
THE WEST WITH THE FRONTAL PASSAGE PRE-DAWN SATURDAY. WEST-
NORTHWEST WINDS AROUND 10 KT WILL BECOME BREEZY WITH GUSTS NEAR 20
KT LATER SATURDAY AFTERNOON.

RATZER

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

* HIGH CONFIDENCE CIGS LOWERING TO LOWER END VFR LATER THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS OVERNIGHT. LOW
  CONFIDENCE IN CIGS IFR/LIFR DEVELOPING.

* MEDIUM CONFIDENCE IN MVFR CIGS OVERNIGHT.

* HIGH CONFIDENCE THAT -SHRA COVERAGE WILL BE LOW LATE THIS
  EVENING.

* HIGH CONFIDENCE IN IMPROVEMENT TO VFR AND WEST WINDS SATURDAY.

RATZER

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

SUNDAY...VFR. SLGT CHC SHRA/TSRA SUNDAY NIGHT. SE WINDS.

MONDAY...VFR BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST-WEST WINDS.

WEDNESDAY AND THURSDAY...VFR. WEST-SOUTHWEST WINDS.

RATZER

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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







000
FXUS63 KLOT 250254
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
954 PM CDT FRI OCT 24 2014

.DISCUSSION...
947 PM CDT

ISOLATED SHOWERS ARE MOVING THROUGH THIS EVENING. MOST AREAS WILL
REMAIN DRY...AND EXPECT SHOWERS TO BE INTO NW INDIANA AFTER
MIDNIGHT...AND EAST OF THE AREA SHORTLY THEREAFTER.
OTHERWISE...EXPECT SOME FOG TO REFORM AGAIN TONIGHT...WITH WESTERN
AREAS FAVORED DUE TO A THINNING AND LOWERING OF CLOUDS.

KMD

&&

.PREV DISCUSSION...
304 PM CDT

THIS EVENING AND TONIGHT...
BROAD SURFACE HIGH STRETCHES FROM THE LOWER MISSISSIPPI VALLEY INTO
THE UPPER OHIO VALLEY AND EASTERN GREAT LAKES THIS AFTERNOON WHILE
LOW PRESSURE LIES OVER ONTARIO WITH A COLD FRONT STRETCHING INTO THE
CENTRAL PLAINS. A NARROW RIBBON OF MOISTURE IS ANALYZED OUT AHEAD OF
THE COLD FRONT WITH 60 DEGREE DEWPOINTS STRETCHING NORTH INTO
NORTHERN IOWA THIS AFTERNOON...AND JUST OFF THE DECK A CORRIDOR OF
LOW/MID LEVEL THETA-E ADVECTION IS DRIVING AT LEAST A FEW VERY WEAK
RADAR RETURNS OVER FAR SE MN AND NE IA. RAP/HRRR GUIDANCE SHOWS THIS
AREA PERSISTING ACROSS NORTHERN ILLINOIS THIS EVENING WITH THE
CHANCE FOR A FEW SHOWERS. GIVEN THE VERY SPARSE COVERAGE SO FAR
UPSTREAM AND THE DRY SOUNDINGS/LIMITED DURATION OF FORCING...NOT
BITING OFF ON PRECIP MOVING ACROSS THE FORECAST AREA...BUT WILL
MAINTAIN SOME LOW END SLIGHT CHANCE POPS SINCE THERE ARE SOME
INGREDIENTS IN PLACE.

SATURDAY THROUGH SUNDAY...
WEAK FRONT WILL PASS ACROSS THE AREA EARLY ON SATURDAY WITH DRY AIR
FILTERING BACK INTO THE REGION AS AN UPPER RIDGE BUILDS OVER THE
AREA AND SUBSIDENCE SETS IN OVERHEAD. EXPECT DEW POINTS TO MIX OUT
NICELY TOMORROW AFTERNOON...ESPECIALLY IN NORTH CENTRAL ILLINOIS
WHERE DEW POINTS MAY DROP INTO THE LOW TO MID 30S. THE DRY
CONDITIONS SHOULD ALLOW FOR A NICE RESPONSE FROM DIABATIC HEATING
WHICH WILL RESULT IN TEMPS A FEW DEGREES WARMER TOMORROW.
MEANWHILE...SURFACE HIGH WILL BUILD FROM THE NORTHERN PLAINS
SATURDAY DIRECTLY OVERHEAD EARLY TUESDAY MORNING WHICH WILL ALLOW
FAVORABLE RADIATIONAL COOLING SUNDAY MORNING WITH LOWS DIPPING INTO
THE 30S IN OUTLYING AREAS AND SOME OF THE TYPICAL COLD SPOTS.
ELSEWHERE EXPECT LOW 40S WITH DOWNTOWN CHICAGO STAYING PROPPED UP IN
THE MID 40S. TEMPERATURES MAY BE A BIT TRICKY SUNDAY WITH WARM
ADVECTION ALOFT INCREASING THROUGH THE DAY ON THE BACKSIDE OF THE
SURFACE HIGH. A COOL STARTING POINT AND INCREASING CLOUD COVER
THROUGH THE DAY WILL KEEP HIGHS ONLY INTO THE 60S SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY...
UPPER RIDGE BEGINS TO BUCKLE SUNDAY NIGHT INTO MONDAY AS SHORTWAVE
TROUGH DIGS FROM THE PAC NW INTO THE CENTRAL PLAINS. BROAD SURFACE
LOW PRESSURE OVER THE PLAINS WILL SHIFT EAST TOWARDS THE MIDWEST
EARLY MONDAY WITH SOUTHWEST FLOW INCREASING OUT AHEAD AND A CORRIDOR
OF MODERATE TO STRONG MID LEVEL THETA-E ADVECTION LIFTING ACROSS THE
LOCAL FORECAST AREA ON THE NOSE OF A 40KT OR SO LOW LEVEL JET.
COLUMN IS FAIRLY DRY OUT AHEAD OF THE BAROCLINIC ZONE BUT A NARROW
LAYER OF SATURATION COULD TAP INTO SOME MODEST INSTABILITY ROOTED
BETWEEN H7-H9. THIS DOES POINT TO SOME CHANCES FOR THUNDERSTORMS
THOUGH CHANCES ARE BETTER TO OUR NORTH WHERE THE MUCAPE ALIGNS
BETTER WITH THE FORCING FROM THE LOW LEVEL JET. EXPECT LOWERING
CLOUDS IN THE PREDAWN HOURS AS THE SURFACE WARM FRONT APPROACHES.
THE MID LEVELS DRY OUT AGAIN AND THE MOISTURE IS FAIRLY SHALLOW SO
ANY ADDITIONAL PRECIP EARLY ON MONDAY MAY JUST BE DRIZZLE. SURFACE
WARM FRONT LIFTS ACROSS THE AREA MID MORNING MONDAY AND EXPECT DRY
CONDITIONS ONCE IN THE WARM SECTOR WITH LOW CLOUD COVER EVENTUALLY
SCATTERING. H85 TEMPS WARM TO 15-16C WITH 17C BEING THE 99TH
PERCENTILE OF UPPER AIR CLIMO FOR THE END OF OCTOBER. SURFACE HIGHS
WILL BE WELL ABOVE NORMAL...POSSIBLY PUSHING 20F ABOVE
NORMAL...THOUGH THE RECORD HIGH SHOULD BE SAFE. LEANED HEAVILY ON
EC/ECBC FOR AFTERNOON HIGHS MONDAY FORECASTING MID 70S...WITH UPPER
70S SOUTH OF I-80. THE WARMER CONDITIONS WILL BE ACCOMPANIED BY
STRONGER WINDS HOWEVER WITH SOUTHWEST WINDS GUSTING 20 TO 25 MPH AND
POSSIBLY 30 MPH AT TIMES.

TUESDAY THROUGH FRIDAY...
MODELS ARE INDICATING A STRONG LOW PRESSURE SYSTEM WILL BEGIN TO
DEVELOP OVER THE REGION EARLY NEXT WEEK WITH A COLD FRONT SWEEPING
ACROSS THE ARE MONDAY NIGHT INTO EARLY TUESDAY BRINGING CHANCES FOR
SHOWER AND THUNDERSTORMS. THE LOW REALLY BEGINS TO DEEPEN IN EARNEST
AS IT LIFTS ACROSS THE GREAT LAKES INTO CANADA TUESDAY INTO
WEDNESDAY WITH DRIVING POLAR AIR SOUTH INTO THE CANADIAN PRAIRIES
AND A COLD POLAR HIGH GRAZING THE LOCAL AREA LATE NEXT WEEK. DETAILS
STILL MURKY THIS FAR OUT BUT DOES APPEAR WE COULD BE IN FOR A BIG
COOL DOWN LATE NEXT WEEK IN TIME FOR HALLOWEEN IF CURRENT GFS/ECMWF
RUNS PAN OUT.

DEUBELBEISS

&&

.AVIATION...

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

* LOWERING CIGS LATE EVENING/OVERNIGHT...MVFR PROBABLE WITH
  IFR/LIFR A LOW POSSIBILITY.

* MVFR VSBY POSSIBLE OVERNIGHT.

* SLIGHT CHANCE OF -SHRA LATE THIS EVENING.

* IMPROVING CIG/VIS SATURDAY MORNING WITH BREEZY WEST-NORTHWEST
  WINDS.

RATZER

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

SUBTLE SURFACE LOW PRESSURE WAVE WAS OVER EASTERN IOWA EARLY THIS
EVENING...AND WILL MOVE EAST ACROSS THE TERMINALS OVERNIGHT. AN
AREA OF IFR/LIFR CIGS AND FOG WAS LOCATED JUST AHEAD OF THIS WAVE
ACROSS EASTERN IOWA/SOUTHWEST MINNESOTA...AND IS EXPECTED TO
ADVANCE INTO PARTS OF SOUTHWEST WISCONSIN AND WESTERN ILLINOIS
OVERNIGHT...AS LIGHT SOUTH-SOUTHWEST WINDS CONTINUE TO ADVECT LOW
LEVEL MOISTURE AHEAD OF THE WAVE. A FASTER MOVING COLD FRONT WITH
A STRONG PUSH OF DRIER AIR WILL OVERTAKE THE WEAKER WAVE
OVERNIGHT. A FEW SPRINKLES WILL BE POSSIBLE LATER THIS EVENING AS
AN ASSOCIATED UPPER LEVEL DISTURBANCE ENHANCES LIFT...THOUGH THESE
SHOULD BE VERY LIGHT AND FAIRLY ISOLATED.

LOW END VFR AND MVFR CIGS ARE EXPECTED TO SPREAD EAST AS FAR AS
THE CHICAGO TERMINALS DURING THE LATE EVENING/OVERNIGHT HOURS...
THOUGH CONFIDENCE IS LOW THAT THE LOWER IFR/LIFR CIGS OVER IOWA
WILL MAKE IT THIS FAR EAST AS THE LOW LEVEL MOIST AXIS GETS
PINCHED OFF BY THE FASTER COLD FRONT. THE SECOND FRONT WILL CLEAR
THE TERMINALS SATURDAY MORNING...WITH MUCH DRIER AIR SCOURING OUT
ANY LOW CLOUDS THAT DO FORM OVERNIGHT.

SOUTH-SOUTHWEST WINDS LESS THAN 10 KT THIS EVENING WILL SHIFT TO
THE WEST WITH THE FRONTAL PASSAGE PRE-DAWN SATURDAY. WEST-
NORTHWEST WINDS AROUND 10 KT WILL BECOME BREEZY WITH GUSTS NEAR 20
KT LATER SATURDAY AFTERNOON.

RATZER

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

* HIGH CONFIDENCE CIGS LOWERING TO LOWER END VFR LATER THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS OVERNIGHT. LOW
  CONFIDENCE IN CIGS IFR/LIFR DEVELOPING.

* MEDIUM CONFIDENCE IN MVFR CIGS OVERNIGHT.

* HIGH CONFIDENCE THAT -SHRA COVERAGE WILL BE LOW LATE THIS
  EVENING.

* HIGH CONFIDENCE IN IMPROVEMENT TO VFR AND WEST WINDS SATURDAY.

RATZER

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

SUNDAY...VFR. SLGT CHC SHRA/TSRA SUNDAY NIGHT. SE WINDS.

MONDAY...VFR BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST-WEST WINDS.

WEDNESDAY AND THURSDAY...VFR. WEST-SOUTHWEST WINDS.

RATZER

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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






000
FXUS63 KILX 250159
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
859 PM CDT Fri Oct 24 2014

.UPDATE...
ISSUED AT 859 PM CDT FRI OCT 24 2014

A shortwave trough is moving southeastward into central Illinois
this evening bringing back low cloudiness from about Lincoln
northwestward...to spread southeast over the next few hours. This
should prevent temperatures from falling much further for a while
tonight, but otherwise little impact as precipitation detection by
radar or surface observations is almost absent as it moves into
the area. Once this feature moves off to the southeast late
tonight, clearing skies should allow good radiational cooling to
resume in a slightly moister air mass, bringing a good scenario
for fog formation overnight. Current forecasts are in good shape
with the cloud cover initially and subsequent fog development.
Later updates may be needed to adjust for fog coverage and
thickness. Have made minor adjustments for low temperatures with
evening update.

&&

.SHORT TERM...(Tonight)
ISSUED AT 309 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 309 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder than the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 638 PM CDT FRI OCT 24 2014

VFR conditions are in place across central/SE Illinois this
evening. A shortwave trough and weak cold front approaching from
the northwest is likely to bring a few hours of MVFR ceilings in
the late evening until early morning. Once this feature passes
through, clearing of the cloud cover will allow fog to develop
toward dawn. Given a similar air mass to last night and winds
expected to become light/variable in the vicinity of the trough,
have reduced vsbys to between 1 and 3 miles at the central
Illinois TAF locations, although some potential exists for
visibilities to drop into LIFR category or worse, mainly for KPIA.
Gradual clearing with winds NW 8-10 kts expected after 14Z.


&&

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

$$

UPDATE...Onton
SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Onton







000
FXUS63 KLOT 242352
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
652 PM CDT FRI OCT 24 2014

.DISCUSSION...
304 PM CDT

THIS EVENING AND TONIGHT...
BROAD SURFACE HIGH STRETCHES FROM THE LOWER MISSISSIPPI VALLEY INTO
THE UPPER OHIO VALLEY AND EASTERN GREAT LAKES THIS AFTERNOON WHILE
LOW PRESSURE LIES OVER ONTARIO WITH A COLD FRONT STRETCHING INTO THE
CENTRAL PLAINS. A NARROW RIBBON OF MOISTURE IS ANALYZED OUT AHEAD OF
THE COLD FRONT WITH 60 DEGREE DEWPOINTS STRETCHING NORTH INTO
NORTHERN IOWA THIS AFTERNOON...AND JUST OFF THE DECK A CORRIDOR OF
LOW/MID LEVEL THETA-E ADVECTION IS DRIVING AT LEAST A FEW VERY WEAK
RADAR RETURNS OVER FAR SE MN AND NE IA. RAP/HRRR GUIDANCE SHOWS THIS
AREA PERSISTING ACROSS NORTHERN ILLINOIS THIS EVENING WITH THE
CHANCE FOR A FEW SHOWERS. GIVEN THE VERY SPARSE COVERAGE SO FAR
UPSTREAM AND THE DRY SOUNDINGS/LIMITED DURATION OF FORCING...NOT
BITING OFF ON PRECIP MOVING ACROSS THE FORECAST AREA...BUT WILL
MAINTAIN SOME LOW END SLIGHT CHANCE POPS SINCE THERE ARE SOME
INGREDIENTS IN PLACE.

SATURDAY THROUGH SUNDAY...
WEAK FRONT WILL PASS ACROSS THE AREA EARLY ON SATURDAY WITH DRY AIR
FILTERING BACK INTO THE REGION AS AN UPPER RIDGE BUILDS OVER THE
AREA AND SUBSIDENCE SETS IN OVERHEAD. EXPECT DEW POINTS TO MIX OUT
NICELY TOMORROW AFTERNOON...ESPECIALLY IN NORTH CENTRAL ILLINOIS
WHERE DEW POINTS MAY DROP INTO THE LOW TO MID 30S. THE DRY
CONDITIONS SHOULD ALLOW FOR A NICE RESPONSE FROM DIABATIC HEATING
WHICH WILL RESULT IN TEMPS A FEW DEGREES WARMER TOMORROW.
MEANWHILE...SURFACE HIGH WILL BUILD FROM THE NORTHERN PLAINS
SATURDAY DIRECTLY OVERHEAD EARLY TUESDAY MORNING WHICH WILL ALLOW
FAVORABLE RADIATIONAL COOLING SUNDAY MORNING WITH LOWS DIPPING INTO
THE 30S IN OUTLYING AREAS AND SOME OF THE TYPICAL COLD SPOTS.
ELSEWHERE EXPECT LOW 40S WITH DOWNTOWN CHICAGO STAYING PROPPED UP IN
THE MID 40S. TEMPERATURES MAY BE A BIT TRICKY SUNDAY WITH WARM
ADVECTION ALOFT INCREASING THROUGH THE DAY ON THE BACKSIDE OF THE
SURFACE HIGH. A COOL STARTING POINT AND INCREASING CLOUD COVER
THROUGH THE DAY WILL KEEP HIGHS ONLY INTO THE 60S SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY...
UPPER RIDGE BEGINS TO BUCKLE SUNDAY NIGHT INTO MONDAY AS SHORTWAVE
TROUGH DIGS FROM THE PAC NW INTO THE CENTRAL PLAINS. BROAD SURFACE
LOW PRESSURE OVER THE PLAINS WILL SHIFT EAST TOWARDS THE MIDWEST
EARLY MONDAY WITH SOUTHWEST FLOW INCREASING OUT AHEAD AND A CORRIDOR
OF MODERATE TO STRONG MID LEVEL THETA-E ADVECTION LIFTING ACROSS THE
LOCAL FORECAST AREA ON THE NOSE OF A 40KT OR SO LOW LEVEL JET.
COLUMN IS FAIRLY DRY OUT AHEAD OF THE BAROCLINIC ZONE BUT A NARROW
LAYER OF SATURATION COULD TAP INTO SOME MODEST INSTABILITY ROOTED
BETWEEN H7-H9. THIS DOES POINT TO SOME CHANCES FOR THUNDERSTORMS
THOUGH CHANCES ARE BETTER TO OUR NORTH WHERE THE MUCAPE ALIGNS
BETTER WITH THE FORCING FROM THE LOW LEVEL JET. EXPECT LOWERING
CLOUDS IN THE PREDAWN HOURS AS THE SURFACE WARM FRONT APPROACHES.
THE MID LEVELS DRY OUT AGAIN AND THE MOISTURE IS FAIRLY SHALLOW SO
ANY ADDITIONAL PRECIP EARLY ON MONDAY MAY JUST BE DRIZZLE. SURFACE
WARM FRONT LIFTS ACROSS THE AREA MID MORNING MONDAY AND EXPECT DRY
CONDITIONS ONCE IN THE WARM SECTOR WITH LOW CLOUD COVER EVENTUALLY
SCATTERING. H85 TEMPS WARM TO 15-16C WITH 17C BEING THE 99TH
PERCENTILE OF UPPER AIR CLIMO FOR THE END OF OCTOBER. SURFACE HIGHS
WILL BE WELL ABOVE NORMAL...POSSIBLY PUSHING 20F ABOVE
NORMAL...THOUGH THE RECORD HIGH SHOULD BE SAFE. LEANED HEAVILY ON
EC/ECBC FOR AFTERNOON HIGHS MONDAY FORECASTING MID 70S...WITH UPPER
70S SOUTH OF I-80. THE WARMER CONDITIONS WILL BE ACCOMPANIED BY
STRONGER WINDS HOWEVER WITH SOUTHWEST WINDS GUSTING 20 TO 25 MPH AND
POSSIBLY 30 MPH AT TIMES.

TUESDAY THROUGH FRIDAY...
MODELS ARE INDICATING A STRONG LOW PRESSURE SYSTEM WILL BEGIN TO
DEVELOP OVER THE REGION EARLY NEXT WEEK WITH A COLD FRONT SWEEPING
ACROSS THE ARE MONDAY NIGHT INTO EARLY TUESDAY BRINGING CHANCES FOR
SHOWER AND THUNDERSTORMS. THE LOW REALLY BEGINS TO DEEPEN IN EARNEST
AS IT LIFTS ACROSS THE GREAT LAKES INTO CANADA TUESDAY INTO
WEDNESDAY WITH DRIVING POLAR AIR SOUTH INTO THE CANADIAN PRAIRIES
AND A COLD POLAR HIGH GRAZING THE LOCAL AREA LATE NEXT WEEK. DETAILS
STILL MURKY THIS FAR OUT BUT DOES APPEAR WE COULD BE IN FOR A BIG
COOL DOWN LATE NEXT WEEK IN TIME FOR HALLOWEEN IF CURRENT GFS/ECMWF
RUNS PAN OUT.

DEUBELBEISS

&&

.AVIATION...

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

* LOWERING CIGS LATE EVENING/OVERNIGHT...MVFR PROBABLE WITH
  IFR/LIFR A LOW POSSIBILITY.

* MVFR VSBY POSSIBLE OVERNIGHT.

* SLIGHT CHANCE OF -SHRA LATE THIS EVENING.

* IMPROVING CIG/VIS SATURDAY MORNING WITH BREEZY WEST-NORTHWEST
  WINDS.

RATZER

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

SUBTLE SURFACE LOW PRESSURE WAVE WAS OVER EASTERN IOWA EARLY THIS
EVENING...AND WILL MOVE EAST ACROSS THE TERMINALS OVERNIGHT. AN
AREA OF IFR/LIFR CIGS AND FOG WAS LOCATED JUST AHEAD OF THIS WAVE
ACROSS EASTERN IOWA/SOUTHWEST MINNESOTA...AND IS EXPECTED TO
ADVANCE INTO PARTS OF SOUTHWEST WISCONSIN AND WESTERN ILLINOIS
OVERNIGHT...AS LIGHT SOUTH-SOUTHWEST WINDS CONTINUE TO ADVECT LOW
LEVEL MOISTURE AHEAD OF THE WAVE. A FASTER MOVING COLD FRONT WITH
A STRONG PUSH OF DRIER AIR WILL OVERTAKE THE WEAKER WAVE
OVERNIGHT. A FEW SPRINKLES WILL BE POSSIBLE LATER THIS EVENING AS
AN ASSOCIATED UPPER LEVEL DISTURBANCE ENHANCES LIFT...THOUGH THESE
SHOULD BE VERY LIGHT AND FAIRLY ISOLATED.

LOW END VFR AND MVFR CIGS ARE EXPECTED TO SPREAD EAST AS FAR AS
THE CHICAGO TERMINALS DURING THE LATE EVENING/OVERNIGHT HOURS...
THOUGH CONFIDENCE IS LOW THAT THE LOWER IFR/LIFR CIGS OVER IOWA
WILL MAKE IT THIS FAR EAST AS THE LOW LEVEL MOIST AXIS GETS
PINCHED OFF BY THE FASTER COLD FRONT. THE SECOND FRONT WILL CLEAR
THE TERMINALS SATURDAY MORNING...WITH MUCH DRIER AIR SCOURING OUT
ANY LOW CLOUDS THAT DO FORM OVERNIGHT.

SOUTH-SOUTHWEST WINDS LESS THAN 10 KT THIS EVENING WILL SHIFT TO
THE WEST WITH THE FRONTAL PASSAGE PRE-DAWN SATURDAY. WEST-
NORTHWEST WINDS AROUND 10 KT WILL BECOME BREEZY WITH GUSTS NEAR 20
KT LATER SATURDAY AFTERNOON.

RATZER


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

* HIGH CONFIDENCE CIGS LOWERING TO LOWER END VFR LATER THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS OVERNIGHT. LOW
  CONFIDENCE IN CIGS IFR/LIFR DEVELOPING.

* MEDIUM CONFIDENCE IN MVFR CIGS OVERNIGHT.

* HIGH CONFIDENCE THAT -SHRA COVERAGE WILL BE LOW LATE THIS
  EVENING.

* HIGH CONFIDENCE IN IMPROVEMENT TO VFR AND WEST WINDS SATURDAY.

RATZER

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

SUNDAY...VFR. SLGT CHC SHRA/TSRA SUNDAY NIGHT. SE WINDS.

MONDAY...VFR BY DAY...SHRA/TSRA LIKELY MONDAY NIGHT. BREEZY
SOUTH WINDS.

TUESDAY...CHC SHRA/TSRA. MVFR POSSIBLE. SOUTHWEST-WEST WINDS.

WEDNESDAY AND THURSDAY...VFR. WEST-SOUTHWEST WINDS.

RATZER

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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






000
FXUS63 KILX 242338
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
638 PM CDT Fri Oct 24 2014

.SHORT TERM...(Tonight)
ISSUED AT 309 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 309 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder than the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 638 PM CDT FRI OCT 24 2014

VFR conditions are in place across central/SE Illinois this
evening. A shortwave trough and weak cold front approaching from
the northwest is likely to bring a few hours of MVFR ceilings in
the late evening until early morning. Once this feature passes
through, clearing of the cloud cover will allow fog to develop
toward dawn. Given a similar air mass to last night and winds
expected to become light/variable in the vicinity of the trough,
have reduced vsbys to between 1 and 3 miles at the central
Illinois TAF locations, although some potential exists for
visibilities to drop into LIFR category or worse, mainly for KPIA.
Gradual clearing with winds NW 8-10 kts expected after 14Z.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Onton







000
FXUS63 KLOT 242207
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
507 PM CDT FRI OCT 24 2014

.DISCUSSION...
304 PM CDT

THIS EVENING AND TONIGHT...
BROAD SURFACE HIGH STRETCHES FROM THE LOWER MISSISSIPPI VALLEY INTO
THE UPPER OHIO VALLEY AND EASTERN GREAT LAKES THIS AFTERNOON WHILE
LOW PRESSURE LIES OVER ONTARIO WITH A COLD FRONT STRETCHING INTO THE
CENTRAL PLAINS. A NARROW RIBBON OF MOISTURE IS ANALYZED OUT AHEAD OF
THE COLD FRONT WITH 60 DEGREE DEWPOINTS STRETCHING NORTH INTO
NORTHERN IOWA THIS AFTERNOON...AND JUST OFF THE DECK A CORRIDOR OF
LOW/MID LEVEL THETA-E ADVECTION IS DRIVING AT LEAST A FEW VERY WEAK
RADAR RETURNS OVER FAR SE MN AND NE IA. RAP/HRRR GUIDANCE SHOWS THIS
AREA PERSISTING ACROSS NORTHERN ILLINOIS THIS EVENING WITH THE
CHANCE FOR A FEW SHOWERS. GIVEN THE VERY SPARSE COVERAGE SO FAR
UPSTREAM AND THE DRY SOUNDINGS/LIMITED DURATION OF FORCING...NOT
BITING OFF ON PRECIP MOVING ACROSS THE FORECAST AREA...BUT WILL
MAINTAIN SOME LOW END SLIGHT CHANCE POPS SINCE THERE ARE SOME
INGREDIENTS IN PLACE.

SATURDAY THROUGH SUNDAY...
WEAK FRONT WILL PASS ACROSS THE AREA EARLY ON SATURDAY WITH DRY AIR
FILTERING BACK INTO THE REGION AS AN UPPER RIDGE BUILDS OVER THE
AREA AND SUBSIDENCE SETS IN OVERHEAD. EXPECT DEW POINTS TO MIX OUT
NICELY TOMORROW AFTERNOON...ESPECIALLY IN NORTH CENTRAL ILLINOIS
WHERE DEW POINTS MAY DROP INTO THE LOW TO MID 30S. THE DRY
CONDITIONS SHOULD ALLOW FOR A NICE RESPONSE FROM DIABATIC HEATING
WHICH WILL RESULT IN TEMPS A FEW DEGREES WARMER TOMORROW.
MEANWHILE...SURFACE HIGH WILL BUILD FROM THE NORTHERN PLAINS
SATURDAY DIRECTLY OVERHEAD EARLY TUESDAY MORNING WHICH WILL ALLOW
FAVORABLE RADIATIONAL COOLING SUNDAY MORNING WITH LOWS DIPPING INTO
THE 30S IN OUTLYING AREAS AND SOME OF THE TYPICAL COLD SPOTS.
ELSEWHERE EXPECT LOW 40S WITH DOWNTOWN CHICAGO STAYING PROPPED UP IN
THE MID 40S. TEMPERATURES MAY BE A BIT TRICKY SUNDAY WITH WARM
ADVECTION ALOFT INCREASING THROUGH THE DAY ON THE BACKSIDE OF THE
SURFACE HIGH. A COOL STARTING POINT AND INCREASING CLOUD COVER
THROUGH THE DAY WILL KEEP HIGHS ONLY INTO THE 60S SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY...
UPPER RIDGE BEGINS TO BUCKLE SUNDAY NIGHT INTO MONDAY AS SHORTWAVE
TROUGH DIGS FROM THE PAC NW INTO THE CENTRAL PLAINS. BROAD SURFACE
LOW PRESSURE OVER THE PLAINS WILL SHIFT EAST TOWARDS THE MIDWEST
EARLY MONDAY WITH SOUTHWEST FLOW INCREASING OUT AHEAD AND A CORRIDOR
OF MODERATE TO STRONG MID LEVEL THETA-E ADVECTION LIFTING ACROSS THE
LOCAL FORECAST AREA ON THE NOSE OF A 40KT OR SO LOW LEVEL JET.
COLUMN IS FAIRLY DRY OUT AHEAD OF THE BAROCLINIC ZONE BUT A NARROW
LAYER OF SATURATION COULD TAP INTO SOME MODEST INSTABILITY ROOTED
BETWEEN H7-H9. THIS DOES POINT TO SOME CHANCES FOR THUNDERSTORMS
THOUGH CHANCES ARE BETTER TO OUR NORTH WHERE THE MUCAPE ALIGNS
BETTER WITH THE FORCING FROM THE LOW LEVEL JET. EXPECT LOWERING
CLOUDS IN THE PREDAWN HOURS AS THE SURFACE WARM FRONT APPROACHES.
THE MID LEVELS DRY OUT AGAIN AND THE MOISTURE IS FAIRLY SHALLOW SO
ANY ADDITIONAL PRECIP EARLY ON MONDAY MAY JUST BE DRIZZLE. SURFACE
WARM FRONT LIFTS ACROSS THE AREA MID MORNING MONDAY AND EXPECT DRY
CONDITIONS ONCE IN THE WARM SECTOR WITH LOW CLOUD COVER EVENTUALLY
SCATTERING. H85 TEMPS WARM TO 15-16C WITH 17C BEING THE 99TH
PERCENTILE OF UPPER AIR CLIMO FOR THE END OF OCTOBER. SURFACE HIGHS
WILL BE WELL ABOVE NORMAL...POSSIBLY PUSHING 20F ABOVE
NORMAL...THOUGH THE RECORD HIGH SHOULD BE SAFE. LEANED HEAVILY ON
EC/ECBC FOR AFTERNOON HIGHS MONDAY FORECASTING MID 70S...WITH UPPER
70S SOUTH OF I-80. THE WARMER CONDITIONS WILL BE ACCOMPANIED BY
STRONGER WINDS HOWEVER WITH SOUTHWEST WINDS GUSTING 20 TO 25 MPH AND
POSSIBLY 30 MPH AT TIMES.

TUESDAY THROUGH FRIDAY...
MODELS ARE INDICATING A STRONG LOW PRESSURE SYSTEM WILL BEGIN TO
DEVELOP OVER THE REGION EARLY NEXT WEEK WITH A COLD FRONT SWEEPING
ACROSS THE ARE MONDAY NIGHT INTO EARLY TUESDAY BRINGING CHANCES FOR
SHOWER AND THUNDERSTORMS. THE LOW REALLY BEGINS TO DEEPEN IN EARNEST
AS IT LIFTS ACROSS THE GREAT LAKES INTO CANADA TUESDAY INTO
WEDNESDAY WITH DRIVING POLAR AIR SOUTH INTO THE CANADIAN PRAIRIES
AND A COLD POLAR HIGH GRAZING THE LOCAL AREA LATE NEXT WEEK. DETAILS
STILL MURKY THIS FAR OUT BUT DOES APPEAR WE COULD BE IN FOR A BIG
COOL DOWN LATE NEXT WEEK IN TIME FOR HALLOWEEN IF CURRENT GFS/ECMWF
RUNS PAN OUT.

DEUBELBEISS

&&

.AVIATION...

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

* CIGS LOWER THIS EVENING...MVFR POSSIBLE AFTER 03-04Z.

* MVFR VSBY POSSIBLE TONIGHT.

* SLIGHT CHANCE -SHRA LATE THIS EVENING.

MDB/RATZER

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

LAKE BREEZE REMAINS LIMITED TO IMMEDIATE COOK COUNTY SHORELINE AND
PARTS OF EASTERN LAKE COUNTY IL AT 22Z...AND IS NOT EXPECTED TO BE
A FACTOR FOR CHICAGO TERMINALS AS WINDS BACK SOUTHWEST. OTHERWISE...
AN AREA OF MVFR/IFR CLOUDINESS OVER EASTERN IA/SOUTHWEST WI
CONTINUES TO BE MONITORED AS IT MOVES EAST. EXTRAPOLATION OF SATELLITE
IMAGES INDICATES ARRIVAL AFTER 01Z FOR RFD AND AFTER 03-04Z FOR
CHICAGO TERMINALS.

RATZER

FROM 18Z...

HIGH PRESSURE OVER THE REGION CONTINUES TO PROVIDE LIGHT WINDS
WHICH HAVE BEEN VARIABLE BETWEEN SOUTH AND WEST. WILL SEE A
STEADIER SOUTH TO SOUTHWEST DIRECTION DEVELOP INTO THE EVENING AS
THE HIGH SHIFTS EASTWARD. FEW-SCT MVFR CLOUDS LINGER ACROSS
NORTHWEST INDIANA WITH MOST AREAS VFR. LOW CIGS/VSBY REMAIN ACROSS
RFD BUT IS QUICKLY ERODING NORTHWESTWARD SO EXPECT VFR AT RFD BY
19Z OR SO.

AN UPPER TROUGH WILL CROSS THE AREA THIS EVENING WHICH WILL BRING
LOWERING CLOUD COVER. EXPECT CIGS TO LOWER TO AT LEAST LOW END VFR
WITH MVFR POSSIBLE GOING INTO THE OVERNIGHT. A FEW SHOWERS ARE
POSSIBLE BUT SHOULD BE BRIEF AND SPOTTY IN COVERAGE. CIGS MAY
FURTHER LOWER TO LOWER END MVFR OVERNIGHT BUT AM NOT HIGHLY
CONFIDENT IN THIS OCCURRING. MAY ALSO SEE VSBY LOWER TO MVFR ACROSS
MOST AREAS AS WELL. AM A LITTLE MORE CONCERNED ABOUT IFR POTENTIAL
AT RFD GIVEN HIGHER RESIDUAL MOISTURE THANKS TO THE STRATUS/FOG
HANGING ON SO LONG TODAY. MAY NEED TO CARRY LOWER CONDITIONS WITH
LATER UPDATES. WINDS WILL SHIFT NORTHWESTERLY SATURDAY MORNING AS
DRIER AIR WORKS IN. THIS WILL ERODE ANY LOW CIGS/VSBY ALLOWING FOR
VFR TO PREVAIL BY MID/LATE MORNING IF NOT SOONER.

MDB

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

* HIGH CONFIDENCE IN CIGS LOWERING TO LOWER END VFR THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS.

* MEDIUM CONFIDENCE IN MVFR VSBY TONIGHT.

* HIGH CONFIDENCE THAT THREAT FOR -SHRA IS LOW LATE THIS EVENING.

MDB/RATZER

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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







000
FXUS63 KILX 242011
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
311 PM CDT Fri Oct 24 2014

.SHORT TERM...(Tonight)
ISSUED AT 309 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 309 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder than the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1257 PM CDT FRI OCT 24 2014

Low clouds are rapidly dissipating across the area early this
afternoon, with 1730z visible satellite imagery showing one
persistent band from KGBG to KTAZ. Based on satellite trends,
will hold on to IFR ceilings at KSPI for one more hour before
clearing things out by 19z. Once these clouds dissipate, only
FEW-SCT diurnal Cu and high/thin cirrus will be noted for the
balance of the day. Main aviation question will be how low
ceilings will go tonight as trough axis approaches from the
northwest. NAM forecast soundings and latest HRRR both suggest at
least MVFR ceilings spreading in from the NW between 02z and 05z.
This band of low clouds will begin clearing out after midnight,
which will likely lead to fog development toward dawn. Given a
similar airmass to last night and winds expected to become
light/variable in the vicinity of the trough, have reduced visbys
to between 1 and 3 miles at the terminals. Once the trough passes,
winds will veer to the W/NW and any low clouds/fog will clear out
by Saturday morning.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Barnes







000
FXUS63 KLOT 242005
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
305 PM CDT FRI OCT 24 2014

.DISCUSSION...
304 PM CDT

THIS EVENING AND TONIGHT...
BROAD SURFACE HIGH STRETCHES FROM THE LOWER MISSISSIPPI VALLEY INTO
THE UPPER OHIO VALLEY AND EASTERN GREAT LAKES THIS AFTERNOON WHILE
LOW PRESSURE LIES OVER ONTARIO WITH A COLD FRONT STRETCHING INTO THE
CENTRAL PLAINS. A NARROW RIBBON OF MOISTURE IS ANALYZED OUT AHEAD OF
THE COLD FRONT WITH 60 DEGREE DEWPOINTS STRETCHING NORTH INTO
NORTHERN IOWA THIS AFTERNOON...AND JUST OFF THE DECK A CORRIDOR OF
LOW/MID LEVEL THETA-E ADVECTION IS DRIVING AT LEAST A FEW VERY WEAK
RADAR RETURNS OVER FAR SE MN AND NE IA. RAP/HRRR GUIDANCE SHOWS THIS
AREA PERSISTING ACROSS NORTHERN ILLINOIS THIS EVENING WITH THE
CHANCE FOR A FEW SHOWERS. GIVEN THE VERY SPARSE COVERAGE SO FAR
UPSTREAM AND THE DRY SOUNDINGS/LIMITED DURATION OF FORCING...NOT
BITING OFF ON PRECIP MOVING ACROSS THE FORECAST AREA...BUT WILL
MAINTAIN SOME LOW END SLIGHT CHANCE POPS SINCE THERE ARE SOME
INGREDIENTS IN PLACE.

SATURDAY THROUGH SUNDAY...
WEAK FRONT WILL PASS ACROSS THE AREA EARLY ON SATURDAY WITH DRY AIR
FILTERING BACK INTO THE REGION AS AN UPPER RIDGE BUILDS OVER THE
AREA AND SUBSIDENCE SETS IN OVERHEAD. EXPECT DEW POINTS TO MIX OUT
NICELY TOMORROW AFTERNOON...ESPECIALLY IN NORTH CENTRAL ILLINOIS
WHERE DEW POINTS MAY DROP INTO THE LOW TO MID 30S. THE DRY
CONDITIONS SHOULD ALLOW FOR A NICE RESPONSE FROM DIABATIC HEATING
WHICH WILL RESULT IN TEMPS A FEW DEGREES WARMER TOMORROW.
MEANWHILE...SURFACE HIGH WILL BUILD FROM THE NORTHERN PLAINS
SATURDAY DIRECTLY OVERHEAD EARLY TUESDAY MORNING WHICH WILL ALLOW
FAVORABLE RADIATIONAL COOLING SUNDAY MORNING WITH LOWS DIPPING INTO
THE 30S IN OUTLYING AREAS AND SOME OF THE TYPICAL COLD SPOTS.
ELSEWHERE EXPECT LOW 40S WITH DOWNTOWN CHICAGO STAYING PROPPED UP IN
THE MID 40S. TEMPERATURES MAY BE A BIT TRICKY SUNDAY WITH WARM
ADVECTION ALOFT INCREASING THROUGH THE DAY ON THE BACKSIDE OF THE
SURFACE HIGH. A COOL STARTING POINT AND INCREASING CLOUD COVER
THROUGH THE DAY WILL KEEP HIGHS ONLY INTO THE 60S SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY...
UPPER RIDGE BEGINS TO BUCKLE SUNDAY NIGHT INTO MONDAY AS SHORTWAVE
TROUGH DIGS FROM THE PAC NW INTO THE CENTRAL PLAINS. BROAD SURFACE
LOW PRESSURE OVER THE PLAINS WILL SHIFT EAST TOWARDS THE MIDWEST
EARLY MONDAY WITH SOUTHWEST FLOW INCREASING OUT AHEAD AND A CORRIDOR
OF MODERATE TO STRONG MID LEVEL THETA-E ADVECTION LIFTING ACROSS THE
LOCAL FORECAST AREA ON THE NOSE OF A 40KT OR SO LOW LEVEL JET.
COLUMN IS FAIRLY DRY OUT AHEAD OF THE BAROCLINIC ZONE BUT A NARROW
LAYER OF SATURATION COULD TAP INTO SOME MODEST INSTABILITY ROOTED
BETWEEN H7-H9. THIS DOES POINT TO SOME CHANCES FOR THUNDERSTORMS
THOUGH CHANCES ARE BETTER TO OUR NORTH WHERE THE MUCAPE ALIGNS
BETTER WITH THE FORCING FROM THE LOW LEVEL JET. EXPECT LOWERING
CLOUDS IN THE PREDAWN HOURS AS THE SURFACE WARM FRONT APPROACHES.
THE MID LEVELS DRY OUT AGAIN AND THE MOISTURE IS FAIRLY SHALLOW SO
ANY ADDITIONAL PRECIP EARLY ON MONDAY MAY JUST BE DRIZZLE. SURFACE
WARM FRONT LIFTS ACROSS THE AREA MID MORNING MONDAY AND EXPECT DRY
CONDITIONS ONCE IN THE WARM SECTOR WITH LOW CLOUD COVER EVENTUALLY
SCATTERING. H85 TEMPS WARM TO 15-16C WITH 17C BEING THE 99TH
PERCENTILE OF UPPER AIR CLIMO FOR THE END OF OCTOBER. SURFACE HIGHS
WILL BE WELL ABOVE NORMAL...POSSIBLY PUSHING 20F ABOVE
NORMAL...THOUGH THE RECORD HIGH SHOULD BE SAFE. LEANED HEAVILY ON
EC/ECBC FOR AFTERNOON HIGHS MONDAY FORECASTING MID 70S...WITH UPPER
70S SOUTH OF I-80. THE WARMER CONDITIONS WILL BE ACCOMPANIED BY
STRONGER WINDS HOWEVER WITH SOUTHWEST WINDS GUSTING 20 TO 25 MPH AND
POSSIBLY 30 MPH AT TIMES.

TUESDAY THROUGH FRIDAY...
MODELS ARE INDICATING A STRONG LOW PRESSURE SYSTEM WILL BEGIN TO
DEVELOP OVER THE REGION EARLY NEXT WEEK WITH A COLD FRONT SWEEPING
ACROSS THE ARE MONDAY NIGHT INTO EARLY TUESDAY BRINGING CHANCES FOR
SHOWER AND THUNDERSTORMS. THE LOW REALLY BEGINS TO DEEPEN IN EARNEST
AS IT LIFTS ACROSS THE GREAT LAKES INTO CANADA TUESDAY INTO
WEDNESDAY WITH DRIVING POLAR AIR SOUTH INTO THE CANADIAN PRAIRIES
AND A COLD POLAR HIGH GRAZING THE LOCAL AREA LATE NEXT WEEK. DETAILS
STILL MURKY THIS FAR OUT BUT DOES APPEAR WE COULD BE IN FOR A BIG
COOL DOWN LATE NEXT WEEK IN TIME FOR HALLOWEEN IF CURRENT GFS/ECMWF
RUNS PAN OUT.

DEUBELBEISS

&&

.AVIATION...

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

* CIGS LOWER THIS EVENING...MVFR POSSIBLE.

* MVFR VSBY POSSIBLE TONIGHT.

* SLIGHT CHANCE -SHRA LATE THIS EVENING.

MDB

//DISCUSSION...UPDATED 20Z...

IFR HAS CLEARED RFD AND SHOULD STAY AWAY THROUGH THE AFTERNOON.
LAKE BREEZE BOUNDARY HAS DEVELOPED CLOSE TO THE LAKESHORE AND HAS
MADE INLAND PROGRESS ACROSS LAKE COUNTY ILLINOIS. EXPECT THIS TO
REMAIN EAST OF THE TERMINALS THROUGH THE AFTERNOON. OTHERWISE
EXPECT LIGHT WINDS WITH A VARIABLE SOUTH TO SOUTHWEST DIRECTION.

FROM 18Z...

HIGH PRESSURE OVER THE REGION CONTINUES TO PROVIDE LIGHT WINDS
WHICH HAVE BEEN VARIABLE BETWEEN SOUTH AND WEST. WILL SEE A
STEADIER SOUTH TO SOUTHWEST DIRECTION DEVELOP INTO THE EVENING AS
THE HIGH SHIFTS EASTWARD. FEW-SCT MVFR CLOUDS LINGER ACROSS
NORTHWEST INDIANA WITH MOST AREAS VFR. LOW CIGS/VSBY REMAIN ACROSS
RFD BUT IS QUICKLY ERODING NORTHWESTWARD SO EXPECT VFR AT RFD BY
19Z OR SO.

AN UPPER TROUGH WILL CROSS THE AREA THIS EVENING WHICH WILL BRING
LOWERING CLOUD COVER. EXPECT CIGS TO LOWER TO AT LEAST LOW END VFR
WITH MVFR POSSIBLE GOING INTO THE OVERNIGHT. A FEW SHOWERS ARE
POSSIBLE BUT SHOULD BE BRIEF AND SPOTTY IN COVERAGE. CIGS MAY
FURTHER LOWER TO LOWER END MVFR OVERNIGHT BUT AM NOT HIGHLY
CONFIDENT IN THIS OCCURRING. MAY ALSO SEE VSBY LOWER TO MVFR ACROSS
MOST AREAS AS WELL. AM A LITTLE MORE CONCERNED ABOUT IFR POTENTIAL
AT RFD GIVEN HIGHER RESIDUAL MOISTURE THANKS TO THE STRATUS/FOG
HANGING ON SO LONG TODAY. MAY NEED TO CARRY LOWER CONDITIONS WITH
LATER UPDATES. WINDS WILL SHIFT NORTHWESTERLY SATURDAY MORNING AS
DRIER AIR WORKS IN. THIS WILL ERODE ANY LOW CIGS/VSBY ALLOWING FOR
VFR TO PREVAIL BY MID/LATE MORNING IF NOT SOONER.

MDB

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

* HIGH CONFIDENCE IN CIGS LOWERING TO LOWER END VFR THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS.

* MEDIUM CONFIDENCE IN MVFR VSBY TONIGHT.

* HIGH CONFIDENCE THAT THREAT FOR -SHRA IS LOW LATE THIS EVENING.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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






000
FXUS63 KLOT 241959
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
259 PM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* CIGS LOWER THIS EVENING...MVFR POSSIBLE.

* MVFR VSBY POSSIBLE TONIGHT.

* SLIGHT CHANCE -SHRA LATE THIS EVENING.

MDB

//DISCUSSION...UPDATED 20Z...

IFR HAS CLEARED RFD AND SHOULD STAY AWAY THROUGH THE AFTERNOON.
LAKE BREEZE BOUNDARY HAS DEVELOPED CLOSE TO THE LAKESHORE AND HAS
MADE INLAND PROGRESS ACROSS LAKE COUNTY ILLINOIS. EXPECT THIS TO
REMAIN EAST OF THE TERMINALS THROUGH THE AFTERNOON. OTHERWISE
EXPECT LIGHT WINDS WITH A VARIABLE SOUTH TO SOUTHWEST DIRECTION.

FROM 18Z...

HIGH PRESSURE OVER THE REGION CONTINUES TO PROVIDE LIGHT WINDS
WHICH HAVE BEEN VARIABLE BETWEEN SOUTH AND WEST. WILL SEE A
STEADIER SOUTH TO SOUTHWEST DIRECTION DEVELOP INTO THE EVENING AS
THE HIGH SHIFTS EASTWARD. FEW-SCT MVFR CLOUDS LINGER ACROSS
NORTHWEST INDIANA WITH MOST AREAS VFR. LOW CIGS/VSBY REMAIN ACROSS
RFD BUT IS QUICKLY ERODING NORTHWESTWARD SO EXPECT VFR AT RFD BY
19Z OR SO.

AN UPPER TROUGH WILL CROSS THE AREA THIS EVENING WHICH WILL BRING
LOWERING CLOUD COVER. EXPECT CIGS TO LOWER TO AT LEAST LOW END VFR
WITH MVFR POSSIBLE GOING INTO THE OVERNIGHT. A FEW SHOWERS ARE
POSSIBLE BUT SHOULD BE BRIEF AND SPOTTY IN COVERAGE. CIGS MAY
FURTHER LOWER TO LOWER END MVFR OVERNIGHT BUT AM NOT HIGHLY
CONFIDENT IN THIS OCCURRING. MAY ALSO SEE VSBY LOWER TO MVFR ACROSS
MOST AREAS AS WELL. AM A LITTLE MORE CONCERNED ABOUT IFR POTENTIAL
AT RFD GIVEN HIGHER RESIDUAL MOISTURE THANKS TO THE STRATUS/FOG
HANGING ON SO LONG TODAY. MAY NEED TO CARRY LOWER CONDITIONS WITH
LATER UPDATES. WINDS WILL SHIFT NORTHWESTERLY SATURDAY MORNING AS
DRIER AIR WORKS IN. THIS WILL ERODE ANY LOW CIGS/VSBY ALLOWING FOR
VFR TO PREVAIL BY MID/LATE MORNING IF NOT SOONER.

MDB

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

* HIGH CONFIDENCE IN CIGS LOWERING TO LOWER END VFR THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS.

* MEDIUM CONFIDENCE IN MVFR VSBY TONIGHT.

* HIGH CONFIDENCE THAT THREAT FOR -SHRA IS LOW LATE THIS EVENING.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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






000
FXUS63 KLOT 241959
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
259 PM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* CIGS LOWER THIS EVENING...MVFR POSSIBLE.

* MVFR VSBY POSSIBLE TONIGHT.

* SLIGHT CHANCE -SHRA LATE THIS EVENING.

MDB

//DISCUSSION...UPDATED 20Z...

IFR HAS CLEARED RFD AND SHOULD STAY AWAY THROUGH THE AFTERNOON.
LAKE BREEZE BOUNDARY HAS DEVELOPED CLOSE TO THE LAKESHORE AND HAS
MADE INLAND PROGRESS ACROSS LAKE COUNTY ILLINOIS. EXPECT THIS TO
REMAIN EAST OF THE TERMINALS THROUGH THE AFTERNOON. OTHERWISE
EXPECT LIGHT WINDS WITH A VARIABLE SOUTH TO SOUTHWEST DIRECTION.

FROM 18Z...

HIGH PRESSURE OVER THE REGION CONTINUES TO PROVIDE LIGHT WINDS
WHICH HAVE BEEN VARIABLE BETWEEN SOUTH AND WEST. WILL SEE A
STEADIER SOUTH TO SOUTHWEST DIRECTION DEVELOP INTO THE EVENING AS
THE HIGH SHIFTS EASTWARD. FEW-SCT MVFR CLOUDS LINGER ACROSS
NORTHWEST INDIANA WITH MOST AREAS VFR. LOW CIGS/VSBY REMAIN ACROSS
RFD BUT IS QUICKLY ERODING NORTHWESTWARD SO EXPECT VFR AT RFD BY
19Z OR SO.

AN UPPER TROUGH WILL CROSS THE AREA THIS EVENING WHICH WILL BRING
LOWERING CLOUD COVER. EXPECT CIGS TO LOWER TO AT LEAST LOW END VFR
WITH MVFR POSSIBLE GOING INTO THE OVERNIGHT. A FEW SHOWERS ARE
POSSIBLE BUT SHOULD BE BRIEF AND SPOTTY IN COVERAGE. CIGS MAY
FURTHER LOWER TO LOWER END MVFR OVERNIGHT BUT AM NOT HIGHLY
CONFIDENT IN THIS OCCURRING. MAY ALSO SEE VSBY LOWER TO MVFR ACROSS
MOST AREAS AS WELL. AM A LITTLE MORE CONCERNED ABOUT IFR POTENTIAL
AT RFD GIVEN HIGHER RESIDUAL MOISTURE THANKS TO THE STRATUS/FOG
HANGING ON SO LONG TODAY. MAY NEED TO CARRY LOWER CONDITIONS WITH
LATER UPDATES. WINDS WILL SHIFT NORTHWESTERLY SATURDAY MORNING AS
DRIER AIR WORKS IN. THIS WILL ERODE ANY LOW CIGS/VSBY ALLOWING FOR
VFR TO PREVAIL BY MID/LATE MORNING IF NOT SOONER.

MDB

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

* HIGH CONFIDENCE IN CIGS LOWERING TO LOWER END VFR THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS.

* MEDIUM CONFIDENCE IN MVFR VSBY TONIGHT.

* HIGH CONFIDENCE THAT THREAT FOR -SHRA IS LOW LATE THIS EVENING.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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






000
FXUS63 KILX 241950
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
250 PM CDT Fri Oct 24 2014

.SHORT TERM...(Tonight)
ISSUED AT 249 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 249 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder and the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1257 PM CDT FRI OCT 24 2014

Low clouds are rapidly dissipating across the area early this
afternoon, with 1730z visible satellite imagery showing one
persistent band from KGBG to KTAZ. Based on satellite trends,
will hold on to IFR ceilings at KSPI for one more hour before
clearing things out by 19z. Once these clouds dissipate, only
FEW-SCT diurnal Cu and high/thin cirrus will be noted for the
balance of the day. Main aviation question will be how low
ceilings will go tonight as trough axis approaches from the
northwest. NAM forecast soundings and latest HRRR both suggest at
least MVFR ceilings spreading in from the NW between 02z and 05z.
This band of low clouds will begin clearing out after midnight,
which will likely lead to fog development toward dawn. Given a
similar airmass to last night and winds expected to become
light/variable in the vicinity of the trough, have reduced visbys
to between 1 and 3 miles at the terminals. Once the trough passes,
winds will veer to the W/NW and any low clouds/fog will clear out
by Saturday morning.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Barnes







000
FXUS63 KILX 241950
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
250 PM CDT Fri Oct 24 2014

.SHORT TERM...(Tonight)
ISSUED AT 249 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 249 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder and the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1257 PM CDT FRI OCT 24 2014

Low clouds are rapidly dissipating across the area early this
afternoon, with 1730z visible satellite imagery showing one
persistent band from KGBG to KTAZ. Based on satellite trends,
will hold on to IFR ceilings at KSPI for one more hour before
clearing things out by 19z. Once these clouds dissipate, only
FEW-SCT diurnal Cu and high/thin cirrus will be noted for the
balance of the day. Main aviation question will be how low
ceilings will go tonight as trough axis approaches from the
northwest. NAM forecast soundings and latest HRRR both suggest at
least MVFR ceilings spreading in from the NW between 02z and 05z.
This band of low clouds will begin clearing out after midnight,
which will likely lead to fog development toward dawn. Given a
similar airmass to last night and winds expected to become
light/variable in the vicinity of the trough, have reduced visbys
to between 1 and 3 miles at the terminals. Once the trough passes,
winds will veer to the W/NW and any low clouds/fog will clear out
by Saturday morning.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Barnes







000
FXUS63 KILX 241950
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
250 PM CDT Fri Oct 24 2014

.SHORT TERM...(Tonight)
ISSUED AT 249 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 249 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder and the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1257 PM CDT FRI OCT 24 2014

Low clouds are rapidly dissipating across the area early this
afternoon, with 1730z visible satellite imagery showing one
persistent band from KGBG to KTAZ. Based on satellite trends,
will hold on to IFR ceilings at KSPI for one more hour before
clearing things out by 19z. Once these clouds dissipate, only
FEW-SCT diurnal Cu and high/thin cirrus will be noted for the
balance of the day. Main aviation question will be how low
ceilings will go tonight as trough axis approaches from the
northwest. NAM forecast soundings and latest HRRR both suggest at
least MVFR ceilings spreading in from the NW between 02z and 05z.
This band of low clouds will begin clearing out after midnight,
which will likely lead to fog development toward dawn. Given a
similar airmass to last night and winds expected to become
light/variable in the vicinity of the trough, have reduced visbys
to between 1 and 3 miles at the terminals. Once the trough passes,
winds will veer to the W/NW and any low clouds/fog will clear out
by Saturday morning.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Barnes







000
FXUS63 KILX 241950
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
250 PM CDT Fri Oct 24 2014

.SHORT TERM...(Tonight)
ISSUED AT 249 PM CDT FRI OCT 24 2014

19z/2pm satellite imagery shows low clouds that persisted for much
of the day across west-central Illinois have finally dissipated,
with just one small patch remaining from south of Lincoln to near
Taylorville.  Based on satellite trends, this patch will dissipate
over the next hour or so as well, leading to mostly clear skies late
this afternoon into the early evening.  Main short-term forecast
concern will be the potential re-development of low clouds/fog
tonight as a weak trough of low pressure moves through the area.
While the overall depth of the atmosphere will be very dry, a
shallow surface-based moist layer will remain in place.  With no
deep-layer moisture to work with, precip is not expected to develop
along the trough despite the NAM hinting at some overnight. As winds
become light/variable and cloud cover associated with the passing
trough begins to clear from northwest to southeast after midnight,
fog will begin to develop.  HRRR is showing widespread fog once
again forming across central/eastern Iowa, then spreading into the
Illinois River Valley toward dawn.  As a result, will carry areas of
fog along/west of the Illinois River, with patchy fog as far east as
Champaign/Danville.  Due to cloud cover and light southerly winds,
low temperatures will be quite a bit warmer than in recent nights,
with readings remaining in the lower to middle 50s.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 249 PM CDT FRI OCT 24 2014

Saturday will start off with some morning fog, mainly N of I-70. The
fog should burn off around mid-morning, as a cold front pushes east
across IL. Some cooler air associated with the front will be mainly
confined to northern IL, with our 850mb temps still remaining the
12-14C range in the post-frontal airmass. Dry-adiabatic warming of
that layer to the surface, coupled with some sunshine should help
push high temps into the low 70s N of I-74 with upper 70s S of
I-70. NW winds will still develop behind the front, so a brief
chill may be added to the air at times.

Mid level warming will develop Saturday night into Sunday, as 850mb
temps climb toward +16C. That warm layer will linger into Monday.
Southerly winds will develop Sunday afternoon once the surface ridge
axis moves east of IL, so highs should once again climb into the 70s
across the board. On Monday, a few 80 degree readings will possible
on Monday across southwest and southeast portions of the forecast
area, which would be nearly 20 degrees above normal for late
October. Record highs for Monday are in the mid 80s and currently
appear safe.

A long wave trough is forecast to move across the northern
Plains on Monday night, with cold front progressing across IL
Tuesday morning and early afternoon. The ECMWF indicates a more
dynamic system developing in the western Great Lakes on Tuesday,
while the GFS remains a bit more progressive and less strong with
the frontal passage in our area of IL. We did maintain widespread
chance PoPs Monday night, as moisture pooling and lift still appear
to be  sufficient a band of rain to affect central IL. We continued
the likely PoPs in SE Illinois for Tuesday, but chances should
diminish Tue afternoon as the main forcing for precip departs into
Indiana, and dry air quickly filters into the area aloft.

A significant cool down is agreed upon by the GFS and ECMWF for
Tuesday and Tuesday night, as 850mb temps plummet to 0 to -3C by
midday Wednesday. That will bring temps back below normal for highs
Wed, with upper 50s north of I-74, with low 60s south near
Jacksonville to Lawrenceville.

Another cold front is indicated for Thursday, with better agreement
on timing of the front between the GFS and ECMWF. Confidence is
increasing that a band of light rain showers may accompany that
front. So low chances for rain was added to the Thurs forecast,
mainly from the Illinois river to I-55.

The GFS is a about 4-5 degrees colder and the ECMWF behind the
front, with 850mb readings in the -2 to -4C range Friday afternoon.
We will continue with the cooling trend for late week. Some freezing
temps could develop for Friday night N of I-74 if the GFS scenario
pans out.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1257 PM CDT FRI OCT 24 2014

Low clouds are rapidly dissipating across the area early this
afternoon, with 1730z visible satellite imagery showing one
persistent band from KGBG to KTAZ. Based on satellite trends,
will hold on to IFR ceilings at KSPI for one more hour before
clearing things out by 19z. Once these clouds dissipate, only
FEW-SCT diurnal Cu and high/thin cirrus will be noted for the
balance of the day. Main aviation question will be how low
ceilings will go tonight as trough axis approaches from the
northwest. NAM forecast soundings and latest HRRR both suggest at
least MVFR ceilings spreading in from the NW between 02z and 05z.
This band of low clouds will begin clearing out after midnight,
which will likely lead to fog development toward dawn. Given a
similar airmass to last night and winds expected to become
light/variable in the vicinity of the trough, have reduced visbys
to between 1 and 3 miles at the terminals. Once the trough passes,
winds will veer to the W/NW and any low clouds/fog will clear out
by Saturday morning.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Barnes







000
FXUS63 KLOT 241929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
229 PM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* CIGS LOWER THIS EVENING...MVFR POSSIBLE.

* MVFR VSBY POSSIBLE TONIGHT.

* SLIGHT CHANCE -SHRA LATE THIS EVENING.

MDB

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

HIGH PRESSURE OVER THE REGION CONTINUES TO PROVIDE LIGHT WINDS
WHICH HAVE BEEN VARIABLE BETWEEN SOUTH AND WEST. WILL SEE A
STEADIER SOUTH TO SOUTHWEST DIRECTION DEVELOP INTO THE EVENING AS
THE HIGH SHIFTS EASTWARD. FEW-SCT MVFR CLOUDS LINGER ACROSS
NORTHWEST INDIANA WITH MOST AREAS VFR. LOW CIGS/VSBY REMAIN ACROSS
RFD BUT IS QUICKLY ERODING NORTHWESTWARD SO EXPECT VFR AT RFD BY
19Z OR SO.

AN UPPER TROUGH WILL CROSS THE AREA THIS EVENING WHICH WILL BRING
LOWERING CLOUD COVER. EXPECT CIGS TO LOWER TO AT LEAST LOW END VFR
WITH MVFR POSSIBLE GOING INTO THE OVERNIGHT. A FEW SHOWERS ARE
POSSIBLE BUT SHOULD BE BRIEF AND SPOTTY IN COVERAGE. CIGS MAY
FURTHER LOWER TO LOWER END MVFR OVERNIGHT BUT AM NOT HIGHLY
CONFIDENT IN THIS OCCURRING. MAY ALSO SEE VSBY LOWER TO MVFR ACROSS
MOST AREAS AS WELL. AM A LITTLE MORE CONCERNED ABOUT IFR POTENTIAL
AT RFD GIVEN HIGHER RESIDUAL MOISTURE THANKS TO THE STRATUS/FOG
HANGING ON SO LONG TODAY. MAY NEED TO CARRY LOWER CONDITIONS WITH
LATER UPDATES. WINDS WILL SHIFT NORTHWESTERLY SATURDAY MORNING AS
DRIER AIR WORKS IN. THIS WILL ERODE ANY LOW CIGS/VSBY ALLOWING FOR
VFR TO PREVAIL BY MID/LATE MORNING IF NOT SOONER.

MDB

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

* HIGH CONFIDENCE IN CIGS LOWERING TO LOWER END VFR THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS.

* MEDIUM CONFIDENCE IN MVFR VSBY TONIGHT.

* HIGH CONFIDENCE THAT THREAT FOR -SHRA IS LOW LATE THIS EVENING.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
228 PM CDT

HIGH PRESSURE IS SLOWLY PUSHING EAST WITH LIGHT SOUTHWEST WINDS OVER
THE LAKE. A WEAK LAKE BREEZE HAS TURNED WINDS ONSHORE OVER LAKE
COUNTY IL.  SOUTHWEST WINDS INCREASE TO 20-25 KT THIS EVENING WITH
OCNL 30 KT GUSTS PSBL OVER THE NORTH HALF OF THE LAKE OVERNIGHT.
WINDS TURN W 20-25 KT BEHIND THE FRONT AND SLOWLY BECOME NW SATURDAY
NIGHT. POINTS NORTH OF WILMETTE HARBOR MAY SEE OCNL GUSTS TO 25 KT
TOMORROW...BUT THINKING SUSTAINED SMALL CRAFT CONDITIONS WILL NOT BE
MET. WINDS DIMINISH AS A HIGH MOVES OVER THE LAKE SUNDAY.  WINDS
BECOME SOUTH BEHIND THE LOW AND THEN TURN SE AND INCREASE TO 20-25
KT AS THE NEXT LOW APPROACHES SUNDAY NIGHT.  THERE IS STILL A LOT OF
VARIABILITY IN THE STRENGTH AND PATH OF THE NEXT LOW SO CONFIDENCE
IS LOW IN THE EXACT WIND SPEEDS. ONE MODEL DOES FEATURE WESTERLY
GALES ON THE BACKSIDE OF THE LOW TUESDAY NIGHT...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO THAT HIGH IN THE FORECAST JUST YET.  HIGH
PRESSURE MOVES IN MID NEXT WEEK AND WINDS SLOWLY DIMINISH WEDNESDAY.

STILL THINKING THERE IS A MARGINAL CHANCE FOR SMALL CRAFT CONDITIONS
TO BE MET MONDAY NIGHT THROUGH TUESDAY...BUT WILL HOLD OFF ON
HEADLINES FOR NOW.

JEE

&&

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

$$

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

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






000
FXUS63 KILX 241757
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1257 PM CDT Fri Oct 24 2014

.UPDATE...
ISSUED AT 1043 AM CDT FRI OCT 24 2014

Low clouds and fog continue to blanket west-central Illinois this
morning, mainly along/west of a Peoria to Taylorville line. A
Dense Fog Advisory remains in effect for this area through noon.
So far, very little erosion of the low cloud cover has been noted
on visible satellite imagery, although the process will likely
begin within the next hour or two, as it did yesterday across
Iowa. HRRR shows this as well, with skies becoming partly sunny
across all but the far northwest KILX CWA by mid-afternoon. If
trends continue, eastern Iowa/northwest Illinois may remain cloudy
for the entire day. Further east, southerly winds and at least
partial sunshine will help boost afternoon highs into the middle
to upper 60s across central Illinois. Forecast update has already
been issued.

&&

.SHORT TERM...(Today)
ISSUED AT 235 AM CDT FRI OCT 24 2014

A weak short wave continues to move through the eastern parts of the
CWA this morning, but this should be out of the state by time the
new forecast is issued, or shortly after. The main concern this
morning is the development and advection of stratus clouds and fog
early this morning. Dense fog is present across most of eastern Iowa
this morning and the HRRR model advects this into the area for this
morning. This will keep lots of clouds in the area for this morning,
and could affect max temps for this afternoon, depending on how
quickly the clouds dissipate. Models have it diminishing during
the late morning hours. And with winds becoming southerly by
afternoon, believe some dissipation of the clouds will happen. So
will have less clouds during the afternoon. However, afternoon
high temps may not be as high as first forecast, so have decreased
max temps 1-2 degrees from previous forecast. MAV guidance is
higher than MET by several degrees, so took a compromise between
the two due to cloud cover issues.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 235 AM CDT FRI OCT 24 2014

Main forecast issue this weekend and into Monday involves
temperatures. Latest model runs for Saturday have been warmer, as
main core of cooler air associated with a frontal boundary track
more across the Great Lakes region. Have bumped up Saturday highs by
a couple degrees. 850 mb warm front progged to lift through the area
late Saturday night and early Sunday, with +16C temperatures
spreading across central Illinois Sunday afternoon, lingering into
Monday. Have also raised highs several degrees both Sunday and
Monday, with a few 80 degree readings possible on Monday across
southwest and southeast portions of the forecast area. Record highs
for Monday are in the mid 80s and currently appear safe.

Split upper flow early next week focuses the deeper part of the next
wave along the northern stream. Model guidance is fairly uniform
with rain chances Monday night through about midday Tuesday, and
pretty much has the forecast area dry by sunset as a high pressure
ridge quickly builds into the mid-Mississippi Valley. However, the
guidance diverges later in the week. The ECMWF persists in a rather
broad trough along the Mississippi River midday Thursday, but now
significantly ramps up rain chances along the associated surface
front. The GFS has a weaker, more progressive wave with little
precipitation. Have leaned more toward the progressive solution for
now. The ECMWF also persists in developing a large closed low over
the Great Lakes late week, which would pump significantly cooler air
into Illinois. Meanwhile, the GFS builds a ridge eastward, with much
warmer air (850 mb temperatures range from -5C to +8C between the
two models). However, this particular aspect is just beyond the
current forecast range, but will need to be addressed with the
afternoon forecast issuance.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1257 PM CDT FRI OCT 24 2014

Low clouds are rapidly dissipating across the area early this
afternoon, with 1730z visible satellite imagery showing one
persistent band from KGBG to KTAZ. Based on satellite trends,
will hold on to IFR ceilings at KSPI for one more hour before
clearing things out by 19z. Once these clouds dissipate, only
FEW-SCT diurnal Cu and high/thin cirrus will be noted for the
balance of the day. Main aviation question will be how low
ceilings will go tonight as trough axis approaches from the
northwest. NAM forecast soundings and latest HRRR both suggest at
least MVFR ceilings spreading in from the NW between 02z and 05z.
This band of low clouds will begin clearing out after midnight,
which will likely lead to fog development toward dawn. Given a
similar airmass to last night and winds expected to become
light/variable in the vicinity of the trough, have reduced visbys
to between 1 and 3 miles at the terminals. Once the trough passes,
winds will veer to the W/NW and any low clouds/fog will clear out
by Saturday morning.

&&

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

$$

UPDATE...Barnes
SHORT TERM...Auten
LONG TERM...Geelhart
AVIATION...Barnes







000
FXUS63 KLOT 241749
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1249 PM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* CIGS LOWER THIS EVENING...MVFR POSSIBLE.

* MVFR VSBY POSSIBLE TONIGHT.

* SLIGHT CHANCE -SHRA LATE THIS EVENING.

MDB

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

HIGH PRESSURE OVER THE REGION CONTINUES TO PROVIDE LIGHT WINDS
WHICH HAVE BEEN VARIABLE BETWEEN SOUTH AND WEST. WILL SEE A
STEADIER SOUTH TO SOUTHWEST DIRECTION DEVELOP INTO THE EVENING AS
THE HIGH SHIFTS EASTWARD. FEW-SCT MVFR CLOUDS LINGER ACROSS
NORTHWEST INDIANA WITH MOST AREAS VFR. LOW CIGS/VSBY REMAIN ACROSS
RFD BUT IS QUICKLY ERODING NORTHWESTWARD SO EXPECT VFR AT RFD BY
19Z OR SO.

AN UPPER TROUGH WILL CROSS THE AREA THIS EVENING WHICH WILL BRING
LOWERING CLOUD COVER. EXPECT CIGS TO LOWER TO AT LEAST LOW END VFR
WITH MVFR POSSIBLE GOING INTO THE OVERNIGHT. A FEW SHOWERS ARE
POSSIBLE BUT SHOULD BE BRIEF AND SPOTTY IN COVERAGE. CIGS MAY
FURTHER LOWER TO LOWER END MVFR OVERNIGHT BUT AM NOT HIGHLY
CONFIDENT IN THIS OCCURRING. MAY ALSO SEE VSBY LOWER TO MVFR ACROSS
MOST AREAS AS WELL. AM A LITTLE MORE CONCERNED ABOUT IFR POTENTIAL
AT RFD GIVEN HIGHER RESIDUAL MOISTURE THANKS TO THE STRATUS/FOG
HANGING ON SO LONG TODAY. MAY NEED TO CARRY LOWER CONDITIONS WITH
LATER UPDATES. WINDS WILL SHIFT NORTHWESTERLY SATURDAY MORNING AS
DRIER AIR WORKS IN. THIS WILL ERODE ANY LOW CIGS/VSBY ALLOWING FOR
VFR TO PREVAIL BY MID/LATE MORNING IF NOT SOONER.

MDB

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

* HIGH CONFIDENCE IN CIGS LOWERING TO LOWER END VFR THIS
  EVENING...MEDIUM CONFIDENCE IN MVFR CIGS.

* MEDIUM CONFIDENCE IN MVFR VSBY TONIGHT.

* HIGH CONFIDENCE THAT THREAT FOR -SHRA IS LOW LATE THIS EVENING.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 241612
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1112 AM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* PATCH OF MVFR 025-030 CIGS EXPECTED TO SCATTER/CLEAR AT MDW BY
  17Z.

* MVFR CIGS/VSBY LIKELY AGAIN LATE TONIGHT. IFR CIGS/VSBY POSSIBLE.

MDB

//DISCUSSION...UPDATED 16Z...

CLOUDS CONTINUE TO ERODE FROM PWK TO DPA TO JOT TO PIA AND POINTS
EAST WITH A LARGE GAP IN COVERAGE HAVING DEVELOPED. A PATCH OF
025-030 STRATUS IS LINGERING FROM MDW TO GYY BUT EXPECT SCATTERING
AT MDW SOON WITH A PERIOD OF BKN SKIES AT GYY PRIOR TO 18Z.
OTHERWISE...EXPANSIVE AREA OF LIFR AND LOWER CIGS/VSBY REMAINS
PERSISTENT TO THE WEST. THE EASTERN FLANK OF THIS HAS SHOWN SOME
VERY SLOW DRIFT TO THE EAST SO AM A LITTLE CONCERNED THAT CLOUDS
COULD FILL IN A BIT AGAIN AT DPA SO WILL KEEP SCATTERED MENTION
THERE BUT THE LONGER IT TAKES FOR ANY CLOUDS TO ARRIVE THERE THE
HIGHER THEY WOULD LIKELY BE THANKS TO SOME WARMING IN THE
MEANTIME. OTHERWISE HAVE FURTHER SLOWED IMPROVEMENT AT RFD AND MAY
STILL BE A BIT FAST...ESPECIALLY SINCE FAIRLY DENSE CIRRUS IS
MOVING IN OVERHEAD. OTHERWISE LIGHT AND VARIABLE SOUTHWEST TO
NORTHWEST WINDS ARE EXPECTED.

MDB

FROM 12Z...

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...HOWEVER...AN AREA OF
STRATUS FILTERED IN BEHIND THE WEAK BOUNDARY. LATEST SATELLITE
IMAGERY INDICATES THAT THE STRATUS IS BREAKING UP OVER NRN IL AND
IN LOCATIONS THAT HAD SEEN SOME PCPN YESTERDAY...MAINLY ARND THE
RFD AREA...SOME PATCHY DENSE FOG HAS FORMED...THOUGH OF THE TAF
SITES...ONLY RFD HAS OBSERVED THE DENSE FOG. BASED ON THE LATEST
HIGH RES MODEL GUIDANCE AND SATELLITE TRENDS...ANTICIPATE THAT
CONDITIONS SHOULD IMPROVE TO VFR OVER THE AREA BY LATE MORNING.

ANOTHER SFC TROUGH WILL TRACK ACROSS THE CNTRL PLAINS TO THE
UPPER MISSISSIPPI VALLEY BY EARLY EVENING. WINDS WILL BECOME SSWLY
THOUGH THE DAY...THOUGH WITH A WEAK PRESSURE GRADIENT...WIND
SPEEDS SHOULD BE LESS THAN 10KT THROUGH THE DAY. FOR THE EARLY
EVENING HOURS...A MODEST MID LEVEL IMPULSE IS EXPECTED TO CROSS
THE AREA INVOF THE WI/IL BORDER. THERE IS A CHANCE THAT THIS
SYSTEM COULD TRIGGER SOME ISOLD/SCT -SHRA...BUT CONFIDENCE IN
TIMING AND COVERAGE IS TOO LOW TO INCLUDE PCPN IN THE TAFS AT THIS
TIME. CONFIDENCE IS A LITTLE HIGHER THAT MORE FOG SHOULD DEVELOP
OVERNIGHT TONIGHT...PER THE LATEST HIGH RES MODEL RH
TIME SECTIONS...SO HAVE INTRODUCED IFR VIS FOR LATE THIS EVENING
AND OVERNIGHT. SOME GUIDANCE IS POINTING TOWARD THE POSSIBILITY OF
VIS DROPPING TO 1/4SM...BUT GIVEN THE AMOUNT OF CLOUD COVER
EXPECTED...DO NOT HAVE HIGH ENOUGH CONFIDENCE TO DROP VIS LOWER
THAN 1SM FOR NOW.

KREIN

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

* HIGH CONFIDENCE IN MVFR CIGS SCATTERING/CLEARING MDW BY AROUND
  17Z.

* MEDIUM CONFIDENCE IN CIG TRENDS LATE TONIGHT.

* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS LATE TONIGHT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KILX 241543
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1043 AM CDT Fri Oct 24 2014

.UPDATE...
ISSUED AT 1043 AM CDT FRI OCT 24 2014

Low clouds and fog continue to blanket west-central Illinois this
morning, mainly along/west of a Peoria to Taylorville line. A
Dense Fog Advisory remains in effect for this area through noon.
So far, very little erosion of the low cloud cover has been noted
on visible satellite imagery, although the process will likely
begin within the next hour or two, as it did yesterday across
Iowa. HRRR shows this as well, with skies becoming partly sunny
across all but the far northwest KILX CWA by mid-afternoon. If
trends continue, eastern Iowa/northwest Illinois may remain cloudy
for the entire day. Further east, southerly winds and at least
partial sunshine will help boost afternoon highs into the middle
to upper 60s across central Illinois. Forecast update has already
been issued.

&&

.SHORT TERM...(Today)
ISSUED AT 235 AM CDT FRI OCT 24 2014

A weak short wave continues to move through the eastern parts of the
CWA this morning, but this should be out of the state by time the
new forecast is issued, or shortly after. The main concern this
morning is the development and advection of stratus clouds and fog
early this morning. Dense fog is present across most of eastern Iowa
this morning and the HRRR model advects this into the area for this
morning. This will keep lots of clouds in the area for this morning,
and could affect max temps for this afternoon, depending on how
quickly the clouds dissipate. Models have it diminishing during
the late morning hours. And with winds becoming southerly by
afternoon, believe some dissipation of the clouds will happen. So
will have less clouds during the afternoon. However, afternoon
high temps may not be as high as first forecast, so have decreased
max temps 1-2 degrees from previous forecast. MAV guidance is
higher than MET by several degrees, so took a compromise between
the two due to cloud cover issues.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 235 AM CDT FRI OCT 24 2014

Main forecast issue this weekend and into Monday involves
temperatures. Latest model runs for Saturday have been warmer, as
main core of cooler air associated with a frontal boundary track
more across the Great Lakes region. Have bumped up Saturday highs by
a couple degrees. 850 mb warm front progged to lift through the area
late Saturday night and early Sunday, with +16C temperatures
spreading across central Illinois Sunday afternoon, lingering into
Monday. Have also raised highs several degrees both Sunday and
Monday, with a few 80 degree readings possible on Monday across
southwest and southeast portions of the forecast area. Record highs
for Monday are in the mid 80s and currently appear safe.

Split upper flow early next week focuses the deeper part of the next
wave along the northern stream. Model guidance is fairly uniform
with rain chances Monday night through about midday Tuesday, and
pretty much has the forecast area dry by sunset as a high pressure
ridge quickly builds into the mid-Mississippi Valley. However, the
guidance diverges later in the week. The ECMWF persists in a rather
broad trough along the Mississippi River midday Thursday, but now
significantly ramps up rain chances along the associated surface
front. The GFS has a weaker, more progressive wave with little
precipitation. Have leaned more toward the progressive solution for
now. The ECMWF also persists in developing a large closed low over
the Great Lakes late week, which would pump significantly cooler air
into Illinois. Meanwhile, the GFS builds a ridge eastward, with much
warmer air (850 mb temperatures range from -5C to +8C between the
two models). However, this particular aspect is just beyond the
current forecast range, but will need to be addressed with the
afternoon forecast issuance.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 644 AM CDT FRI OCT 24 2014

Complicated forecast for the first 6hrs with some of the TAFs this
morning. An area of stratus and very low vis is slowly moving east
into the area and is already effecting SPI, and should effect PIA
in next couple of hours. Question is how far east will this area
of IFR/LIFR conditions get...will it effect BMI/DEC and CMI.
Believe it will effect DEC and BMI some, but not as much as SPI
and PIA. Conditions should improve this morning, around 16z at PIA
and SPI, but still remain lower MVFR for the rest of the morning.
HRRR model brings some of the lower cigs into BMI and DEC, but not
as long. So going to be a little bit more optimistic at these
sites this morning and just have IFR cigs for this morning at DEC
and lower MVFR at BMI. CMI will have just a TEMPO group for cigs
around 1kft this morning. Conditions should be VFR this afternoon,
but models bring more MVFR cigs back into the area this evening
and continue into the overnight hours. Winds will be light and
variable this morning, but then become more south-southwest for
the rest of the TAF period. Speeds this afternoon will be around
5-10kts.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until Noon CDT today FOR ILZ027>031-036-037-
040-041-047>051.

&&

$$

UPDATE...Barnes
SHORT TERM...Auten
LONG TERM...Geelhart
AVIATION...Auten







000
FXUS63 KLOT 241511
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1011 AM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 15Z...

* MVFR CIGS/VSBY LIKELY AGAIN LATE TONIGHT. IFR CIGS/VSBY POSSIBLE.

MDB

//DISCUSSION...UPDATED 15Z...

CLOUDS CONTINUE TO ERODE FROM PWK TO DPA TO JOT TO PIA AND POINTS
EAST WITH A LARGE GAP IN COVERAGE HAVING DEVELOPED. EXPANSIVE AREA
OF LIFR AND LOWER CIGS/VSBY REMAINS PERSISTENT TO THE WEST. THE
EASTERN FLANK OF THIS HAS SHOWN SOME VERY SLOW DRIFT TO THE EAST
SO AM A LITTLE CONCERNED THAT CLOUDS COULD FILL IN A BIT AGAIN AT
DPA SO WILL KEEP SCATTERED MENTION THERE BUT THE LONGER IT TAKES
FOR ANY CLOUDS TO ARRIVE THERE THE HIGHER THEY WOULD LIKELY BE
THANKS TO SOME WARMING IN THE MEANTIME. OTHERWISE HAVE FURTHER
SLOWED IMPROVEMENT AT RFD AND MAY STILL BE A BIT FAST...ESPECIALLY
SINCE FAIRLY DENSE CIRRUS IS MOVING IN OVERHEAD. OTHERWISE LIGHT
AND VARIABLE SOUTHWEST TO NORTHWEST WINDS ARE EXPECTED.

MDB

FROM 12Z...

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...HOWEVER...AN AREA OF
STRATUS FILTERED IN BEHIND THE WEAK BOUNDARY. LATEST SATELLITE
IMAGERY INDICATES THAT THE STRATUS IS BREAKING UP OVER NRN IL AND
IN LOCATIONS THAT HAD SEEN SOME PCPN YESTERDAY...MAINLY ARND THE
RFD AREA...SOME PATCHY DENSE FOG HAS FORMED...THOUGH OF THE TAF
SITES...ONLY RFD HAS OBSERVED THE DENSE FOG. BASED ON THE LATEST
HIGH RES MODEL GUIDANCE AND SATELLITE TRENDS...ANTICIPATE THAT
CONDITIONS SHOULD IMPROVE TO VFR OVER THE AREA BY LATE MORNING.

ANOTHER SFC TROUGH WILL TRACK ACROSS THE CNTRL PLAINS TO THE
UPPER MISSISSIPPI VALLEY BY EARLY EVENING. WINDS WILL BECOME SSWLY
THOUGH THE DAY...THOUGH WITH A WEAK PRESSURE GRADIENT...WIND
SPEEDS SHOULD BE LESS THAN 10KT THROUGH THE DAY. FOR THE EARLY
EVENING HOURS...A MODEST MID LEVEL IMPULSE IS EXPECTED TO CROSS
THE AREA INVOF THE WI/IL BORDER. THERE IS A CHANCE THAT THIS
SYSTEM COULD TRIGGER SOME ISOLD/SCT -SHRA...BUT CONFIDENCE IN
TIMING AND COVERAGE IS TOO LOW TO INCLUDE PCPN IN THE TAFS AT THIS
TIME. CONFIDENCE IS A LITTLE HIGHER THAT MORE FOG SHOULD DEVELOP
OVERNIGHT TONIGHT...PER THE LATEST HIGH RES MODEL RH
TIME SECTIONS...SO HAVE INTRODUCED IFR VIS FOR LATE THIS EVENING
AND OVERNIGHT. SOME GUIDANCE IS POINTING TOWARD THE POSSIBILITY OF
VIS DROPPING TO 1/4SM...BUT GIVEN THE AMOUNT OF CLOUD COVER
EXPECTED...DO NOT HAVE HIGH ENOUGH CONFIDENCE TO DROP VIS LOWER
THAN 1SM FOR NOW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 15Z...

* MEDIUM CONFIDENCE IN CIG TRENDS LATE TONIGHT.

* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS LATE TONIGHT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 241409
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
909 AM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS SCATTERING NEXT 1-2 HRS.

* MVFR CIGS/VSBY LIKELY AGAIN LATE TONIGHT. IFR CIGS/VSBY POSSIBLE.

MDB

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

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...HOWEVER...AN AREA OF
STRATUS FILTERED IN BEHIND THE WEAK BOUNDARY. LATEST SATELLITE
IMAGERY INDICATES THAT THE STRATUS IS BREAKING UP OVER NRN IL AND
IN LOCATIONS THAT HAD SEEN SOME PCPN YESTERDAY...MAINLY ARND THE
RFD AREA...SOME PATCHY DENSE FOG HAS FORMED...THOUGH OF THE TAF
SITES...ONLY RFD HAS OBSERVED THE DENSE FOG. BASED ON THE LATEST
HIGH RES MODEL GUIDANCE AND SATELLITE TRENDS...ANTICIPTE THAT
CONDITIONS SHOULD IMPROVE TO VFR OVER THE AREA BY LATE MORNING.

ANOTHER SFC TROUGH WILL TRACK ACROSS THE CNTRL PLAINS TO THE
UPPER MISSISSIPPI VALLEY BY EARLY EVENING. WINDS WILL BECOME SSWLY
THOUGH THE DAY...THOUGH WITH A WEAK PRESSURE GRADIENT...WIND
SPEEDS SHOULD BE LESS THAN 10KT THROUGH THE DAY. FOR THE EARLY
EVENING HOURS...A MODEST MID LEVEL IMPULSE IS EXPECTED TO CROSS
THE AREA INVOF THE WI/IL BORDER. THERE IS A CHANCE THAT THIS
SYSTEM COULD TRIGGER SOME ISOLD/SCT -SHRA...BUT CONFIDENCE IN
TIMING AND COVERAGE IS TOO LOW TO INCLUDE PCPN IN THE TAFS AT THIS
TIME. CONFIDENCE IS A LITTLE HIGHER THAT MORE FOG SHOULD DEVELOP
OVERNIGHT TONIGHT...PER THE LATEST HIGH RES MODEL RH
TIMESECTIONS...SO HAVE INTRODUCED IFR VIS FOR LATE THIS EVENING
AND OVERNIGHT. SOME GUIDANCE IS POINTING TOWARD THE POSSIBILITY OF
VIS DROPPING TO 1/4SM...BUT GIVEN THE AMOUNT OF CLOUD COVER
EXPECTED...DO NOT HAVE HIGH ENOUGH CONFIDENCE TO DROP VIS LOWER
THAN 1SM FOR NOW.

KREIN

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

* HIGH CONFIDENCE IN CIG TRENDS THIS MORNING.

* MEDIUM CONFIDENCE IN CIG TRENDS LATE TONIGHT.

* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS LATE TONIGHT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 241409
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
909 AM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS SCATTERING NEXT 1-2 HRS.

* MVFR CIGS/VSBY LIKELY AGAIN LATE TONIGHT. IFR CIGS/VSBY POSSIBLE.

MDB

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

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...HOWEVER...AN AREA OF
STRATUS FILTERED IN BEHIND THE WEAK BOUNDARY. LATEST SATELLITE
IMAGERY INDICATES THAT THE STRATUS IS BREAKING UP OVER NRN IL AND
IN LOCATIONS THAT HAD SEEN SOME PCPN YESTERDAY...MAINLY ARND THE
RFD AREA...SOME PATCHY DENSE FOG HAS FORMED...THOUGH OF THE TAF
SITES...ONLY RFD HAS OBSERVED THE DENSE FOG. BASED ON THE LATEST
HIGH RES MODEL GUIDANCE AND SATELLITE TRENDS...ANTICIPTE THAT
CONDITIONS SHOULD IMPROVE TO VFR OVER THE AREA BY LATE MORNING.

ANOTHER SFC TROUGH WILL TRACK ACROSS THE CNTRL PLAINS TO THE
UPPER MISSISSIPPI VALLEY BY EARLY EVENING. WINDS WILL BECOME SSWLY
THOUGH THE DAY...THOUGH WITH A WEAK PRESSURE GRADIENT...WIND
SPEEDS SHOULD BE LESS THAN 10KT THROUGH THE DAY. FOR THE EARLY
EVENING HOURS...A MODEST MID LEVEL IMPULSE IS EXPECTED TO CROSS
THE AREA INVOF THE WI/IL BORDER. THERE IS A CHANCE THAT THIS
SYSTEM COULD TRIGGER SOME ISOLD/SCT -SHRA...BUT CONFIDENCE IN
TIMING AND COVERAGE IS TOO LOW TO INCLUDE PCPN IN THE TAFS AT THIS
TIME. CONFIDENCE IS A LITTLE HIGHER THAT MORE FOG SHOULD DEVELOP
OVERNIGHT TONIGHT...PER THE LATEST HIGH RES MODEL RH
TIMESECTIONS...SO HAVE INTRODUCED IFR VIS FOR LATE THIS EVENING
AND OVERNIGHT. SOME GUIDANCE IS POINTING TOWARD THE POSSIBILITY OF
VIS DROPPING TO 1/4SM...BUT GIVEN THE AMOUNT OF CLOUD COVER
EXPECTED...DO NOT HAVE HIGH ENOUGH CONFIDENCE TO DROP VIS LOWER
THAN 1SM FOR NOW.

KREIN

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

* HIGH CONFIDENCE IN CIG TRENDS THIS MORNING.

* MEDIUM CONFIDENCE IN CIG TRENDS LATE TONIGHT.

* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS LATE TONIGHT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

MDB

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 241159
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
659 AM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS POSSIBLE THROUGH LATE MORNING.

* MVFR CIGS/VIS LIKELY AGAIN LATE TONIGHT. IFR CIGS/VIS POSSIBLE.

KREIN

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

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...HOWEVER...AN AREA OF
STRATUS FILTERED IN BEHIND THE WEAK BOUNDARY. LATEST SATELLITE
IMAGERY INDICATES THAT THE STRATUS IS BREAKING UP OVER NRN IL AND
IN LOCATIONS THAT HAD SEEN SOME PCPN YESTERDAY...MAINLY ARND THE
RFD AREA...SOME PATCHY DENSE FOG HAS FORMED...THOUGH OF THE TAF
SITES...ONLY RFD HAS OBSERVED THE DENSE FOG. BASED ON THE LATEST
HIGH RES MODEL GUIDANCE AND SATELLITE TRENDS...ANTICIPTE THAT
CONDITIONS SHOULD IMPROVE TO VFR OVER THE AREA BY LATE MORNING.

ANOTHER SFC TROUGH WILL TRACK ACROSS THE CNTRL PLAINS TO THE
UPPER MISSISSIPPI VALLEY BY EARLY EVENING. WINDS WILL BECOME SSWLY
THOUGH THE DAY...THOUGH WITH A WEAK PRESSURE GRADIENT...WIND
SPEEDS SHOULD BE LESS THAN 10KT THROUGH THE DAY. FOR THE EARLY
EVENING HOURS...A MODEST MID LEVEL IMPULSE IS EXPECTED TO CROSS
THE AREA INVOF THE WI/IL BORDER. THERE IS A CHANCE THAT THIS
SYSTEM COULD TRIGGER SOME ISOLD/SCT -SHRA...BUT CONFIDENCE IN
TIMING AND COVERAGE IS TOO LOW TO INCLUDE PCPN IN THE TAFS AT THIS
TIME. CONFIDENCE IS A LITTLE HIGHER THAT MORE FOG SHOULD DEVELOP
OVERNIGHT TONIGHT...PER THE LATEST HIGH RES MODEL RH
TIMESECTIONS...SO HAVE INTRODUCED IFR VIS FOR LATE THIS EVENING
AND OVERNIGHT. SOME GUIDANCE IS POINTING TOWARD THE POSSIBILITY OF
VIS DROPPING TO 1/4SM...BUT GIVEN THE AMOUNT OF CLOUD COVER
EXPECTED...DO NOT HAVE HIGH ENOUGH CONFIDENCE TO DROP VIS LOWER
THAN 1SM FOR NOW.

KREIN


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

* MEDIUM TO HIGH CONFIDENCE IN CIG TRENDS THIS MORNING.

* MEDIUM CONFIDENCE IN CIG TRENDS LATE TONIGHT.

* LOW TO MEDIUM CONFIDENCE IN VIS TRENDS LATE TONIGHT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KREIN

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

SATURDAY NIGHT...VFR. WX NIL.

SUNDAY...VFR. WX NIL.

MONDAY...VFR. WX NIL.

MONDAY NIGHT AND TUESDAY...CHANCE SHRA/SLIGHT CHANCE TSRA.

TUESDAY NIGHT...SLIGHT CHANCE SHRA.

WEDNESDAY AND THURSDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KILX 241144
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
644 AM CDT Fri Oct 24 2014

.SHORT TERM...(Today)
ISSUED AT 235 AM CDT FRI OCT 24 2014

A weak short wave continues to move through the eastern parts of the
CWA this morning, but this should be out of the state by time the
new forecast is issued, or shortly after. The main concern this
morning is the development and advection of stratus clouds and fog
early this morning. Dense fog is present across most of eastern Iowa
this morning and the HRRR model advects this into the area for this
morning. This will keep lots of clouds in the area for this morning,
and could affect max temps for this afternoon, depending on how
quickly the clouds dissipate. Models have it diminishing during
the late morning hours. And with winds becoming southerly by
afternoon, believe some dissipation of the clouds will happen. So
will have less clouds during the afternoon. However, afternoon
high temps may not be as high as first forecast, so have decreased
max temps 1-2 degrees from previous forecast. MAV guidance is
higher than MET by several degrees, so took a compromise between
the two due to cloud cover issues.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 235 AM CDT FRI OCT 24 2014

Main forecast issue this weekend and into Monday involves
temperatures. Latest model runs for Saturday have been warmer, as
main core of cooler air associated with a frontal boundary track
more across the Great Lakes region. Have bumped up Saturday highs by
a couple degrees. 850 mb warm front progged to lift through the area
late Saturday night and early Sunday, with +16C temperatures
spreading across central Illinois Sunday afternoon, lingering into
Monday. Have also raised highs several degrees both Sunday and
Monday, with a few 80 degree readings possible on Monday across
southwest and southeast portions of the forecast area. Record highs
for Monday are in the mid 80s and currently appear safe.

Split upper flow early next week focuses the deeper part of the next
wave along the northern stream. Model guidance is fairly uniform
with rain chances Monday night through about midday Tuesday, and
pretty much has the forecast area dry by sunset as a high pressure
ridge quickly builds into the mid-Mississippi Valley. However, the
guidance diverges later in the week. The ECMWF persists in a rather
broad trough along the Mississippi River midday Thursday, but now
significantly ramps up rain chances along the associated surface
front. The GFS has a weaker, more progressive wave with little
precipitation. Have leaned more toward the progressive solution for
now. The ECMWF also persists in developing a large closed low over
the Great Lakes late week, which would pump significantly cooler air
into Illinois. Meanwhile, the GFS builds a ridge eastward, with much
warmer air (850 mb temperatures range from -5C to +8C between the
two models). However, this particular aspect is just beyond the
current forecast range, but will need to be addressed with the
afternoon forecast issuance.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 644 AM CDT FRI OCT 24 2014

Complicated forecast for the first 6hrs with some of the TAFs this
morning. An area of stratus and very low vis is slowly moving east
into the area and is already effecting SPI, and should effect PIA
in next couple of hours. Question is how far east will this area
of IFR/LIFR conditions get...will it effect BMI/DEC and CMI.
Believe it will effect DEC and BMI some, but not as much as SPI
and PIA. Conditions should improve this morning, around 16z at PIA
and SPI, but still remain lower MVFR for the rest of the morning.
HRRR model brings some of the lower cigs into BMI and DEC, but not
as long. So going to be a little bit more optimistic at these
sites this morning and just have IFR cigs for this morning at DEC
and lower MVFR at BMI. CMI will have just a TEMPO group for cigs
around 1kft this morning. Conditions should be VFR this afternoon,
but models bring more MVFR cigs back into the area this evening
and continue into the overnight hours. Winds will be light and
variable this morning, but then become more south-southwest for
the rest of the TAF period. Speeds this afternoon will be around
5-10kts.

&&

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

$$

SHORT TERM...Auten
LONG TERM...Geelhart
AVIATION...Auten







000
FXUS63 KLOT 240903
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
403 AM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS DURG THE EARLY MORNING HOURS. CHANCE CIGS MAY SCT AND
  VIS MAY DROP TO MVFR LEVELS.

KREIN

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

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...ANY RESIDUAL PCPN
REMAINS ISOLD AND SOUTH OF THE TERMINALS. HOWEVER...THERE IS SOLE
RESIDUAL LOW LEVEL MOISTURE AND AS HIGH CLOUD PUSHES AWAY...A BAND
OF STRATUS CAN BE SEEN IN THE LATEST SATELLITE IMAGERY. AS A
NOCTURNAL SUBSIDENCE INVERSION LOWERS OVERNIGHT...CLOUD BASES
SHOULD GRADUALLY LOWER TO LOWER END MVFR LEVELS. THERE IS A CHANCE
FOR SOME PATCHY IFR CIGS DURG THE EARLY MORNING HOURS...ESPECIALLY
OVER NWRN IL WHERE SOME RAIN FELL EARLIER...WHICH WOULD MOST
LIKELY AFFECT RFD AND POSSIBLY DPA. AS WINDS BECM LGT/VRBL
OVERNIGHT...VIS SHOULD DROP TO 3-5SM DURG THE EARLY MORNING
HOURS...AND IF THE WESTERN EDGE OF THE STRATUS DECK CAN ERODE OVER
NWRN IL BEFORE SUNRISE...THERE IS A CHANCE FOR RFD TO DROP INTO
IFR OR EVEN LIFR VIS LEVELS. HOWEVER...THAT WOULD BE HIGHLY
DEPENDENT ON THE CIG TRENDS.

THROUGH THE DAY ON FRIDAY...ANOTHER SFC TROUGH WILL TRACK ACROSS
THE CNTRL PLAINS TO THE UPPER MISSISSIPPI VALLEY BY EARLY EVENING.
WINDS WILL BECOME SSWLY THOUGH THE DAY...THOUGH WITH A WEAK
PRESSURE GRADIENT...WIND SPEEDS SHOULD BE LESS THAN 10KT THROUGH
THE DAY. FOR THE EARLY EVENING HOURS...SOME OF THE MODELS ARE
SUGGESTING THAT THERE COULD BE SOME LIGHT PCPN WITH THE PASSAGE OF
THE NEXT SFC TROUGH. HOWEVER...SINCE FORCING WITH THIS TROUGH AXIS
LOOKS TO BE RATHER WEAK...CONFIDENCE IS TOO LOW TO ADD PCPN TO THE
TAFS AT THIS TIME.

KREIN

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

* MEDIUM CONFIDENCE IN CIG/VIS TRENDS OVERNIGHT.

* LOW CONFIDENCE IN SPECIFIC TIMING OF IMPROVEMENT TO VFR FRIDAY.

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE DAY ON
  FRIDAY.

* LOW CONFIDENCE IN THE CHANCES FOR PCPN FRIDAY EVENING.

KREIN

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 240827
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
327 AM CDT FRI OCT 24 2014

.DISCUSSION...
326 AM CDT

SHORT TERM...THROUGH FRIDAY NIGHT...
FOR THE REMAINDER OF THE NIGHT AND INTO FRIDAY MORNING...THE INITIAL
CONCERN WILL BE CLOUD COVER...AND IMPACTS ON VISIBILITY.  FOLLOWING
THE PASSAGE OF A WEAK SFC TROUGH/PACIFIC-SOURCED WEAK COLD
FRONT...WEAK HIGH PRESSURE HAS BUILT ACROSS THE REGION.  A LOW
STRATUS DECK HAS BEEN IN PLACE FOLLOWING THE FROPA...BUT THE STRATUS
DECK IS ERODING IN PLACES...AND WITH CALM TO LGT/VRBL WINDS IN
PLACE...THE CLEARING LOCATIONS ARE EXPERIENCING RAPID FOG
DEVELOPMENT.  THE FOG IS INITIALLY MOSTLY IMPACTING NWRN IL...ARND
THE ROCKFORD AREA...BUT AS THE STRATUS CONTINUES TO
DISSIPATE...ADDITIONAL FOG MAY DEVELOP...BUT ANY DENSE FOG SHOULD BE
LIMITED TO NORTH CENTRAL AND NWRN IL...AWAY FROM THE CHICAGO METRO
AREA.  EXCEPT FOR LOCATIONS THAT CLEAR OUT...TEMPERATURES SHOULD
GENERALLY BOTTOM OUT IN THE LOWER TO MIDDLE 50S...EXCEPT FOR SOME
ISOLATED...SHELTERED LOW LYING AREAS...WHICH COULD RADIATE DOWN INTO
THE UPPER 40S.

FOR THE REMAINDER OF FRIDAY...THE WARMING TREND SHOULD CONTINUE AS
UPPER RIDGING CONTINUES TO BUILD OUT OF THE ROCKIES AND INTO THE
WESTERN PLAINS.  THE MORNING STRATUS AND STRATOCU SHOULD DISSIPATE
THROUGH THE MORNING HOURS...BUT TOTAL SUNSHINE WILL BE LIMITED AS A
THICK CIRRUS LAYER AND SOME MID LEVEL CLOUDINESS WILL OVERSPREAD THE
REGION THROUGH THIS AFTERNOON AND EVENING AS A STRONG UPPER LEVEL
JET STREAM DIVES OVER THE UPPER MISSISSIPPI VALLEY AND INTO THE
MIDWEST. THE SHORT RANGE GUIDANCE IS ALSO INDICATING SOME SHORTWAVE
ENERGY OVERTOPPING THE RIDGE THIS EVENING...WITH SOME GUIDANCE
INDICATING A LITTLE QPF.  HAVE A HARD TIME INTRODUCING ANY
MENTIONABLE POPS WITH THIS SYSTEM AS MOISTURE PROFILE FORECASTS ALSO
INDICATE LITTLE DEEP LAYER MOISTURE.  HOWEVER...SOME OF THE HIGH RES
SHORT TERM GUIDANCE IS SHOWING SOME INCREASE RH LATE FRIDAY NIGHT
UNDER INCREASINGLY SWLY FLOW...BUT AS FLOW OFF OF THE GULF OF MEXICO
WILL BE LIMITED BY HIGH PRESSURE RIDGING EXTENDING FROM THE CNTRL
APPALACHIANS THROUGH ERN TX...FEEL THAT THIS INCREASED RH COULD BE
MORE INDICATIVE OF SOME FOG POTENTIAL RATHER THAN PCPN POTENTIAL.
AS FOR TEMPERATURES...UNDER INCREASING LOW LEVEL WARM ADVECTION AND
BUILDING HEIGHTS ALOFT...EXPECT THAT TEMPERATURES FOR FRIDAY WILL
LIKELY BE AROUND 5 DEGREES HIGHER THAN THURSDAY WITH HIGHS IN THE
MIDDLE 60S. FRIDAY NIGHT SHOULD REMAIN MILD WITH DEWPOINTS
INCREASING INTO LOWER TO MIDDLE 50S THROUGH FRIDAY AND INTO FRIDAY
EVENING...SO OVERNIGHT LOWS SATURDAY MORNING SHOULD BE UNSEASONABLY
MILD...AND ONLY DROP INTO THE LOWER TO MIDDLE 50S.

KREIN

SATURDAY THROUGH MONDAY...
500MB TROUGH AXIS WILL BE PIVOTING EAST ACROSS THE GREAT LAKES
REGION...WITH A TRAILING FRONTAL BOUNDARY STRETCHING SOUTH AND
EXPECTED TO PUSH EAST ACROSS THE FORECAST AREA SATURDAY MORNING.
MID-LVL HEIGHTS WILL STEADILY RISE AS THE RIDGE PARKED ACROSS THE
CENTRAL CONUS PUSHES EAST...BRINGING MILDER AIR TO THE REGION SAT
WITH HIGHS IN THE MID/UPR 60S. THE FAR SOUTHERN CWFA COULD TOUCH 70
DEG SAT. TEMPS SUN ARE EXPECTED TO BE SLIGHTLY COOLER AS THE FLOW
BEGINS TO TRANSITION BRIEFLY INTO A QUASI-ZONAL SETUP. HOWEVER THIS
DOES NOT LOOK TO REMAIN VERY LONG...AS RIDGING RETURNS FOR MON AND
TEMPS SHUD QUICKLY WARM INTO THE 70S ACROSS MUCH OF THE AREA. A WARM
FRONTAL BOUNDARY WILL LIFT ACROSS THE AREA EARLY MON...AS SOUTHERLY
FLOW STRENGTHENS. EXPECT MUCH OF THE DAY MON TO REMAIN DRY...HOWEVER
LATE AFTN/EVE A DEVELOPING LOW ACROSS THE CENTRAL PLAINS MAY HELP TO
GENERATE A FEW SHOWERS/THUNDERSTORMS LATE MON.

TUESDAY-WEDNESDAY...
TOWARDS THE MIDDLE OF NEXT WEEK ENSEMBLES CONTINUE TO SUGGEST THE
RIDGING OVERHEAD WILL SHIFT EAST...WITH FLOW TRYING TO FLATTEN.
SUGGESTING THAT A SEMI-ZONAL SETUP MAY DEVELOP BY WED...WHICH WILL
LIKELY RESULT IN PERIODIC CHANCES FOR SHOWERS. TEMPS SHUD RETURN TO
MORE SEASONAL CONDS TUE/WED.

BEACHLER

&&

.AVIATION...

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

* MVFR CIGS/VIS DURG THE LATE NIGHT/EARLY MORNING HOURS. CHANCE
  CIGS COULD DROP TO IFR LEVELS.

KREIN

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

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...ANY RESIDUAL PCPN
REMAINS ISOLD AND SOUTH OF THE TERMINALS. HOWEVER...THERE IS SOLE
RESIDUAL LOW LEVEL MOISTURE AND AS HIGH CLOUD PUSHES AWAY...A BAND
OF STRATUS CAN BE SEEN IN THE LATEST SATELLITE IMAGERY. AS A
NOCTURNAL SUBSIDENCE INVERSION LOWERS OVERNIGHT...CLOUD BASES
SHOULD GRADUALLY LOWER TO LOWER END MVFR LEVELS. THERE IS A CHANCE
FOR SOME PATCHY IFR CIGS DURG THE EARLY MORNING HOURS...ESPECIALLY
OVER NWRN IL WHERE SOME RAIN FELL EARLIER...WHICH WOULD MOST
LIKELY AFFECT RFD AND POSSIBLY DPA. AS WINDS BECM LGT/VRBL
OVERNIGHT...VIS SHOULD DROP TO 3-5SM DURG THE EARLY MORNING
HOURS...AND IF THE WESTERN EDGE OF THE STRATUS DECK CAN ERODE OVER
NWRN IL BEFORE SUNRISE...THERE IS A CHANCE FOR RFD TO DROP INTO
IFR OR EVEN LIFR VIS LEVELS. HOWEVER...THAT WOULD BE HIGHLY
DEPENDENT ON THE CIG TRENDS.

THROUGH THE DAY ON FRIDAY...ANOTHER SFC TROUGH WILL TRACK ACROSS
THE CNTRL PLAINS TO THE UPPER MISSISSIPPI VALLEY BY EARLY EVENING.
WINDS WILL BECOME SSWLY THOUGH THE DAY...THOUGH WITH A WEAK
PRESSURE GRADIENT...WIND SPEEDS SHOULD BE LESS THAN 10KT THROUGH
THE DAY. FOR THE EARLY EVENING HOURS...SOME OF THE MODELS ARE
SUGGESTING THAT THERE COULD BE SOME LIGHT PCPN WITH THE PASSAGE OF
THE NEXT SFC TROUGH. HOWEVER...SINCE FORCING WITH THIS TROUGH AXIS
LOOKS TO BE RATHER WEAK...CONFIDENCE IS TOO LOW TO ADD PCPN TO THE
TAFS AT THIS TIME.

KREIN

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

* MEDIUM CONFIDENCE IN CIG/VIS TRENDS OVERNIGHT.

* LOW CONFIDENCE IN SPECIFIC TIMING OF IMPROVEMENT TO VFR FRIDAY.

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE DAY ON
  FRIDAY.

* LOW CONFIDENCE IN THE CHANCES FOR PCPN FRIDAY EVENING.

KREIN

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KILX 240736
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
236 AM CDT Fri Oct 24 2014

.SHORT TERM...(Today)
ISSUED AT 235 AM CDT FRI OCT 24 2014

A weak short wave continues to move through the eastern parts of the
CWA this morning, but this should be out of the state by time the
new forecast is issued, or shortly after. The main concern this
morning is the development and advection of stratus clouds and fog
early this morning. Dense fog is present across most of eastern Iowa
this morning and the HRRR model advects this into the area for this
morning. This will keep lots of clouds in the area for this morning,
and could affect max temps for this afternoon, depending on how
quickly the clouds dissipate. Models have it diminishing during
the late morning hours. And with winds becoming southerly by
afternoon, believe some dissipation of the clouds will happen. So
will have less clouds during the afternoon. However, afternoon
high temps may not be as high as first forecast, so have decreased
max temps 1-2 degrees from previous forecast. MAV guidance is
higher than MET by several degrees, so took a compromise between
the two due to cloud cover issues.


&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 235 AM CDT FRI OCT 24 2014

Main forecast issue this weekend and into Monday involves
temperatures. Latest model runs for Saturday have been warmer, as
main core of cooler air associated with a frontal boundary track
more across the Great Lakes region. Have bumped up Saturday highs by
a couple degrees. 850 mb warm front progged to lift through the area
late Saturday night and early Sunday, with +16C temperatures
spreading across central Illinois Sunday afternoon, lingering into
Monday. Have also raised highs several degrees both Sunday and
Monday, with a few 80 degree readings possible on Monday across
southwest and southeast portions of the forecast area. Record highs
for Monday are in the mid 80s and currently appear safe.

Split upper flow early next week focuses the deeper part of the next
wave along the northern stream. Model guidance is fairly uniform
with rain chances Monday night through about midday Tuesday, and
pretty much has the forecast area dry by sunset as a high pressure
ridge quickly builds into the mid-Mississippi Valley. However, the
guidance diverges later in the week. The ECMWF persists in a rather
broad trough along the Mississippi River midday Thursday, but now
significantly ramps up rain chances along the associated surface
front. The GFS has a weaker, more progressive wave with little
precipitation. Have leaned more toward the progressive solution for
now. The ECMWF also persists in developing a large closed low over
the Great Lakes late week, which would pump significantly cooler air
into Illinois. Meanwhile, the GFS builds a ridge eastward, with much
warmer air (850 mb temperatures range from -5C to +8C between the
two models). However, this particular aspect is just beyond the
current forecast range, but will need to be addressed with the
afternoon forecast issuance.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1141 PM CDT THU OCT 23 2014

A trailing shortwave feature will produce a few additional
showers over east central IL until 9-12Z, but otherwise mid- and
upper-level clearing overnight will allow areas of fog and low
cloud to continue, especially west of the Illinois River.
Potential IFR or worse vsby/cigs expected, however potential for
dense fog is mainly west of central IL TAF sites. Daytime heating
expected to dissipate fog around 15Z Friday leaving cloud cover
SCT-BKN025 through afternoon. Another weak disturbance will bring
additional potential for MVFR ceilings after 00Z Saturday.


&&

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

$$

SHORT TERM...Auten
LONG TERM...Geelhart
AVIATION...Onton







000
FXUS63 KLOT 240730
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
230 AM CDT FRI OCT 24 2014

.DISCUSSION...
903 PM CDT

THE CHANGES TO THE FORECAST WERE TO DISSIPATE POPS AT A QUICKER
RATE...HOLD ONTO MORE CLOUD COVER THROUGH THE NIGHT...AND ADD
DENSE MENTION TO THE FOG WORDING OVER NORTH CENTRAL ILLINOIS.

THE SURFACE TROUGH THAT HAD BEEN APPROACHING STEADILY TOWARD THE
AREA THE PAST 24 HOURS HAS DIMINISHED GREATLY SINCE MID-
AFTERNOON...LOSING MUCH OF ITS LOW-LEVEL CONVERGENCE. FORCING FOR
RAIN SHOWERS HAS ALSO BEEN DIMINISHING WITH MORE LIMITED MOISTURE
CONVERGENCE WITHIN THE AREA OF ASCENT...SO SHOWERS HAVE QUICKLY
BEEN WANING. THE SPOTTY LIGHT SHOWERS SURVIVING SHOULD CONTINUE
SLOWLY EAST WITH A GRADUAL FADE INTO OVERNIGHT.

WITH THE HIGHER DEW POINT PLUME OF UPPER 40S TO LOWER 50S BROUGHT
UP TO EASTERN IA AND NORTHWEST/NORTH CENTRAL IL BY THE
TROUGH...CONDITIONS ARE IN PLACE FOR FOG. ONE THING AGAINST FOG
DEVELOPMENT IS EXISTING CLOUDS WHICH AS SEEN ON THE 00Z DVN RAOB
ARE FAIRLY DEEP /SEVERAL THOUSAND FEET SATURATED LAYER/. THIS AREA
LOOKS TO SLOW ITS MOVEMENT EAST OVER THE CWA THUS NOT ALLOWING
MUCH CLEARING FOR NORTHEAST IL AND NORTHWEST IN...INCLUDING
CHICAGO. MORE PROBLEMATIC WILL BE POSSIBLY SOME CLEARING OF THIS
CLOUD LAYER IN NORTH CENTRAL IL LATE ALLOWING FOR NEARBY VERY LOW
STRATUS AND SOME FOG ALREADY BEING OBSERVED TO JUST EXPAND IN AND
WORSEN THROUGH DAYBREAK. FORECAST SOUNDINGS AND HIGH-RES GUIDANCE
FIELDS HAVE TRENDED THIS ROUTE IN THE GENERAL ROCKFORD AND DIXON
AREAS. HAVE BUMPED UP FOG WORDING THERE AND COULD SEE A DENSE FOG
ADVISORY BEING NEEDED DEPENDING ON HOW AGGRESSIVE THE LOWERING IS.
AGAIN FURTHER EASTWARD TOWARD CHICAGO EXPECT THE CLOUDS TO LIMIT
ANY FOG THAT GRADUALLY DEVELOPS FROM GETTING TOO BAD.

HAVE BUMPED UP MINS A DEGREE OR TWO WARMER WITH THE CLOUDS
EXPECTED TO HANG ON A GOOD PART OF THE NIGHT IN MOST PLACES.

MTF

//PREV DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* MVFR CIGS/VIS DURG THE LATE NIGHT/EARLY MORNING HOURS. CHANCE
  CIGS COULD DROP TO IFR LEVELS.

KREIN

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

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...ANY RESIDUAL PCPN
REMAINS ISOLD AND SOUTH OF THE TERMINALS. HOWEVER...THERE IS SOLE
RESIDUAL LOW LEVEL MOISTURE AND AS HIGH CLOUD PUSHES AWAY...A BAND
OF STRATUS CAN BE SEEN IN THE LATEST SATELLITE IMAGERY. AS A
NOCTURNAL SUBSIDENCE INVERSION LOWERS OVERNIGHT...CLOUD BASES
SHOULD GRADUALLY LOWER TO LOWER END MVFR LEVELS. THERE IS A CHANCE
FOR SOME PATCHY IFR CIGS DURG THE EARLY MORNING HOURS...ESPECIALLY
OVER NWRN IL WHERE SOME RAIN FELL EARLIER...WHICH WOULD MOST
LIKELY AFFECT RFD AND POSSIBLY DPA. AS WINDS BECM LGT/VRBL
OVERNIGHT...VIS SHOULD DROP TO 3-5SM DURG THE EARLY MORNING
HOURS...AND IF THE WESTERN EDGE OF THE STRATUS DECK CAN ERODE OVER
NWRN IL BEFORE SUNRISE...THERE IS A CHANCE FOR RFD TO DROP INTO
IFR OR EVEN LIFR VIS LEVELS. HOWEVER...THAT WOULD BE HIGHLY
DEPENDENT ON THE CIG TRENDS.

THROUGH THE DAY ON FRIDAY...ANOTHER SFC TROUGH WILL TRACK ACROSS
THE CNTRL PLAINS TO THE UPPER MISSISSIPPI VALLEY BY EARLY EVENING.
WINDS WILL BECOME SSWLY THOUGH THE DAY...THOUGH WITH A WEAK
PRESSURE GRADIENT...WIND SPEEDS SHOULD BE LESS THAN 10KT THROUGH
THE DAY. FOR THE EARLY EVENING HOURS...SOME OF THE MODELS ARE
SUGGESTING THAT THERE COULD BE SOME LIGHT PCPN WITH THE PASSAGE OF
THE NEXT SFC TROUGH. HOWEVER...SINCE FORCING WITH THIS TROUGH AXIS
LOOKS TO BE RATHER WEAK...CONFIDENCE IS TOO LOW TO ADD PCPN TO THE
TAFS AT THIS TIME.

KREIN

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

* MEDIUM CONFIDENCE IN CIG/VIS TRENDS OVERNIGHT.

* LOW CONFIDENCE IN SPECIFIC TIMING OF IMPROVEMENT TO VFR FRIDAY.

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE DAY ON
  FRIDAY.

* LOW CONFIDENCE IN THE CHANCES FOR PCPN FRIDAY EVENING.

KREIN

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
215 AM CDT

A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM WESTERN QUEBEC
SOUTHWEST THROUGH THE CENTRAL GREAT LAKES...INTO THE TENNESSEE
VALLEY. THIS RIDGE WILL CONTINUE TO DRIFT EAST OF THE REGION THIS
AFTERNOON...MEANWHILE A TROUGH OF LOW PRESSURE OVER CENTRAL CANADA
CONTINUES TO SLIDE EAST TOWARDS HUDSON BAY SATURDAY. THE GRADIENT
WILL REMAIN LIGHT THROUGH THIS AFTERNOON...THEN SLOWLY TURN
SOUTH/SOUTHWESTERLY. AS THE LOW NEARS HUDSON BAY ON SATURDAY...A
FRONTAL BOUNDARY WILL TRAIL AND SLOWLY SLIDE SOUTH ACROSS LAKE
MICHIGAN. THIS WILL RESULT IN WINDS TURNING WEST/NORTHWEST
SATURDAY AFTERNOON/EVENING. COOLER AIR WILL FLOW ACROSS THE LAKE
ALONG WITH A TIGHTENING GRADIENT...RESULTING IN INCREASING WINDS
NEARING 30KT AT TIMES. THEN ANOTHER RIDGE OF HIGH PRESSURE WILL
QUICKLY SLIDE SOUTHEAST FROM THE UPPER MIDWEST/NORTHERN PLAINS
SUNDAY...STEADILY DIMINISHING THE GRADIENT. ANOTHER TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP EARLY NEXT WEEK ACROSS THE CENTRAL
PLAINS...THEN APPROACH LAKE MICHIGAN CLOSER TO MID-WEEK. THIS WILL
BRING WINDS BACK TO THE SOUTHWEST WITH OCCASIONALLY WINDS GUSTING
TO 30KT.

BEACHLER

&&

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

$$

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

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






000
FXUS63 KLOT 240549
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1249 AM CDT FRI OCT 24 2014

.DISCUSSION...
903 PM CDT

THE CHANGES TO THE FORECAST WERE TO DISSIPATE POPS AT A QUICKER
RATE...HOLD ONTO MORE CLOUD COVER THROUGH THE NIGHT...AND ADD
DENSE MENTION TO THE FOG WORDING OVER NORTH CENTRAL ILLINOIS.

THE SURFACE TROUGH THAT HAD BEEN APPROACHING STEADILY TOWARD THE
AREA THE PAST 24 HOURS HAS DIMINISHED GREATLY SINCE MID-
AFTERNOON...LOSING MUCH OF ITS LOW-LEVEL CONVERGENCE. FORCING FOR
RAIN SHOWERS HAS ALSO BEEN DIMINISHING WITH MORE LIMITED MOISTURE
CONVERGENCE WITHIN THE AREA OF ASCENT...SO SHOWERS HAVE QUICKLY
BEEN WANING. THE SPOTTY LIGHT SHOWERS SURVIVING SHOULD CONTINUE
SLOWLY EAST WITH A GRADUAL FADE INTO OVERNIGHT.

WITH THE HIGHER DEW POINT PLUME OF UPPER 40S TO LOWER 50S BROUGHT
UP TO EASTERN IA AND NORTHWEST/NORTH CENTRAL IL BY THE
TROUGH...CONDITIONS ARE IN PLACE FOR FOG. ONE THING AGAINST FOG
DEVELOPMENT IS EXISTING CLOUDS WHICH AS SEEN ON THE 00Z DVN RAOB
ARE FAIRLY DEEP /SEVERAL THOUSAND FEET SATURATED LAYER/. THIS AREA
LOOKS TO SLOW ITS MOVEMENT EAST OVER THE CWA THUS NOT ALLOWING
MUCH CLEARING FOR NORTHEAST IL AND NORTHWEST IN...INCLUDING
CHICAGO. MORE PROBLEMATIC WILL BE POSSIBLY SOME CLEARING OF THIS
CLOUD LAYER IN NORTH CENTRAL IL LATE ALLOWING FOR NEARBY VERY LOW
STRATUS AND SOME FOG ALREADY BEING OBSERVED TO JUST EXPAND IN AND
WORSEN THROUGH DAYBREAK. FORECAST SOUNDINGS AND HIGH-RES GUIDANCE
FIELDS HAVE TRENDED THIS ROUTE IN THE GENERAL ROCKFORD AND DIXON
AREAS. HAVE BUMPED UP FOG WORDING THERE AND COULD SEE A DENSE FOG
ADVISORY BEING NEEDED DEPENDING ON HOW AGGRESSIVE THE LOWERING IS.
AGAIN FURTHER EASTWARD TOWARD CHICAGO EXPECT THE CLOUDS TO LIMIT
ANY FOG THAT GRADUALLY DEVELOPS FROM GETTING TOO BAD.

HAVE BUMPED UP MINS A DEGREE OR TWO WARMER WITH THE CLOUDS
EXPECTED TO HANG ON A GOOD PART OF THE NIGHT IN MOST PLACES.

MTF

//PREV DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* MVFR CIGS/VIS DURG THE LATE NIGHT/EARLY MORNING HOURS. CHANCE
  CIGS COULD DROP TO IFR LEVELS.

KREIN

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

FOLLOWING THE PASSAGE OF A WEAK SFC TROUGH...ANY RESIDUAL PCPN
REMAINS ISOLD AND SOUTH OF THE TERMINALS. HOWEVER...THERE IS SOLE
RESIDUAL LOW LEVEL MOISTURE AND AS HIGH CLOUD PUSHES AWAY...A BAND
OF STRATUS CAN BE SEEN IN THE LATEST SATELLITE IMAGERY. AS A
NOCTURNAL SUBSIDENCE INVERSION LOWERS OVERNIGHT...CLOUD BASES
SHOULD GRADUALLY LOWER TO LOWER END MVFR LEVELS. THERE IS A CHANCE
FOR SOME PATCHY IFR CIGS DURG THE EARLY MORNING HOURS...ESPECIALLY
OVER NWRN IL WHERE SOME RAIN FELL EARLIER...WHICH WOULD MOST
LIKELY AFFECT RFD AND POSSIBLY DPA. AS WINDS BECM LGT/VRBL
OVERNIGHT...VIS SHOULD DROP TO 3-5SM DURG THE EARLY MORNING
HOURS...AND IF THE WESTERN EDGE OF THE STRATUS DECK CAN ERODE OVER
NWRN IL BEFORE SUNRISE...THERE IS A CHANCE FOR RFD TO DROP INTO
IFR OR EVEN LIFR VIS LEVELS. HOWEVER...THAT WOULD BE HIGHLY
DEPENDENT ON THE CIG TRENDS.

THROUGH THE DAY ON FRIDAY...ANOTHER SFC TROUGH WILL TRACK ACROSS
THE CNTRL PLAINS TO THE UPPER MISSISSIPPI VALLEY BY EARLY EVENING.
WINDS WILL BECOME SSWLY THOUGH THE DAY...THOUGH WITH A WEAK
PRESSURE GRADIENT...WIND SPEEDS SHOULD BE LESS THAN 10KT THROUGH
THE DAY. FOR THE EARLY EVENING HOURS...SOME OF THE MODELS ARE
SUGGESTING THAT THERE COULD BE SOME LIGHT PCPN WITH THE PASSAGE OF
THE NEXT SFC TROUGH. HOWEVER...SINCE FORCING WITH THIS TROUGH AXIS
LOOKS TO BE RATHER WEAK...CONFIDENCE IS TOO LOW TO ADD PCPN TO THE
TAFS AT THIS TIME.

KREIN

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

* MEDIUM CONFIDENCE IN CIG/VIS TRENDS OVERNIGHT.

* LOW CONFIDENCE IN SPECIFIC TIMING OF IMPROVEMENT TO VFR FRIDAY.

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE DAY ON
  FRIDAY.

* LOW CONFIDENCE IN THE CHANCES FOR PCPN FRIDAY EVENING.

KREIN

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 240441
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1141 PM CDT Thu Oct 23 2014

.UPDATE...
ISSUED AT 841 PM CDT THU OCT 23 2014

The upper level trough axis of weak storm system is crossing
Illinois this evening with isolated light showers and virga
detected by radar just ahead of the axis over central Illinois.
Behind the trough axis, mid-level clouds can be seen on satellite
rapidly dissipating over western Illinois, however low clouds
continue. Any additional clearing will likely be replaced by fog
formation overnight. The system will continue to move east, with
any showers likely to end by early morning eastward to the IL/IN
state line, after little or no rainfall accumulation. Patchy fog
is included in overnight forecast from near the Illinois River
westward. Low temperatures should reach the mid to upper 40s at
most locations. Current forecast is still on track with these
features and only updates have been to convert slight chance PoPs
to isolated showers.

&&

.SHORT TERM...(Tonight)
ISSUED AT 229 PM CDT THU OCT 23 2014

19z/2pm surface analysis shows weak cold front/trough axis extending
from Minnesota to northern Kansas.  Band of clouds and light showers
accompanies this feature from Missouri northeastward into Wisconsin,
although showers have been struggling to spread eastward into the
very dry airmass across Illinois.  Forecast soundings suggest
continued top-down moistening this afternoon and evening as 500mb
trough approaches from the west.  Despite decent lift ahead of the
trough, dry airmass will be the main mitigating factor for
widespread precip development.  Will therefore continue to feature
just slight chance PoPs this evening across all locations north of
the I-70 corridor and across the N/NE KILX CWA overnight.  Rainfall
totals will be quite light, amounting to little more than a couple
hundredths of an inch at best.  Due to the clouds, overnight lows
will be quite a but warmer than in recent nights, with readings
remaining in the middle to upper 40s.  Skies may temporarily clear
along/west of the Illinois River late tonight: however, with light
winds and plenty of surface-based moisture in place, think fog
and/or low clouds will develop toward dawn.  Have therefore included
patchy fog mention across the W/NW overnight.  HRRR suggests
widespread fog and lowest visbys will develop further west
along/west of the Mississippi River.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 245 PM CDT THU OCT 23 2014

Initial forecast challenge will be how quickly the low level
moisture/clouds are able to clear out during the day Friday as
forecast soundings not looking very optimistic, at least thru
the morning hours. However, we do see some drying taking place
in the lower levels of the atmosphere in the wake of the shortwave
by late morning/early afternoon. Will keep the clouds and mention
of early morning fog in for a few hours after sunrise and then
forecast a gradual decrease in clouds from northwest to southeast
during the day. Models continue to bring a weak cold front into
our area late Friday night into Saturday with very little moisture
to work, with so will continue with the dry forecast later Friday
night thru Saturday morning. After that, some very nice weather in
store for the area thru Monday evening as upper level ridging
builds across the center of the country in response to a rather
deep trof pushing across the western U.S.

Models in decent agreement with respect to the magnitude of the
trof forecast to push across our area on Tuesday and the timing
of the cold frontal passage and rain chances ahead of it starting
late Monday night with likely POPs most areas on Tuesday. Before
the rain moves in though, some pleasantly warm weather is in store
for the region this weekend with summer-like temperatures on Monday
thanks to a gusty south to southwest wind. Despite the weak cold
frontal passage on Saturday, temperatures on Sunday will only cool
about 5 degrees most areas, but rise well into the 70s on Monday
afternoon with low 80s possible in the southeast. Rain chances will
increase ahead of the low pressure system late Monday night in the
west and over all of our area on Tuesday as the front sweeps across
the area. Strong dynamics aloft with 0-6km shear values of 40-50
kts and models indicating surface dew points climbing to around 60
just ahead of the front. Will have to monitor for the possibility
for strong to severe storms Tuesday afternoon if the models continue
with the slowing trend with the frontal passage.

Rain chances start to decrease from west to east Tuesday evening in the
wake of the storm system with dry weather expected for the remainder
of the period. Temperatures will cool back closer to where they should
be for the end of October.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1141 PM CDT THU OCT 23 2014

A trailing shortwave feature will produce a few additional
showers over east central IL until 9-12Z, but otherwise mid- and
upper-level clearing overnight will allow areas of fog and low
cloud to continue, especially west of the Illinois River.
Potential IFR or worse vsby/cigs expected, however potential for
dense fog is mainly west of central IL TAF sites. Daytime heating
expected to dissipate fog around 15Z Friday leaving cloud cover
sct-bkn025 through afternoon. Another weak disturbance will bring
additional potential for MVFR ceilings after 00Z Saturday.

&&

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

$$

UPDATE...Onton
SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Onton








000
FXUS63 KLOT 240257
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
957 PM CDT THU OCT 23 2014

.DISCUSSION...
903 PM CDT

THE CHANGES TO THE FORECAST WERE TO DISSIPATE POPS AT A QUICKER
RATE...HOLD ONTO MORE CLOUD COVER THROUGH THE NIGHT...AND ADD
DENSE MENTION TO THE FOG WORDING OVER NORTH CENTRAL ILLINOIS.

THE SURFACE TROUGH THAT HAD BEEN APPROACHING STEADILY TOWARD THE
AREA THE PAST 24 HOURS HAS DIMINISHED GREATLY SINCE MID-
AFTERNOON...LOSING MUCH OF ITS LOW-LEVEL CONVERGENCE. FORCING FOR
RAIN SHOWERS HAS ALSO BEEN DIMINISHING WITH MORE LIMITED MOISTURE
CONVERGENCE WITHIN THE AREA OF ASCENT...SO SHOWERS HAVE QUICKLY
BEEN WANING. THE SPOTTY LIGHT SHOWERS SURVIVING SHOULD CONTINUE
SLOWLY EAST WITH A GRADUAL FADE INTO OVERNIGHT.

WITH THE HIGHER DEW POINT PLUME OF UPPER 40S TO LOWER 50S BROUGHT
UP TO EASTERN IA AND NORTHWEST/NORTH CENTRAL IL BY THE
TROUGH...CONDITIONS ARE IN PLACE FOR FOG. ONE THING AGAINST FOG
DEVELOPMENT IS EXISTING CLOUDS WHICH AS SEEN ON THE 00Z DVN RAOB
ARE FAIRLY DEEP /SEVERAL THOUSAND FEET SATURATED LAYER/. THIS AREA
LOOKS TO SLOW ITS MOVEMENT EAST OVER THE CWA THUS NOT ALLOWING
MUCH CLEARING FOR NORTHEAST IL AND NORTHWEST IN...INCLUDING
CHICAGO. MORE PROBLEMATIC WILL BE POSSIBLY SOME CLEARING OF THIS
CLOUD LAYER IN NORTH CENTRAL IL LATE ALLOWING FOR NEARBY VERY LOW
STRATUS AND SOME FOG ALREADY BEING OBSERVED TO JUST EXPAND IN AND
WORSEN THROUGH DAYBREAK. FORECAST SOUNDINGS AND HIGH-RES GUIDANCE
FIELDS HAVE TRENDED THIS ROUTE IN THE GENERAL ROCKFORD AND DIXON
AREAS. HAVE BUMPED UP FOG WORDING THERE AND COULD SEE A DENSE FOG
ADVISORY BEING NEEDED DEPENDING ON HOW AGGRESSIVE THE LOWERING IS.
AGAIN FURTHER EASTWARD TOWARD CHICAGO EXPECT THE CLOUDS TO LIMIT
ANY FOG THAT GRADUALLY DEVELOPS FROM GETTING TOO BAD.

HAVE BUMPED UP MINS A DEGREE OR TWO WARMER WITH THE CLOUDS
EXPECTED TO HANG ON A GOOD PART OF THE NIGHT IN MOST PLACES.

MTF

//PREV DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* MVFR CIGS AND VSBY OVERNIGHT INTO FRIDAY MORNING. IFR CONDITIONS
  POSSIBLE LATE TONIGHT.

KMD

//DISCUSSION...UPDATED 03Z...

SHOWERS ARE GENERALLY FALLING APART OVER NE ILLINOIS...JUST SOME
ISOLATED -SHRA AT THIS POINT. CIGS ARE SLOWLY LOWERING FROM WEST
TO EAST. GUIDANCE IS BACKING OFF ON THE EASTWARD EXTEND OF LOW
VISIBILITIES GIVEN THAT THE CLOUD COVER WILL REMAIN PERSISTENT
THROUGH THE NIGHT...BUT WE DO EXPECT CONTINUED GRADUAL LOWERING OF
CIGS INTO MVFR EVERYWHERE....AND TO IFR IN WESTERN AREAS.
WIDESPREAD DENSE FOG IS NO LONGER EXPECTED...BUT THERE COULD BE
SOME MVFR OR POSSIBLY IFR VSBYS TOWARD DAYBREAK GIVEN THE MOIST
LOW LEVELS AND LIGHT FLOW AND THE LOWERING INVERSION. KMD

PREVIOUS DISCUSSION FROM 00Z...

SLOW MOVING BAND OF SCATTERED SHOWERS WILL CONTINUE TO MIGRATE
EAST THIS EVENING. EXPECT THE BEST CHANCE FOR A SHOWER WILL BE
ALONG AND NORTH OF A KRPJ-KDPA-KORD LINE OR GENERALLY NORTH OF
INTERSTATE 88.

WIDESPREAD MVFR CIGS BEHIND THE SHOWERS WILL SPREAD INTO NE
ILLINOIS AND NW INDIANA THROUGH THE NIGHT. EXPECT WITH LIGHT WINDS
AND NO DRY AIR PUSHING IN BEHIND THE FRONT THAT CONDITIONS WILL
DETERIORATE THROUGH THE NIGHT. AREAS TO THE WEST SUCH AS AROUND
KRFD AND WEST OF THE MAIN CHICAGOLAND TERMINALS HAVE THE BEST
CHANCE OF REALLY TANKING TONIGHT WITH LIFR CIGS AND VSBYS.
GUIDANCE IS HINTING AT IFR AND EVEN LIFR CONDITIONS EAST TO
CHICAGO LATE TONIGHT AS WELL...BUT WILL HAVE TO WATCH TRENDS AS WE
HAVE A HARD TIME BELIEVING CLOUDS WILL CLEAR AWAY FROM WESTERN
AREAS AND WOULD STILL GENERALLY EXPECT A GRADUAL LOWERING TO LOW
END MVFR. IF CLOUDS ARE ABLE TO CLEAR FARTHER EAST...THEN THE LIFR
CONDITIONS SUGGESTED BY MOS GUIDANCE THE HRRR WOULD BE POSSIBLE
ACROSS THE AREA.

EXPECT DECENT CLEARING TO BE SLOW GOING BUT EXPECT LIFTING TO VFR
BY THE MIDDAY OR SO. LAKE BREEZE LOOKS TO BE CONTAINED ALONG THE
LAKESHORE FRIDAY AFTERNOON.

KMD

KMD

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

* HIGH IN CEILING TRENDS...BUT LOW-MEDIUM IN HOW LOW THE CIGS/VSBY
  WILL BE.

* LOW-MEDIUM IN SPECIFIC LIFTING TIMES ON FRIDAY.

KMD

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 240257
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
957 PM CDT THU OCT 23 2014

.DISCUSSION...
903 PM CDT

THE CHANGES TO THE FORECAST WERE TO DISSIPATE POPS AT A QUICKER
RATE...HOLD ONTO MORE CLOUD COVER THROUGH THE NIGHT...AND ADD
DENSE MENTION TO THE FOG WORDING OVER NORTH CENTRAL ILLINOIS.

THE SURFACE TROUGH THAT HAD BEEN APPROACHING STEADILY TOWARD THE
AREA THE PAST 24 HOURS HAS DIMINISHED GREATLY SINCE MID-
AFTERNOON...LOSING MUCH OF ITS LOW-LEVEL CONVERGENCE. FORCING FOR
RAIN SHOWERS HAS ALSO BEEN DIMINISHING WITH MORE LIMITED MOISTURE
CONVERGENCE WITHIN THE AREA OF ASCENT...SO SHOWERS HAVE QUICKLY
BEEN WANING. THE SPOTTY LIGHT SHOWERS SURVIVING SHOULD CONTINUE
SLOWLY EAST WITH A GRADUAL FADE INTO OVERNIGHT.

WITH THE HIGHER DEW POINT PLUME OF UPPER 40S TO LOWER 50S BROUGHT
UP TO EASTERN IA AND NORTHWEST/NORTH CENTRAL IL BY THE
TROUGH...CONDITIONS ARE IN PLACE FOR FOG. ONE THING AGAINST FOG
DEVELOPMENT IS EXISTING CLOUDS WHICH AS SEEN ON THE 00Z DVN RAOB
ARE FAIRLY DEEP /SEVERAL THOUSAND FEET SATURATED LAYER/. THIS AREA
LOOKS TO SLOW ITS MOVEMENT EAST OVER THE CWA THUS NOT ALLOWING
MUCH CLEARING FOR NORTHEAST IL AND NORTHWEST IN...INCLUDING
CHICAGO. MORE PROBLEMATIC WILL BE POSSIBLY SOME CLEARING OF THIS
CLOUD LAYER IN NORTH CENTRAL IL LATE ALLOWING FOR NEARBY VERY LOW
STRATUS AND SOME FOG ALREADY BEING OBSERVED TO JUST EXPAND IN AND
WORSEN THROUGH DAYBREAK. FORECAST SOUNDINGS AND HIGH-RES GUIDANCE
FIELDS HAVE TRENDED THIS ROUTE IN THE GENERAL ROCKFORD AND DIXON
AREAS. HAVE BUMPED UP FOG WORDING THERE AND COULD SEE A DENSE FOG
ADVISORY BEING NEEDED DEPENDING ON HOW AGGRESSIVE THE LOWERING IS.
AGAIN FURTHER EASTWARD TOWARD CHICAGO EXPECT THE CLOUDS TO LIMIT
ANY FOG THAT GRADUALLY DEVELOPS FROM GETTING TOO BAD.

HAVE BUMPED UP MINS A DEGREE OR TWO WARMER WITH THE CLOUDS
EXPECTED TO HANG ON A GOOD PART OF THE NIGHT IN MOST PLACES.

MTF

//PREV DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* MVFR CIGS AND VSBY OVERNIGHT INTO FRIDAY MORNING. IFR CONDITIONS
  POSSIBLE LATE TONIGHT.

KMD

//DISCUSSION...UPDATED 03Z...

SHOWERS ARE GENERALLY FALLING APART OVER NE ILLINOIS...JUST SOME
ISOLATED -SHRA AT THIS POINT. CIGS ARE SLOWLY LOWERING FROM WEST
TO EAST. GUIDANCE IS BACKING OFF ON THE EASTWARD EXTEND OF LOW
VISIBILITIES GIVEN THAT THE CLOUD COVER WILL REMAIN PERSISTENT
THROUGH THE NIGHT...BUT WE DO EXPECT CONTINUED GRADUAL LOWERING OF
CIGS INTO MVFR EVERYWHERE....AND TO IFR IN WESTERN AREAS.
WIDESPREAD DENSE FOG IS NO LONGER EXPECTED...BUT THERE COULD BE
SOME MVFR OR POSSIBLY IFR VSBYS TOWARD DAYBREAK GIVEN THE MOIST
LOW LEVELS AND LIGHT FLOW AND THE LOWERING INVERSION. KMD

PREVIOUS DISCUSSION FROM 00Z...

SLOW MOVING BAND OF SCATTERED SHOWERS WILL CONTINUE TO MIGRATE
EAST THIS EVENING. EXPECT THE BEST CHANCE FOR A SHOWER WILL BE
ALONG AND NORTH OF A KRPJ-KDPA-KORD LINE OR GENERALLY NORTH OF
INTERSTATE 88.

WIDESPREAD MVFR CIGS BEHIND THE SHOWERS WILL SPREAD INTO NE
ILLINOIS AND NW INDIANA THROUGH THE NIGHT. EXPECT WITH LIGHT WINDS
AND NO DRY AIR PUSHING IN BEHIND THE FRONT THAT CONDITIONS WILL
DETERIORATE THROUGH THE NIGHT. AREAS TO THE WEST SUCH AS AROUND
KRFD AND WEST OF THE MAIN CHICAGOLAND TERMINALS HAVE THE BEST
CHANCE OF REALLY TANKING TONIGHT WITH LIFR CIGS AND VSBYS.
GUIDANCE IS HINTING AT IFR AND EVEN LIFR CONDITIONS EAST TO
CHICAGO LATE TONIGHT AS WELL...BUT WILL HAVE TO WATCH TRENDS AS WE
HAVE A HARD TIME BELIEVING CLOUDS WILL CLEAR AWAY FROM WESTERN
AREAS AND WOULD STILL GENERALLY EXPECT A GRADUAL LOWERING TO LOW
END MVFR. IF CLOUDS ARE ABLE TO CLEAR FARTHER EAST...THEN THE LIFR
CONDITIONS SUGGESTED BY MOS GUIDANCE THE HRRR WOULD BE POSSIBLE
ACROSS THE AREA.

EXPECT DECENT CLEARING TO BE SLOW GOING BUT EXPECT LIFTING TO VFR
BY THE MIDDAY OR SO. LAKE BREEZE LOOKS TO BE CONTAINED ALONG THE
LAKESHORE FRIDAY AFTERNOON.

KMD

KMD

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

* HIGH IN CEILING TRENDS...BUT LOW-MEDIUM IN HOW LOW THE CIGS/VSBY
  WILL BE.

* LOW-MEDIUM IN SPECIFIC LIFTING TIMES ON FRIDAY.

KMD

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 240203 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
903 PM CDT THU OCT 23 2014

.DISCUSSION...
903 PM CDT

THE CHANGES TO THE FORECAST WERE TO DISSIPATE POPS AT A QUICKER
RATE...HOLD ONTO MORE CLOUD COVER THROUGH THE NIGHT...AND ADD
DENSE MENTION TO THE FOG WORDING OVER NORTH CENTRAL ILLINOIS.

THE SURFACE TROUGH THAT HAD BEEN APPROACHING STEADILY TOWARD THE
AREA THE PAST 24 HOURS HAS DIMINISHED GREATLY SINCE MID-
AFTERNOON...LOSING MUCH OF ITS LOW-LEVEL CONVERGENCE. FORCING FOR
RAIN SHOWERS HAS ALSO BEEN DIMINISHING WITH MORE LIMITED MOISTURE
CONVERGENCE WITHIN THE AREA OF ASCENT...SO SHOWERS HAVE QUICKLY
BEEN WANING. THE SPOTTY LIGHT SHOWERS SURVIVING SHOULD CONTINUE
SLOWLY EAST WITH A GRADUAL FADE INTO OVERNIGHT.

WITH THE HIGHER DEW POINT PLUME OF UPPER 40S TO LOWER 50S BROUGHT
UP TO EASTERN IA AND NORTHWEST/NORTH CENTRAL IL BY THE
TROUGH...CONDITIONS ARE IN PLACE FOR FOG. ONE THING AGAINST FOG
DEVELOPMENT IS EXISTING CLOUDS WHICH AS SEEN ON THE 00Z DVN RAOB
ARE FAIRLY DEEP /SEVERAL THOUSAND FEET SATURATED LAYER/. THIS AREA
LOOKS TO SLOW ITS MOVEMENT EAST OVER THE CWA THUS NOT ALLOWING
MUCH CLEARING FOR NORTHEAST IL AND NORTHWEST IN...INCLUDING
CHICAGO. MORE PROBLEMATIC WILL BE POSSIBLY SOME CLEARING OF THIS
CLOUD LAYER IN NORTH CENTRAL IL LATE ALLOWING FOR NEARBY VERY LOW
STRATUS AND SOME FOG ALREADY BEING OBSERVED TO JUST EXPAND IN AND
WORSEN THROUGH DAYBREAK. FORECAST SOUNDINGS AND HIGH-RES GUIDANCE
FIELDS HAVE TRENDED THIS ROUTE IN THE GENERAL ROCKFORD AND DIXON
AREAS. HAVE BUMPED UP FOG WORDING THERE AND COULD SEE A DENSE FOG
ADVISORY BEING NEEDED DEPENDING ON HOW AGGRESSIVE THE LOWERING IS.
AGAIN FURTHER EASTWARD TOWARD CHICAGO EXPECT THE CLOUDS TO LIMIT
ANY FOG THAT GRADUALLY DEVELOPS FROM GETTING TOO BAD.

HAVE BUMPED UP MINS A DEGREE OR TWO WARMER WITH THE CLOUDS
EXPECTED TO HANG ON A GOOD PART OF THE NIGHT IN MOST PLACES.

MTF

&&

.PREV DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL LATE TONIGHT.

KMD

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

SLOW MOVING BAND OF SCATTERED SHOWERS WILL CONTINUE TO MIGRATE
EAST THIS EVENING. EXPECT THE BEST CHANCE FOR A SHOWER WILL BE
ALONG AND NORTH OF A KRPJ-KDPA-KORD LINE OR GENERALLY NORTH OF
INTERSTATE 88.

WIDESPREAD MVFR CIGS BEHIND THE SHOWERS WILL SPREAD INTO NE
ILLINOIS AND NW INDIANA THROUGH THE NIGHT. EXPECT WITH LIGHT WINDS
AND NO DRY AIR PUSHING IN BEHIND THE FRONT THAT CONDITIONS WILL
DETERIORATE THROUGH THE NIGHT. AREAS TO THE WEST SUCH AS AROUND
KRFD AND WEST OF THE MAIN CHICAGOLAND TERMINALS HAVE THE BEST
CHANCE OF REALLY TANKING TONIGHT WITH LIFR CIGS AND VSBYS.
GUIDANCE IS HINTING AT IFR AND EVEN LIFR CONDITIONS EAST TO
CHICAGO LATE TONIGHT AS WELL...BUT WILL HAVE TO WATCH TRENDS AS WE
HAVE A HARD TIME BELIEVING CLOUDS WILL CLEAR AWAY FROM WESTERN
AREAS AND WOULD STILL GENERALLY EXPECT A GRADUAL LOWERING TO LOW
END MVFR. IF CLOUDS ARE ABLE TO CLEAR FARTHER EAST...THEN THE LIFR
CONDITIONS SUGGESTED BY MOS GUIDANCE THE HRRR WOULD BE POSSIBLE
ACROSS THE AREA.

EXPECT DECENT CLEARING TO BE SLOW GOING BUT EXPECT LIFTING TO VFR
BY THE MIDDAY OR SO. LAKE BREEZE LOOKS TO BE CONTAINED ALONG THE
LAKESHORE FRIDAY AFTERNOON.

KMD

KMD

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

* MEDIUM IN COVERAGE AND OCCURRENCE OF -SHRA. BETTER CHANCE FOR
  ORD. HIGH CONFIDENCE IN TIMING.

* HIGH IN MVFR CIGS/VSBY AND MEDIUM ON TIMING. LOW-MEDIUM IN HOW
  LOW THE CIGS/VSBY WILL BE. MEDIUM ON LIFTING TIMES.

KMD

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 240203 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
903 PM CDT THU OCT 23 2014

.DISCUSSION...
903 PM CDT

THE CHANGES TO THE FORECAST WERE TO DISSIPATE POPS AT A QUICKER
RATE...HOLD ONTO MORE CLOUD COVER THROUGH THE NIGHT...AND ADD
DENSE MENTION TO THE FOG WORDING OVER NORTH CENTRAL ILLINOIS.

THE SURFACE TROUGH THAT HAD BEEN APPROACHING STEADILY TOWARD THE
AREA THE PAST 24 HOURS HAS DIMINISHED GREATLY SINCE MID-
AFTERNOON...LOSING MUCH OF ITS LOW-LEVEL CONVERGENCE. FORCING FOR
RAIN SHOWERS HAS ALSO BEEN DIMINISHING WITH MORE LIMITED MOISTURE
CONVERGENCE WITHIN THE AREA OF ASCENT...SO SHOWERS HAVE QUICKLY
BEEN WANING. THE SPOTTY LIGHT SHOWERS SURVIVING SHOULD CONTINUE
SLOWLY EAST WITH A GRADUAL FADE INTO OVERNIGHT.

WITH THE HIGHER DEW POINT PLUME OF UPPER 40S TO LOWER 50S BROUGHT
UP TO EASTERN IA AND NORTHWEST/NORTH CENTRAL IL BY THE
TROUGH...CONDITIONS ARE IN PLACE FOR FOG. ONE THING AGAINST FOG
DEVELOPMENT IS EXISTING CLOUDS WHICH AS SEEN ON THE 00Z DVN RAOB
ARE FAIRLY DEEP /SEVERAL THOUSAND FEET SATURATED LAYER/. THIS AREA
LOOKS TO SLOW ITS MOVEMENT EAST OVER THE CWA THUS NOT ALLOWING
MUCH CLEARING FOR NORTHEAST IL AND NORTHWEST IN...INCLUDING
CHICAGO. MORE PROBLEMATIC WILL BE POSSIBLY SOME CLEARING OF THIS
CLOUD LAYER IN NORTH CENTRAL IL LATE ALLOWING FOR NEARBY VERY LOW
STRATUS AND SOME FOG ALREADY BEING OBSERVED TO JUST EXPAND IN AND
WORSEN THROUGH DAYBREAK. FORECAST SOUNDINGS AND HIGH-RES GUIDANCE
FIELDS HAVE TRENDED THIS ROUTE IN THE GENERAL ROCKFORD AND DIXON
AREAS. HAVE BUMPED UP FOG WORDING THERE AND COULD SEE A DENSE FOG
ADVISORY BEING NEEDED DEPENDING ON HOW AGGRESSIVE THE LOWERING IS.
AGAIN FURTHER EASTWARD TOWARD CHICAGO EXPECT THE CLOUDS TO LIMIT
ANY FOG THAT GRADUALLY DEVELOPS FROM GETTING TOO BAD.

HAVE BUMPED UP MINS A DEGREE OR TWO WARMER WITH THE CLOUDS
EXPECTED TO HANG ON A GOOD PART OF THE NIGHT IN MOST PLACES.

MTF

&&

.PREV DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL LATE TONIGHT.

KMD

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

SLOW MOVING BAND OF SCATTERED SHOWERS WILL CONTINUE TO MIGRATE
EAST THIS EVENING. EXPECT THE BEST CHANCE FOR A SHOWER WILL BE
ALONG AND NORTH OF A KRPJ-KDPA-KORD LINE OR GENERALLY NORTH OF
INTERSTATE 88.

WIDESPREAD MVFR CIGS BEHIND THE SHOWERS WILL SPREAD INTO NE
ILLINOIS AND NW INDIANA THROUGH THE NIGHT. EXPECT WITH LIGHT WINDS
AND NO DRY AIR PUSHING IN BEHIND THE FRONT THAT CONDITIONS WILL
DETERIORATE THROUGH THE NIGHT. AREAS TO THE WEST SUCH AS AROUND
KRFD AND WEST OF THE MAIN CHICAGOLAND TERMINALS HAVE THE BEST
CHANCE OF REALLY TANKING TONIGHT WITH LIFR CIGS AND VSBYS.
GUIDANCE IS HINTING AT IFR AND EVEN LIFR CONDITIONS EAST TO
CHICAGO LATE TONIGHT AS WELL...BUT WILL HAVE TO WATCH TRENDS AS WE
HAVE A HARD TIME BELIEVING CLOUDS WILL CLEAR AWAY FROM WESTERN
AREAS AND WOULD STILL GENERALLY EXPECT A GRADUAL LOWERING TO LOW
END MVFR. IF CLOUDS ARE ABLE TO CLEAR FARTHER EAST...THEN THE LIFR
CONDITIONS SUGGESTED BY MOS GUIDANCE THE HRRR WOULD BE POSSIBLE
ACROSS THE AREA.

EXPECT DECENT CLEARING TO BE SLOW GOING BUT EXPECT LIFTING TO VFR
BY THE MIDDAY OR SO. LAKE BREEZE LOOKS TO BE CONTAINED ALONG THE
LAKESHORE FRIDAY AFTERNOON.

KMD

KMD

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

* MEDIUM IN COVERAGE AND OCCURRENCE OF -SHRA. BETTER CHANCE FOR
  ORD. HIGH CONFIDENCE IN TIMING.

* HIGH IN MVFR CIGS/VSBY AND MEDIUM ON TIMING. LOW-MEDIUM IN HOW
  LOW THE CIGS/VSBY WILL BE. MEDIUM ON LIFTING TIMES.

KMD

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
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000
FXUS63 KILX 240141
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
841 PM CDT Thu Oct 23 2014

.UPDATE...
ISSUED AT 841 PM CDT THU OCT 23 2014

The upper level trough axis of weak storm system is crossing
Illinois this evening with isolated light showers and virga
detected by radar just ahead of the axis over central Illinois.
Behind the trough axis, mid-level clouds can be seen on satellite
rapidly dissipating over western Illinois, however low clouds
continue. Any additional clearing will likely be replaced by fog
formation overnight. The system will continue to move east, with
any showers likely to end by early morning eastward to the IL/IN
state line, after little or no rainfall accumulation. Patchy fog
is included in overnight forecast from near the Illinois River
westward. Low temperatures should reach the mid to upper 40s at
most locations. Current forecast is still on track with these
features and only updates have been to convert slight chance PoPs
to isolated showers.

&&

.SHORT TERM...(Tonight)
ISSUED AT 229 PM CDT THU OCT 23 2014

19z/2pm surface analysis shows weak cold front/trough axis extending
from Minnesota to northern Kansas.  Band of clouds and light showers
accompanies this feature from Missouri northeastward into Wisconsin,
although showers have been struggling to spread eastward into the
very dry airmass across Illinois.  Forecast soundings suggest
continued top-down moistening this afternoon and evening as 500mb
trough approaches from the west.  Despite decent lift ahead of the
trough, dry airmass will be the main mitigating factor for
widespread precip development.  Will therefore continue to feature
just slight chance PoPs this evening across all locations north of
the I-70 corridor and across the N/NE KILX CWA overnight.  Rainfall
totals will be quite light, amounting to little more than a couple
hundredths of an inch at best.  Due to the clouds, overnight lows
will be quite a but warmer than in recent nights, with readings
remaining in the middle to upper 40s.  Skies may temporarily clear
along/west of the Illinois River late tonight: however, with light
winds and plenty of surface-based moisture in place, think fog
and/or low clouds will develop toward dawn.  Have therefore included
patchy fog mention across the W/NW overnight.  HRRR suggests
widespread fog and lowest visbys will develop further west
along/west of the Mississippi River.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 245 PM CDT THU OCT 23 2014

Initial forecast challenge will be how quickly the low level
moisture/clouds are able to clear out during the day Friday as
forecast soundings not looking very optimistic, at least thru
the morning hours. However, we do see some drying taking place
in the lower levels of the atmosphere in the wake of the shortwave
by late morning/early afternoon. Will keep the clouds and mention
of early morning fog in for a few hours after sunrise and then
forecast a gradual decrease in clouds from northwest to southeast
during the day. Models continue to bring a weak cold front into
our area late Friday night into Saturday with very little moisture
to work, with so will continue with the dry forecast later Friday
night thru Saturday morning. After that, some very nice weather in
store for the area thru Monday evening as upper level ridging
builds across the center of the country in response to a rather
deep trof pushing across the western U.S.

Models in decent agreement with respect to the magnitude of the
trof forecast to push across our area on Tuesday and the timing
of the cold frontal passage and rain chances ahead of it starting
late Monday night with likely POPs most areas on Tuesday. Before
the rain moves in though, some pleasantly warm weather is in store
for the region this weekend with summer-like temperatures on Monday
thanks to a gusty south to southwest wind. Despite the weak cold
frontal passage on Saturday, temperatures on Sunday will only cool
about 5 degrees most areas, but rise well into the 70s on Monday
afternoon with low 80s possible in the southeast. Rain chances will
increase ahead of the low pressure system late Monday night in the
west and over all of our area on Tuesday as the front sweeps across
the area. Strong dynamics aloft with 0-6km shear values of 40-50
kts and models indicating surface dew points climbing to around 60
just ahead of the front. Will have to monitor for the possibility
for strong to severe storms Tuesday afternoon if the models continue
with the slowing trend with the frontal passage.

Rain chances start to decrease from west to east Tuesday evening in the
wake of the storm system with dry weather expected for the remainder
of the period. Temperatures will cool back closer to where they should
be for the end of October.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 625 PM CDT THU OCT 23 2014

A band of isold -SHRA with mainly VFR vsby/cigs spreading eastward
through central Illinois this evening. Local MVFR cigs likely to
develop a few hours after shower activity arrives. This band
expected to move slowly across the state with showers ending
around 3Z-5Z in west-central IL and 8-10Z in east-central IL. Low
level moisture will linger after precipitation ends, allowing
areas of fog and low cloud to continue, especially west of the
Illinois River. Potential IFR or worse vsby/cigs expected, however
potential for dense fog is mainly west of central IL TAF sites.
Daytime heating expected to dissipate fog around 15Z Friday
leaving cloud cover sct-bkn025 through afternoon.


&&

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

$$

UPDATE...Onton
SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Onton







000
FXUS63 KLOT 240018
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
718 PM CDT THU OCT 23 2014

.DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL LATE TONIGHT.

KMD

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

SLOW MOVING BAND OF SCATTERED SHOWERS WILL CONTINUE TO MIGRATE
EAST THIS EVENING. EXPECT THE BEST CHANCE FOR A SHOWER WILL BE
ALONG AND NORTH OF A KRPJ-KDPA-KORD LINE OR GENERALLY NORTH OF
INTERSTATE 88.

WIDESPREAD MVFR CIGS BEHIND THE SHOWERS WILL SPREAD INTO NE
ILLINOIS AND NW INDIANA THROUGH THE NIGHT. EXPECT WITH LIGHT WINDS
AND NO DRY AIR PUSHING IN BEHIND THE FRONT THAT CONDITIONS WILL
DETERIORATE THROUGH THE NIGHT. AREAS TO THE WEST SUCH AS AROUND
KRFD AND WEST OF THE MAIN CHICAGOLAND TERMINALS HAVE THE BEST
CHANCE OF REALLY TANKING TONIGHT WITH LIFR CIGS AND VSBYS.
GUIDANCE IS HINTING AT IFR AND EVEN LIFR CONDITIONS EAST TO
CHICAGO LATE TONIGHT AS WELL...BUT WILL HAVE TO WATCH TRENDS AS WE
HAVE A HARD TIME BELIEVING CLOUDS WILL CLEAR AWAY FROM WESTERN
AREAS AND WOULD STILL GENERALLY EXPECT A GRADUAL LOWERING TO LOW
END MVFR. IF CLOUDS ARE ABLE TO CLEAR FARTHER EAST...THEN THE LIFR
CONDITIONS SUGGESTED BY MOS GUIDANCE THE HRRR WOULD BE POSSIBLE
ACROSS THE AREA.

EXPECT DECENT CLEARING TO BE SLOW GOING BUT EXPECT LIFTING TO VFR
BY THE MIDDAY OR SO. LAKE BREEZE LOOKS TO BE CONTAINED ALONG THE
LAKESHORE FRIDAY AFTERNOON.

KMD

KMD


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

* MEDIUM IN COVERAGE AND OCCURRENCE OF -SHRA. BETTER CHANCE FOR
  ORD. HIGH CONFIDENCE IN TIMING.

* HIGH IN MVFR CIGS/VSBY AND MEDIUM ON TIMING. LOW-MEDIUM IN HOW
  LOW THE CIGS/VSBY WILL BE. MEDIUM ON LIFTING TIMES.

KMD

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

* FRIDAY NIGHT...MAINLY DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTHEAST WINDS.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST-SOUTHWEST WINDS.

KMD

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 232325
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
625 PM CDT Thu Oct 23 2014

.SHORT TERM...(Tonight)
ISSUED AT 229 PM CDT THU OCT 23 2014

19z/2pm surface analysis shows weak cold front/trough axis extending
from Minnesota to northern Kansas.  Band of clouds and light showers
accompanies this feature from Missouri northeastward into Wisconsin,
although showers have been struggling to spread eastward into the
very dry airmass across Illinois.  Forecast soundings suggest
continued top-down moistening this afternoon and evening as 500mb
trough approaches from the west.  Despite decent lift ahead of the
trough, dry airmass will be the main mitigating factor for
widespread precip development.  Will therefore continue to feature
just slight chance PoPs this evening across all locations north of
the I-70 corridor and across the N/NE KILX CWA overnight.  Rainfall
totals will be quite light, amounting to little more than a couple
hundredths of an inch at best.  Due to the clouds, overnight lows
will be quite a but warmer than in recent nights, with readings
remaining in the middle to upper 40s.  Skies may temporarily clear
along/west of the Illinois River late tonight: however, with light
winds and plenty of surface-based moisture in place, think fog
and/or low clouds will develop toward dawn.  Have therefore included
patchy fog mention across the W/NW overnight.  HRRR suggests
widespread fog and lowest visbys will develop further west
along/west of the Mississippi River.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 245 PM CDT THU OCT 23 2014

Initial forecast challenge will be how quickly the low level
moisture/clouds are able to clear out during the day Friday as
forecast soundings not looking very optimistic, at least thru
the morning hours. However, we do see some drying taking place
in the lower levels of the atmosphere in the wake of the shortwave
by late morning/early afternoon. Will keep the clouds and mention
of early morning fog in for a few hours after sunrise and then
forecast a gradual decrease in clouds from northwest to southeast
during the day. Models continue to bring a weak cold front into
our area late Friday night into Saturday with very little moisture
to work, with so will continue with the dry forecast later Friday
night thru Saturday morning. After that, some very nice weather in
store for the area thru Monday evening as upper level ridging
builds across the center of the country in response to a rather
deep trof pushing across the western U.S.

Models in decent agreement with respect to the magnitude of the
trof forecast to push across our area on Tuesday and the timing
of the cold frontal passage and rain chances ahead of it starting
late Monday night with likely POPs most areas on Tuesday. Before
the rain moves in though, some pleasantly warm weather is in store
for the region this weekend with summer-like temperatures on Monday
thanks to a gusty south to southwest wind. Despite the weak cold
frontal passage on Saturday, temperatures on Sunday will only cool
about 5 degrees most areas, but rise well into the 70s on Monday
afternoon with low 80s possible in the southeast. Rain chances will
increase ahead of the low pressure system late Monday night in the
west and over all of our area on Tuesday as the front sweeps across
the area. Strong dynamics aloft with 0-6km shear values of 40-50
kts and models indicating surface dew points climbing to around 60
just ahead of the front. Will have to monitor for the possibility
for strong to severe storms Tuesday afternoon if the models continue
with the slowing trend with the frontal passage.

Rain chances start to decrease from west to east Tuesday evening in the
wake of the storm system with dry weather expected for the remainder
of the period. Temperatures will cool back closer to where they should
be for the end of October.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 625 PM CDT THU OCT 23 2014

A band of isold -SHRA with mainly VFR vsby/cigs spreading eastward
through central Illinois this evening. Local MVFR cigs likely to
develop a few hours after shower activity arrives. This band
expected to move slowly across the state with showers ending
around 3Z-5Z in west-central IL and 8-10Z in east-central IL. Low
level moisture will linger after precipitation ends, allowing
areas of fog and low cloud to continue, especially west of the
Illinois River. Potential IFR or worse vsby/cigs expected, however
potential for dense fog is mainly west of central IL TAF sites.
Daytime heating expected to dissipate fog around 15Z Friday
leaving cloud cover sct-bkn025 through afternoon.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Onton







000
FXUS63 KLOT 232211
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
511 PM CDT THU OCT 23 2014

.DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL.

JEE

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

AN UPPER LEVEL WAVE IS APPROACHING FROM THE WEST WITH A LINE OF
SHOWERS EXTENDING INTO NORTHWEST IL. THE BAND OF SHOWERS WILL
CONTINUE EAST AND EXPECTING IT TO REMAIN RAGGED WITH HIT OR MISS
SHOWERS. RFD HAS THE BEST CHANCE OF SEEING AN ORGANIZED SHOWER
THIS AFTN. THE EASTERN TERMINALS WILL MOST LIKELY SEE SCATTERED
SHOWERS OR DRIZZLE THIS EVENING.

UPSTREAM OBS INDICATE THAT CIGS WILL FALL TO MVFR OR LOWER BEHIND
THE SHOWERS. HAVE THE MOST CONFIDENCE IN THE RFD TAF WITH IFR
CIGS. HAVE HIGH CONFIDENCE IN FOG AT RFD AND MEDIUM IN 1/4SM.

CLOUDS SHOULD LAST LONGER OVER THE EASTERN TERMINALS SO KEPT CIGS
IN THE MVFR RANGE WITH FOG ONLY AT DPA. CONDITIONS WILL IMPROVE TO
VFR QUICKLY TOMORROW AS THE CLOUDS SHIFT EAST. LIGHT WINDS
OVERNIGHT BECOME SW BTWN 5 AND 8 KT.

JEE

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

* MEDIUM CONFIDENCE IN COVERAGE AND OCCURRENCE OF -SHRA. BETTER
  CHANCE FOR ORD. HIGH CONFIDENCE IN TIMING.

* MEDIUM CONFIDENCE IN MVFR CIGS AND TIMING...LOW-MEDIUM CONFIDENCE
  IN HOW LOW THE CIGS WILL BE.

KMD


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

* FRIDAY NIGHT...DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. WEST WINDS BECOMING SOUTHEAST.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST WINDS.

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 232027
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
327 PM CDT THU OCT 23 2014

.DISCUSSION...
327 PM CDT

AFTERNOON GOES VAPOR IMAGERY DEPICTS A MID-LEVEL SHORT WAVE TROUGH
PROPAGATING THROUGH THE UPPER MISSISSIPPI VALLEY...WITH A WEAK
SURFACE LOW PRESSURE REFLECTION OVER EAST CENTRAL IOWA. AS EXPECTED
THE MOISTURE TRANSPORT AHEAD/INTO THIS SYSTEM IS RATHER SPARSE...
WITH A FAIRLY NARROW RIBBON OF LOW LEVEL MOISTURE AHEAD OF THE
TROUGH INTO PORTIONS OF NORTHWEST IL AND SOUTHERN WI. HIGH-RES
GUIDANCE CONTINUES TO INDICATE THE POTENTIAL OF SCATTERED SHOWERS
SPREADING EAST ACROSS THE CWA THROUGH THIS EVENING...THOUGH WITH
COVERAGE ANTICIPATED TO REMAIN SOMEWHAT LIMITED AS LOW LEVEL
MOISTURE TRANSPORT CONTINUES TO WEAKEN WITH LOSS OF DEFINITION OF
THE SURFACE WAVE AND LOW PRESSURE TROUGH. IN ADDITION TO THE
EXTENSIVE MID-HIGH LEVEL CLOUD COVER ACROSS THE AREA THIS
AFTERNOON...WHICH WILL LIKELY OBSCURE PARTIAL SOLAR ECLIPSE LATE
THIS AFTERNOON...LOWER CLOUDS ALSO EXPECTED AS LOW LEVEL MOISTURE
AXIS ARRIVES. SOME POTENTIAL FOR FOG DEVELOPMENT ESPECIALLY ACROSS
THE WESTERN PORTION OF THE CWA WHERE LIGHT WINDS AND 45-50 DEGREE
SURFACE DEW POINT TEMPS WILL RESULT IN HIGH LOW LEVEL RH...THOUGH
CLEARING SKIES WILL BE MORE LIKELY WEST OF THE CWA WHERE SIGNIFICANT
DENSE FOG/STRATUS DEVELOPMENT IS POSSIBLE LATE TONIGHT/EARLY FRIDAY
MORNING. AT LEAST CLOUD COVER AND MORE HUMID AIR WILL KEEP TEMPS A
LITTLE MILDER OVERNIGHT.

SHORT-WAVE WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA FRIDAY
MORNING...WITH MODEST HEIGHT RISES AND A SUBTLE SURFACE RIDGE AXIS
DEVELOPING OVER THE AREA. ANOTHER TRAILING SHORT WAVE CURRENTLY OVER
THE ROCKIES IS PROGGED TO MOVE SOUTHEAST ACROSS MISSOURI AND
CENTRAL/SOUTHERN ILLINOIS FRIDAY MORNING/EARLY AFTERNOON WHICH MAY
KEEP A LITTLE CLOUD COVER AROUND. OTHERWISE...DOMINANT WEATHER
FEATURE BECOMES A BROAD UPPER RIDGE CENTERED OVER WEST TEXAS WHICH
COVERS MUCH OF THE CENTRAL CONUS INTO THE WEEKEND. A STRONG 150+ KT
UPPER JET FLATTENS THE TOP OF THE RIDGE AS IT RIDES ALONG THE
CANADIAN BORDER FRIDAY...THOUGH THE MAIN AREA OF SFC LOW PRESSURE
REMAINS WELL NORTH OF THE GREAT LAKES REGION THROUGH SATURDAY. A
COLD FRONT DOES TRAIL INTO THE REGION HOWEVER...MOVING ACROSS THE
CWA EARLY SATURDAY MORNING. SOME GUIDANCE DOES INDICATE SOME VERY
SPOTTY/VERY LIGHT QPF WITH FROPA DURING THE PRE-DAWN HOURS SATURDAY
ALTHOUGH MODELS ARE MUCH LESS IMPRESSIVE WITH PRECIP THAN WITH
CURRENT WAVE...WITH SREF POPS LESS THAN 20 PERCENT. COLD FRONT
COMPLETES THE TRANSIT OF THE CWA SATURDAY MORNING...THOUGH PACIFIC
NATURE OF THE FRONT PRODUCES ONLY MODEST COOLING AS IT SHIFTS WINDS
TO THE WEST-NORTHWEST DURING THE DAY. LOW LEVEL THERMAL PROGS AND
POTENTIAL FOR A GOOD DEAL OF SUNSHINE SUPPORT TEMPS IN THE 65-AROUND
70 RANGE DESPITE THE SLIGHT COOL ADVECTION BEHIND THE FRONT...AS
UPPER RIDGE BEGINS TO AMPLIFY AND DEVELOP INTO THE CENTRAL CONUS
THROUGH SATURDAY NIGHT. UPPER RIDGE CONTINUES TO AMPLIFY SUNDAY AS
LARGE SCALE UPPER TROUGH PUSHES ASHORE IN THE WEST...WITH A LARGE
LEE TROUGH DEVELOPING EAST OF THE CENTRAL AND NORTHERN ROCKIES. LOW
PRESSURE BEGINS TO DEVELOP ACROSS THE PLAINS...WITH A WARM FRONT
LIFTING ACROSS IA-IL SUNDAY NIGHT. SOUTHEAST LOW LEVEL FLOW AHEAD OF
THE WARM FRONT...IN ADDITION TO CLOUD DEVELOPMENT NORTH OF THE WARM
FRONT LOOK TO TEMPER WARM-UP ONLY SLIGHTLY...WITH 60-66 FOR HIGHS
WITH COOLEST AIR ALONG THE IL LAKE SHORE. SOME POTENTIAL FOR
ELEVATED SHOWERS/ISOLATED THUNDERSTORMS NORTH OF THE WARM FRONT
SUNDAY NIGHT...PARTICULARLY ACROSS FAR NORTHERN IL.

WARM FRONT LIFTS NORTH OF THE CWA MONDAY...WITH BREEZY/WARM AND MORE
HUMID AIR IN THE WARM SECTOR SUPPORTING TEMPS IN THE 70S AREA-WIDE.
ECMWF/GFS AND GEM ALL INDICATE VERY LITTLE PRECIP IN THE WARM SECTOR
WITH THE MAIN FOCUS ALONG THE TRAILING COLD FRONT TO OUR WEST. RAIN
AND THUNDERSTORM CHANCES THUS INCREASE MONDAY NIGHT AND TUESDAY AS
THE SURFACE LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS THE UPPER
MIDWEST AND TRAILING COLD FRONT PUSHES EAST THROUGH THE REGION.
BREEZY AND COOLER CONDITIONS THEN RETURN AS THE LOW PULLS AWAY TO
THE NORTHEAST TUESDAY NIGHT AND WEDNESDAY. SOME DIFFERENCES REMAIN
WITH THE HANDLING OF THE LOW DEVELOPMENT AND TRACK...THOUGH THIS
MAINLY AFFECTS HOW QUICKLY WE DRY OUT ON TUESDAY. OTHERWISE GUIDANCE
IS ACTUALLY QUITE REASONABLE IN AGREEMENT THROUGH THE PERIOD.

RATZER

&&

.AVIATION...

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

* SW WINDS GUSTING TO ARND 17KT THIS AFTN.

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL.

JEE

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

AN UPPER LEVEL WAVE IS APPROACHING FROM THE WEST WITH A LINE OF
SHOWERS EXTENDING INTO NORTHWEST IL. THE BAND OF SHOWERS WILL
CONTINUE EAST AND EXPECTING IT TO REMAIN RAGGED WITH HIT OR MISS
SHOWERS. RFD HAS THE BEST CHANCE OF SEEING AN ORGANIZED SHOWER
THIS AFTN. THE EASTERN TERMINALS WILL MOST LIKELY SEE SCATTERED
SHOWERS OR DRIZZLE THIS EVENING.

UPSTREAM OBS INDICATE THAT CIGS WILL FALL TO MVFR OR LOWER BEHIND
THE SHOWERS. HAVE THE MOST CONFIDENCE IN THE RFD TAF WITH IFR
CIGS. HAVE HIGH CONFIDENCE IN FOG AT RFD AND MEDIUM IN 1/4SM.

CLOUDS SHOULD LAST LONGER OVER THE EASTERN TERMINALS SO KEPT CIGS
IN THE MVFR RANGE WITH FOG ONLY AT DPA. CONDITIONS WILL IMPROVE TO
VFR QUICKLY TOMORROW AS THE CLOUDS SHIFT EAST. LIGHT WINDS
OVERNIGHT BECOME SW BTWN 5 AND 8 KT.

JEE

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

* MEDIUM CONFIDENCE IN COVERAGE AND OCCURRENCE OF -SHRA...MEDIUM-
  HIGH CONFIDENCE IN TIMING.

* MEDIUM CONFIDENCE IN MVFR CIGS AND TIMING...LOW CONFIDENCE IN
  HOW LOW THE CIGS WILL BE.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

* FRIDAY NIGHT...DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. WEST WINDS BECOMING SOUTHEAST.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST WINDS.

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KILX 231957
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
257 PM CDT Thu Oct 23 2014

.SHORT TERM...(Tonight)
ISSUED AT 229 PM CDT THU OCT 23 2014

19z/2pm surface analysis shows weak cold front/trough axis extending
from Minnesota to northern Kansas.  Band of clouds and light showers
accompanies this feature from Missouri northeastward into Wisconsin,
although showers have been struggling to spread eastward into the
very dry airmass across Illinois.  Forecast soundings suggest
continued top-down moistening this afternoon and evening as 500mb
trough approaches from the west.  Despite decent lift ahead of the
trough, dry airmass will be the main mitigating factor for
widespread precip development.  Will therefore continue to feature
just slight chance PoPs this evening across all locations north of
the I-70 corridor and across the N/NE KILX CWA overnight.  Rainfall
totals will be quite light, amounting to little more than a couple
hundredths of an inch at best.  Due to the clouds, overnight lows
will be quite a but warmer than in recent nights, with readings
remaining in the middle to upper 40s.  Skies may temporarily clear
along/west of the Illinois River late tonight: however, with light
winds and plenty of surface-based moisture in place, think fog
and/or low clouds will develop toward dawn.  Have therefore included
patchy fog mention across the W/NW overnight.  HRRR suggests
widespread fog and lowest visbys will develop further west
along/west of the Mississippi River.


&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 245 PM CDT THU OCT 23 2014

Initial forecast challenge will be how quickly the low level
moisture/clouds are able to clear out during the day Friday as
forecast soundings not looking very optimistic, at least thru
the morning hours. However, we do see some drying taking place
in the lower levels of the atmosphere in the wake of the shortwave
by late morning/early afternoon. Will keep the clouds and mention
of early morning fog in for a few hours after sunrise and then
forecast a gradual decrease in clouds from northwest to southeast
during the day. Models continue to bring a weak cold front into
our area late Friday night into Saturday with very little moisture
to work, with so will continue with the dry forecast later Friday
night thru Saturday morning. After that, some very nice weather in
store for the area thru Monday evening as upper level ridging
builds across the center of the country in response to a rather
deep trof pushing across the western U.S.

Models in decent agreement with respect to the magnitude of the
trof forecast to push across our area on Tuesday and the timing
of the cold frontal passage and rain chances ahead of it starting
late Monday night with likely POPs most areas on Tuesday. Before
the rain moves in though, some pleasantly warm weather is in store
for the region this weekend with summer-like temperatures on Monday
thanks to a gusty south to southwest wind. Despite the weak cold
frontal passage on Saturday, temperatures on Sunday will only cool
about 5 degrees most areas, but rise well into the 70s on Monday
afternoon with low 80s possible in the southeast. Rain chances will
increase ahead of the low pressure system late Monday night in the
west and over all of our area on Tuesday as the front sweeps across
the area. Strong dynamics aloft with 0-6km shear values of 40-50
kts and models indicating surface dew points climbing to around 60
just ahead of the front. Will have to monitor for the possibility
for strong to severe storms Tuesday afternoon if the models continue
with the slowing trend with the frontal passage.

Rain chances start to decrease from west to east Tuesday evening in the
wake of the storm system with dry weather expected for the remainder
of the period. Temperatures will cool back closer to where they should
be for the end of October.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1229 PM CDT THU OCT 23 2014

Mid/high clouds continue to spread eastward across central
Illinois early this afternoon, while MVFR ceilings remain further
west along/behind a trough axis extending from eastern Iowa into
northern Missouri. As this feature moves slowly eastward, clouds
will lower later this afternoon into the evening and a few light
showers will be possible. HRRR guidance suggests low clouds will
stay west of the central Illinois terminals until this evening,
with MVFR ceilings arriving at KPIA by 01z then further east to
KCMI by 08z. Based on 12z NAM forecast soundings and latest HRRR,
think clearing late tonight into Friday morning will be much
slower than previously expected. While skies may temporarily clear
along/west of the Illinois late tonight, light winds/ample low-level
moisture will lead to fog and low cloud re-development. End result
will be overcast conditions until mid-morning Friday at the earliest.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Barnes





000
FXUS63 KILX 231957
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
257 PM CDT Thu Oct 23 2014

.SHORT TERM...(Tonight)
ISSUED AT 229 PM CDT THU OCT 23 2014

19z/2pm surface analysis shows weak cold front/trough axis extending
from Minnesota to northern Kansas.  Band of clouds and light showers
accompanies this feature from Missouri northeastward into Wisconsin,
although showers have been struggling to spread eastward into the
very dry airmass across Illinois.  Forecast soundings suggest
continued top-down moistening this afternoon and evening as 500mb
trough approaches from the west.  Despite decent lift ahead of the
trough, dry airmass will be the main mitigating factor for
widespread precip development.  Will therefore continue to feature
just slight chance PoPs this evening across all locations north of
the I-70 corridor and across the N/NE KILX CWA overnight.  Rainfall
totals will be quite light, amounting to little more than a couple
hundredths of an inch at best.  Due to the clouds, overnight lows
will be quite a but warmer than in recent nights, with readings
remaining in the middle to upper 40s.  Skies may temporarily clear
along/west of the Illinois River late tonight: however, with light
winds and plenty of surface-based moisture in place, think fog
and/or low clouds will develop toward dawn.  Have therefore included
patchy fog mention across the W/NW overnight.  HRRR suggests
widespread fog and lowest visbys will develop further west
along/west of the Mississippi River.


&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 245 PM CDT THU OCT 23 2014

Initial forecast challenge will be how quickly the low level
moisture/clouds are able to clear out during the day Friday as
forecast soundings not looking very optimistic, at least thru
the morning hours. However, we do see some drying taking place
in the lower levels of the atmosphere in the wake of the shortwave
by late morning/early afternoon. Will keep the clouds and mention
of early morning fog in for a few hours after sunrise and then
forecast a gradual decrease in clouds from northwest to southeast
during the day. Models continue to bring a weak cold front into
our area late Friday night into Saturday with very little moisture
to work, with so will continue with the dry forecast later Friday
night thru Saturday morning. After that, some very nice weather in
store for the area thru Monday evening as upper level ridging
builds across the center of the country in response to a rather
deep trof pushing across the western U.S.

Models in decent agreement with respect to the magnitude of the
trof forecast to push across our area on Tuesday and the timing
of the cold frontal passage and rain chances ahead of it starting
late Monday night with likely POPs most areas on Tuesday. Before
the rain moves in though, some pleasantly warm weather is in store
for the region this weekend with summer-like temperatures on Monday
thanks to a gusty south to southwest wind. Despite the weak cold
frontal passage on Saturday, temperatures on Sunday will only cool
about 5 degrees most areas, but rise well into the 70s on Monday
afternoon with low 80s possible in the southeast. Rain chances will
increase ahead of the low pressure system late Monday night in the
west and over all of our area on Tuesday as the front sweeps across
the area. Strong dynamics aloft with 0-6km shear values of 40-50
kts and models indicating surface dew points climbing to around 60
just ahead of the front. Will have to monitor for the possibility
for strong to severe storms Tuesday afternoon if the models continue
with the slowing trend with the frontal passage.

Rain chances start to decrease from west to east Tuesday evening in the
wake of the storm system with dry weather expected for the remainder
of the period. Temperatures will cool back closer to where they should
be for the end of October.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1229 PM CDT THU OCT 23 2014

Mid/high clouds continue to spread eastward across central
Illinois early this afternoon, while MVFR ceilings remain further
west along/behind a trough axis extending from eastern Iowa into
northern Missouri. As this feature moves slowly eastward, clouds
will lower later this afternoon into the evening and a few light
showers will be possible. HRRR guidance suggests low clouds will
stay west of the central Illinois terminals until this evening,
with MVFR ceilings arriving at KPIA by 01z then further east to
KCMI by 08z. Based on 12z NAM forecast soundings and latest HRRR,
think clearing late tonight into Friday morning will be much
slower than previously expected. While skies may temporarily clear
along/west of the Illinois late tonight, light winds/ample low-level
moisture will lead to fog and low cloud re-development. End result
will be overcast conditions until mid-morning Friday at the earliest.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Barnes





000
FXUS63 KLOT 231946
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
246 PM CDT THU OCT 23 2014

.DISCUSSION...
303 AM CDT

A RIDGE OF HIGH PRESSURE STRETCHES FROM CENTRAL QUEBEC SOUTHWEST
THROUGH LOWER MICHIGAN INTO THE OHIO VALLEY. EARLY THIS MORNING THIS
RIDGE HAS BEEN ABLE TO KEEP CLOUD COVER DISPLACED WEST OF THE
REGION. BASED ON LATEST SFC OBS THE PRESSURE FALLS ARE NOT VERY
LARGE...WHICH COULD BE AN INDICATOR THAT LATER TODAY THE ABILITY FOR
THE ATMOSPHERE TO PRODUCE ABUNDANT MOISTURE/PRECIP MAY BE
DIMINISHED. IR IMAGERY EARLY THIS MORNING SHOWS A MOIST CHANNEL THAT
EXTENDS FROM THE CANADIAN BORDER OF THE UPPER MIDWEST...SOUTH TO
THE MEXICO BORDER/WESTERN GULF. THE PROGRESSION TO THE EAST HAS BEEN
VERY SLOW...AND LATEST HI-RES GUIDANCE INDICATES THAT AS THIS
FEATURE PUSHES EAST IT WILL ENCOUNTER MUCH DRIER AIR AND DIMINISH
THE COVERAGE AND INTENSITY OF PRECIP.

WITH THE LGT WINDS AND MINIMAL CLOUD COVER EARLY THIS MORNING...SOME
LOCATIONS ARE BEGINNING TO SEE PATCHY FOG DEVELOP...MAINLY ACROSS
NORTHWEST INDIANA. TEMPS HAVE BEEN ABLE TO RADIATE INTO THE MID
30S...WITH THE EXCEPTION OF THE FAR WESTERN CWFA WHERE A THIN
CIRRUS DECK HAS ARRIVED AND HELD TEMPS IN THE UPR 30S/NEAR 40.

AS THE MOIST CHANNEL SLOWLY SLIDES EAST TODAY...EXPECT A STEADY
THICKENING TO THE CLOUD COVER. WINDS WILL TURN SOUTHERLY WITH SOME
BETTER MIXING DEVELOPING AND PERHAPS BRINGING WINDS UP TO 10-20MPH
BY LATE AFTN. GUIDANCE HAS BECOME MORE PESSIMISTIC WITH PRECIP
COVERAGE/INTENSITY LATER TODAY...AND AS A RESULT HAVE BACKED OFF ON
POPS ALONG WITH QUANTITY OF PRECIP. THE NEAR SFC ENVIRONMENT STILL
LOOKS TO REMAIN RELATIVELY DRY...ALTHOUGH SOME MOISTENING WILL
OCCUR. EXPECT THE BEST PRECIP COVERAGE TO OCCUR FURTHER
NORTH...HOWEVER WILL CONTINUE THE MENTION OF LGT RAIN ACROSS ENTIRE
FORECAST AREA LATE THIS AFTN/EARLY EVE. TROUGH AXIS WILL BE SLIDING
EAST ACROSS EAST-CENTRAL WISC BY 3Z. TEMPS TODAY WILL WARM INTO THE
50S FOR MUCH OF THE AREA...AND SOUTH OF I-80 A FEW 60S.

FOR TONIGHT ON THE BACK SIDE OF THE TROUGH...AND DEPARTING
PRECIP/CLOUD COVER...THERE IS SOME CONCERN THAT PATCHY FOG WILL
DEVELOP. UPSTREAM THIS HAS ALREADY BEEN NOTED...AND EXPECT THIS
SIMILAR SETUP TO OCCUR OVER A PORTION OF THE CWFA OVERNIGHT TONIGHT
BUT WILL HINGE UPON HOW QUICKLY CLOUDS WILL DEPART. LOWS WILL
GENERALLY BE IN THE MID/UPR 40S.

FRIDAY THROUGH SUNDAY...
A WEAK LOBE OF VORTICITY IS PROGGED TO SLIDE EAST ACROSS THE CENTRAL
PLAINS...ARRIVING OVER THE FORECAST AREA FRI AFTN/EVE. LOCAL ARW8KM
GUIDANCE AND NAM SUGGEST SOME LGT PRECIP MAY DEVELOP WITH THIS
SYSTEM...BUT NOT EXPECTING MUCH TO THE COVERAGE AT THIS TIME. HAVE
OPTED TO HOLD ONTO THE DRY FORECAST...BUT MAY NEED TO ADJUST POPS
SLIGHTLY TO REFLECT A FEW SPRINKLES/LGT RAIN SHOWERS. THEN BY EARLY
SAT MORNING ANTI-CYCLONIC FLOW BUILDS INTO THE REGION AND DRIES THE
ATMOSPHERE OUT. SFC RIDGE WILL REMAIN IN PLACE THRU SUN...THEN THE
MID-LVL RIDGE OVERHEAD FLATTENS AND THE FLOW BECOMES QUASI-ZONAL FOR
LATE IN THE WEEKEND INTO EARLY NEXT WEEK.

TEMPS FRI-SUN WILL BE SLOWLY MODERATING...WITH HIGHS IN THE 60S TO
PERHAPS A FEW LOW 70S FRI/SAT. A WEAK FRONTAL BOUNDARY WILL SLIDE
ACROSS THE REGION SUN AND COULD BRING TEMPS BACK INTO THE UPR
50S/LOW 60S.

MONDAY-WEDNESDAY...
ENSEMBLES ARE SHOWING THE WESTERN CONUS TROUGH PUSHING EAST BY EARLY
NEXT WEEK...HELPING TO SETUP THE POTENTIAL FOR PERIODIC CHANCES FOR
SHOWERS AND PERHAPS A FEW THUNDERSTORMS IN THE MON/TUE TIMEFRAME.
TEMPS MON SHUD REBOUND WITH A SOUTHWEST FLOW AND PUSH INTO THE UPR
60S/LOW 70S. THEN INCREASED CLOUD COVER TUE/WED WILL KEEP TEMPS IN
THE UPR 50S TO LOW 60S.

BEACHLER

&&

.AVIATION...

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

* SW WINDS GUSTING TO ARND 17KT THIS AFTN.

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL.

JEE

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

AN UPPER LEVEL WAVE IS APPROACHING FROM THE WEST WITH A LINE OF
SHOWERS EXTENDING INTO NORTHWEST IL. THE BAND OF SHOWERS WILL
CONTINUE EAST AND EXPECTING IT TO REMAIN RAGGED WITH HIT OR MISS
SHOWERS. RFD HAS THE BEST CHANCE OF SEEING AN ORGANIZED SHOWER
THIS AFTN. THE EASTERN TERMINALS WILL MOST LIKELY SEE SCATTERED
SHOWERS OR DRIZZLE THIS EVENING.

UPSTREAM OBS INDICATE THAT CIGS WILL FALL TO MVFR OR LOWER BEHIND
THE SHOWERS. HAVE THE MOST CONFIDENCE IN THE RFD TAF WITH IFR
CIGS. HAVE HIGH CONFIDENCE IN FOG AT RFD AND MEDIUM IN 1/4SM.

CLOUDS SHOULD LAST LONGER OVER THE EASTERN TERMINALS SO KEPT CIGS
IN THE MVFR RANGE WITH FOG ONLY AT DPA. CONDITIONS WILL IMPROVE TO
VFR QUICKLY TOMORROW AS THE CLOUDS SHIFT EAST. LIGHT WINDS
OVERNIGHT BECOME SW BTWN 5 AND 8 KT.

JEE

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

* MEDIUM CONFIDENCE IN COVERAGE AND OCCURRENCE OF -SHRA...MEDIUM-
  HIGH CONFIDENCE IN TIMING.

* MEDIUM CONFIDENCE IN MVFR CIGS AND TIMING...LOW CONFIDENCE IN
  HOW LOW THE CIGS WILL BE.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

* FRIDAY NIGHT...DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. WEST WINDS BECOMING SOUTHEAST.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST WINDS.

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 231946
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
246 PM CDT THU OCT 23 2014

.DISCUSSION...
303 AM CDT

A RIDGE OF HIGH PRESSURE STRETCHES FROM CENTRAL QUEBEC SOUTHWEST
THROUGH LOWER MICHIGAN INTO THE OHIO VALLEY. EARLY THIS MORNING THIS
RIDGE HAS BEEN ABLE TO KEEP CLOUD COVER DISPLACED WEST OF THE
REGION. BASED ON LATEST SFC OBS THE PRESSURE FALLS ARE NOT VERY
LARGE...WHICH COULD BE AN INDICATOR THAT LATER TODAY THE ABILITY FOR
THE ATMOSPHERE TO PRODUCE ABUNDANT MOISTURE/PRECIP MAY BE
DIMINISHED. IR IMAGERY EARLY THIS MORNING SHOWS A MOIST CHANNEL THAT
EXTENDS FROM THE CANADIAN BORDER OF THE UPPER MIDWEST...SOUTH TO
THE MEXICO BORDER/WESTERN GULF. THE PROGRESSION TO THE EAST HAS BEEN
VERY SLOW...AND LATEST HI-RES GUIDANCE INDICATES THAT AS THIS
FEATURE PUSHES EAST IT WILL ENCOUNTER MUCH DRIER AIR AND DIMINISH
THE COVERAGE AND INTENSITY OF PRECIP.

WITH THE LGT WINDS AND MINIMAL CLOUD COVER EARLY THIS MORNING...SOME
LOCATIONS ARE BEGINNING TO SEE PATCHY FOG DEVELOP...MAINLY ACROSS
NORTHWEST INDIANA. TEMPS HAVE BEEN ABLE TO RADIATE INTO THE MID
30S...WITH THE EXCEPTION OF THE FAR WESTERN CWFA WHERE A THIN
CIRRUS DECK HAS ARRIVED AND HELD TEMPS IN THE UPR 30S/NEAR 40.

AS THE MOIST CHANNEL SLOWLY SLIDES EAST TODAY...EXPECT A STEADY
THICKENING TO THE CLOUD COVER. WINDS WILL TURN SOUTHERLY WITH SOME
BETTER MIXING DEVELOPING AND PERHAPS BRINGING WINDS UP TO 10-20MPH
BY LATE AFTN. GUIDANCE HAS BECOME MORE PESSIMISTIC WITH PRECIP
COVERAGE/INTENSITY LATER TODAY...AND AS A RESULT HAVE BACKED OFF ON
POPS ALONG WITH QUANTITY OF PRECIP. THE NEAR SFC ENVIRONMENT STILL
LOOKS TO REMAIN RELATIVELY DRY...ALTHOUGH SOME MOISTENING WILL
OCCUR. EXPECT THE BEST PRECIP COVERAGE TO OCCUR FURTHER
NORTH...HOWEVER WILL CONTINUE THE MENTION OF LGT RAIN ACROSS ENTIRE
FORECAST AREA LATE THIS AFTN/EARLY EVE. TROUGH AXIS WILL BE SLIDING
EAST ACROSS EAST-CENTRAL WISC BY 3Z. TEMPS TODAY WILL WARM INTO THE
50S FOR MUCH OF THE AREA...AND SOUTH OF I-80 A FEW 60S.

FOR TONIGHT ON THE BACK SIDE OF THE TROUGH...AND DEPARTING
PRECIP/CLOUD COVER...THERE IS SOME CONCERN THAT PATCHY FOG WILL
DEVELOP. UPSTREAM THIS HAS ALREADY BEEN NOTED...AND EXPECT THIS
SIMILAR SETUP TO OCCUR OVER A PORTION OF THE CWFA OVERNIGHT TONIGHT
BUT WILL HINGE UPON HOW QUICKLY CLOUDS WILL DEPART. LOWS WILL
GENERALLY BE IN THE MID/UPR 40S.

FRIDAY THROUGH SUNDAY...
A WEAK LOBE OF VORTICITY IS PROGGED TO SLIDE EAST ACROSS THE CENTRAL
PLAINS...ARRIVING OVER THE FORECAST AREA FRI AFTN/EVE. LOCAL ARW8KM
GUIDANCE AND NAM SUGGEST SOME LGT PRECIP MAY DEVELOP WITH THIS
SYSTEM...BUT NOT EXPECTING MUCH TO THE COVERAGE AT THIS TIME. HAVE
OPTED TO HOLD ONTO THE DRY FORECAST...BUT MAY NEED TO ADJUST POPS
SLIGHTLY TO REFLECT A FEW SPRINKLES/LGT RAIN SHOWERS. THEN BY EARLY
SAT MORNING ANTI-CYCLONIC FLOW BUILDS INTO THE REGION AND DRIES THE
ATMOSPHERE OUT. SFC RIDGE WILL REMAIN IN PLACE THRU SUN...THEN THE
MID-LVL RIDGE OVERHEAD FLATTENS AND THE FLOW BECOMES QUASI-ZONAL FOR
LATE IN THE WEEKEND INTO EARLY NEXT WEEK.

TEMPS FRI-SUN WILL BE SLOWLY MODERATING...WITH HIGHS IN THE 60S TO
PERHAPS A FEW LOW 70S FRI/SAT. A WEAK FRONTAL BOUNDARY WILL SLIDE
ACROSS THE REGION SUN AND COULD BRING TEMPS BACK INTO THE UPR
50S/LOW 60S.

MONDAY-WEDNESDAY...
ENSEMBLES ARE SHOWING THE WESTERN CONUS TROUGH PUSHING EAST BY EARLY
NEXT WEEK...HELPING TO SETUP THE POTENTIAL FOR PERIODIC CHANCES FOR
SHOWERS AND PERHAPS A FEW THUNDERSTORMS IN THE MON/TUE TIMEFRAME.
TEMPS MON SHUD REBOUND WITH A SOUTHWEST FLOW AND PUSH INTO THE UPR
60S/LOW 70S. THEN INCREASED CLOUD COVER TUE/WED WILL KEEP TEMPS IN
THE UPR 50S TO LOW 60S.

BEACHLER

&&

.AVIATION...

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

* SW WINDS GUSTING TO ARND 17KT THIS AFTN.

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL.

JEE

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

AN UPPER LEVEL WAVE IS APPROACHING FROM THE WEST WITH A LINE OF
SHOWERS EXTENDING INTO NORTHWEST IL. THE BAND OF SHOWERS WILL
CONTINUE EAST AND EXPECTING IT TO REMAIN RAGGED WITH HIT OR MISS
SHOWERS. RFD HAS THE BEST CHANCE OF SEEING AN ORGANIZED SHOWER
THIS AFTN. THE EASTERN TERMINALS WILL MOST LIKELY SEE SCATTERED
SHOWERS OR DRIZZLE THIS EVENING.

UPSTREAM OBS INDICATE THAT CIGS WILL FALL TO MVFR OR LOWER BEHIND
THE SHOWERS. HAVE THE MOST CONFIDENCE IN THE RFD TAF WITH IFR
CIGS. HAVE HIGH CONFIDENCE IN FOG AT RFD AND MEDIUM IN 1/4SM.

CLOUDS SHOULD LAST LONGER OVER THE EASTERN TERMINALS SO KEPT CIGS
IN THE MVFR RANGE WITH FOG ONLY AT DPA. CONDITIONS WILL IMPROVE TO
VFR QUICKLY TOMORROW AS THE CLOUDS SHIFT EAST. LIGHT WINDS
OVERNIGHT BECOME SW BTWN 5 AND 8 KT.

JEE

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

* MEDIUM CONFIDENCE IN COVERAGE AND OCCURRENCE OF -SHRA...MEDIUM-
  HIGH CONFIDENCE IN TIMING.

* MEDIUM CONFIDENCE IN MVFR CIGS AND TIMING...LOW CONFIDENCE IN
  HOW LOW THE CIGS WILL BE.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

* FRIDAY NIGHT...DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. WEST WINDS BECOMING SOUTHEAST.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST WINDS.

&&

.MARINE...
244 PM CDT

HIGH PRESSURE WILL CONTINUE TO MOVE AWAY FROM LAKE MICHIGAN THROUGH
THE REMAINDER OF THE WEEK INTO THE WEEKEND AS LOW PRESSURE MOVES
EAST ACROSS THE CANADIAN PRAIRIES RESULTING IN GENERALLY SOUTH TO
SOUTHWEST FLOW OVER THE LAKE. THIS LOW WILL MOVE OVER JAMES BAY
SATURDAY DRAGGING A COLD FRONT ACROSS LAKE MICHIGAN AND TURNING
WINDS TO THE WEST/NORTHWEST. THE COLD AIR BEHIND THE FRONT IS SLOW
TO TRICKLE IN AND THE AIRMASS IS SHALLOW...SO WHILE THERE ARE
GALES JUST OFF THE DECK...IT DOESNT APPEAR THAT THEY WOULD MIX
DOWN TO THE LAKE SURFACE AT THIS TIME. WINDS WILL PEAK
OCCASIONALLY TO 30 KT SATURDAY AND SATURDAY NIGHT...THEN SHOULD
TREND DOWN THROUGH THE DAY SUNDAY AS HIGH PRESSURE BUILDS BACK
OVER THE REGION. ANOTHER AREA OF LOW PRESSURE IS PROGGED TO LIFT
ACROSS THE REGION AROUND MIDWEEK NEXT WEEK AND WILL ONCE AGAIN
BRING MODERATE WINDS TO LAKE MICHIGAN.

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/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 231755
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1255 PM CDT Thu Oct 23 2014

.UPDATE...
ISSUED AT 1042 AM CDT THU OCT 23 2014

Morning surface analysis shows weak frontal boundary across the
Plains, accompanied by a band of clouds and light showers from
Missouri northeastward into western Wisconsin. Airmass ahead of
this system is very dry, as shown by the 12z KILX upper air
sounding. As a result, precip will have a difficult time
spreading/developing eastward. Latest radar trends continue to
show a decrease in precip areal coverage across northern/central
Missouri, so have updated PoPs to slow the eastward progression of
the rain chances. Will continue to carry just slight chance PoPs
west of I-57 this afternoon. Further east, precip will hold off
until evening. Rainfall amounts will be quite light, only
amounting to a couple hundredths of an inch at best.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CDT THU OCT 23 2014

Main concern for today revolves around how much (if any) rainfall is
expected, as well as how soon it will arrive. Line of showers
upstream along a decaying cold front currently extends from the
upper Midwest into the central Plains. The front and driving upper
wave have not been making very quick progress to the east due to the
blocking upper low along the east coast and the weakening ridge
overhead it is trying to push into. This scenario should continue to
slow the arrival of the upstream front, as well as support its
continued weakening. With this thinking in mind, supported by a
strong consensus of the models, have removed all PoPs from this
morning, and limited them to slight chance for the afternoon across
northern 1/2 of forecast area (southern 1/2 of forecast area stays
dry). The slower arrival of the clouds and minimal precipitation
threat with this system should also allow temperatures to warm a bit
more than previously expected, with most locations able to make it
into the 60s.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 307 AM CDT THU OCT 23 2014

Shower threat to diminish quickly this evening as the wave passes,
as forecast soundings near Champaign only show a moist layer about
2000 feet thick and quickly eroding from the top down. However,
clouds will be slower to exit as a weak wave moves in behind the
initial one.

Dry frontal passage expected Friday night, as what little
precipitation is shown by the models stays to our north. The cooler
air lags behind this front some distance, so highs 70-75 are still
anticipated for Saturday. While Sunday briefly cools off with the
arrival of a fast moving high, the warming trend kicks in again
early next week.

Main focus for rain in the longer term remains with a broad trough
that will be emerging from the Rockies Monday evening. Latest ECMWF
run is coming more in line with the GFS solution, with better
phasing of this trough in the northern/southern streams. However,
the GFS is a tad faster, spreading rain in most areas late Monday
night while the ECMWF is more during the day Tuesday. Both models
quickly end the rain from northwest to southeast Tuesday night.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1255 PM CDT THU OCT 23 2014

Mid/high clouds continue to spread eastward across central
Illinois early this afternoon, while MVFR ceilings remain further
west along/behind a trough axis extending from eastern Iowa into
northern Missouri. As this feature moves slowly eastward, clouds
will lower later this afternoon into the evening and a few light
showers will be possible. HRRR guidance suggests low clouds will
stay west of the central Illinois terminals until this evening,
with MVFR ceilings arriving at KPIA by 01z then further east to
KCMI by 08z. Based on 12z NAM forecast soundings and latest HRRR,
think clearing late tonight into Friday morning will be much
slower than previously expected. While skies may temporarily clear
along/west of the Illinois late tonight, light winds/ample low-level
moisture will lead to fog and low cloud re-development. End result
will be overcast conditions until mid-morning Friday at the earliest.


&&

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

$$

UPDATE...Barnes
SHORT TERM...Bak
LONG TERM...Geelhart
AVIATION...Barnes







000
FXUS63 KILX 231755
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1255 PM CDT Thu Oct 23 2014

.UPDATE...
ISSUED AT 1042 AM CDT THU OCT 23 2014

Morning surface analysis shows weak frontal boundary across the
Plains, accompanied by a band of clouds and light showers from
Missouri northeastward into western Wisconsin. Airmass ahead of
this system is very dry, as shown by the 12z KILX upper air
sounding. As a result, precip will have a difficult time
spreading/developing eastward. Latest radar trends continue to
show a decrease in precip areal coverage across northern/central
Missouri, so have updated PoPs to slow the eastward progression of
the rain chances. Will continue to carry just slight chance PoPs
west of I-57 this afternoon. Further east, precip will hold off
until evening. Rainfall amounts will be quite light, only
amounting to a couple hundredths of an inch at best.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CDT THU OCT 23 2014

Main concern for today revolves around how much (if any) rainfall is
expected, as well as how soon it will arrive. Line of showers
upstream along a decaying cold front currently extends from the
upper Midwest into the central Plains. The front and driving upper
wave have not been making very quick progress to the east due to the
blocking upper low along the east coast and the weakening ridge
overhead it is trying to push into. This scenario should continue to
slow the arrival of the upstream front, as well as support its
continued weakening. With this thinking in mind, supported by a
strong consensus of the models, have removed all PoPs from this
morning, and limited them to slight chance for the afternoon across
northern 1/2 of forecast area (southern 1/2 of forecast area stays
dry). The slower arrival of the clouds and minimal precipitation
threat with this system should also allow temperatures to warm a bit
more than previously expected, with most locations able to make it
into the 60s.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 307 AM CDT THU OCT 23 2014

Shower threat to diminish quickly this evening as the wave passes,
as forecast soundings near Champaign only show a moist layer about
2000 feet thick and quickly eroding from the top down. However,
clouds will be slower to exit as a weak wave moves in behind the
initial one.

Dry frontal passage expected Friday night, as what little
precipitation is shown by the models stays to our north. The cooler
air lags behind this front some distance, so highs 70-75 are still
anticipated for Saturday. While Sunday briefly cools off with the
arrival of a fast moving high, the warming trend kicks in again
early next week.

Main focus for rain in the longer term remains with a broad trough
that will be emerging from the Rockies Monday evening. Latest ECMWF
run is coming more in line with the GFS solution, with better
phasing of this trough in the northern/southern streams. However,
the GFS is a tad faster, spreading rain in most areas late Monday
night while the ECMWF is more during the day Tuesday. Both models
quickly end the rain from northwest to southeast Tuesday night.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1255 PM CDT THU OCT 23 2014

Mid/high clouds continue to spread eastward across central
Illinois early this afternoon, while MVFR ceilings remain further
west along/behind a trough axis extending from eastern Iowa into
northern Missouri. As this feature moves slowly eastward, clouds
will lower later this afternoon into the evening and a few light
showers will be possible. HRRR guidance suggests low clouds will
stay west of the central Illinois terminals until this evening,
with MVFR ceilings arriving at KPIA by 01z then further east to
KCMI by 08z. Based on 12z NAM forecast soundings and latest HRRR,
think clearing late tonight into Friday morning will be much
slower than previously expected. While skies may temporarily clear
along/west of the Illinois late tonight, light winds/ample low-level
moisture will lead to fog and low cloud re-development. End result
will be overcast conditions until mid-morning Friday at the earliest.


&&

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

$$

UPDATE...Barnes
SHORT TERM...Bak
LONG TERM...Geelhart
AVIATION...Barnes







000
FXUS63 KLOT 231737
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1237 PM CDT THU OCT 23 2014

.DISCUSSION...
303 AM CDT

A RIDGE OF HIGH PRESSURE STRETCHES FROM CENTRAL QUEBEC SOUTHWEST
THROUGH LOWER MICHIGAN INTO THE OHIO VALLEY. EARLY THIS MORNING THIS
RIDGE HAS BEEN ABLE TO KEEP CLOUD COVER DISPLACED WEST OF THE
REGION. BASED ON LATEST SFC OBS THE PRESSURE FALLS ARE NOT VERY
LARGE...WHICH COULD BE AN INDICATOR THAT LATER TODAY THE ABILITY FOR
THE ATMOSPHERE TO PRODUCE ABUNDANT MOISTURE/PRECIP MAY BE
DIMINISHED. IR IMAGERY EARLY THIS MORNING SHOWS A MOIST CHANNEL THAT
EXTENDS FROM THE CANADIAN BORDER OF THE UPPER MIDWEST...SOUTH TO
THE MEXICO BORDER/WESTERN GULF. THE PROGRESSION TO THE EAST HAS BEEN
VERY SLOW...AND LATEST HI-RES GUIDANCE INDICATES THAT AS THIS
FEATURE PUSHES EAST IT WILL ENCOUNTER MUCH DRIER AIR AND DIMINISH
THE COVERAGE AND INTENSITY OF PRECIP.

WITH THE LGT WINDS AND MINIMAL CLOUD COVER EARLY THIS MORNING...SOME
LOCATIONS ARE BEGINNING TO SEE PATCHY FOG DEVELOP...MAINLY ACROSS
NORTHWEST INDIANA. TEMPS HAVE BEEN ABLE TO RADIATE INTO THE MID
30S...WITH THE EXCEPTION OF THE FAR WESTERN CWFA WHERE A THIN
CIRRUS DECK HAS ARRIVED AND HELD TEMPS IN THE UPR 30S/NEAR 40.

AS THE MOIST CHANNEL SLOWLY SLIDES EAST TODAY...EXPECT A STEADY
THICKENING TO THE CLOUD COVER. WINDS WILL TURN SOUTHERLY WITH SOME
BETTER MIXING DEVELOPING AND PERHAPS BRINGING WINDS UP TO 10-20MPH
BY LATE AFTN. GUIDANCE HAS BECOME MORE PESSIMISTIC WITH PRECIP
COVERAGE/INTENSITY LATER TODAY...AND AS A RESULT HAVE BACKED OFF ON
POPS ALONG WITH QUANTITY OF PRECIP. THE NEAR SFC ENVIRONMENT STILL
LOOKS TO REMAIN RELATIVELY DRY...ALTHOUGH SOME MOISTENING WILL
OCCUR. EXPECT THE BEST PRECIP COVERAGE TO OCCUR FURTHER
NORTH...HOWEVER WILL CONTINUE THE MENTION OF LGT RAIN ACROSS ENTIRE
FORECAST AREA LATE THIS AFTN/EARLY EVE. TROUGH AXIS WILL BE SLIDING
EAST ACROSS EAST-CENTRAL WISC BY 3Z. TEMPS TODAY WILL WARM INTO THE
50S FOR MUCH OF THE AREA...AND SOUTH OF I-80 A FEW 60S.

FOR TONIGHT ON THE BACK SIDE OF THE TROUGH...AND DEPARTING
PRECIP/CLOUD COVER...THERE IS SOME CONCERN THAT PATCHY FOG WILL
DEVELOP. UPSTREAM THIS HAS ALREADY BEEN NOTED...AND EXPECT THIS
SIMILAR SETUP TO OCCUR OVER A PORTION OF THE CWFA OVERNIGHT TONIGHT
BUT WILL HINGE UPON HOW QUICKLY CLOUDS WILL DEPART. LOWS WILL
GENERALLY BE IN THE MID/UPR 40S.

FRIDAY THROUGH SUNDAY...
A WEAK LOBE OF VORTICITY IS PROGGED TO SLIDE EAST ACROSS THE CENTRAL
PLAINS...ARRIVING OVER THE FORECAST AREA FRI AFTN/EVE. LOCAL ARW8KM
GUIDANCE AND NAM SUGGEST SOME LGT PRECIP MAY DEVELOP WITH THIS
SYSTEM...BUT NOT EXPECTING MUCH TO THE COVERAGE AT THIS TIME. HAVE
OPTED TO HOLD ONTO THE DRY FORECAST...BUT MAY NEED TO ADJUST POPS
SLIGHTLY TO REFLECT A FEW SPRINKLES/LGT RAIN SHOWERS. THEN BY EARLY
SAT MORNING ANTI-CYCLONIC FLOW BUILDS INTO THE REGION AND DRIES THE
ATMOSPHERE OUT. SFC RIDGE WILL REMAIN IN PLACE THRU SUN...THEN THE
MID-LVL RIDGE OVERHEAD FLATTENS AND THE FLOW BECOMES QUASI-ZONAL FOR
LATE IN THE WEEKEND INTO EARLY NEXT WEEK.

TEMPS FRI-SUN WILL BE SLOWLY MODERATING...WITH HIGHS IN THE 60S TO
PERHAPS A FEW LOW 70S FRI/SAT. A WEAK FRONTAL BOUNDARY WILL SLIDE
ACROSS THE REGION SUN AND COULD BRING TEMPS BACK INTO THE UPR
50S/LOW 60S.

MONDAY-WEDNESDAY...
ENSEMBLES ARE SHOWING THE WESTERN CONUS TROUGH PUSHING EAST BY EARLY
NEXT WEEK...HELPING TO SETUP THE POTENTIAL FOR PERIODIC CHANCES FOR
SHOWERS AND PERHAPS A FEW THUNDERSTORMS IN THE MON/TUE TIMEFRAME.
TEMPS MON SHUD REBOUND WITH A SOUTHWEST FLOW AND PUSH INTO THE UPR
60S/LOW 70S. THEN INCREASED CLOUD COVER TUE/WED WILL KEEP TEMPS IN
THE UPR 50S TO LOW 60S.

BEACHLER

&&

.AVIATION...

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

* SW WINDS GUSTING TO ARND 17KT THIS AFTN.

* SCATTERED -SHRA THIS EVENING.

* MVFR CIGS EXPECTED AFTER THE SHOWERS...IFR PSBL.

JEE

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

AN UPPER LEVEL WAVE IS APPROACHING FROM THE WEST WITH A LINE OF
SHOWERS EXTENDING INTO NORTHWEST IL. THE BAND OF SHOWERS WILL
CONTINUE EAST AND EXPECTING IT TO REMAIN RAGGED WITH HIT OR MISS
SHOWERS. RFD HAS THE BEST CHANCE OF SEEING AN ORGANIZED SHOWER
THIS AFTN. THE EASTERN TERMINALS WILL MOST LIKELY SEE SCATTERED
SHOWERS OR DRIZZLE THIS EVENING.

UPSTREAM OBS INDICATE THAT CIGS WILL FALL TO MVFR OR LOWER BEHIND
THE SHOWERS. HAVE THE MOST CONFIDENCE IN THE RFD TAF WITH IFR
CIGS. HAVE HIGH CONFIDENCE IN FOG AT RFD AND MEDIUM IN 1/4SM.

CLOUDS SHOULD LAST LONGER OVER THE EASTERN TERMINALS SO KEPT CIGS
IN THE MVFR RANGE WITH FOG ONLY AT DPA. CONDITIONS WILL IMPROVE TO
VFR QUICKLY TOMORROW AS THE CLOUDS SHIFT EAST. LIGHT WINDS
OVERNIGHT BECOME SW BTWN 5 AND 8 KT.

JEE


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

* MEDIUM CONFIDENCE IN COVERAGE AND OCCURRENCE OF -SHRA...MEDIUM-
  HIGH CONFIDENCE IN TIMING.

* MEDIUM CONFIDENCE IN MVFR CIGS AND TIMING...LOW CONFIDENCE IN
  HOW LOW THE CIGS WILL BE.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

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

* FRIDAY NIGHT...DRY. MVFR/FOG POSSIBLE.
* SATURDAY...DRY/VFR. GUSTY WEST/NORTHWEST WINDS.
* SUNDAY...DRY/VFR. WEST WINDS BECOMING SOUTHEAST.
* MONDAY...DRY/VFR. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.
* WEDNESDAY...CHANCE OF SHRA. WEST WINDS.

&&

.MARINE...

245 AM...FAIRLY ACTIVE PATTERN IS EXPECTED INTO EARLY NEXT WEEK.
HIGH PRESSURE EXTENDING FROM QUEBEC SOUTHWEST THROUGH THE CENTRAL
LAKES REGION WILL SPLIT TODAY...WITH THE HIGH WEAKENING AND MOVING
SOUTH INTO THE OHIO VALLEY TONIGHT. LOW PRESSURE OVER MANITOBA
WILL MOVE NORTH TODAY AS A WEAK COLD FRONT APPROACHES THE WESTERN
LAKES. THE GRADIENT WILL TIGHTEN SOME TODAY AHEAD OF THIS FRONT...
BUT THE FRONT IS EXPECTED TO DISSIPATE OVER THE WESTERN LAKES
TONIGHT. THUS WINDS MAY SHIFT WESTERLY FOR A TIME BUT WILL QUICKLY
GO BACK SOUTHWEST BY FRIDAY MORNING.

THE LOW LIFTING NORTH OVER MANITOBA WILL BE ABSORBED BY A STRONGER
LOW MOVING ACROSS CENTRAL CANADA TONIGHT AND FRIDAY. THIS LOW WILL
THEN MOVE ACROSS ONTARIO REACHING JAMES BAY SATURDAY AFTERNOON AS
IT DEEPENS. ANOTHER COLD FRONT TRAILING THIS LOW WILL MOVE ACROSS
LAKE MICHIGAN LATE FRIDAY NIGHT INTO SATURDAY MORNING. AHEAD OF
THIS FRONT...SOUTHERLY WINDS WILL INCREASE AGAIN. BEHIND THE FRONT
WINDS WILL SHIFT NORTHWEST 20-25KTS AND MAY APPROACH 30 KTS FOR A
TIME SATURDAY AFTERNOON INTO SATURDAY EVENING.

A WEAK RIDGE WILL MOVE FROM THE PLAINS SATURDAY TO THE WESTERN
LAKES SUNDAY...WITH WINDS QUICKLY SHIFTING FROM WEST SUNDAY
MORNING TO SOUTH/SOUTHEAST SUNDAY EVENING. THE GRADIENT WILL THEN
TIGHTEN WITH INCREASING SOUTHERLY WINDS AS A LARGE AREA OF LOW
PRESSURE DEVELOPS OVER THE PLAINS SUNDAY INTO MONDAY. CMS

&&

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

$$

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