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000
FXUS63 KLOT 290604
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1204 AM CST SAT NOV 29 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* POSSIBLE MVFR VSBYS WITH PATCHY FOG OVERNIGHT/PRE-DAWN.

* CHANCE OF MVFR REDEVELOPING AFT 00Z SUN.

* SOUTH WINDS ARND 5-7KT...INCREASING WITH GUSTS TO 20-24KT LATE
  MORNING THRU AFTN.

BEACHLER

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

IR IMAGERY SHOWS CONSIDERABLE MID/HIGH BASED CLOUDS SLIDING
EAST/SOUTHEAST ACROSS THE REGION. A WARM FRONTAL BOUNDARY WAS
BEGINNING TO LIFT NORTH...HOWEVER IT IS LIKELY NOT GOING TO ARRIVE
ACROSS THE TAF SITES UNTIL LATER THIS MORNING. PRIOR TO THIS WINDS
WILL REMAIN SOUTHERLY WITH PATCHY FOG DEVELOPING. IT APPEARS THE
BEST CHANCE FOR MVFR VSBYS FROM FOG WILL BE WEST OF ORD/MDW...SO
HAVE MAINTAINED RFD/DPA SEEING ARND 3SM VSBYS OVERNIGHT. BUT
CONFIDENCE IN REDUCTIONS HAS BACKED OFF DUE TO THE CONTINUED WINDS
KEEPING THINGS MIXED. GUIDANCE CONTINUES TO POINT TOWARDS DRY
CONDS THRU DAYBREAK AND CONTINUE THRU THIS EVE. BETTER MIXING
LATER THIS MORNING WILL LIKELY ALLOW GUSTY WINDS TO
REDEVELOP BETWEEN 20-24KT FOR THE BULK OF THE DAY INTO EARLY THIS
EVENING. THERE IS THE POTENTIAL THAT STRATUS CLOUDS MAY DEVELOP
ALONG THE WARM FRONT...AND THIS COULD POSE A SIGNIFICANT CHANGE TO
THE CURRENT VFR CONDS EXPECTED ACROSS THE TAF SITES LATER TODAY.

BEACHLER


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

* MEDIUM CONFIDENCE IN FOG DEVELOPING...HIGH CONFIDENCE IN VFR
  CONDS FOR ORD/MDW WITH FOG REMAINING WEST.

* MEDIUM CONFIDENCE IN WIND DIR/SPEED...HIGH CONFIDENCE IN GUSTS
  DEVELOPING.

* MEDIUM/HIGH CONFIDENCE IN DRY CONDS.

* MEDIUM CONFIDENCE IN CIGS FORECAST LATER TODAY.

BEACHLER

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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KLOT 290604
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1204 AM CST SAT NOV 29 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* POSSIBLE MVFR VSBYS WITH PATCHY FOG OVERNIGHT/PRE-DAWN.

* CHANCE OF MVFR REDEVELOPING AFT 00Z SUN.

* SOUTH WINDS ARND 5-7KT...INCREASING WITH GUSTS TO 20-24KT LATE
  MORNING THRU AFTN.

BEACHLER

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

IR IMAGERY SHOWS CONSIDERABLE MID/HIGH BASED CLOUDS SLIDING
EAST/SOUTHEAST ACROSS THE REGION. A WARM FRONTAL BOUNDARY WAS
BEGINNING TO LIFT NORTH...HOWEVER IT IS LIKELY NOT GOING TO ARRIVE
ACROSS THE TAF SITES UNTIL LATER THIS MORNING. PRIOR TO THIS WINDS
WILL REMAIN SOUTHERLY WITH PATCHY FOG DEVELOPING. IT APPEARS THE
BEST CHANCE FOR MVFR VSBYS FROM FOG WILL BE WEST OF ORD/MDW...SO
HAVE MAINTAINED RFD/DPA SEEING ARND 3SM VSBYS OVERNIGHT. BUT
CONFIDENCE IN REDUCTIONS HAS BACKED OFF DUE TO THE CONTINUED WINDS
KEEPING THINGS MIXED. GUIDANCE CONTINUES TO POINT TOWARDS DRY
CONDS THRU DAYBREAK AND CONTINUE THRU THIS EVE. BETTER MIXING
LATER THIS MORNING WILL LIKELY ALLOW GUSTY WINDS TO
REDEVELOP BETWEEN 20-24KT FOR THE BULK OF THE DAY INTO EARLY THIS
EVENING. THERE IS THE POTENTIAL THAT STRATUS CLOUDS MAY DEVELOP
ALONG THE WARM FRONT...AND THIS COULD POSE A SIGNIFICANT CHANGE TO
THE CURRENT VFR CONDS EXPECTED ACROSS THE TAF SITES LATER TODAY.

BEACHLER


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

* MEDIUM CONFIDENCE IN FOG DEVELOPING...HIGH CONFIDENCE IN VFR
  CONDS FOR ORD/MDW WITH FOG REMAINING WEST.

* MEDIUM CONFIDENCE IN WIND DIR/SPEED...HIGH CONFIDENCE IN GUSTS
  DEVELOPING.

* MEDIUM/HIGH CONFIDENCE IN DRY CONDS.

* MEDIUM CONFIDENCE IN CIGS FORECAST LATER TODAY.

BEACHLER

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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 10 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 290547
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1147 PM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 844 PM CST FRI NOV 28 2014

A Warm frontal boundary has pushed north of the central Illinois
forecast area with central Illinois now in a region of relatively
mild temperatures in the 30s and steady south winds around 10-15
mph. With still milder temperatures to the south, not expecting
temperatures to drop much overnight. Forecast soundings indicate
saturated conditions below 3000 feet elevation below a deep
temperature inversion, so hazy conditions and patchy fog remain a
possibility mainly Galesburg to Robinson southward where snowmelt
has been most pronounced. Current forecast package is on track
with these features and no significant updates are planned this
evening.

&&

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1147 PM CST FRI NOV 28 2014

VFR conditions across central/SE IL expected to deteriorate early
Saturday morning as low level moisture overruns a warm frontal
zone. Model forecast soundings indicate saturation down to surface
in this scenario, but based TAFs more on typical MOS guidance
values which look more likely. Went with MVFR cigs/vsby by 14Z
with cloud cover becoming scattered after 19Z. Winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours. Took low level
wind shear out of TAFs for this update as winds sampled by area
soundings have been a bit slower than previous model forecasts,
meaning total wind shear below 2 kft AGL will struggle to reach
30 kts.

&&

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

$$

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






000
FXUS63 KLOT 290302
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
902 PM CST FRI NOV 28 2014

.EVENING UPDATE...
820 PM CST

FORECAST GENERALLY ON TRACK FOR THE REMAINDER OF THE NIGHT.
TEMPERATURE TRENDS WILL BE A LITTLE TRICKY AS PERSISTENT WARM
ADVECTION AND INCREASING SLY FLOW WILL KEEP TEMPS STEADY OR SLOWLY
RISE THROUGH THE NIGHT. DEWPOINTS SHOULD ALSO BE ON A SLOW UPWARD
TREND AS WELL. WILL CONTINUE TO CARRY SOME MENTION OF PATCHY FOG
FOR GENERALLY THE NORTHERN AND WESTERN PORTIONS OF THE
CWA...ESPECIALLY LOCATIONS THAT HAD A LITTLE SNOW COVER.  HOWEVER...
FEEL THAT ANY PATCHY FOG THAT MAY DEVELOP WILL NOT BE PARTICULARLY
DENSE...WITH VISIBILITY DROPPING INTO THE 3-5SM RANGE. ANY FOG
FORMATION WOULD ALSO BE DEPENDENT ON WHETHER THE HIGH CLOUD
CURRENTLY STREAMING OVER THE AREA CAN CLEAR OUT ENOUGH TO ALLOW AT
LEAST A LITTLE DIURNAL COOLING DURG THE EARLY MORNING HOURS.

KREIN

&&

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* LOW CHANCE FOR MVFR CIGS ON SATURDAY AND SATURDAY EVENING.

* SOUTH-SOUTHEAST WINDS TONIGHT BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.


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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.


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

* MEDIUM-HIGH IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.


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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KLOT 290302
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
902 PM CST FRI NOV 28 2014

.EVENING UPDATE...
820 PM CST

FORECAST GENERALLY ON TRACK FOR THE REMAINDER OF THE NIGHT.
TEMPERATURE TRENDS WILL BE A LITTLE TRICKY AS PERSISTENT WARM
ADVECTION AND INCREASING SLY FLOW WILL KEEP TEMPS STEADY OR SLOWLY
RISE THROUGH THE NIGHT. DEWPOINTS SHOULD ALSO BE ON A SLOW UPWARD
TREND AS WELL. WILL CONTINUE TO CARRY SOME MENTION OF PATCHY FOG
FOR GENERALLY THE NORTHERN AND WESTERN PORTIONS OF THE
CWA...ESPECIALLY LOCATIONS THAT HAD A LITTLE SNOW COVER.  HOWEVER...
FEEL THAT ANY PATCHY FOG THAT MAY DEVELOP WILL NOT BE PARTICULARLY
DENSE...WITH VISIBILITY DROPPING INTO THE 3-5SM RANGE. ANY FOG
FORMATION WOULD ALSO BE DEPENDENT ON WHETHER THE HIGH CLOUD
CURRENTLY STREAMING OVER THE AREA CAN CLEAR OUT ENOUGH TO ALLOW AT
LEAST A LITTLE DIURNAL COOLING DURG THE EARLY MORNING HOURS.

KREIN

&&

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* LOW CHANCE FOR MVFR CIGS ON SATURDAY AND SATURDAY EVENING.

* SOUTH-SOUTHEAST WINDS TONIGHT BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.


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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.


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

* MEDIUM-HIGH IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.


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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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






000
FXUS63 KLOT 290302
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
902 PM CST FRI NOV 28 2014

.EVENING UPDATE...
820 PM CST

FORECAST GENERALLY ON TRACK FOR THE REMAINDER OF THE NIGHT.
TEMPERATURE TRENDS WILL BE A LITTLE TRICKY AS PERSISTENT WARM
ADVECTION AND INCREASING SLY FLOW WILL KEEP TEMPS STEADY OR SLOWLY
RISE THROUGH THE NIGHT. DEWPOINTS SHOULD ALSO BE ON A SLOW UPWARD
TREND AS WELL. WILL CONTINUE TO CARRY SOME MENTION OF PATCHY FOG
FOR GENERALLY THE NORTHERN AND WESTERN PORTIONS OF THE
CWA...ESPECIALLY LOCATIONS THAT HAD A LITTLE SNOW COVER.  HOWEVER...
FEEL THAT ANY PATCHY FOG THAT MAY DEVELOP WILL NOT BE PARTICULARLY
DENSE...WITH VISIBILITY DROPPING INTO THE 3-5SM RANGE. ANY FOG
FORMATION WOULD ALSO BE DEPENDENT ON WHETHER THE HIGH CLOUD
CURRENTLY STREAMING OVER THE AREA CAN CLEAR OUT ENOUGH TO ALLOW AT
LEAST A LITTLE DIURNAL COOLING DURG THE EARLY MORNING HOURS.

KREIN

&&

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* LOW CHANCE FOR MVFR CIGS ON SATURDAY AND SATURDAY EVENING.

* SOUTH-SOUTHEAST WINDS TONIGHT BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.


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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.


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

* MEDIUM-HIGH IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.


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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KILX 290244
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
844 PM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 844 PM CST FRI NOV 28 2014

A Warm frontal boundary has pushed north of the central Illinois
forecast area with central Illinois now in a region of relatively
mild temperatures in the 30s and steady south winds around 10-15
mph. With still milder temperatures to the south, not expecting
temperatures to drop much overnight. Forecast soundings indicate
saturated conditions below 3000 feet elevation below a deep
temperature inversion, so hazy conditions and patchy fog remain a
possibility mainly Galesburg to Robinson southward where snowmelt
has been most pronounced. Current forecast package is on track
with these features and no significant updates are planned this
evening.

&&

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 507 PM CST FRI NOV 28 2014

Mainly VFR conditions expected for the 24 hour TAF forecast
period. Main aviation forecast issues include possibility of fog
developing overnight due to pronounced low level moisture and
melting snow, mainly affecting KSPI, and low level wind shear
overnight throughout central IL. For fog, HRRR model indicating
widespread 6SM vsby which looks reasonable given steady winds
expected overnight. Could be areas MVFR vsby, but generally should
be in VFR category. Have included MVFR cigs at KSPI where snow
melt has been most pronounced. LLWS starting around 06Z is due to
40 kt SW jet at 2 kft AGL providing speed and directional shear
from S sfc winds. With wind profile becoming more unidirectional
during daytime hours, ended LLWS at 12-13Z. Sfc winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours.


&&

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

$$

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







000
FXUS63 KILX 290244
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
844 PM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 844 PM CST FRI NOV 28 2014

A Warm frontal boundary has pushed north of the central Illinois
forecast area with central Illinois now in a region of relatively
mild temperatures in the 30s and steady south winds around 10-15
mph. With still milder temperatures to the south, not expecting
temperatures to drop much overnight. Forecast soundings indicate
saturated conditions below 3000 feet elevation below a deep
temperature inversion, so hazy conditions and patchy fog remain a
possibility mainly Galesburg to Robinson southward where snowmelt
has been most pronounced. Current forecast package is on track
with these features and no significant updates are planned this
evening.

&&

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 507 PM CST FRI NOV 28 2014

Mainly VFR conditions expected for the 24 hour TAF forecast
period. Main aviation forecast issues include possibility of fog
developing overnight due to pronounced low level moisture and
melting snow, mainly affecting KSPI, and low level wind shear
overnight throughout central IL. For fog, HRRR model indicating
widespread 6SM vsby which looks reasonable given steady winds
expected overnight. Could be areas MVFR vsby, but generally should
be in VFR category. Have included MVFR cigs at KSPI where snow
melt has been most pronounced. LLWS starting around 06Z is due to
40 kt SW jet at 2 kft AGL providing speed and directional shear
from S sfc winds. With wind profile becoming more unidirectional
during daytime hours, ended LLWS at 12-13Z. Sfc winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours.


&&

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

$$

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







000
FXUS63 KILX 290244
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
844 PM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 844 PM CST FRI NOV 28 2014

A Warm frontal boundary has pushed north of the central Illinois
forecast area with central Illinois now in a region of relatively
mild temperatures in the 30s and steady south winds around 10-15
mph. With still milder temperatures to the south, not expecting
temperatures to drop much overnight. Forecast soundings indicate
saturated conditions below 3000 feet elevation below a deep
temperature inversion, so hazy conditions and patchy fog remain a
possibility mainly Galesburg to Robinson southward where snowmelt
has been most pronounced. Current forecast package is on track
with these features and no significant updates are planned this
evening.

&&

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 507 PM CST FRI NOV 28 2014

Mainly VFR conditions expected for the 24 hour TAF forecast
period. Main aviation forecast issues include possibility of fog
developing overnight due to pronounced low level moisture and
melting snow, mainly affecting KSPI, and low level wind shear
overnight throughout central IL. For fog, HRRR model indicating
widespread 6SM vsby which looks reasonable given steady winds
expected overnight. Could be areas MVFR vsby, but generally should
be in VFR category. Have included MVFR cigs at KSPI where snow
melt has been most pronounced. LLWS starting around 06Z is due to
40 kt SW jet at 2 kft AGL providing speed and directional shear
from S sfc winds. With wind profile becoming more unidirectional
during daytime hours, ended LLWS at 12-13Z. Sfc winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours.


&&

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

$$

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







000
FXUS63 KILX 290244
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
844 PM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 844 PM CST FRI NOV 28 2014

A Warm frontal boundary has pushed north of the central Illinois
forecast area with central Illinois now in a region of relatively
mild temperatures in the 30s and steady south winds around 10-15
mph. With still milder temperatures to the south, not expecting
temperatures to drop much overnight. Forecast soundings indicate
saturated conditions below 3000 feet elevation below a deep
temperature inversion, so hazy conditions and patchy fog remain a
possibility mainly Galesburg to Robinson southward where snowmelt
has been most pronounced. Current forecast package is on track
with these features and no significant updates are planned this
evening.

&&

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 507 PM CST FRI NOV 28 2014

Mainly VFR conditions expected for the 24 hour TAF forecast
period. Main aviation forecast issues include possibility of fog
developing overnight due to pronounced low level moisture and
melting snow, mainly affecting KSPI, and low level wind shear
overnight throughout central IL. For fog, HRRR model indicating
widespread 6SM vsby which looks reasonable given steady winds
expected overnight. Could be areas MVFR vsby, but generally should
be in VFR category. Have included MVFR cigs at KSPI where snow
melt has been most pronounced. LLWS starting around 06Z is due to
40 kt SW jet at 2 kft AGL providing speed and directional shear
from S sfc winds. With wind profile becoming more unidirectional
during daytime hours, ended LLWS at 12-13Z. Sfc winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours.


&&

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

$$

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







000
FXUS63 KILX 290244
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
844 PM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 844 PM CST FRI NOV 28 2014

A Warm frontal boundary has pushed north of the central Illinois
forecast area with central Illinois now in a region of relatively
mild temperatures in the 30s and steady south winds around 10-15
mph. With still milder temperatures to the south, not expecting
temperatures to drop much overnight. Forecast soundings indicate
saturated conditions below 3000 feet elevation below a deep
temperature inversion, so hazy conditions and patchy fog remain a
possibility mainly Galesburg to Robinson southward where snowmelt
has been most pronounced. Current forecast package is on track
with these features and no significant updates are planned this
evening.

&&

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 507 PM CST FRI NOV 28 2014

Mainly VFR conditions expected for the 24 hour TAF forecast
period. Main aviation forecast issues include possibility of fog
developing overnight due to pronounced low level moisture and
melting snow, mainly affecting KSPI, and low level wind shear
overnight throughout central IL. For fog, HRRR model indicating
widespread 6SM vsby which looks reasonable given steady winds
expected overnight. Could be areas MVFR vsby, but generally should
be in VFR category. Have included MVFR cigs at KSPI where snow
melt has been most pronounced. LLWS starting around 06Z is due to
40 kt SW jet at 2 kft AGL providing speed and directional shear
from S sfc winds. With wind profile becoming more unidirectional
during daytime hours, ended LLWS at 12-13Z. Sfc winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours.


&&

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

$$

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






000
FXUS63 KLOT 290225
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
825 PM CST FRI NOV 28 2014

.EVENING UPDATE...
820 PM CST

FORECAST GENERALLY ON TRACK FOR THE REMAINDER OF THE NIGHT.
TEMPERATURE TRENDS WILL BE A LITTLE TRICKY AS PERSISTENT WARM
ADVECTION AND INCREASING SLY FLOW WILL KEEP TEMPS STEADY OR SLOWLY
RISE THROUGH THE NIGHT. DEWPOINTS SHOULD ALSO BE ON A SLOW UPWARD
TREND AS WELL. WILL CONTINUE TO CARRY SOME MENTION OF PATCHY FOG
FOR GENERALLY THE NORTHERN AND WESTERN PORTIONS OF THE
CWA...ESPECIALLY LOCATIONS THAT HAD A LITTLE SNOW COVER.  HOWEVER...
FEEL THAT ANY PATCHY FOG THAT MAY DEVELOP WILL NOT BE PARTICULARLY
DENSE...WITH VISIBILITY DROPPING INTO THE 3-5SM RANGE. ANY FOG
FORMATION WOULD ALSO BE DEPENDENT ON WHETHER THE HIGH CLOUD
CURRENTLY STREAMING OVER THE AREA CAN CLEAR OUT ENOUGH TO ALLOW AT
LEAST A LITTLE DIURNAL COOLING DURG THE EARLY MORNING HOURS.

KREIN

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS THIS EVENING WITH A LOW CHANCE FOR MVFR CIGS AGAIN ON
  SATURDAY AND SATURDAY EVENING.

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* SOUTH-SOUTHEAST WINDS THIS EVENING BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.

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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.

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

* HIGH IN CIGS REMAINING MAINLY 1500-2000 FT THIS EVENING. MEDIUM
  IN DURATION OF CIGS.

* MEDIUM IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.

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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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






000
FXUS63 KLOT 290225
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
825 PM CST FRI NOV 28 2014

.EVENING UPDATE...
820 PM CST

FORECAST GENERALLY ON TRACK FOR THE REMAINDER OF THE NIGHT.
TEMPERATURE TRENDS WILL BE A LITTLE TRICKY AS PERSISTENT WARM
ADVECTION AND INCREASING SLY FLOW WILL KEEP TEMPS STEADY OR SLOWLY
RISE THROUGH THE NIGHT. DEWPOINTS SHOULD ALSO BE ON A SLOW UPWARD
TREND AS WELL. WILL CONTINUE TO CARRY SOME MENTION OF PATCHY FOG
FOR GENERALLY THE NORTHERN AND WESTERN PORTIONS OF THE
CWA...ESPECIALLY LOCATIONS THAT HAD A LITTLE SNOW COVER.  HOWEVER...
FEEL THAT ANY PATCHY FOG THAT MAY DEVELOP WILL NOT BE PARTICULARLY
DENSE...WITH VISIBILITY DROPPING INTO THE 3-5SM RANGE. ANY FOG
FORMATION WOULD ALSO BE DEPENDENT ON WHETHER THE HIGH CLOUD
CURRENTLY STREAMING OVER THE AREA CAN CLEAR OUT ENOUGH TO ALLOW AT
LEAST A LITTLE DIURNAL COOLING DURG THE EARLY MORNING HOURS.

KREIN

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS THIS EVENING WITH A LOW CHANCE FOR MVFR CIGS AGAIN ON
  SATURDAY AND SATURDAY EVENING.

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* SOUTH-SOUTHEAST WINDS THIS EVENING BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.

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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.

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

* HIGH IN CIGS REMAINING MAINLY 1500-2000 FT THIS EVENING. MEDIUM
  IN DURATION OF CIGS.

* MEDIUM IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.

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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KLOT 282331
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
531 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS THIS EVENING WITH A LOW CHANCE FOR MVFR CIGS AGAIN ON
  SATURDAY AND SATURDAY EVENING.

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* SOUTH-SOUTHEAST WINDS THIS EVENING BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.


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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.


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

* HIGH IN CIGS REMAINING MAINLY 1500-2000 FT THIS EVENING. MEDIUM
  IN DURATION OF CIGS.

* MEDIUM IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.


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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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






000
FXUS63 KLOT 282331
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
531 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS THIS EVENING WITH A LOW CHANCE FOR MVFR CIGS AGAIN ON
  SATURDAY AND SATURDAY EVENING.

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* SOUTH-SOUTHEAST WINDS THIS EVENING BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.


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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.


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

* HIGH IN CIGS REMAINING MAINLY 1500-2000 FT THIS EVENING. MEDIUM
  IN DURATION OF CIGS.

* MEDIUM IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.


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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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






000
FXUS63 KLOT 282331
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
531 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS THIS EVENING WITH A LOW CHANCE FOR MVFR CIGS AGAIN ON
  SATURDAY AND SATURDAY EVENING.

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* SOUTH-SOUTHEAST WINDS THIS EVENING BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.


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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.


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

* HIGH IN CIGS REMAINING MAINLY 1500-2000 FT THIS EVENING. MEDIUM
  IN DURATION OF CIGS.

* MEDIUM IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.


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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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






000
FXUS63 KLOT 282331
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
531 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS THIS EVENING WITH A LOW CHANCE FOR MVFR CIGS AGAIN ON
  SATURDAY AND SATURDAY EVENING.

* CHANCE FOR MVFR VISIBILITY LATER TONIGHT INTO EARLY SATURDAY
  MORNING.

* SOUTH-SOUTHEAST WINDS THIS EVENING BECOMING SOUTH-SOUTHWEST AND
  GUSTY ON SATURDAY.


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

WARM AND MOIST AIR IS GRADUALLY RETURNING TO THE REGION AS LOW
PRESSURE ORGANIZES ACROSS THE PLAINS. AN INITIAL WARM FRONT IS
DRAPED FROM JUST SOUTH OF THE QUAD CITIES TO NORTHWEST INDIANA AND
IMMEDIATELY NORTH OF THIS IS AN AREA OF MVFR CIGS. DUE TO THE
LIKELIHOOD OF THIS WARM FRONT NOT RUSHING NORTHWARD THIS
EVENING...HAVE EXTENDED THE DURATION OF MVFR CIGS. WHILE THERE
COULD BE SOME GRADUAL LOWERING IN THESE CIGS THEY SHOULD REMAIN IN
THE MVFR CATEGORY. EXPECT THESE CIGS TO SLOWLY INCH THEIR WAY
NORTHWARD BY LATE THIS EVENING OR OVERNIGHT AS SOUTH-SOUTHEAST
SURFACE WINDS CONTINUE. INCREASING SURFACE DEW POINTS HAVE HELPED
ALREADY RESULT IN SOME LIGHT HAZE AND DO THINK MVFR FOG WILL
BECOME MORE WIDESPREAD NORTH OF INTERSTATE 80 WITH SOME IFR
POTENTIAL...THOUGH MAINLY ONLY AT OUTLYING TAF SITES.

MORE STRATUS IS EXPECTED TO DEVELOP ACROSS THE ARKLATEX REGION
LATER TONIGHT AND EXPAND NORTHEAST BEHIND THE PRIMARY WARM FRONT.
MODEL DEPICTED LOW-LEVEL MOISTURE VS ACARS OBSERVED MOISTURE OVER
THIS REGION INDICATE THE MODELS ARE ALREADY TOO MOIST WHICH LEADS
TO QUESTIONS ON HOW WIDESPREAD AND FAR NORTH STRATUS WILL REACH ON
SATURDAY. FOR RIGHT NOW HAVE LEANED TOWARD NORTHERN ILLINOIS
REMAINING OUT OF THE WIDESPREAD STRATUS ALTHOUGH SOME IS PROBABLE
DOWNSTATE AND INTO INDIANA. SOUTH-SOUTHWEST WINDS WILL BE GUSTY
ON SATURDAY ESPECIALLY IF THERE IS NO WIDESPREAD STRATUS.


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

* HIGH IN CIGS REMAINING MAINLY 1500-2000 FT THIS EVENING. MEDIUM
  IN DURATION OF CIGS.

* MEDIUM IN VISIBILITY FORECAST TONIGHT.

* MEDIUM THAT ANY IFR/MVFR STRATUS WILL STAY SOUTH OF ORD AND MDW
  ON SATURDAY AND SATURDAY EVENING.

* HIGH IN SUSTAINED WIND SPEEDS AND MEDIUM IN GUSTS ON
  SATURDAY...AS THAT WILL DEPEND ON DEGREE OF CLOUD COVER.


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

SUNDAY...MVFR CIGS POSSIBLE. SOUTHWEST WINDS BECOMING NORTHWEST.
MONDAY...VFR. NORTHWEST WINDS BECOMING NORTH BY EVENING.
TUESDAY...VFR. SOUTH WINDS.
WEDNESDAY...VFR. WEST WINDS.
THURSDAY...CHANCE OF RAIN AND SNOW. EAST WINDS.

MTF

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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






000
FXUS63 KILX 282307
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
507 PM CST Fri Nov 28 2014

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 507 PM CST FRI NOV 28 2014

Mainly VFR conditions expected for the 24 hour TAF forecast
period. Main aviation forecast issues include possibility of fog
developing overnight due to pronounced low level moisture and
melting snow, mainly affecting KSPI, and low level wind shear
overnight throughout central IL. For fog, HRRR model indicating
widespread 6SM vsby which looks reasonable given steady winds
expected overnight. Could be areas MVFR vsby, but generally should
be in VFR category. Have included MVFR cigs at KSPI where snow
melt has been most pronounced. LLWS starting around 06Z is due to
40 kt SW jet at 2 kft AGL providing speed and directional shear
from S sfc winds. With wind profile becoming more unidirectional
during daytime hours, ended LLWS at 12-13Z. Sfc winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours.

&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Onton







000
FXUS63 KILX 282307
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
507 PM CST Fri Nov 28 2014

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 507 PM CST FRI NOV 28 2014

Mainly VFR conditions expected for the 24 hour TAF forecast
period. Main aviation forecast issues include possibility of fog
developing overnight due to pronounced low level moisture and
melting snow, mainly affecting KSPI, and low level wind shear
overnight throughout central IL. For fog, HRRR model indicating
widespread 6SM vsby which looks reasonable given steady winds
expected overnight. Could be areas MVFR vsby, but generally should
be in VFR category. Have included MVFR cigs at KSPI where snow
melt has been most pronounced. LLWS starting around 06Z is due to
40 kt SW jet at 2 kft AGL providing speed and directional shear
from S sfc winds. With wind profile becoming more unidirectional
during daytime hours, ended LLWS at 12-13Z. Sfc winds generally
S10-15 kts. Gusts 20-25 kts during afternoon hours.

&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Onton






000
FXUS63 KLOT 282138
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
338 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS OF 1500-2200 FT THROUGH AT 00Z-01Z WITH A LOW CHANCE
  OF LINGERING LONGER.

* SOUTH-SOUTHEAST WINDS GUSTING 15-20 KT THROUGH 00Z.

* LOW CHANCE FOR MVFR CIGS TO LINGER THIS EVENING.

MDB/MTF


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

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB


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

* MEDIUM-HIGH IN CIGS AND WINDS.

MDB/MTF


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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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

$$

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

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





000
FXUS63 KLOT 282138
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
338 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

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

* MVFR CIGS OF 1500-2200 FT THROUGH AT 00Z-01Z WITH A LOW CHANCE
  OF LINGERING LONGER.

* SOUTH-SOUTHEAST WINDS GUSTING 15-20 KT THROUGH 00Z.

* LOW CHANCE FOR MVFR CIGS TO LINGER THIS EVENING.

MDB/MTF


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

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB


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

* MEDIUM-HIGH IN CIGS AND WINDS.

MDB/MTF


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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

.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 282110
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
310 PM CST Fri Nov 28 2014

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1133 AM CST FRI NOV 28 2014

Gusty southerly winds to around 20-25 knots will continue for a
few more hours, before the gusts start to subside with sunset.
Have added mention of LLWS at all TAF sites, as southwesterly jet
of 40-45 knots starts to move in mid to late evening, persisting
much of the night.

Have kept most of the TAF sites VFR for now. Main concern will be
near KSPI, which will be melting some snow today. Most of the
models are showing a good inversion around 2000 feet developing
tonight, which would trap this additional moisture in place. Have
added some MVFR ceilings here for later tonight.


&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Geelhart








000
FXUS63 KILX 282110
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
310 PM CST Fri Nov 28 2014

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST FRI NOV 28 2014

Southerly winds gusting over 30 mph at times this afternoon, as
35-40 knot winds around 3000 feet (per radar wind profile) get mixed
down to the surface. This has helped erode much of the snow cover,
with visible satellite imagery showing much of the remaining snow in
areas from Rushville to Jacksonville southeast to Effingham.
Temperatures have reached the upper 30s over most of the forecast
area with some 40s across the far southwest as the snow disappears.

Mid and high clouds continue to stream southeast along the warm
frontal boundary, which was stretching from northwest Iowa across
northern Illinois and central Indiana. Will continue to see periods
of clouds through the night over our area. Despite winds staying up
during the night, have added some patchy fog to the forecast for
tonight due to the snow melt, as forecast soundings are showing a
good inversion around 2000 feet to trap the moisture in place.
Temperatures expected to fall only modestly this evening and then
level off most of the night, as south-southwest low level jet around
925 mb starts to ramp up. Consequently, lows should remain above
freezing.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 310 PM CST FRI NOV 28 2014

Saturday will see another round of gusty south winds bringing warmer
air into the region. 850mb temps are projected to climb into the
12-14C range, which would support highs well into the 50s in dry
mixing conditions. The increasing moisture could lead to increasing
cloudiness, which would temper how warm the surface temps would
climb. The better chances of enhanced lift in the strong waa flows
looks to be in the southeastern half of our forecast area, where
warm frontogenesis will be a bit more focused. With added lift in
that area, will increase cloud cover in the SE areas, with less
clouds NW toward GBG. SE areas may even see a few sprinkles at
times, which the NAM and GFS are suggesting with their output of QPF
on Saturday. Did not introduce any precip with this update, but did
bump up highs a couple degrees above guidance in most areas, with
less increase in the cloudier ESE areas. Highs should reach the mid
50 in most areas, with upper 50s in areas with less clouds.

A strong cold front still looks on track for Sunday, with decent
agreement among the models on frontal passage Sunday afternoon. The
increasing SW low level jet ahead of the front across SE IL will aid
the lift in the pre-frontal circulation, triggering scattered
showers mainly east of I-55, especially in the afternoon. High temps
will likely occur before Noon in the NW half of the area, with
strong NW winds behind the front bringing a sharp cool down the
remainder of the day. Mid-day highs will range from the upper 40s
near GBG to the low-mid 60s near LWV. The 1040mb Canadian high will
blast into IL through Sunday night, pushing temps below freezing by
Monday morning. There is some question to if the precipitation will
continue fall after the temps fall below freezing. With a lack of
ice crystals above the shallow surface moisture, any continued
precipitation would most likely reach the ground as freezing
rain/drizzle instead of snow. That could cause some problems for the
morning commute on Monday, mainly along and just south of the I-70
corridor.

The continued surge of cold air on Monday will keep highs mainly in
the 20s, with some low 30s S of I-70. Some light freezing rain or
rain will be possible Monday morning S of I-70, with diminishing
chances in the afternoon as the front sags away to the SE.

The cold surface high will slide east across the Great Lakes on
Tuesday, allowing a quick return of southerly winds by Tuesday
afternoon. The warming winds should combine with plenty of sunshine
to help most areas climb above freezing. Wednesday could see
increasing mid and high clouds, but highs are still forecast to
reach the upper 30s north of Peoria and low to mid 40s south.

Differences remain the extended forecast for Wed night through
Friday, but not as dramatic as the last few days.
The GFS continues to develop low pressure in the south central
Plains and moving the low across IL in the Wed-Thur time frame.
However, now the ECMWF is showing a shortwave in the general
vicinity, triggering showers about 18-24 hours after the GFS. The
Canadian GEM is also indicating that shortwave in line with the
ECMWF timing. We have not altered the precip forecast much, with
slight chances Wed night in the west, and chance PoPs in most areas
Thur and Thur night. Slight chances were held into Friday SE of the
IL river. Based on temp profiles, we went with snow chances at night
and rain during the day for now, but this will need refining future
model runs arrive.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1133 AM CST FRI NOV 28 2014

Gusty southerly winds to around 20-25 knots will continue for a
few more hours, before the gusts start to subside with sunset.
Have added mention of LLWS at all TAF sites, as southwesterly jet
of 40-45 knots starts to move in mid to late evening, persisting
much of the night.

Have kept most of the TAF sites VFR for now. Main concern will be
near KSPI, which will be melting some snow today. Most of the
models are showing a good inversion around 2000 feet developing
tonight, which would trap this additional moisture in place. Have
added some MVFR ceilings here for later tonight.


&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Geelhart







000
FXUS63 KLOT 282101
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
301 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMEPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KLOT 282101
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
301 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMEPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KLOT 282101
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
301 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMEPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KLOT 282101
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
301 PM CST FRI NOV 28 2014

.SHORT TERM...
300 PM CST

THROUGH SUNDAY...

A TEMPERATURE ROLLER COASTER RIDE OVER THE NEXT FEW DAYS IS THE MAIN
FOCUS OF THE FORECAST.

TONIGHT AND SATURDAY...

W/V IMAGERY SHOWS THAT HIGHLY AMPLIFIED PATTERN THAT
RESULTED IN ALL THE COLD AIR THE PAST FEW WEEKS IS RAPIDLY BEING
REPLACED BY ZONAL MID AND UPPER FLOW. A VERY WARM AND DRY AIR MASS
OVER THE CENTRAL PLAINS THIS MORNING WILL RAPIDLY BE ADVECTED INTO
THE AREA TONIGHT INTO SATURDAY BY DECENT SOUTHWEST FLOW AT H85. IN
ADDITION...A SFC WARM FRONTAL FEATURE IS ALSO BEGINNING THE
PROCESS OF LIFTING WARMER AND MORE MOIST AIR NORTHWARD THIS
AFTERNOON...WHICH RESULTED IN PATCHY LOW CLOUD DEVELOPMENT FOR A
TIME. STILL SOME CONCERN FOR LIGHT QPF EARLY THIS EVENING IN THE
FAR NORTH...WHICH IF ANY COULD REACH THE GROUND WOULD LIKELY BE IN
THE FORM OF LIGHT SNOW OR PELLETS DUE TO WET BULB PROCESSES. THINK
THE FOCUS WILL BE JUST NORTH OF THE CWA SO HAVE REMOVED SLIGHT
POPS BUT WILL NEED TO MONITOR THIS. THE MODELS APPEAR TO BE
STRUGGLING GREATLY WITH AMOUNT OF SNOW COVER ON THE GROUND OVER
THE CWA...ESPECIALLY THE NAM AND RAP. EXPECTING THAT SKIES WILL
TREND TO PARTLY CLOUDY TONIGHT...WHICH DESPITE STEADY SOUTHERLY
WINDS...COULD SET THE STAGE FOR PATCHY GROUND FOG OVER STILL SNOW
COVERED AREAS. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR
SLOWLY RISE OVERNIGHT.

THE SNOW COVER/CLOUD COVER ISSUE COMES TO A HEAD ON SATURDAY.
LOOKING IN THE WARM SECTOR OF THE DEVELOPING HIGH PLAINS LOW
TODAY...THERE IS LITTLE IN THE WAY OF CLOUD COVER. HOWEVER...MANY
MODELS INSIST ON BREAKING OUT LOW CLOUDS/LOW LEVEL SATURATION. WITH
A +12 TO +15C AIR MASS AT 850 MB MOVING INTO THE AREA...SUSPECT THAT
MUCH OF THE GUIDANCE IS BIASED FAR TOO COLD TOMORROW. IT SEEMS THAT
THE CANADIAN GLOBAL AND REGIONAL MODELS...WHICH TYPICALLY DO BETTER
IN COOL SEASON WARM-UPS...HAVE A MUCH BETTER HANDLE ON LIKELY LACK
OF LOW LEVEL CLOUD COVER...WHICH CAN BE SEEN ON FORECAST SOUNDINGS.
HAVE BUMPED UP TEMPERATURES IN THE LOW-MID 50S AREA WIDE...EXCEPT
FOR NEAR 50 ALONG IMMEDIATE WI BORDER WHERE 2-4 INCHES OF SNOW DEPTH
WERE REPORTED TODAY. HAVE CONSERVATIVELY LOWERED SKY COVER
PERCENTAGE AS WELL...AS OTHER THAN SOME MID/HIGH CLOUDS...IT APPEARS
A DECENT AMOUNT OF SUN COULD BE IN STORE.

SATURDAY NIGHT AND SUNDAY...

A VERY MILD SATURDAY NIGHT WILL ALLOW FOR A ANOTHER WARM SUNDAY
FOR PARTS OF THE CWA. HOWEVER...THERE WILL BE AN ARCTIC FRONT
SURGING SOUTHWARD AHEAD OF EXPANSIVE AND STRONG HIGH PRESSURE OVER
THE NORTHERN PLAINS. TIMING OF THIS FRONT IS KEY AND NOW THINK IT
WILL BE INTO THE NORTHERN CWA BY LATE AM/MID DAY...CAPPING HIGHS
NEAR 40/LOW 40S THERE. FAR SOUTHERN CWA COULD CONCEIVABLY APPROACH
60 DEGREES GIVEN MORE TIME TO WARM UP AHEAD OF THE FRONT. UPPER
FORCING IS NOT IMPRESSIVE WITH THE FRONT BUT LOW LEVEL MOISTURE
CONVERGENCE AND DECENT LOW/MID F-GEN DUE TO QUICKLY TIGHTENING
THERMAL GRADIENT COULD BE ENOUGH FOR ISOLATED/WIDELY SCT`D RAIN
SHOWERS MAINLY IN AFTERNOON IN SOUTHEAST 1/3 OF CWA.

RC

&&

.LONG TERM...
249 PM CST

SUNDAY NIGHT THROUGH FRIDAY...

LOW LEVEL ARCTIC AIR MASS WILL QUICKLY SPILL SOUTHWARD SUNDAY NIGHT
AS UPPER TROUGH BRIEFLY DIGS ACROSS NORTHERN TIER AND STRONG HIGH
PRESSURE SPREADS SOUTHEAST. AIR MASS LOOKS FAIRLY DRY OVER THE
LAKE...BUT LAKE EFFECT PARAMETERS ARE MARGINALLY FAVORABLE FOR SOME
LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY MORNING FOR THE
SOUTHEAST TIP OF THE LAKE. TEMPERATURES WILL TUMBLE INTO THE TEENS
AND 20S BY MONDAY MORNING...WITH CONTINUED COLD ADVECTION RESULTING
IN A WELL BELOW NORMAL START TO METEOROLOGICAL WINTER. HIGHS WILL
LIKELY  BE IN 20S CWA WIDE/IF NOT COLDER IN FAR NORTH...FOLLOWED BY
A COLD NIGHT MONDAY NIGHT AS 1040 MB+ HIGH PRESSURE MOVES OVERHEAD.
PATTERN WILL QUICKLY TURN ZONAL AGAIN BUT COLD AIR REMAINING JUST TO
NORTH SHOULD KEEP TEMEPERATURES ON THE COOLER SIDE THROUGH MID WEEK.
BIG TIMING DIFFERENCES IN THE LATE WEEK TIMEFRAME WITH ECMWF AND
GFS/GEFS...AS ECMWF KEEPS DRY/COOL HIGH LOCKED IN TIL THURSDAY
MORNING...WHILE GFS BREAKS OUT PRECIP ALONG BAROCLINIC ZONE
WEDNESDAY NIGHT INTO THURSDAY. HAVE MAINTAINED LOW GUIDANCE BLEND
POPS BUT CONFIDENCE IS FAIRLY LOW IN TEMPS AND SENSIBLE WX
WEDS-THURSDAY...THOUGH A MILD PERIOD DOES LOOK TO BE IN THE CARDS
LATE NEXT WORK WEEK INTO THE WEEKEND.

RC

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

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





000
FXUS63 KLOT 281925
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
125 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

.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 281925
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
125 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

.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 281920
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
120 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORTHERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281920
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
120 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORTHERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281920
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
120 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORTHERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281920
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
120 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORTHERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281807
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1207 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* SOUTH-SOUTHEAST WINDS GUSTING NEAR 20 KT THROUGH THE AFTERNOON.

* LOW CHANCE FOR MVFR CLOUDS TO DEVELOP EARLY EVENING.

MDB

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

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

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

* HIGH CONFIDENCE IN WIND TRENDS.

* MEDIUM CONFIDENCE THAT POTENTIAL FOR MVFR CLOUDS THIS EVENING IS
  LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORTHERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281807
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1207 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* SOUTH-SOUTHEAST WINDS GUSTING NEAR 20 KT THROUGH THE AFTERNOON.

* LOW CHANCE FOR MVFR CLOUDS TO DEVELOP EARLY EVENING.

MDB

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

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

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

* HIGH CONFIDENCE IN WIND TRENDS.

* MEDIUM CONFIDENCE THAT POTENTIAL FOR MVFR CLOUDS THIS EVENING IS
  LOW.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORTHERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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
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000
FXUS63 KILX 281733
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1133 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1133 AM CST FRI NOV 28 2014

Gusty southerly winds to around 20-25 knots will continue for a
few more hours, before the gusts start to subside with sunset.
Have added mention of LLWS at all TAF sites, as southwesterly jet
of 40-45 knots starts to move in mid to late evening, persisting
much of the night.

Have kept most of the TAF sites VFR for now. Main concern will be
near KSPI, which will be melting some snow today. Most of the
models are showing a good inversion around 2000 feet developing
tonight, which would trap this additional moisture in place. Have
added some MVFR ceilings here for later tonight.

&&

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

$$

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






000
FXUS63 KILX 281733
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1133 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1133 AM CST FRI NOV 28 2014

Gusty southerly winds to around 20-25 knots will continue for a
few more hours, before the gusts start to subside with sunset.
Have added mention of LLWS at all TAF sites, as southwesterly jet
of 40-45 knots starts to move in mid to late evening, persisting
much of the night.

Have kept most of the TAF sites VFR for now. Main concern will be
near KSPI, which will be melting some snow today. Most of the
models are showing a good inversion around 2000 feet developing
tonight, which would trap this additional moisture in place. Have
added some MVFR ceilings here for later tonight.

&&

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

$$

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






000
FXUS63 KILX 281733
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1133 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1133 AM CST FRI NOV 28 2014

Gusty southerly winds to around 20-25 knots will continue for a
few more hours, before the gusts start to subside with sunset.
Have added mention of LLWS at all TAF sites, as southwesterly jet
of 40-45 knots starts to move in mid to late evening, persisting
much of the night.

Have kept most of the TAF sites VFR for now. Main concern will be
near KSPI, which will be melting some snow today. Most of the
models are showing a good inversion around 2000 feet developing
tonight, which would trap this additional moisture in place. Have
added some MVFR ceilings here for later tonight.

&&

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

$$

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






000
FXUS63 KILX 281733
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1133 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1133 AM CST FRI NOV 28 2014

Gusty southerly winds to around 20-25 knots will continue for a
few more hours, before the gusts start to subside with sunset.
Have added mention of LLWS at all TAF sites, as southwesterly jet
of 40-45 knots starts to move in mid to late evening, persisting
much of the night.

Have kept most of the TAF sites VFR for now. Main concern will be
near KSPI, which will be melting some snow today. Most of the
models are showing a good inversion around 2000 feet developing
tonight, which would trap this additional moisture in place. Have
added some MVFR ceilings here for later tonight.

&&

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

$$

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






000
FXUS63 KLOT 281611
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1011 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* SOUTH WINDS INCREASING WITH GUSTS NEAR 20 KT BY MIDDAY.

* CHANCE FOR MVFR CIGS TO DEVELOP LATE THIS AFTERNOON/EARLY
  EVENING.

* POSSIBLE PATCHY FOG DEVELOPING OVERNIGHT.

MDB

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

SNOW HAS MOVED BEYOND THE TERMINALS WITH CIGS QUICKLY IMPROVING TO
10000 FT OR BETTER. WINDS ARE STARTING TO GUST AS WARMING OCCURS
AND STILL EXPECT GUSTS NEAR 20 KT. STILL MONITORING LOW CLOUD
POTENTIAL LATER THIS AFTERNOON INTO TONIGHT. GUIDANCE IS CURRENTLY
OVERDONE ON LOW CLOUD UPSTREAM AND HAVE BEEN DISCUSSING THAT THIS
MAY CONTINUE TO BE THE CASE INTO THE AFTERNOON. WILL CONTINUE WITH
TAF AS-IS FOR THE AFTERNOON/OVERNIGHT FOR NOW. LOW CLOUD COVER
WOULD NEED TO START DEVELOPING TO THE WEST AND SOUTHWEST EARLY
THIS AFTERNOON FOR GUIDANCE TO VERIFY SO WILL HOPEFULLY BE ABLE TO
HAVE A BETTER GAGE IN THE NEXT FEW HOURS.

MDB

FROM 12Z...

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAINED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER

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

* HIGH CONFIDENCE IN WIND TRENDS.

* LOW CONFIDENCE IN MVFR CIG POTENTIAL LATE THIS AFTERNOON/EARLY
  THIS EVENING.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPMENT OVERNIGHT.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281611
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1011 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* SOUTH WINDS INCREASING WITH GUSTS NEAR 20 KT BY MIDDAY.

* CHANCE FOR MVFR CIGS TO DEVELOP LATE THIS AFTERNOON/EARLY
  EVENING.

* POSSIBLE PATCHY FOG DEVELOPING OVERNIGHT.

MDB

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

SNOW HAS MOVED BEYOND THE TERMINALS WITH CIGS QUICKLY IMPROVING TO
10000 FT OR BETTER. WINDS ARE STARTING TO GUST AS WARMING OCCURS
AND STILL EXPECT GUSTS NEAR 20 KT. STILL MONITORING LOW CLOUD
POTENTIAL LATER THIS AFTERNOON INTO TONIGHT. GUIDANCE IS CURRENTLY
OVERDONE ON LOW CLOUD UPSTREAM AND HAVE BEEN DISCUSSING THAT THIS
MAY CONTINUE TO BE THE CASE INTO THE AFTERNOON. WILL CONTINUE WITH
TAF AS-IS FOR THE AFTERNOON/OVERNIGHT FOR NOW. LOW CLOUD COVER
WOULD NEED TO START DEVELOPING TO THE WEST AND SOUTHWEST EARLY
THIS AFTERNOON FOR GUIDANCE TO VERIFY SO WILL HOPEFULLY BE ABLE TO
HAVE A BETTER GAGE IN THE NEXT FEW HOURS.

MDB

FROM 12Z...

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAINED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER

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

* HIGH CONFIDENCE IN WIND TRENDS.

* LOW CONFIDENCE IN MVFR CIG POTENTIAL LATE THIS AFTERNOON/EARLY
  THIS EVENING.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPMENT OVERNIGHT.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281534
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
934 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 534 AM CST FRI NOV 28 2014

VFR conditions will prevail at all TAF sites next 24hrs. Scattered
to broken mid clouds around 12kft will continue through the day at
all sites. Clouds will then rise a little during the evening and
become broken, along with some lower clouds around 5kft. Based on
model RH fields, looks like mid clouds will dissipate, but 5kft
clouds could remain around remainder of the night. Winds will be
southerly through the period, with speeds of around 12kts. During
the day, gust could reach up to 20-22kts.


&&

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

$$

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






000
FXUS63 KILX 281534
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
934 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 534 AM CST FRI NOV 28 2014

VFR conditions will prevail at all TAF sites next 24hrs. Scattered
to broken mid clouds around 12kft will continue through the day at
all sites. Clouds will then rise a little during the evening and
become broken, along with some lower clouds around 5kft. Based on
model RH fields, looks like mid clouds will dissipate, but 5kft
clouds could remain around remainder of the night. Winds will be
southerly through the period, with speeds of around 12kts. During
the day, gust could reach up to 20-22kts.


&&

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

$$

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






000
FXUS63 KILX 281534
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
934 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 534 AM CST FRI NOV 28 2014

VFR conditions will prevail at all TAF sites next 24hrs. Scattered
to broken mid clouds around 12kft will continue through the day at
all sites. Clouds will then rise a little during the evening and
become broken, along with some lower clouds around 5kft. Based on
model RH fields, looks like mid clouds will dissipate, but 5kft
clouds could remain around remainder of the night. Winds will be
southerly through the period, with speeds of around 12kts. During
the day, gust could reach up to 20-22kts.


&&

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

$$

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






000
FXUS63 KILX 281534
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
934 AM CST Fri Nov 28 2014

.UPDATE...
ISSUED AT 930 AM CST FRI NOV 28 2014

Earlier altocumulus deck continues to scrape the northeast CWA, but
a larger area of mid and high clouds has been streaming southeast
into the forecast area. Have sent some updates to increase the
cloud cover for today to reflect this particular cloud deck.
Have also made some adjustments to the hourly temperature trends
for this morning as they were a couple degrees too warm, but think
the overall highs are still OK for now as southerly winds have
been picking up quite a bit.

&&

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dew points increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder air mass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold air mass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 534 AM CST FRI NOV 28 2014

VFR conditions will prevail at all TAF sites next 24hrs. Scattered
to broken mid clouds around 12kft will continue through the day at
all sites. Clouds will then rise a little during the evening and
become broken, along with some lower clouds around 5kft. Based on
model RH fields, looks like mid clouds will dissipate, but 5kft
clouds could remain around remainder of the night. Winds will be
southerly through the period, with speeds of around 12kts. During
the day, gust could reach up to 20-22kts.


&&

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

$$

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






000
FXUS63 KLOT 281356
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
756 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* LIGHT SNOW NOW DEPARTING.

* SOUTH WINDS INCREASING WITH GUSTS NEAR 20 KT BY MIDDAY.

* CHANCE FOR MVFR CIGS TO DEVELOP LATE THIS AFTERNOON/EARLY
  EVENING.

* POSSIBLE PATCHY FOG DEVELOPING OVERNIGHT.

MDB

//DISCUSSION...UPDATED 14Z...

LIGHT SNOW HAS MAINLY SKIRTED ORD/MDW/GYY THE LAST FEW HOURS AND
IS BEGINNING TO PUSH TO THE EAST. ASSOCIATED 040-050 CIGS WILL
ALSO BE EXITING TO THE EAST LEAVING CIGS IN THE 070-100 RANGE.
NEXT CONCERN IS POSSIBLE MVFR CIG DEVELOPMENT LATE THIS AFTERNOON
AS LOW LEVEL WARM AIR PUSHES OVER THE AREA. WILL NOT MAKE ANY
CHANGES TO THE AFTERNOON/EVENING PERIOD AT THIS POINT BUT WILL BE
EVALUATING THE POTENTIAL OVER THE NEXT FEW HOURS AND MAY NEED TO
ADD LOWER END MVFR CLOUD MENTION AFTER 21/22Z OR SO. CONFIDENCE IS
LOW AT THE MOMENT.

MDB

FROM 12Z...

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAINED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER

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

* HIGH CONFIDENCE IN LIGHT SNOW DEPARTING NEXT HOUR.

* HIGH CONFIDENCE IN WIND TRENDS.

* LOW CONFIDENCE IN MVFR CIG POTENTIAL LATE THIS AFTERNOON/EARLY
  THIS EVENING.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPMENT OVERNIGHT.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN THE WEEK.

BEACHLER

&&

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

$$

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

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000
FXUS63 KLOT 281356
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
756 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* LIGHT SNOW NOW DEPARTING.

* SOUTH WINDS INCREASING WITH GUSTS NEAR 20 KT BY MIDDAY.

* CHANCE FOR MVFR CIGS TO DEVELOP LATE THIS AFTERNOON/EARLY
  EVENING.

* POSSIBLE PATCHY FOG DEVELOPING OVERNIGHT.

MDB

//DISCUSSION...UPDATED 14Z...

LIGHT SNOW HAS MAINLY SKIRTED ORD/MDW/GYY THE LAST FEW HOURS AND
IS BEGINNING TO PUSH TO THE EAST. ASSOCIATED 040-050 CIGS WILL
ALSO BE EXITING TO THE EAST LEAVING CIGS IN THE 070-100 RANGE.
NEXT CONCERN IS POSSIBLE MVFR CIG DEVELOPMENT LATE THIS AFTERNOON
AS LOW LEVEL WARM AIR PUSHES OVER THE AREA. WILL NOT MAKE ANY
CHANGES TO THE AFTERNOON/EVENING PERIOD AT THIS POINT BUT WILL BE
EVALUATING THE POTENTIAL OVER THE NEXT FEW HOURS AND MAY NEED TO
ADD LOWER END MVFR CLOUD MENTION AFTER 21/22Z OR SO. CONFIDENCE IS
LOW AT THE MOMENT.

MDB

FROM 12Z...

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAINED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER

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

* HIGH CONFIDENCE IN LIGHT SNOW DEPARTING NEXT HOUR.

* HIGH CONFIDENCE IN WIND TRENDS.

* LOW CONFIDENCE IN MVFR CIG POTENTIAL LATE THIS AFTERNOON/EARLY
  THIS EVENING.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPMENT OVERNIGHT.

MDB

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
544 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* PATCHY HIGH END MVFR THRU 13Z WITH LGT SNOW.

* SOUTH WINDS ARND 5-7KT WILL INCREASE WITH GUSTS NEARING 20KT
  MIDDAY.

* POSSIBLE PATCHY FOG DEVELOPING AFTER MIDNIGHT TONIGHT.

BEACHLER

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

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAININED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER


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

* HIGH CONFIDENCE IN LGT SNOW ENDING SHORTLY AFT 13Z.

* HIGH CONFIDENCE IN CIGS REMAINING VFR THIS MORNING WITH THE LGT
  SNOW. THEN REMAINING VFR FOR THE REST OF TODAY.

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPING LATE TONIGHT.

BEACHLER

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
544 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* PATCHY HIGH END MVFR THRU 13Z WITH LGT SNOW.

* SOUTH WINDS ARND 5-7KT WILL INCREASE WITH GUSTS NEARING 20KT
  MIDDAY.

* POSSIBLE PATCHY FOG DEVELOPING AFTER MIDNIGHT TONIGHT.

BEACHLER

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

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAININED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER


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

* HIGH CONFIDENCE IN LGT SNOW ENDING SHORTLY AFT 13Z.

* HIGH CONFIDENCE IN CIGS REMAINING VFR THIS MORNING WITH THE LGT
  SNOW. THEN REMAINING VFR FOR THE REST OF TODAY.

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPING LATE TONIGHT.

BEACHLER

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
544 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* PATCHY HIGH END MVFR THRU 13Z WITH LGT SNOW.

* SOUTH WINDS ARND 5-7KT WILL INCREASE WITH GUSTS NEARING 20KT
  MIDDAY.

* POSSIBLE PATCHY FOG DEVELOPING AFTER MIDNIGHT TONIGHT.

BEACHLER

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

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAININED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER


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

* HIGH CONFIDENCE IN LGT SNOW ENDING SHORTLY AFT 13Z.

* HIGH CONFIDENCE IN CIGS REMAINING VFR THIS MORNING WITH THE LGT
  SNOW. THEN REMAINING VFR FOR THE REST OF TODAY.

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPING LATE TONIGHT.

BEACHLER

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281144
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
544 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* PATCHY HIGH END MVFR THRU 13Z WITH LGT SNOW.

* SOUTH WINDS ARND 5-7KT WILL INCREASE WITH GUSTS NEARING 20KT
  MIDDAY.

* POSSIBLE PATCHY FOG DEVELOPING AFTER MIDNIGHT TONIGHT.

BEACHLER

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

CONSIDERABLE HIGH BASED CLOUDS CONTINUE TO SLIDE SOUTHEAST ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS EARLY THIS MORNING. REGIONAL
RADAR INDICATES THE BACK EDGE OF THE LIGHT PRECIPITATION NEARING
KRFD...AND SHUD BE SLOWLY ENDING ARND 13-14Z FOR ORD/MDW/GYY. MOST
OF THE CIGS WITH THE LGT SNOW HAVE REMAININED ABOVE 6KFT
AGL...HOWEVER THERE MAY BE BRIEF DIP TO 3KFT AGL FOR ORD/RFD
BEFORE LIFTING BACK UP. THE LGT SNOW SHUD ONLY REDUCE VSBYS TO
5-7SM...OTHERWISE NOT EXPECTING ANY FURTHER REDUCTIONS TO VSBYS
THIS MORNING. BETTER MIXING WILL DEVELOP MIDDAY AND ALLOW
SOUTHERLY WINDS TO SLOWLY INCREASE...AND LIKELY PRODUCE GUSTS NEAR
20KT. THEN AFT 02Z GUSTS WILL QUICKLY DISSIPATE. HIGH BASED CLOUDS
WILL LINGER ALL AFTN/EVE...THEN SLIDE NORTHEAST. THERE IS SOME
INDICATION FROM GUIDANCE THAT PATCHY FOG MAY TRY TO DEVELOP LATE
TONIGHT AS WARM AIR ALOFT PUSHES NORTH OVER NORTHERN IL/NORTHWEST
IN AIRFIELDS. THIS MAY BE ABLE TO PRODUCE SOME PATCHY LOW CLOUDS
AND REDUCE VSBYS. GUIDANCE ALSO INDICATES THE LGT PRECIP TO REMAIN
NORTH OF THE AIRFIELDS.

BEACHLER


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

* HIGH CONFIDENCE IN LGT SNOW ENDING SHORTLY AFT 13Z.

* HIGH CONFIDENCE IN CIGS REMAINING VFR THIS MORNING WITH THE LGT
  SNOW. THEN REMAINING VFR FOR THE REST OF TODAY.

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPING LATE TONIGHT.

BEACHLER

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

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 281134
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
534 AM CST Fri Nov 28 2014

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dewpoints increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder airmass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold airmass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 534 AM CST FRI NOV 28 2014

VFR conditions will prevail at all TAF sites next 24hrs. Scattered
to broken mid clouds around 12kft will continue through the day at
all sites. Clouds will then rise a little during the evening and
become broken, along with some lower clouds around 5kft. Based on
model RH fields, looks like mid clouds will dissipate, but 5kft
clouds could remain around remainder of the night. Winds will be
southerly through the period, with speeds of around 12kts. During
the day, gust could reach up to 20-22kts.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten







000
FXUS63 KILX 281134
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
534 AM CST Fri Nov 28 2014

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dewpoints increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder airmass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold airmass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 534 AM CST FRI NOV 28 2014

VFR conditions will prevail at all TAF sites next 24hrs. Scattered
to broken mid clouds around 12kft will continue through the day at
all sites. Clouds will then rise a little during the evening and
become broken, along with some lower clouds around 5kft. Based on
model RH fields, looks like mid clouds will dissipate, but 5kft
clouds could remain around remainder of the night. Winds will be
southerly through the period, with speeds of around 12kts. During
the day, gust could reach up to 20-22kts.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten






000
FXUS63 KLOT 280942
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 280942
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 280942
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 280942
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 AM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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:
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000
FXUS63 KLOT 280922
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
322 AM CST FRI NOV 28 2014

.UPDATE...

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THERE MAY BE A PERIOD THIS EVENING THAT SMALL
CRAFT CONDITIONS COULD DEVELOP IN THE NORTHWEST INDIANA NEARSHORE
WATERS. OTHERWISE WIND SPEEDS SHOULD REMAIN JUST UNDER CRITERIA. THIS
WILL MAINTAIN A RELATIVELY TIGHT GRADIENT OVER THE LAKE THROUGH
SATURDAY...THEN AS THE LOW MOVES NORTHEAST TOWARDS JAMES BAY EARLY
SUNDAY THE GRADIENT SHOULD BRIEFLY DIMINISH. THEN THE FOCUS TURNS
TOWARDS SUNDAY AFTERNOON/EVENING AS A STRONG RIDGE OF HIGH
PRESSURE IS EXPECTED TO SLIDE SOUTH FROM THE CANADIAN ROCKIES INTO
THE NORHTERN PLAINS. THIS IS EXPECTED TO REDEVELOP THE TIGHT
GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS TO AROUND 30 KT. AT
THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING STRONGER FOR MONDAY.
HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE LAKE MONDAY
NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH PRESSURE MOVES
EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG ENOUGH TO
PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF THE LAKE
TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT INTO
EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER INCREASE
TO THE WINDS MAY OCCUR LATER IN 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 280907
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
307 AM CST Fri Nov 28 2014

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.


&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dewpoints increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder airmass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold airmass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1117 PM CST THU NOV 27 2014

Mainly VFR conditions expected for the next 24 hours across
central IL. Lcl MVFR vsby possible until around 08Z from
K1H2-KRSV southward. Cloud cover BKN070-090 to spread across area
remainder of the night inhibiting fog formation. Cloud cover
dissipating after 13Z. Winds light and variable overnight
increasing after 12Z to become S11-17kts with gusts up to 25 kts
through afternoon. Wind gusts decreasing after 00z but steady S
winds 10-12 kts continuing.


&&

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

$$

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







000
FXUS63 KILX 280907
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
307 AM CST Fri Nov 28 2014

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.


&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dewpoints increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder airmass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold airmass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1117 PM CST THU NOV 27 2014

Mainly VFR conditions expected for the next 24 hours across
central IL. Lcl MVFR vsby possible until around 08Z from
K1H2-KRSV southward. Cloud cover BKN070-090 to spread across area
remainder of the night inhibiting fog formation. Cloud cover
dissipating after 13Z. Winds light and variable overnight
increasing after 12Z to become S11-17kts with gusts up to 25 kts
through afternoon. Wind gusts decreasing after 00z but steady S
winds 10-12 kts continuing.


&&

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

$$

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







000
FXUS63 KILX 280907
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
307 AM CST Fri Nov 28 2014

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.


&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dewpoints increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder airmass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold airmass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1117 PM CST THU NOV 27 2014

Mainly VFR conditions expected for the next 24 hours across
central IL. Lcl MVFR vsby possible until around 08Z from
K1H2-KRSV southward. Cloud cover BKN070-090 to spread across area
remainder of the night inhibiting fog formation. Cloud cover
dissipating after 13Z. Winds light and variable overnight
increasing after 12Z to become S11-17kts with gusts up to 25 kts
through afternoon. Wind gusts decreasing after 00z but steady S
winds 10-12 kts continuing.


&&

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

$$

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







000
FXUS63 KILX 280907
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
307 AM CST Fri Nov 28 2014

.SHORT TERM...(Today)
ISSUED AT 307 AM CST FRI NOV 28 2014

Band of mid-level cloudiness associated with an approaching 850mb
warm front currently blankets central and southeast Illinois:
however, these clouds are expected to shift slowly northeastward
later this morning.  Forecast soundings show skies clearing from
southwest to northeast across the area by midday, with partly to
mostly sunny skies expected across the board this afternoon.  As
surface high pressure shifts east of the region, strong S/SE winds
will develop.  Due to the increasing sunshine and southerly flow,
temperatures will rebound quite nicely from very cold overnight
lows in the single digits and teens.  Have gone a couple of
degrees above guidance numbers, resulting in afternoon highs in
the upper 30s and lower 40s.


&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 307 AM CST FRI NOV 28 2014

Continued strong southerly flow will bring even warmer air into the
region on Saturday: however, warming trend may be tempered by
increasing cloudiness.  Both the NAM and GFS show a fetch of
low-level moisture developing from the western Gulf of Mexico into
Illinois on Saturday, with surface dewpoints increasing from the
lower 30s early in the day to well into the 40s by late afternoon.
Forecast soundings and model RH profiles show significant moistening
within the surface-850mb layer, suggesting the development of a low
overcast.  Despite the cloudy skies, strong WAA will still push high
temperatures into the lower to middle 50s.

Strong cold front will approach from the northwest on Sunday, with
excellent model agreement concerning FROPA during the afternoon.
Ahead of the front, the depth of the shallow surface-based moist
layer increases just enough to support a low chance PoP for light
rain showers, mainly east of the I-55 corridor during the
afternoon.  High temperatures will be achieved by around midday,
ranging from the upper 40s northwest of the Illinois River to the
lower 60s along/south of I-70.  After that, gusty northwesterly
winds will usher much colder air into the region, resulting in temps
dropping into the 30s and 40s by mid to late afternoon across all
but the far SE KILX CWA.

Models continue to show minor differences with their QPF fields
Sunday night, with the GEM being the most aggressive with developing
light precip north of the front into the colder airmass overnight.
With no clear upper support seen for post-frontal precip that far
north, have rejected this solution in favor of the much further south
GFS.  As a result, will carry low chance PoPs along/southeast of a
Champaign to Taylorville line Sunday evening, then only along/south
of I-70 after midnight.  As the cold airmass sinks southward, precip
type may become an issue late Sunday night into Monday morning.
Forecast soundings continue to show a shallow moist layer, with no
ice crystals present.  With surface temperatures dropping to near or
just below freezing, light freezing rain/drizzle may occur
along/south of I-70.  Will need to keep an eye on this situation
over the next couple of model runs, as some parts of southeast
Illinois could experience a light glaze of ice and some potentially
slick driving conditions for the Monday morning commute.  Elsewhere
around central Illinois, dry but very cold weather will be on tap
with highs mainly in the 20s.

After a brief shot of very cold air on Monday, temperatures will
moderate as a zonal upper flow pattern establishes itself across the
CONUS next week.  This will help temps recover into the 30s on
Tuesday, then well into the 30s and perhaps the lower 40s by
Wednesday.  Big question in the latter half of the extended
continues to be how models handle closed upper low over the
central Pacific.  00z Nov 28 models continue to be in poor
agreement, although a consensus of a slower eastward ejection
seems to be developing.  Prior runs of the GFS had shown the low
weakening, then shearing eastward across the central U.S. by
Wednesday, while the ECMWF/GEM kept it further west.  Latest GFS
has slowed, but still features a lead short-wave that produces
light precip across Illinois Wednesday night into Thursday.
Meanwhile, the ECMWF shows no lead wave, but instead high pressure
across the area at that time.  It delays the arrival of the
weakening central Pacific wave until Thursday night into Friday.
At this point, will make very few changes to the going forecast
due to model uncertainty.  Will maintain chance PoPs on Thursday,
but these will likely need to be pushed back to Thursday night or
even Friday if current trends continue.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1117 PM CST THU NOV 27 2014

Mainly VFR conditions expected for the next 24 hours across
central IL. Lcl MVFR vsby possible until around 08Z from
K1H2-KRSV southward. Cloud cover BKN070-090 to spread across area
remainder of the night inhibiting fog formation. Cloud cover
dissipating after 13Z. Winds light and variable overnight
increasing after 12Z to become S11-17kts with gusts up to 25 kts
through afternoon. Wind gusts decreasing after 00z but steady S
winds 10-12 kts continuing.


&&

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

$$

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







000
FXUS63 KLOT 280828
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
228 AM CST FRI NOV 28 2014

.UPDATE...914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THIS WILL MAINTAIN A RELATIVELY TIGHT GRADIENT
OVER THE LAKE THROUGH SATURDAY...THEN AS THE LOW MOVES NORTHEAST
TOWARDS JAMES BAY EARLY SUNDAY THE GRADIENT SHOULD BRIEFLY
DIMINISH. THEN THE FOCUS TURNS TOWARDS SUNDAY AFTERNOON/EVENING AS
A STRONG RIDGE OF HIGH PRESSURE IS EXPECTED TO SLIDE SOUTH FROM
THE CANADIAN ROCKIES INTO THE NORHTERN PLAINS. THIS IS EXPECTED TO
REDEVELOP THE TIGHT GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS
TO AROUND 30 KT. AT THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING
STRONGER FOR MONDAY. HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE
LAKE MONDAY NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH
PRESSURE MOVES EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG
ENOUGH TO PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF
THE LAKE TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT
INTO EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER
INCREASE TO THE WINDS MAY OCCUR LATER IN THE WEEK.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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 280828
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
228 AM CST FRI NOV 28 2014

.UPDATE...914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THIS WILL MAINTAIN A RELATIVELY TIGHT GRADIENT
OVER THE LAKE THROUGH SATURDAY...THEN AS THE LOW MOVES NORTHEAST
TOWARDS JAMES BAY EARLY SUNDAY THE GRADIENT SHOULD BRIEFLY
DIMINISH. THEN THE FOCUS TURNS TOWARDS SUNDAY AFTERNOON/EVENING AS
A STRONG RIDGE OF HIGH PRESSURE IS EXPECTED TO SLIDE SOUTH FROM
THE CANADIAN ROCKIES INTO THE NORHTERN PLAINS. THIS IS EXPECTED TO
REDEVELOP THE TIGHT GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS
TO AROUND 30 KT. AT THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING
STRONGER FOR MONDAY. HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE
LAKE MONDAY NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH
PRESSURE MOVES EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG
ENOUGH TO PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF
THE LAKE TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT
INTO EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER
INCREASE TO THE WINDS MAY OCCUR LATER IN THE WEEK.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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 280828
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
228 AM CST FRI NOV 28 2014

.UPDATE...914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THIS WILL MAINTAIN A RELATIVELY TIGHT GRADIENT
OVER THE LAKE THROUGH SATURDAY...THEN AS THE LOW MOVES NORTHEAST
TOWARDS JAMES BAY EARLY SUNDAY THE GRADIENT SHOULD BRIEFLY
DIMINISH. THEN THE FOCUS TURNS TOWARDS SUNDAY AFTERNOON/EVENING AS
A STRONG RIDGE OF HIGH PRESSURE IS EXPECTED TO SLIDE SOUTH FROM
THE CANADIAN ROCKIES INTO THE NORHTERN PLAINS. THIS IS EXPECTED TO
REDEVELOP THE TIGHT GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS
TO AROUND 30 KT. AT THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING
STRONGER FOR MONDAY. HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE
LAKE MONDAY NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH
PRESSURE MOVES EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG
ENOUGH TO PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF
THE LAKE TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT
INTO EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER
INCREASE TO THE WINDS MAY OCCUR LATER IN THE WEEK.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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 280828
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
228 AM CST FRI NOV 28 2014

.UPDATE...914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER

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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
218 AM CST

WEAKENING RIDGE OF HIGH PRESSURE CENTERED OVER THE TENNESSEE
VALLEY THIS MORNING...WILL SLIDE EAST ACROSS THE MID-ATLANTIC
REGION THIS EVENING. THIS WILL ALLOW A TIGHTENING GRADIENT TO
DEVELOP OVER THE LAKE...ALLOWING SOUTHERLY WINDS TO STEADILY
INCREASE. ACROSS THE NORTHERN PLAINS...AN AREA OF LOW PRESSURE IS
EXPECTED TO DEVELOP AND SLOWLY PUSH EAST TOWARDS THE UPPER MIDWEST
SATURDAY MORNING. THIS WILL MAINTAIN A RELATIVELY TIGHT GRADIENT
OVER THE LAKE THROUGH SATURDAY...THEN AS THE LOW MOVES NORTHEAST
TOWARDS JAMES BAY EARLY SUNDAY THE GRADIENT SHOULD BRIEFLY
DIMINISH. THEN THE FOCUS TURNS TOWARDS SUNDAY AFTERNOON/EVENING AS
A STRONG RIDGE OF HIGH PRESSURE IS EXPECTED TO SLIDE SOUTH FROM
THE CANADIAN ROCKIES INTO THE NORHTERN PLAINS. THIS IS EXPECTED TO
REDEVELOP THE TIGHT GRADIENT OVER THE LAKE AND MAY PUSH WIND GUSTS
TO AROUND 30 KT. AT THIS TIME GUIDANCE HAS NOT SUGGESTED ANYTHING
STRONGER FOR MONDAY. HIGH PRESSURE THEN QUICKLY SLIDES ACROSS THE
LAKE MONDAY NIGHT/EARLY TUESDAY. THEN LATER ON TUESDAY AS HIGH
PRESSURE MOVES EAST...A TIGHT GRADIENT RETURNS AND COULD BE STRONG
ENOUGH TO PRODUCE GALES ACROSS THE CENTRAL/NORTHERN PORTIONS OF
THE LAKE TUESDAY EVENING. WINDS SHUD SLOWLY DIMINISH WEDNESDAY NGT
INTO EARLY THURSDAY...ALTHOUGH GUIDANCE THEN INDICATES ANOTHER
INCREASE TO THE WINDS MAY OCCUR LATER IN THE WEEK.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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 280603
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1203 AM CST FRI NOV 28 2014

.UPDATE...
914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER


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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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 280603
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1203 AM CST FRI NOV 28 2014

.UPDATE...
914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER


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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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 280603
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1203 AM CST FRI NOV 28 2014

.UPDATE...
914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER


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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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

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





000
FXUS63 KLOT 280603
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1203 AM CST FRI NOV 28 2014

.UPDATE...
914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* LIGHT AND VARIABLE WINDS ARND 2-4KT SLOWLY TURNING
  SOUTHWEST/SOUTH BEFORE DAYBREAK AND INCREASING.

* POSSIBLE LIGHT SNOW DEVELOPING ARND 12Z THRU 14Z. COULD PRODUCE
  PATCHY MVFR CIGS AND VSBYS TO ARND 3-5SM.

* INCREASED MIXING MIDDAY WITH WIND GUSTS NEARING 20KT FROM THE
  SOUTH THRU 00Z SAT.

BEACHLER

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

IR IMAGERY SHOWS A WEDGE OF CLOUDS ARRIVING ACROSS NORTHERN IL
FROM THE NORTHWEST. THESE CLOUDS APPEAR TO BE STEADILY
THICKENING. ACROSS SOUTHEAST MINNESOTA SFC OBS ARE INDICATING LGT
SNOW...AND BASED ON LATEST GUIDANCE THIS AREA OF LGT SNOW WILL
ARRIVE AT NORTHERN IL TAF SITES ARND DAYBREAK. THERE CONTINUES TO
BE SOME DIFFERENCES ON IF THE SNOW WILL BE STEADY ENOUGH TO LIMIT
VSBYS/CIGS. HAVE HELD ONTO THE MENTION OF A SLIGHT REDUCTION TO
THE CIGS DOWN TO HIGH END MVFR/LOW END VFR CONDS...AND ALSO ONLY
BRINGING VSBYS DOWN TO 5SM. SNOW SHUD QUICKLY DEPART ARND
14-15Z...WITH CIGS LIFTING BACK TO VFR CONDS. WINDS WILL REMAIN
SOUTHERLY THRU THE AFTN/EVE...WITH BETTER MIXING ALLOWING GUSTS TO
20KT TO DEVELOP. SOME CLOUDS WILL HOLD IN PLACE THRU THE AFTN/EVE
BUT SHUD REMAIN AT OR ABOVE 7KFT AGL.

BEACHLER


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

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN LGT SNOW TIMING. MEDIUM CONFIDENCE IN
  SNOW LIMITING TO VSBYS/CIGS TO MVFR CONDS.

* HIGH CONFIDENCE IN ALL ELEMENTS AFT 16Z.

BEACHLER

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.

&&

$$

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 280517
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1117 PM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 850 PM CST THU NOV 27 2014

Skies have become mostly clear across central Illinois this
evening allowing temperatures to drop rapidly. Current
temperatures are mainly in the teens, with 20s near the Indiana
border where skies have taken longer to clear. Surface high
pressure will drift east across the region late this evening
causing winds to become light and variable, while cloud cover will
move in from the west. The increase in cloud cover will cause
temperatures to stop falling or even increase gradually by early
morning. Winds will be increasing early in the morning as well due
to the weather system bringing in the cloud cover. Have sent
updates for tonight`s temperature and cloud cover trends.

&&

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST THU NOV 27 2014

Small area of light snow and flurries, which moved in from the Quad
Cities area around mid morning, has held together relatively well
and was now over by Champaign. Have had a tenth or two of
accumulation accompany this feature in the heavier snow bands, which
have reduced visibility down to a mile at times. While remaining
mostly cloudy during the day, the clouds are now breaking up
northwest of the Illinois River, although temperatures there were
only in the lower 20s as stronger cold-air advection spreads in from
the northwest.

Latest surface map shows high pressure axis extending north-south
along the Mississippi Valley. This will slowly settle southeast
across the Midwest tonight, as the next clipper system quickly moves
into the upper Mississippi Valley. The snow from this feature will
remain well to our north, but a band of mid-level clouds will
quickly be moving in later this evening. Low temperatures will
likely be set this evening before the arrival of the clouds, with
temperatures steady or drifting upward overnight as winds start to
turn to the southeast. Teens will be widespread this evening,
possibly as low as 10 degrees near Galesburg.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CST THU NOV 27 2014

The upper trough will translate east of Illinois for Friday, leaving
zonal flow across the Plains and into Illinois through the weekend.
That pattern change will allow a return flow of warm air and
increasing dewpoints from Friday through Sunday. Highs on Friday may
be tempered a few degrees down due to some lingering snow cover in a
corridor from Rushville to Effingham, and have trimmed a couple
degrees from highs in that area. Periodic mid and high clouds across
the north on Friday may also help to keep highs down slightly,
especially with such a cold start to the day.

Saturday will see low clouds developing in the east and south due to
lift from increasing warm frontogenesis in the 850 mb layer. Despite
the cloud cover, surface temps should be noticeably warmer as highs
reach the low to mid 50s. The GFS even triggers a few showers during
the afternoon, but confidence is low that any measurable rain will
occur. Sunday will see a continued increase in low clouds with the
arrival of a cold front from the NW. Some added energy from an
intensifying 300mb jet max will increase lift ahead of the front and
a few showers will possible in our southeastern counties. Rain
chances will be mainly confined to areas SE of a line from Effingham
to Danville, but sprinkles could extend as far west as Peoria to
Jacksonville.

The front is forecast to progress into the Ohio River Valley by
Sunday night, with a colder airmass settling southward early next
week. Any lingering rain showers Sunday night into Monday morning
across our SE counties could transition to light snow due to
deepening of the cold pool. No snow accumulation is expected
however.

Dry and cooler conditions are forecast for Tuesday and Wednesday
under a high pressure ridge. Major model differences are still
present beyond that with respect to the evolution of a closed low
off the West Coast of California. The GFS continues to progress
that wave across the Rockies, triggering surface cyclogenesis
across the Plains on Wednesday. It then progresses that deepening
low into the Great Lakes Thursday-Friday, dragging a cold front
across IL Thursday night. Pre-frontal showers are forecast as
early as Wed night and lingering through Thurs night. The ECMWF
takes the low and gradually absorbs it into a stronger low over
the Gulf of Alaska, with a downstream trough providing cool/dry
weather to Illinois on Wednesday-Thursday. The Canadian GEM shows
indications of primarily keeping the low off the coast, or at
least keeping a long wave trough along the west coast through the
end of the week, providing a dry scenario for IL during that time.
The SuperBlend was biased by the strong GFS precip signal, but
through collaboration with surrounding offices, we lowered precip
chances to the slight category Wed night and Thurs due to so much
uncertainty.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1117 PM CST THU NOV 27 2014

Mainly VFR conditions expected for the next 24 hours across
central IL. Lcl MVFR vsby possible until around 08Z from
K1H2-KRSV southward. Cloud cover BKN070-090 to spread across area
remainder of the night inhibiting fog formation. Cloud cover
dissipating after 13Z. Winds light and variable overnight
increasing after 12Z to become S11-17kts with gusts up to 25 kts
through afternoon. Wind gusts decreasing after 00z but steady S
winds 10-12 kts continuing.

&&

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

$$

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







000
FXUS63 KILX 280517
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1117 PM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 850 PM CST THU NOV 27 2014

Skies have become mostly clear across central Illinois this
evening allowing temperatures to drop rapidly. Current
temperatures are mainly in the teens, with 20s near the Indiana
border where skies have taken longer to clear. Surface high
pressure will drift east across the region late this evening
causing winds to become light and variable, while cloud cover will
move in from the west. The increase in cloud cover will cause
temperatures to stop falling or even increase gradually by early
morning. Winds will be increasing early in the morning as well due
to the weather system bringing in the cloud cover. Have sent
updates for tonight`s temperature and cloud cover trends.

&&

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST THU NOV 27 2014

Small area of light snow and flurries, which moved in from the Quad
Cities area around mid morning, has held together relatively well
and was now over by Champaign. Have had a tenth or two of
accumulation accompany this feature in the heavier snow bands, which
have reduced visibility down to a mile at times. While remaining
mostly cloudy during the day, the clouds are now breaking up
northwest of the Illinois River, although temperatures there were
only in the lower 20s as stronger cold-air advection spreads in from
the northwest.

Latest surface map shows high pressure axis extending north-south
along the Mississippi Valley. This will slowly settle southeast
across the Midwest tonight, as the next clipper system quickly moves
into the upper Mississippi Valley. The snow from this feature will
remain well to our north, but a band of mid-level clouds will
quickly be moving in later this evening. Low temperatures will
likely be set this evening before the arrival of the clouds, with
temperatures steady or drifting upward overnight as winds start to
turn to the southeast. Teens will be widespread this evening,
possibly as low as 10 degrees near Galesburg.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CST THU NOV 27 2014

The upper trough will translate east of Illinois for Friday, leaving
zonal flow across the Plains and into Illinois through the weekend.
That pattern change will allow a return flow of warm air and
increasing dewpoints from Friday through Sunday. Highs on Friday may
be tempered a few degrees down due to some lingering snow cover in a
corridor from Rushville to Effingham, and have trimmed a couple
degrees from highs in that area. Periodic mid and high clouds across
the north on Friday may also help to keep highs down slightly,
especially with such a cold start to the day.

Saturday will see low clouds developing in the east and south due to
lift from increasing warm frontogenesis in the 850 mb layer. Despite
the cloud cover, surface temps should be noticeably warmer as highs
reach the low to mid 50s. The GFS even triggers a few showers during
the afternoon, but confidence is low that any measurable rain will
occur. Sunday will see a continued increase in low clouds with the
arrival of a cold front from the NW. Some added energy from an
intensifying 300mb jet max will increase lift ahead of the front and
a few showers will possible in our southeastern counties. Rain
chances will be mainly confined to areas SE of a line from Effingham
to Danville, but sprinkles could extend as far west as Peoria to
Jacksonville.

The front is forecast to progress into the Ohio River Valley by
Sunday night, with a colder airmass settling southward early next
week. Any lingering rain showers Sunday night into Monday morning
across our SE counties could transition to light snow due to
deepening of the cold pool. No snow accumulation is expected
however.

Dry and cooler conditions are forecast for Tuesday and Wednesday
under a high pressure ridge. Major model differences are still
present beyond that with respect to the evolution of a closed low
off the West Coast of California. The GFS continues to progress
that wave across the Rockies, triggering surface cyclogenesis
across the Plains on Wednesday. It then progresses that deepening
low into the Great Lakes Thursday-Friday, dragging a cold front
across IL Thursday night. Pre-frontal showers are forecast as
early as Wed night and lingering through Thurs night. The ECMWF
takes the low and gradually absorbs it into a stronger low over
the Gulf of Alaska, with a downstream trough providing cool/dry
weather to Illinois on Wednesday-Thursday. The Canadian GEM shows
indications of primarily keeping the low off the coast, or at
least keeping a long wave trough along the west coast through the
end of the week, providing a dry scenario for IL during that time.
The SuperBlend was biased by the strong GFS precip signal, but
through collaboration with surrounding offices, we lowered precip
chances to the slight category Wed night and Thurs due to so much
uncertainty.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1117 PM CST THU NOV 27 2014

Mainly VFR conditions expected for the next 24 hours across
central IL. Lcl MVFR vsby possible until around 08Z from
K1H2-KRSV southward. Cloud cover BKN070-090 to spread across area
remainder of the night inhibiting fog formation. Cloud cover
dissipating after 13Z. Winds light and variable overnight
increasing after 12Z to become S11-17kts with gusts up to 25 kts
through afternoon. Wind gusts decreasing after 00z but steady S
winds 10-12 kts continuing.

&&

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

$$

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






000
FXUS63 KLOT 280315 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
915 PM CST THU NOV 27 2014

.UPDATE...
914 PM CST

NO MAJOR CHANGES MADE TO THE FORECAST THE REMAINDER OF THIS
THANKSGIVING NIGHT AND INTO FRIDAY. DID ISSUE A SPECIAL WEATHER
STATEMENT FOR THE FAR NORTHERN FOUR COUNTIES OF THE FORECAST AREA
TO HIGHLIGHT THE LIKELY BRIEF PERIOD OF SNOW BETWEEN 4 AND 9 AM
FRIDAY MORNING.

A STRONG 1032MB HIGH PRESSURE RIDGE IS MOVING OVER NORTH CENTRAL
IL AND WILL SHIFT EAST OVER CHICAGO BY MIDNIGHT. THE BREAK IN THE
CLOUDS HAS LED TO THE EXPECTED SHARP DROP IN TEMPERATURES...WITH
SOME SINGLE DIGIT VALUES IN NORTH CENTRAL ILLINOIS. WARM AIR
ADVECTION MID CLOUDS SHOULD SPREAD OVER THE WESTERN FORECAST AREA
ALREADY IN THE NEXT 1-2 HOURS SO EXPECTED TEMPERATURES TO BEGIN TO
SLOWLY RECOVER FROM WEST TO EAST. JUST SOME MINOR TOUCH-UPS MADE
TO THE TEMPERATURE FORECAST THE REST OF TONIGHT.

THE 00Z RAOBS INDICATED THE UPSTREAM WARM ADVECTION TEMPERATURE
GRADIENT TAKING SHAPE WITH JUST A 20C 850MB GRADIENT ACROSS SOUTH
DAKOTA /RAP TO ABR/. SOME SPOTTY SNOW HAS ALREADY BEEN SEEN AS FAR
SOUTH AS DES MOINES WITHIN THIS ZONE OF ASCENT AND DEVELOPING
FRONTOGENETIC VERTICAL CIRCULATION. WHILE THERE IS SUBSTANTIAL DRY
AIR NOTED ON THE DVN SOUNDING OVER OUR AREA...THE 00Z NAM CAPTURED
THIS DRYNESS WELL AND DOES INDICATE AS THE SHEARED SHORT WAVE IN
WESTERN MN DROPS SOUTHWARD THE NARROW BUT STRONG LIFT SHOULD
OFFSET THIS LATE TONIGHT INTO EARLY FRIDAY MORNING. FORECAST
TIMING AND SPATIAL COVERAGE IN SNOW POTENTIAL LOOKS GOOD. HAVE JUST
BUMPED UP POPS IN THE FAR NORTHERN FOUR COUNTIES...BUT EXPECT
SOUTH OF THERE ANY SNOW TO MAINLY JUST BE FLURRIES. THOUGHT AN SPS
NEAR THE WI BORDER TO HIGHLIGHT THE TEMPORARY SNOW DURING THE FIRST
THING IN THE MORNING MAY BE BENEFICIAL GIVEN THE EXTRA AMOUNT OF
PEOPLE OUT AT THE VERY EARLY HOUR FOR BLACK FRIDAY.

MTF

&&

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

LATEST SATELLITE AND RADAR TRENDS INDICATING THAT CLOUD COVER AND
SNOW SHOWERS ARE BECOMING MORE RAGGED AND DECREASING IN COVERAGE
WITH SUNSET AND AS HIGH PRESSURE BUILDS ACROSS THE REGION. ANY
LINGERING SNOW SHOWERS SHOULD COME TO AN END BY ARND 01Z...EXCEPT
FOR GYY...WHICH IS STILL UNDER A LAKE FETCH WITH NWLY WINDS. AS
WINDS BECOME MORE WLY LATER THIS EVENING...ANY LAKE INFLUENCE WILL
SHUT OFF AND CONDITIONS AT GYY SHOULD BECOME QUIET AS WELL.

THE NEXT CONCERN IS FOR THE POTENTIAL FOR ANOTHER BRIEF PERIOD OF
SNOW TOMORROW MORNING. THE LATEST MODEL GUIDANCE STILL INDICATES A
MID LEVEL IMPULSE DROPPING OUT OF THE NRN PLAINS WHILE A WEAK WARM
FRONT SETS UP ACROSS THE UPPER MISSOURI VALLEY TO NEAR THE IL/WI
BORDER. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR SOME LIGHT
SNOW IF THERE IS A DEEP ENOUGH LAYER OF MOISTURE IN PLACE AT THE
TIME OF OPTIMAL UPPER LEVEL FORCING. THE LATEST HIGH RESOLUTION
MODEL GUIDANCE SUGGESTS THAT THERE COULD BE A PERIOD OF LIGHT SNOW
DURG THE MORNING HOURS FOR PERHAPS 2 HOURS...BUT TIMING THE SNOW
IS STILL UNCERTAIN. SO...WILL MAINTAIN THE GOING FORECAST OF A 3
HOUR TEMPO GROUP...THOUGH THIS IS LIKELY TOO LONG MORE PRECISE
TIMING SHOULD BE DETERMINED IN LATER UPDATES. REGARDLESS OF EXACT
TIMING...ONLY LIGHT ACCUMULATIONS...PERHAPS A HALF INCH OR LESS IS
EXPECTED.

FOR THE REMAINDER OF THE DAY TOMORROW...FORECAST CONCERNS SHIFT TO
GUSTY SOUTHERLY WINDS DEVELOPING IN THE MID/LATE MORNING AS HIGH
PRESSURE SETTLES OVER THE SERN CONUS AND LOW PRESSURE DEVELOPS
OVER THE NRN PLAINS. OCCASIONAL GUSTS TO ARND 20KT ARE
LIKELY...AND POTENTIALLY HIGHER ARE POSSIBLE WITH DEEPER MIXING IF
ENOUGH SUNSHINE CAN BREAK THROUGH THE CLOUD COVER.

KREIN

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

* MEDIUM CONFIDENCE IN CIG TRENDS.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF A SHORT 1-2
  HR PERIOD OF SNOW OCCURRING FRIDAY MORNING.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

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

&&

$$

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 280250
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
850 PM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 850 PM CST THU NOV 27 2014

Skies have become mostly clear across central Illinois this
evening allowing temperatures to drop rapidly. Current
temperatures are mainly in the teens, with 20s near the Indiana
border where skies have taken longer to clear. Surface high
pressure will drift east across the region late this evening
causing winds to become light and variable, while cloud cover will
move in from the west. The increase in cloud cover will cause
temperatures to stop falling or even increase gradually by early
morning. Winds will be increasing early in the morning as well due
to the weather system bringing in the cloud cover. Have sent
updates for tonight`s temperature and cloud cover trends.

&&

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST THU NOV 27 2014

Small area of light snow and flurries, which moved in from the Quad
Cities area around mid morning, has held together relatively well
and was now over by Champaign. Have had a tenth or two of
accumulation accompany this feature in the heavier snow bands, which
have reduced visibility down to a mile at times. While remaining
mostly cloudy during the day, the clouds are now breaking up
northwest of the Illinois River, although temperatures there were
only in the lower 20s as stronger cold-air advection spreads in from
the northwest.

Latest surface map shows high pressure axis extending north-south
along the Mississippi Valley. This will slowly settle southeast
across the Midwest tonight, as the next clipper system quickly moves
into the upper Mississippi Valley. The snow from this feature will
remain well to our north, but a band of mid-level clouds will
quickly be moving in later this evening. Low temperatures will
likely be set this evening before the arrival of the clouds, with
temperatures steady or drifting upward overnight as winds start to
turn to the southeast. Teens will be widespread this evening,
possibly as low as 10 degrees near Galesburg.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CST THU NOV 27 2014

The upper trough will translate east of Illinois for Friday, leaving
zonal flow across the Plains and into Illinois through the weekend.
That pattern change will allow a return flow of warm air and
increasing dewpoints from Friday through Sunday. Highs on Friday may
be tempered a few degrees down due to some lingering snow cover in a
corridor from Rushville to Effingham, and have trimmed a couple
degrees from highs in that area. Periodic mid and high clouds across
the north on Friday may also help to keep highs down slightly,
especially with such a cold start to the day.

Saturday will see low clouds developing in the east and south due to
lift from increasing warm frontogenesis in the 850 mb layer. Despite
the cloud cover, surface temps should be noticeably warmer as highs
reach the low to mid 50s. The GFS even triggers a few showers during
the afternoon, but confidence is low that any measurable rain will
occur. Sunday will see a continued increase in low clouds with the
arrival of a cold front from the NW. Some added energy from an
intensifying 300mb jet max will increase lift ahead of the front and
a few showers will possible in our southeastern counties. Rain
chances will be mainly confined to areas SE of a line from Effingham
to Danville, but sprinkles could extend as far west as Peoria to
Jacksonville.

The front is forecast to progress into the Ohio River Valley by
Sunday night, with a colder airmass settling southward early next
week. Any lingering rain showers Sunday night into Monday morning
across our SE counties could transition to light snow due to
deepening of the cold pool. No snow accumulation is expected
however.

Dry and cooler conditions are forecast for Tuesday and Wednesday
under a high pressure ridge. Major model differences are still
present beyond that with respect to the evolution of a closed low
off the West Coast of California. The GFS continues to progress
that wave across the Rockies, triggering surface cyclogenesis
across the Plains on Wednesday. It then progresses that deepening
low into the Great Lakes Thursday-Friday, dragging a cold front
across IL Thursday night. Pre-frontal showers are forecast as
early as Wed night and lingering through Thurs night. The ECMWF
takes the low and gradually absorbs it into a stronger low over
the Gulf of Alaska, with a downstream trough providing cool/dry
weather to Illinois on Wednesday-Thursday. The Canadian GEM shows
indications of primarily keeping the low off the coast, or at
least keeping a long wave trough along the west coast through the
end of the week, providing a dry scenario for IL during that time.
The SuperBlend was biased by the strong GFS precip signal, but
through collaboration with surrounding offices, we lowered precip
chances to the slight category Wed night and Thurs due to so much
uncertainty.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 515 PM CST THU NOV 27 2014

An area of predominantly MVFR cigs with sct -shsn occasionally
bringing IFR-MVFR vsby will continue to affect areas east of
K1H2-KBMI until around 03Z. Otherwise, VFR conditions expected for
the next 24 hours. Winds NW up to 10 kts until 04Z, becoming
light and variable overnight as surface high pressure crosses the
region. Winds increasing after 12Z becoming S10-16kts with gusts
up to 25 kts through afternoon as a clipper system moves by to the
north.


&&

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

$$

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






000
FXUS63 KLOT 272359
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
559 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

LATEST SATELLITE AND RADAR TRENDS INDICATING THAT CLOUD COVER AND
SNOW SHOWERS ARE BECOMING MORE RAGGED AND DECREASING IN COVERAGE
WITH SUNSET AND AS HIGH PRESSURE BUILDS ACROSS THE REGION. ANY
LINGERING SNOW SHOWERS SHOULD COME TO AN END BY ARND 01Z...EXCEPT
FOR GYY...WHICH IS STILL UNDER A LAKE FETCH WITH NWLY WINDS. AS
WINDS BECOME MORE WLY LATER THIS EVENING...ANY LAKE INFLUENCE WILL
SHUT OFF AND CONDITIONS AT GYY SHOULD BECOME QUIET AS WELL.

THE NEXT CONCERN IS FOR THE POTENTIAL FOR ANOTHER BRIEF PERIOD OF
SNOW TOMORROW MORNING. THE LATEST MODEL GUIDANCE STILL INDICATES A
MID LEVEL IMPULSE DROPPING OUT OF THE NRN PLAINS WHILE A WEAK WARM
FRONT SETS UP ACROSS THE UPPER MISSOURI VALLEY TO NEAR THE IL/WI
BORDER. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR SOME LIGHT
SNOW IF THERE IS A DEEP ENOUGH LAYER OF MOISTURE IN PLACE AT THE
TIME OF OPTIMAL UPPER LEVEL FORCING. THE LATEST HIGH RESOLUTION
MODEL GUIDANCE SUGGESTS THAT THERE COULD BE A PERIOD OF LIGHT SNOW
DURG THE MORNING HOURS FOR PERHAPS 2 HOURS...BUT TIMING THE SNOW
IS STILL UNCERTAIN. SO...WILL MAINTAIN THE GOING FORECAST OF A 3
HOUR TEMPO GROUP...THOUGH THIS IS LIKELY TOO LONG MORE PRECISE
TIMING SHOULD BE DETERMINED IN LATER UPDATES. REGARDLESS OF EXACT
TIMING...ONLY LIGHT ACCUMULATIONS...PERHAPS A HALF INCH OR LESS IS
EXPECTED.

FOR THE REMAINDER OF THE DAY TOMORROW...FORECAST CONCERNS SHIFT TO
GUSTY SOUTHERLY WINDS DEVELOPING IN THE MID/LATE MORNING AS HIGH
PRESSURE SETTLES OVER THE SERN CONUS AND LOW PRESSURE DEVELOPS
OVER THE NRN PLAINS. OCCASIONAL GUSTS TO ARND 20KT ARE
LIKELY...AND POTENTIALLY HIGHER ARE POSSIBLE WITH DEEPER MIXING IF
ENOUGH SUNSHINE CAN BREAK THROUGH THE CLOUD COVER.

KREIN

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

* MEDIUM CONFIDENCE IN CIG TRENDS.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF A SHORT 1-2
  HR PERIOD OF SNOW OCCURRING FRIDAY MORNING.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272359
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
559 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

LATEST SATELLITE AND RADAR TRENDS INDICATING THAT CLOUD COVER AND
SNOW SHOWERS ARE BECOMING MORE RAGGED AND DECREASING IN COVERAGE
WITH SUNSET AND AS HIGH PRESSURE BUILDS ACROSS THE REGION. ANY
LINGERING SNOW SHOWERS SHOULD COME TO AN END BY ARND 01Z...EXCEPT
FOR GYY...WHICH IS STILL UNDER A LAKE FETCH WITH NWLY WINDS. AS
WINDS BECOME MORE WLY LATER THIS EVENING...ANY LAKE INFLUENCE WILL
SHUT OFF AND CONDITIONS AT GYY SHOULD BECOME QUIET AS WELL.

THE NEXT CONCERN IS FOR THE POTENTIAL FOR ANOTHER BRIEF PERIOD OF
SNOW TOMORROW MORNING. THE LATEST MODEL GUIDANCE STILL INDICATES A
MID LEVEL IMPULSE DROPPING OUT OF THE NRN PLAINS WHILE A WEAK WARM
FRONT SETS UP ACROSS THE UPPER MISSOURI VALLEY TO NEAR THE IL/WI
BORDER. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR SOME LIGHT
SNOW IF THERE IS A DEEP ENOUGH LAYER OF MOISTURE IN PLACE AT THE
TIME OF OPTIMAL UPPER LEVEL FORCING. THE LATEST HIGH RESOLUTION
MODEL GUIDANCE SUGGESTS THAT THERE COULD BE A PERIOD OF LIGHT SNOW
DURG THE MORNING HOURS FOR PERHAPS 2 HOURS...BUT TIMING THE SNOW
IS STILL UNCERTAIN. SO...WILL MAINTAIN THE GOING FORECAST OF A 3
HOUR TEMPO GROUP...THOUGH THIS IS LIKELY TOO LONG MORE PRECISE
TIMING SHOULD BE DETERMINED IN LATER UPDATES. REGARDLESS OF EXACT
TIMING...ONLY LIGHT ACCUMULATIONS...PERHAPS A HALF INCH OR LESS IS
EXPECTED.

FOR THE REMAINDER OF THE DAY TOMORROW...FORECAST CONCERNS SHIFT TO
GUSTY SOUTHERLY WINDS DEVELOPING IN THE MID/LATE MORNING AS HIGH
PRESSURE SETTLES OVER THE SERN CONUS AND LOW PRESSURE DEVELOPS
OVER THE NRN PLAINS. OCCASIONAL GUSTS TO ARND 20KT ARE
LIKELY...AND POTENTIALLY HIGHER ARE POSSIBLE WITH DEEPER MIXING IF
ENOUGH SUNSHINE CAN BREAK THROUGH THE CLOUD COVER.

KREIN

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

* MEDIUM CONFIDENCE IN CIG TRENDS.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF A SHORT 1-2
  HR PERIOD OF SNOW OCCURRING FRIDAY MORNING.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272359
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
559 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

LATEST SATELLITE AND RADAR TRENDS INDICATING THAT CLOUD COVER AND
SNOW SHOWERS ARE BECOMING MORE RAGGED AND DECREASING IN COVERAGE
WITH SUNSET AND AS HIGH PRESSURE BUILDS ACROSS THE REGION. ANY
LINGERING SNOW SHOWERS SHOULD COME TO AN END BY ARND 01Z...EXCEPT
FOR GYY...WHICH IS STILL UNDER A LAKE FETCH WITH NWLY WINDS. AS
WINDS BECOME MORE WLY LATER THIS EVENING...ANY LAKE INFLUENCE WILL
SHUT OFF AND CONDITIONS AT GYY SHOULD BECOME QUIET AS WELL.

THE NEXT CONCERN IS FOR THE POTENTIAL FOR ANOTHER BRIEF PERIOD OF
SNOW TOMORROW MORNING. THE LATEST MODEL GUIDANCE STILL INDICATES A
MID LEVEL IMPULSE DROPPING OUT OF THE NRN PLAINS WHILE A WEAK WARM
FRONT SETS UP ACROSS THE UPPER MISSOURI VALLEY TO NEAR THE IL/WI
BORDER. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR SOME LIGHT
SNOW IF THERE IS A DEEP ENOUGH LAYER OF MOISTURE IN PLACE AT THE
TIME OF OPTIMAL UPPER LEVEL FORCING. THE LATEST HIGH RESOLUTION
MODEL GUIDANCE SUGGESTS THAT THERE COULD BE A PERIOD OF LIGHT SNOW
DURG THE MORNING HOURS FOR PERHAPS 2 HOURS...BUT TIMING THE SNOW
IS STILL UNCERTAIN. SO...WILL MAINTAIN THE GOING FORECAST OF A 3
HOUR TEMPO GROUP...THOUGH THIS IS LIKELY TOO LONG MORE PRECISE
TIMING SHOULD BE DETERMINED IN LATER UPDATES. REGARDLESS OF EXACT
TIMING...ONLY LIGHT ACCUMULATIONS...PERHAPS A HALF INCH OR LESS IS
EXPECTED.

FOR THE REMAINDER OF THE DAY TOMORROW...FORECAST CONCERNS SHIFT TO
GUSTY SOUTHERLY WINDS DEVELOPING IN THE MID/LATE MORNING AS HIGH
PRESSURE SETTLES OVER THE SERN CONUS AND LOW PRESSURE DEVELOPS
OVER THE NRN PLAINS. OCCASIONAL GUSTS TO ARND 20KT ARE
LIKELY...AND POTENTIALLY HIGHER ARE POSSIBLE WITH DEEPER MIXING IF
ENOUGH SUNSHINE CAN BREAK THROUGH THE CLOUD COVER.

KREIN

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

* MEDIUM CONFIDENCE IN CIG TRENDS.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF A SHORT 1-2
  HR PERIOD OF SNOW OCCURRING FRIDAY MORNING.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272359
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
559 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

LATEST SATELLITE AND RADAR TRENDS INDICATING THAT CLOUD COVER AND
SNOW SHOWERS ARE BECOMING MORE RAGGED AND DECREASING IN COVERAGE
WITH SUNSET AND AS HIGH PRESSURE BUILDS ACROSS THE REGION. ANY
LINGERING SNOW SHOWERS SHOULD COME TO AN END BY ARND 01Z...EXCEPT
FOR GYY...WHICH IS STILL UNDER A LAKE FETCH WITH NWLY WINDS. AS
WINDS BECOME MORE WLY LATER THIS EVENING...ANY LAKE INFLUENCE WILL
SHUT OFF AND CONDITIONS AT GYY SHOULD BECOME QUIET AS WELL.

THE NEXT CONCERN IS FOR THE POTENTIAL FOR ANOTHER BRIEF PERIOD OF
SNOW TOMORROW MORNING. THE LATEST MODEL GUIDANCE STILL INDICATES A
MID LEVEL IMPULSE DROPPING OUT OF THE NRN PLAINS WHILE A WEAK WARM
FRONT SETS UP ACROSS THE UPPER MISSOURI VALLEY TO NEAR THE IL/WI
BORDER. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR SOME LIGHT
SNOW IF THERE IS A DEEP ENOUGH LAYER OF MOISTURE IN PLACE AT THE
TIME OF OPTIMAL UPPER LEVEL FORCING. THE LATEST HIGH RESOLUTION
MODEL GUIDANCE SUGGESTS THAT THERE COULD BE A PERIOD OF LIGHT SNOW
DURG THE MORNING HOURS FOR PERHAPS 2 HOURS...BUT TIMING THE SNOW
IS STILL UNCERTAIN. SO...WILL MAINTAIN THE GOING FORECAST OF A 3
HOUR TEMPO GROUP...THOUGH THIS IS LIKELY TOO LONG MORE PRECISE
TIMING SHOULD BE DETERMINED IN LATER UPDATES. REGARDLESS OF EXACT
TIMING...ONLY LIGHT ACCUMULATIONS...PERHAPS A HALF INCH OR LESS IS
EXPECTED.

FOR THE REMAINDER OF THE DAY TOMORROW...FORECAST CONCERNS SHIFT TO
GUSTY SOUTHERLY WINDS DEVELOPING IN THE MID/LATE MORNING AS HIGH
PRESSURE SETTLES OVER THE SERN CONUS AND LOW PRESSURE DEVELOPS
OVER THE NRN PLAINS. OCCASIONAL GUSTS TO ARND 20KT ARE
LIKELY...AND POTENTIALLY HIGHER ARE POSSIBLE WITH DEEPER MIXING IF
ENOUGH SUNSHINE CAN BREAK THROUGH THE CLOUD COVER.

KREIN

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

* MEDIUM CONFIDENCE IN CIG TRENDS.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF A SHORT 1-2
  HR PERIOD OF SNOW OCCURRING FRIDAY MORNING.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
239 PM CST

HIGH PRESSURE STRETCHING FROM WESTERN ONTARIO TO THE LOUISIANA COAST
WILL MOVE EAST ACROSS LAKE MICHIGAN TONIGHT BEFORE SHIFTING TO THE
EAST COAST BY SATURDAY MORNING. GUSTY NORTHWEST WINDS WILL DIMINISH
THROUGH THE EVENING AND TURN SOUTHWESTERLY OVERNIGHT AS THE RIDGE
AXIS CRESTS THE LAKE. LOW PRESSURE DEVELOPING OVER MONTANA WILL MOVE
EASTWARD ACROSS THE NORTHERN PLAINS AND TURN NORTHEASTERLY ACROSS
LAKE SUPERIOR LATER SATURDAY. THIS WILL TIGHTEN THE PRESSURE
GRADIENT ACROSS THE LAKE FRIDAY MORNING LEADING TO AN INCREASE IN
SOUTH WINDS. CENTRAL AND SOUTHERN SECTIONS OF THE LAKE SHOULD PUSH
30 KT FRIDAY AFTERNOON BEFORE EASING FRIDAY NIGHT. WINDS LOOK TO
INCREASE AGAIN SATURDAY MORNING AS THE GRADIENT IS REINFORCED AS THE
LOW PASSES TO THE NORTH. THE LOW WILL DRAG A COLD FRONT ACROSS THE
LAKE SUNDAY SHIFTING WINDS TO THE NORTHWEST WHILE VERY STRONG HIGH
PRESSURE DEVELOPS AND MOVES ACROSS THE NORTHERN PLAINS. COLD
ADVECTION WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO KEEP A
PERIOD OF STRONG NORTHWEST WINDS ACROSS THE LAKE FROM SUNDAY
AFTERNOON INTO MONDAY AFTERNOON WITH LOW TO MID RANGE GALES A
POSSIBILITY. WINDS WILL QUICKLY DROP OFF MONDAY NIGHT AS THE HIGH
MOVES RIGHT OVERHEAD. ANOTHER LOW IS EXPECTED TO TRACK FROM THE
CANADIAN PRAIRIES TOWARD JAMES BAY NEXT TUESDAY/WEDNESDAY ALLOWING
SOUTHERLY WINDS TO RETURN TO THE LAKE WHICH MAY BE STRONG GIVEN THE
STRENGTH OF THE DEPARTING HIGH.

MDB

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272354
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
554 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

LATEST SATELLITE AND RADAR TRENDS INDICATING THAT CLOUD COVER AND
SNOW SHOWERS ARE BECOMING MORE RAGGED AND DECREASING IN COVERAGE
WITH SUNSET AND AS HIGH PRESSURE BUILDS ACROSS THE REGION. ANY
LINGERING SNOW SHOWERS SHOULD COME TO AN END BY ARND 01Z...EXCEPT
FOR GYY...WHICH IS STILL UNDER A LAKE FETCH WITH NWLY WINDS. AS
WINDS BECOME MORE WLY LATER THIS EVENING...ANY LAKE INFLUENCE WILL
SHUT OFF AND CONDITIONS AT GYY SHOULD BECOME QUIET AS WELL.

THE NEXT CONCERN IS FOR THE POTENTIAL FOR ANOTHER BRIEF PERIOD OF
SNOW TOMORROW MORNING. THE LATEST MODEL GUIDANCE STILL INDICATES A
MID LEVEL IMPULSE DROPPING OUT OF THE NRN PLAINS WHILE A WEAK WARM
FRONT SETS UP ACROSS THE UPPER MISSOURI VALLEY TO NEAR THE IL/WI
BORDER. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR SOME LIGHT
SNOW IF THERE IS A DEEP ENOUGH LAYER OF MOISTURE IN PLACE AT THE
TIME OF OPTIMAL UPPER LEVEL FORCING. THE LATEST HIGH RESOLUTION
MODEL GUIDANCE SUGGESTS THAT THERE COULD BE A PERIOD OF LIGHT SNOW
DURG THE MORNING HOURS FOR PERHAPS 2 HOURS...BUT TIMING THE SNOW
IS STILL UNCERTAIN. SO...WILL MAINTAIN THE GOING FORECAST OF A 3
HOUR TEMPO GROUP...THOUGH THIS IS LIKELY TOO LONG MORE PRECISE
TIMING SHOULD BE DETERMINED IN LATER UPDATES. REGARDLESS OF EXACT
TIMING...ONLY LIGHT ACCUMULATIONS...PERHAPS A HALF INCH OR LESS IS
EXPECTED.

FOR THE REMAINDER OF THE DAY TOMORROW...FORECAST CONCERNS SHIFT TO
GUSTY SOUTHERLY WINDS DEVELOPING IN THE MID/LATE MORNING AS HIGH
PRESSURE SETTLES OVER THE SERN CONUS AND LOW PRESSURE DEVELOPS
OVER THE NRN PLAINS. OCCASIONAL GUSTS TO ARND 20KT ARE
LIKELY...AND POTENTIALLY HIGHER ARE POSSIBLE WITH DEEPER MIXING IF
ENOUGH SUNSHINE CAN BREAK THROUGH THE CLOUD COVER.

KREIN

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

* MEDIUM CONFIDENCE IN CIG TRENDS.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF A SHORT 1-2
  HR PERIOD OF SNOW OCCURRING FRIDAY MORNING.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272354
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
554 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

LATEST SATELLITE AND RADAR TRENDS INDICATING THAT CLOUD COVER AND
SNOW SHOWERS ARE BECOMING MORE RAGGED AND DECREASING IN COVERAGE
WITH SUNSET AND AS HIGH PRESSURE BUILDS ACROSS THE REGION. ANY
LINGERING SNOW SHOWERS SHOULD COME TO AN END BY ARND 01Z...EXCEPT
FOR GYY...WHICH IS STILL UNDER A LAKE FETCH WITH NWLY WINDS. AS
WINDS BECOME MORE WLY LATER THIS EVENING...ANY LAKE INFLUENCE WILL
SHUT OFF AND CONDITIONS AT GYY SHOULD BECOME QUIET AS WELL.

THE NEXT CONCERN IS FOR THE POTENTIAL FOR ANOTHER BRIEF PERIOD OF
SNOW TOMORROW MORNING. THE LATEST MODEL GUIDANCE STILL INDICATES A
MID LEVEL IMPULSE DROPPING OUT OF THE NRN PLAINS WHILE A WEAK WARM
FRONT SETS UP ACROSS THE UPPER MISSOURI VALLEY TO NEAR THE IL/WI
BORDER. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR SOME LIGHT
SNOW IF THERE IS A DEEP ENOUGH LAYER OF MOISTURE IN PLACE AT THE
TIME OF OPTIMAL UPPER LEVEL FORCING. THE LATEST HIGH RESOLUTION
MODEL GUIDANCE SUGGESTS THAT THERE COULD BE A PERIOD OF LIGHT SNOW
DURG THE MORNING HOURS FOR PERHAPS 2 HOURS...BUT TIMING THE SNOW
IS STILL UNCERTAIN. SO...WILL MAINTAIN THE GOING FORECAST OF A 3
HOUR TEMPO GROUP...THOUGH THIS IS LIKELY TOO LONG MORE PRECISE
TIMING SHOULD BE DETERMINED IN LATER UPDATES. REGARDLESS OF EXACT
TIMING...ONLY LIGHT ACCUMULATIONS...PERHAPS A HALF INCH OR LESS IS
EXPECTED.

FOR THE REMAINDER OF THE DAY TOMORROW...FORECAST CONCERNS SHIFT TO
GUSTY SOUTHERLY WINDS DEVELOPING IN THE MID/LATE MORNING AS HIGH
PRESSURE SETTLES OVER THE SERN CONUS AND LOW PRESSURE DEVELOPS
OVER THE NRN PLAINS. OCCASIONAL GUSTS TO ARND 20KT ARE
LIKELY...AND POTENTIALLY HIGHER ARE POSSIBLE WITH DEEPER MIXING IF
ENOUGH SUNSHINE CAN BREAK THROUGH THE CLOUD COVER.

KREIN

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

* MEDIUM CONFIDENCE IN CIG TRENDS.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF A SHORT 1-2
  HR PERIOD OF SNOW OCCURRING FRIDAY MORNING.

* HIGH CONFIDENCE IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...WX NIL. CHANCE MVFR VIS LATE.

SATURDAY...WX NIL. CHANCE MVFR VIS EARLY MORNING.

SUNDAY...SLIGHT CHANCE OF RAIN EARLY. OTRW...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE...WITH MVFR CIGS/VIS.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW WITH MVFR CIGS/VIS
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272332
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
532 PM CST Thu Nov 27 2014

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST THU NOV 27 2014

Small area of light snow and flurries, which moved in from the Quad
Cities area around mid morning, has held together relatively well
and was now over by Champaign. Have had a tenth or two of
accumulation accompany this feature in the heavier snow bands, which
have reduced visibility down to a mile at times. While remaining
mostly cloudy during the day, the clouds are now breaking up
northwest of the Illinois River, although temperatures there were
only in the lower 20s as stronger cold-air advection spreads in from
the northwest.

Latest surface map shows high pressure axis extending north-south
along the Mississippi Valley. This will slowly settle southeast
across the Midwest tonight, as the next clipper system quickly moves
into the upper Mississippi Valley. The snow from this feature will
remain well to our north, but a band of mid-level clouds will
quickly be moving in later this evening. Low temperatures will
likely be set this evening before the arrival of the clouds, with
temperatures steady or drifting upward overnight as winds start to
turn to the southeast. Teens will be widespread this evening,
possibly as low as 10 degrees near Galesburg.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CST THU NOV 27 2014

The upper trough will translate east of Illinois for Friday, leaving
zonal flow across the Plains and into Illinois through the weekend.
That pattern change will allow a return flow of warm air and
increasing dewpoints from Friday through Sunday. Highs on Friday may
be tempered a few degrees down due to some lingering snow cover in a
corridor from Rushville to Effingham, and have trimmed a couple
degrees from highs in that area. Periodic mid and high clouds across
the north on Friday may also help to keep highs down slightly,
especially with such a cold start to the day.

Saturday will see low clouds developing in the east and south due to
lift from increasing warm frontogenesis in the 850 mb layer. Despite
the cloud cover, surface temps should be noticeably warmer as highs
reach the low to mid 50s. The GFS even triggers a few showers during
the afternoon, but confidence is low that any measurable rain will
occur. Sunday will see a continued increase in low clouds with the
arrival of a cold front from the NW. Some added energy from an
intensifying 300mb jet max will increase lift ahead of the front and
a few showers will possible in our southeastern counties. Rain
chances will be mainly confined to areas SE of a line from Effingham
to Danville, but sprinkles could extend as far west as Peoria to
Jacksonville.

The front is forecast to progress into the Ohio River Valley by
Sunday night, with a colder airmass settling southward early next
week. Any lingering rain showers Sunday night into Monday morning
across our SE counties could transition to light snow due to
deepening of the cold pool. No snow accumulation is expected
however.

Dry and cooler conditions are forecast for Tuesday and Wednesday
under a high pressure ridge. Major model differences are still
present beyond that with respect to the evolution of a closed low
off the West Coast of California. The GFS continues to progress
that wave across the Rockies, triggering surface cyclogenesis
across the Plains on Wednesday. It then progresses that deepening
low into the Great Lakes Thursday-Friday, dragging a cold front
across IL Thursday night. Pre-frontal showers are forecast as
early as Wed night and lingering through Thurs night. The ECMWF
takes the low and gradually absorbs it into a stronger low over
the Gulf of Alaska, with a downstream trough providing cool/dry
weather to Illinois on Wednesday-Thursday. The Canadian GEM shows
indications of primarily keeping the low off the coast, or at
least keeping a long wave trough along the west coast through the
end of the week, providing a dry scenario for IL during that time.
The SuperBlend was biased by the strong GFS precip signal, but
through collaboration with surrounding offices, we lowered precip
chances to the slight category Wed night and Thurs due to so much
uncertainty.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 515 PM CST THU NOV 27 2014

An area of predominantly MVFR cigs with sct -shsn occasionally
bringing IFR-MVFR vsby will continue to affect areas east of
K1H2-KBMI until around 03Z. Otherwise, VFR conditions expected for
the next 24 hours. Winds NW up to 10 kts until 04Z, becoming
light and variable overnight as surface high pressure crosses the
region. Winds increasing after 12Z becoming S10-16kts with gusts
up to 25 kts through afternoon as a clipper system moves by to the
north.

&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Onton







000
FXUS63 KILX 272332
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
532 PM CST Thu Nov 27 2014

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST THU NOV 27 2014

Small area of light snow and flurries, which moved in from the Quad
Cities area around mid morning, has held together relatively well
and was now over by Champaign. Have had a tenth or two of
accumulation accompany this feature in the heavier snow bands, which
have reduced visibility down to a mile at times. While remaining
mostly cloudy during the day, the clouds are now breaking up
northwest of the Illinois River, although temperatures there were
only in the lower 20s as stronger cold-air advection spreads in from
the northwest.

Latest surface map shows high pressure axis extending north-south
along the Mississippi Valley. This will slowly settle southeast
across the Midwest tonight, as the next clipper system quickly moves
into the upper Mississippi Valley. The snow from this feature will
remain well to our north, but a band of mid-level clouds will
quickly be moving in later this evening. Low temperatures will
likely be set this evening before the arrival of the clouds, with
temperatures steady or drifting upward overnight as winds start to
turn to the southeast. Teens will be widespread this evening,
possibly as low as 10 degrees near Galesburg.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CST THU NOV 27 2014

The upper trough will translate east of Illinois for Friday, leaving
zonal flow across the Plains and into Illinois through the weekend.
That pattern change will allow a return flow of warm air and
increasing dewpoints from Friday through Sunday. Highs on Friday may
be tempered a few degrees down due to some lingering snow cover in a
corridor from Rushville to Effingham, and have trimmed a couple
degrees from highs in that area. Periodic mid and high clouds across
the north on Friday may also help to keep highs down slightly,
especially with such a cold start to the day.

Saturday will see low clouds developing in the east and south due to
lift from increasing warm frontogenesis in the 850 mb layer. Despite
the cloud cover, surface temps should be noticeably warmer as highs
reach the low to mid 50s. The GFS even triggers a few showers during
the afternoon, but confidence is low that any measurable rain will
occur. Sunday will see a continued increase in low clouds with the
arrival of a cold front from the NW. Some added energy from an
intensifying 300mb jet max will increase lift ahead of the front and
a few showers will possible in our southeastern counties. Rain
chances will be mainly confined to areas SE of a line from Effingham
to Danville, but sprinkles could extend as far west as Peoria to
Jacksonville.

The front is forecast to progress into the Ohio River Valley by
Sunday night, with a colder airmass settling southward early next
week. Any lingering rain showers Sunday night into Monday morning
across our SE counties could transition to light snow due to
deepening of the cold pool. No snow accumulation is expected
however.

Dry and cooler conditions are forecast for Tuesday and Wednesday
under a high pressure ridge. Major model differences are still
present beyond that with respect to the evolution of a closed low
off the West Coast of California. The GFS continues to progress
that wave across the Rockies, triggering surface cyclogenesis
across the Plains on Wednesday. It then progresses that deepening
low into the Great Lakes Thursday-Friday, dragging a cold front
across IL Thursday night. Pre-frontal showers are forecast as
early as Wed night and lingering through Thurs night. The ECMWF
takes the low and gradually absorbs it into a stronger low over
the Gulf of Alaska, with a downstream trough providing cool/dry
weather to Illinois on Wednesday-Thursday. The Canadian GEM shows
indications of primarily keeping the low off the coast, or at
least keeping a long wave trough along the west coast through the
end of the week, providing a dry scenario for IL during that time.
The SuperBlend was biased by the strong GFS precip signal, but
through collaboration with surrounding offices, we lowered precip
chances to the slight category Wed night and Thurs due to so much
uncertainty.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 515 PM CST THU NOV 27 2014

An area of predominantly MVFR cigs with sct -shsn occasionally
bringing IFR-MVFR vsby will continue to affect areas east of
K1H2-KBMI until around 03Z. Otherwise, VFR conditions expected for
the next 24 hours. Winds NW up to 10 kts until 04Z, becoming
light and variable overnight as surface high pressure crosses the
region. Winds increasing after 12Z becoming S10-16kts with gusts
up to 25 kts through afternoon as a clipper system moves by to the
north.

&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Onton






000
FXUS63 KLOT 272152
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
352 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH LATE AFTERNOON.

* POTENTIAL FOR A PERIOD OF LIGHT SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

KREIN

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC

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

* MEDIUM CONFIDENCE IN MVFR CIG TRENDS THROUGH LATE AFTERNOON...
  HIGH IN CIGS SCATTERING BY EARLY EVENING.

* LOW TO MEDIUM CONFIDENCE IN TIMING AND AFFECTS OF SHORT 1-2 HR
  PERIOD OF STEADY SNOW OCCURRING EARLY FRIDAY.

* HIGH IN WIND TRENDS.

KREIN

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272142
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC

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

* MEDIUM IN MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON...HIGH IN
  CIGS SCATTERING BY EARLY EVENING.

* LOW IN SHORT 1-2 HR PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING IF IT OCCURS.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272142
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
342 PM CST

SATURDAY NIGHT THROUGH FRIDAY...

VERY MILD CONDITIONS WILL CONTINUE THROUGH SUNDAY AS WE REMAIN WELL
ENTRENCHED IN THE WARM SECTOR OF A STORM SYSTEM ACROSS THE UPPER
MIDWEST. SOUTH-SOUTHWESTERLY FLOW WILL LIKELY KEEP LOW TEMPERATURES
WELL INTO THE 40S SATURDAY NIGHT...AND THUS A VERY WARM START IS
EXPECTED FOR SUNDAY. THIS WARM START COULD ALLOW TEMPERATURES TO BE
THE WARMEST ON SUNDAY BEFORE A COLD FRONT PUSHES OVER THE AREA. THE
MAIN QUESTION THAT REMAINS...IS THE TIMING OF THIS COLD FRONTAL
PASSAGE. NCEP MODEL GUIDANCE SUGGESTS THIS FRONT MAY MOVE ACROSS
THE AREA EARLY IN DAY ON SUNDAY...WHICH WOULD NOT GO TO WELL TO
SUPPORT VERY WARM CONDITIONS. HOWEVER...THE 12 UTC ECMWF AND GEM
SOLUTIONS SUGGEST THE FRONT WILL NOT ARRIVE UNTIL VERY LATE SUNDAY
AFTERNOON OR EVENING...AND AS SUCH THEY SUGGEST VERY WARM CONDITIONS
AREA-WIDE ON SUNDAY. AT THIS TIME I AM LEANING TOWARDS A SLOWER
FRONTAL TIMING AND HENCE WARMER CONDITIONS ON SUNDAY THEN THE GFS AND
NAM WOULD SUGGEST.

IN THE WAKE OF THIS COLD FRONT...TEMPERATURES WILL LIKELY DROP BACK
INTO THE UPPER 20S FOR MONDAY. HOWEVER...TEMPERATURES ARE EXPECTED
TO MODERATE THROUGH THE WEEK AS THE HEART OF THIS NEXT PUSH OF COLD
AIR LOOKS TO REMAIN NORTHEAST OF THE REGION. MODEL GUIDANCE IS NOT
IN GOOD AGREEMENT LATER IN THE PERIOD. THE 12 UTC GFS SUGGESTS THAT
A PACIFIC SYSTEM WILL SPREAD RAIN ACROSS THE AREA WEDNESDAY NIGHT
THROUGH THURSDAY. HOWEVER...THE ECMWF WEAKENS TO SYSTEM AS IT MOVES
ONSHORE ACROSS THE WEST COAST...AND THEREFORE REMAINS DRY ACROSS THE
REGION DURING THIS PERIOD. AT THIS TIME WE WILL CONTINUE TO RUN WITH
LOW END POPS UNTIL A BETTER CONSENSUS CAN BE REACHED.

KJB

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC

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

* MEDIUM IN MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON...HIGH IN
  CIGS SCATTERING BY EARLY EVENING.

* LOW IN SHORT 1-2 HR PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING IF IT OCCURS.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272128
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
328 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
337 AM CST

SATURDAY NIGHT THROUGH THURSDAY...

COMING SHORTLY.

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC

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

* MEDIUM IN MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON...HIGH IN
  CIGS SCATTERING BY EARLY EVENING.

* LOW IN SHORT 1-2 HR PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING IF IT OCCURS.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272128
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
328 PM CST THU NOV 27 2014

.SHORT TERM...
320 PM CST

THROUGH SATURDAY...

THE PRIMARY FORECAST CONCERNS WILL BE:
-TEMPERATURES THROUGH MUCH OF THE PERIOD...WITH A BIT OF A SEE SAW
EXPECTED.
-THE POTENTIAL FOR A QUICK HIT OF SNOW VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING.

A COLD 1034 MB HIGH IS BUILDING SOUTH-SOUTHEASTWARD ACROSS THE
MISSISSIPPI VALLEY THIS AFTERNOON. TEMPERATURES UNDER THIS HIGH HAVE
REMAINED IN THE SINGLE DIGITS. HOWEVER...FARTHER EAST ACROSS
NORTHERN ILLINOIS MOSTLY CLOUDY SKIES AND SCATTERED FLURRIES HAVE
BEEN THE RULE. THIS SURFACE HIGH WILL SET UP OVER THE TENNESSEE VALLEY
LATER THIS EVENING...AND THIS SHOULD SET UP A VERY COLD NIGHT ACROSS
THE REGION...WITH SINGLE DIGIT TEMPERATURES LIKELY ACROSS MOST OF
FAR NORTHERN ILLINOIS OUTSIDE OF CHICAGO. IT APPEARS THAT CLOUD
COVER WILL DECREASE FOR A COUPLE HOURS THIS EVENING...WHICH SHOULD
ALLOW TEMPERATURES TO TUMBLE QUICKLY. HOWEVER...CLOUDINESS WILL
QUICKLY INCREASE LATER THIS EVENING AND OVERNIGHT AHEAD OF OUR NEXT
WEATHER SYSTEM.

THIS CURRENT SURGE OF COLD AIR WILL BEGIN TO QUICKLY SHIFT EASTWARD
LATER TONIGHT INTO FRIDAY AS THE LARGE SCALE FLOW PATTERN REMAINS
PROGRESSIVE. UPPER LEVEL HEIGHT RISES...ASSOCIATED WITH UPPER LEVEL
RIDGING BUILDING EASTWARD OVER THE PLAINS...WILL SHIFT A MUCH WARMER
AIRMASS EASTWARD TOWARDS THE UPPER MIDWEST AND GREAT LAKES
AREA OVER THE NEXT 24 HOURS. AS THIS OCCURS...A RATHER STOUT
BAROCLINIC ZONE BETWEEN THE TWO AIRMASS WILL SET UP RIGHT ACROSS THE
AREA INTO FRIDAY. AS A RESULT OF THIS...THE INCREASING SOUTHWESTERLY
FLOW ALOFT WILL ALLOW SOME GOOD ISENTROPIC ASCENT/WARM AIR ADVECT TO
RAMP UP QUICKLY OVER THE UPPER MIDWEST AND INTO THE WESTERN LAKES
REGION TONIGHT AND FRIDAY. ENHANCED MESOSCALE FORCING FOR
ASCENT...WITHIN THE VICINITY OF THE BEST FRONTOGENESIS BAND...SHOULD
FOCUS A FAIRLY QUICK MOVING BAND OF MODERATE TO POSSIBLY BRIEFLY
HEAVY SNOWFALL LATE TONIGHT INTO FRIDAY OVER THE UPPER MIDWEST. THE
MAIN QUESTION IS HOW FAR SOUTH WILL THIS SNOWFALL BAND DEVELOP. IT
APPEARS NORTHERN ILLINOIS WILL BE ON THE SOUTHERN END OF THE AREA
FAVORED FOR THE DEVELOPMENT OF THIS BAND. THE MAIN ISSUE WE WILL BE
FIGHTING LOCALLY...IS A DECENT AMOUNT OF DRY AIR. HOWEVER...I THINK
THAT THE ENHANCE FORCING FOR ASCENT ALONG THE STRENGTHENING BAROCLINIC
ZONE WILL BE ENOUGH TO SATURATE THE COLUMN LATE TONIGHT INTO FRIDAY
MORNING BEFORE THE BEST FORCING QUICKLY MOVES EAST OF THE AREA.
THEREFORE...IT APPEARS THAT WE WILL HAVE A SHORT WINDOW OF TIME TO
SUPPORT A QUICK MOVING BURST OF SNOW ACROSS NORTHERN ILLINOIS DURING
THE EARLY MORNING HOURS FRIDAY.

IT APPEARS THAT THIS BAND OF SNOW COULD RESULT IN A BRIEF PERIOD OF
MODERATE TO POSSIBLY HEAVY SNOW. MID LEVEL LAPSE RATES ARE EXPECTED
TO BE AROUND 6.5 DEGREES C PER KM WITHIN THE 500-700 MB
LEVEL...WHICH SUGGESTS THAT SOME HIGHER SNOW RATES MAY BE POSSIBLE.
THE GOOD NEWS IS THAT THIS BAND OF SNOW SHOULD NOT LAST TOO LONG
OVER ANY GIVEN AREA. THEREFORE...ONLY LIGHT ACCUMULATIONS UNDER AND
INCH ARE POSSIBLE EARLY FRIDAY MORNING...WITH THE BEST CHANCES FOR
THIS ACROSS FAR NORTHERN ILLINOIS...MAINLY ALONG AND NORTH OF I88.

FOLLOWING THIS POTENTIAL BAND OF SNOW...THINGS LOOK TO WARM UP
NICELY BY SATURDAY. TEMPERATURES AT 925 MB ARE PROGGED TO REACH +5
TO +6 DEGREES C BY MIDDAY SATURDAY. CLIMATOLOGY THIS TIME OF YEAR
SUGGESTS TEMPERATURES COULD REACH INTO THE LOWER 50S FOR HIGH
TEMPERATURES. THIS IS CURRENTLY WHAT WE HAVE GOING...SO I MADE NO
CHANGES TO TEMPS ON SATURDAY. THE ONLY POSSIBLE THING THAT COULD
KEEP TEMPERATURES FROM WARMING THIS MUCH IS IF LOW LEVEL
CLOUDINESS AND FOG REMAIN MORE EXTENSIVE DURING THE DAY.

KJB

&&

.LONG TERM...
337 AM CST

SATURDAY NIGHT THROUGH THURSDAY...

COMING SHORTLY.

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC

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

* MEDIUM IN MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON...HIGH IN
  CIGS SCATTERING BY EARLY EVENING.

* LOW IN SHORT 1-2 HR PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING IF IT OCCURS.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 272101
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
301 PM CST Thu Nov 27 2014

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST THU NOV 27 2014

Small area of light snow and flurries, which moved in from the Quad
Cities area around mid morning, has held together relatively well
and was now over by Champaign. Have had a tenth or two of
accumulation accompany this feature in the heavier snow bands, which
have reduced visibility down to a mile at times. While remaining
mostly cloudy during the day, the clouds are now breaking up
northwest of the Illinois River, although temperatures there were
only in the lower 20s as stronger cold-air advection spreads in from
the northwest.

Latest surface map shows high pressure axis extending north-south
along the Mississippi Valley. This will slowly settle southeast
across the Midwest tonight, as the next clipper system quickly moves
into the upper Mississippi Valley. The snow from this feature will
remain well to our north, but a band of mid-level clouds will
quickly be moving in later this evening. Low temperatures will
likely be set this evening before the arrival of the clouds, with
temperatures steady or drifting upward overnight as winds start to
turn to the southeast. Teens will be widespread this evening,
possibly as low as 10 degrees near Galesburg.


&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CST THU NOV 27 2014

The upper trough will translate east of Illinois for Friday, leaving
zonal flow across the Plains and into Illinois through the weekend.
That pattern change will allow a return flow of warm air and
increasing dewpoints from Friday through Sunday. Highs on Friday may
be tempered a few degrees down due to some lingering snow cover in a
corridor from Rushville to Effingham, and have trimmed a couple
degrees from highs in that area. Periodic mid and high clouds across
the north on Friday may also help to keep highs down slightly,
especially with such a cold start to the day.

Saturday will see low clouds developing in the east and south due to
lift from increasing warm frontogenesis in the 850 mb layer. Despite
the cloud cover, surface temps should be noticeably warmer as highs
reach the low to mid 50s. The GFS even triggers a few showers during
the afternoon, but confidence is low that any measurable rain will
occur. Sunday will see a continued increase in low clouds with the
arrival of a cold front from the NW. Some added energy from an
intensifying 300mb jet max will increase lift ahead of the front and
a few showers will possible in our southeastern counties. Rain
chances will be mainly confined to areas SE of a line from Effingham
to Danville, but sprinkles could extend as far west as Peoria to
Jacksonville.

The front is forecast to progress into the Ohio River Valley by
Sunday night, with a colder airmass settling southward early next
week. Any lingering rain showers Sunday night into Monday morning
across our SE counties could transition to light snow due to
deepening of the cold pool. No snow accumulation is expected
however.

Dry and cooler conditions are forecast for Tuesday and Wednesday
under a high pressure ridge. Major model differences are still
present beyond that with respect to the evolution of a closed low
off the West Coast of California. The GFS continues to progress
that wave across the Rockies, triggering surface cyclogenesis
across the Plains on Wednesday. It then progresses that deepening
low into the Great Lakes Thursday-Friday, dragging a cold front
across IL Thursday night. Pre-frontal showers are forecast as
early as Wed night and lingering through Thurs night. The ECMWF
takes the low and gradually absorbs it into a stronger low over
the Gulf of Alaska, with a downstream trough providing cool/dry
weather to Illinois on Wednesday-Thursday. The Canadian GEM shows
indications of primarily keeping the low off the coast, or at
least keeping a long wave trough along the west coast through the
end of the week, providing a dry scenario for IL during that time.
The SuperBlend was biased by the strong GFS precip signal, but
through collaboration with surrounding offices, we lowered precip
chances to the slight category Wed night and Thurs due to so much
uncertainty.


&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1123 AM CST THU NOV 27 2014

Small area of light snow showers has been reducing visibilities to
1 to 2 miles as it moves southeast. Currently moving through KDEC
and may clip KCMI over the next hour or two, although it will
largely track south of there. Otherwise, MVFR conditions will
prevail into mid afternoon, although an area of clearing is not
too far west of KPIA and will be spreading eastward through the
afternoon. Later on in the forecast period, northwest winds to
turn more southeast overnight, following the passage of an area of
high pressure. Strong low level winds will arrive on Friday
morning and mix down toward the surface, producing some gusts up
to 15-20 knots by mid to late morning. Some higher clouds around
8000 feet or so will move through overnight and exit Friday
morning, as a clipper system passes to our north.


&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Geelhart






000
FXUS63 KILX 272101
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
301 PM CST Thu Nov 27 2014

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST THU NOV 27 2014

Small area of light snow and flurries, which moved in from the Quad
Cities area around mid morning, has held together relatively well
and was now over by Champaign. Have had a tenth or two of
accumulation accompany this feature in the heavier snow bands, which
have reduced visibility down to a mile at times. While remaining
mostly cloudy during the day, the clouds are now breaking up
northwest of the Illinois River, although temperatures there were
only in the lower 20s as stronger cold-air advection spreads in from
the northwest.

Latest surface map shows high pressure axis extending north-south
along the Mississippi Valley. This will slowly settle southeast
across the Midwest tonight, as the next clipper system quickly moves
into the upper Mississippi Valley. The snow from this feature will
remain well to our north, but a band of mid-level clouds will
quickly be moving in later this evening. Low temperatures will
likely be set this evening before the arrival of the clouds, with
temperatures steady or drifting upward overnight as winds start to
turn to the southeast. Teens will be widespread this evening,
possibly as low as 10 degrees near Galesburg.


&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CST THU NOV 27 2014

The upper trough will translate east of Illinois for Friday, leaving
zonal flow across the Plains and into Illinois through the weekend.
That pattern change will allow a return flow of warm air and
increasing dewpoints from Friday through Sunday. Highs on Friday may
be tempered a few degrees down due to some lingering snow cover in a
corridor from Rushville to Effingham, and have trimmed a couple
degrees from highs in that area. Periodic mid and high clouds across
the north on Friday may also help to keep highs down slightly,
especially with such a cold start to the day.

Saturday will see low clouds developing in the east and south due to
lift from increasing warm frontogenesis in the 850 mb layer. Despite
the cloud cover, surface temps should be noticeably warmer as highs
reach the low to mid 50s. The GFS even triggers a few showers during
the afternoon, but confidence is low that any measurable rain will
occur. Sunday will see a continued increase in low clouds with the
arrival of a cold front from the NW. Some added energy from an
intensifying 300mb jet max will increase lift ahead of the front and
a few showers will possible in our southeastern counties. Rain
chances will be mainly confined to areas SE of a line from Effingham
to Danville, but sprinkles could extend as far west as Peoria to
Jacksonville.

The front is forecast to progress into the Ohio River Valley by
Sunday night, with a colder airmass settling southward early next
week. Any lingering rain showers Sunday night into Monday morning
across our SE counties could transition to light snow due to
deepening of the cold pool. No snow accumulation is expected
however.

Dry and cooler conditions are forecast for Tuesday and Wednesday
under a high pressure ridge. Major model differences are still
present beyond that with respect to the evolution of a closed low
off the West Coast of California. The GFS continues to progress
that wave across the Rockies, triggering surface cyclogenesis
across the Plains on Wednesday. It then progresses that deepening
low into the Great Lakes Thursday-Friday, dragging a cold front
across IL Thursday night. Pre-frontal showers are forecast as
early as Wed night and lingering through Thurs night. The ECMWF
takes the low and gradually absorbs it into a stronger low over
the Gulf of Alaska, with a downstream trough providing cool/dry
weather to Illinois on Wednesday-Thursday. The Canadian GEM shows
indications of primarily keeping the low off the coast, or at
least keeping a long wave trough along the west coast through the
end of the week, providing a dry scenario for IL during that time.
The SuperBlend was biased by the strong GFS precip signal, but
through collaboration with surrounding offices, we lowered precip
chances to the slight category Wed night and Thurs due to so much
uncertainty.


&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1123 AM CST THU NOV 27 2014

Small area of light snow showers has been reducing visibilities to
1 to 2 miles as it moves southeast. Currently moving through KDEC
and may clip KCMI over the next hour or two, although it will
largely track south of there. Otherwise, MVFR conditions will
prevail into mid afternoon, although an area of clearing is not
too far west of KPIA and will be spreading eastward through the
afternoon. Later on in the forecast period, northwest winds to
turn more southeast overnight, following the passage of an area of
high pressure. Strong low level winds will arrive on Friday
morning and mix down toward the surface, producing some gusts up
to 15-20 knots by mid to late morning. Some higher clouds around
8000 feet or so will move through overnight and exit Friday
morning, as a clipper system passes to our north.


&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Geelhart







000
FXUS63 KLOT 271956
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
156 PM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC

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

* MEDIUM IN MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON...HIGH IN
  CIGS SCATTERING BY EARLY EVENING.

* LOW IN SHORT 1-2 HR PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING IF IT OCCURS.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271956
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
156 PM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC

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

* MEDIUM IN MVFR CIG TRENDS THROUGH MID-LATE AFTERNOON...HIGH IN
  CIGS SCATTERING BY EARLY EVENING.

* LOW IN SHORT 1-2 HR PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING IF IT OCCURS.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271808
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1208 PM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS INTO EARLY-MID AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC


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

* MEDIUM IN TIMING OF MVFR CIGS SCATTERING THIS AFTERNOON.

* LOW IN SHORT PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271808
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1208 PM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS INTO EARLY-MID AFTERNOON.

* POTENTIAL FOR A PERIOD OF SNOW EARLY FRIDAY MORNING.

* GUSTY SOUTHERLY WINDS MID FRIDAY MORNING THROUGH THE AFTERNOON.

RC

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

MAIN AVIATION CONCERN IS POTENTIAL FOR A SHORT PERIOD OF SNOW
EARLY FRIDAY MORNING. PRIOR TO THAT...STILL EXPECTING MVFR CIGS TO
SCATTER THIS AFTERNOON AND GUSTY NORTHWEST WINDS TO DIMINISH EARLY
THIS EVENING AS HIGH PRESSURE MOVES OVERHEAD. REGARDING THE PERIOD
OF SNOW...MAIN QUESTION IS IF SATURATION OCCURS WHILE GOOD FORCING
PASSES ACROSS THE AREA IN THE EARLY MORNING HOURS. IF IT
DOES...LOOKING AT A FAIRLY NARROW BAND OF SNOW TO TRACK WEST TO
EAST...WITH GYY POSSIBLY ON THE SOUTHERN FRINGE. HAVE INTRODUCED
A 3-4 HR PROB 30 IN THE TAFS...BUT SNOW IS ONLY FAVORED TO LAST
1-2 HOURS AT MOST UPON ONSET...WITH UNDER 1 INCH OF ACCUMULATION.
SHOULD THE ORGANIZED BAND OF SNOW MATERIALIZE...THEN IFR TO LOWER
MVFR VSBY WOULD BE LIKELY.

AFTER ANY SNOW ENDS...CONCERN SHIFTS TO GUSTY SOUTHERLY WINDS
(160-180 DEG) DEVELOPING IN THE MID/LATE MORNING AND CONTINUING
THROUGH THE AFTERNOON ON FRIDAY. GUSTS COULD BE IN THE LOW 20KT
RANGE AND POTENTIALLY HIGHER IF MIXING IS A BIT DEEPER. VFR
CONDITIONS ARE EXPECTED DURING THE STRONGER SOUTHERLY WINDS.

RC


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

* MEDIUM IN TIMING OF MVFR CIGS SCATTERING THIS AFTERNOON.

* LOW IN SHORT PERIOD OF STEADY SNOW OCCURRING EARLY
  FRIDAY...MEDIUM IN TIMING.

* HIGH IN WIND TRENDS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271723
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1123 AM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 1000 AM CST THU NOV 27 2014

Have updated the forecast to significantly ramp up the PoP`s for
the next few hours from about Decatur northwest to Galesburg. An
area of light snow and flurries has been moving southeast out of
the Quad Cities. While significant accumulation is not
anticipated, the visibilities have been getting down to 1 to 2
miles at times which would imply more than just flurries, and
web cams around Peoria suggest a dusting of accumulation is
occurring in the heavier bands. The snow has been weakening as it
moves southeast through central Illinois, so have kept the
afternoon dry for now. Back edge of the cloud deck is along the
Illinois/Iowa border and slowly moving east, with the RAP guidance
continuing to indicate some gradual clearing from west to east
across our forecast area this afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dew points increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder air mass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder air mass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1123 AM CST THU NOV 27 2014

Small area of light snow showers has been reducing visibilities to
1 to 2 miles as it moves southeast. Currently moving through KDEC
and may clip KCMI over the next hour or two, although it will
largely track south of there. Otherwise, MVFR conditions will
prevail into mid afternoon, although an area of clearing is not
too far west of KPIA and will be spreading eastward through the
afternoon. Later on in the forecast period, northwest winds to
turn more southeast overnight, following the passage of an area of
high pressure. Strong low level winds will arrive on Friday
morning and mix down toward the surface, producing some gusts up
to 15-20 knots by mid to late morning. Some higher clouds around
8000 feet or so will move through overnight and exit Friday
morning, as a clipper system passes to our north.

&&

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

$$

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






000
FXUS63 KILX 271723
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1123 AM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 1000 AM CST THU NOV 27 2014

Have updated the forecast to significantly ramp up the PoP`s for
the next few hours from about Decatur northwest to Galesburg. An
area of light snow and flurries has been moving southeast out of
the Quad Cities. While significant accumulation is not
anticipated, the visibilities have been getting down to 1 to 2
miles at times which would imply more than just flurries, and
web cams around Peoria suggest a dusting of accumulation is
occurring in the heavier bands. The snow has been weakening as it
moves southeast through central Illinois, so have kept the
afternoon dry for now. Back edge of the cloud deck is along the
Illinois/Iowa border and slowly moving east, with the RAP guidance
continuing to indicate some gradual clearing from west to east
across our forecast area this afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dew points increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder air mass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder air mass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1123 AM CST THU NOV 27 2014

Small area of light snow showers has been reducing visibilities to
1 to 2 miles as it moves southeast. Currently moving through KDEC
and may clip KCMI over the next hour or two, although it will
largely track south of there. Otherwise, MVFR conditions will
prevail into mid afternoon, although an area of clearing is not
too far west of KPIA and will be spreading eastward through the
afternoon. Later on in the forecast period, northwest winds to
turn more southeast overnight, following the passage of an area of
high pressure. Strong low level winds will arrive on Friday
morning and mix down toward the surface, producing some gusts up
to 15-20 knots by mid to late morning. Some higher clouds around
8000 feet or so will move through overnight and exit Friday
morning, as a clipper system passes to our north.

&&

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

$$

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






000
FXUS63 KILX 271723
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1123 AM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 1000 AM CST THU NOV 27 2014

Have updated the forecast to significantly ramp up the PoP`s for
the next few hours from about Decatur northwest to Galesburg. An
area of light snow and flurries has been moving southeast out of
the Quad Cities. While significant accumulation is not
anticipated, the visibilities have been getting down to 1 to 2
miles at times which would imply more than just flurries, and
web cams around Peoria suggest a dusting of accumulation is
occurring in the heavier bands. The snow has been weakening as it
moves southeast through central Illinois, so have kept the
afternoon dry for now. Back edge of the cloud deck is along the
Illinois/Iowa border and slowly moving east, with the RAP guidance
continuing to indicate some gradual clearing from west to east
across our forecast area this afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dew points increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder air mass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder air mass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1123 AM CST THU NOV 27 2014

Small area of light snow showers has been reducing visibilities to
1 to 2 miles as it moves southeast. Currently moving through KDEC
and may clip KCMI over the next hour or two, although it will
largely track south of there. Otherwise, MVFR conditions will
prevail into mid afternoon, although an area of clearing is not
too far west of KPIA and will be spreading eastward through the
afternoon. Later on in the forecast period, northwest winds to
turn more southeast overnight, following the passage of an area of
high pressure. Strong low level winds will arrive on Friday
morning and mix down toward the surface, producing some gusts up
to 15-20 knots by mid to late morning. Some higher clouds around
8000 feet or so will move through overnight and exit Friday
morning, as a clipper system passes to our north.

&&

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

$$

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






000
FXUS63 KILX 271723
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1123 AM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 1000 AM CST THU NOV 27 2014

Have updated the forecast to significantly ramp up the PoP`s for
the next few hours from about Decatur northwest to Galesburg. An
area of light snow and flurries has been moving southeast out of
the Quad Cities. While significant accumulation is not
anticipated, the visibilities have been getting down to 1 to 2
miles at times which would imply more than just flurries, and
web cams around Peoria suggest a dusting of accumulation is
occurring in the heavier bands. The snow has been weakening as it
moves southeast through central Illinois, so have kept the
afternoon dry for now. Back edge of the cloud deck is along the
Illinois/Iowa border and slowly moving east, with the RAP guidance
continuing to indicate some gradual clearing from west to east
across our forecast area this afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dew points increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder air mass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder air mass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1123 AM CST THU NOV 27 2014

Small area of light snow showers has been reducing visibilities to
1 to 2 miles as it moves southeast. Currently moving through KDEC
and may clip KCMI over the next hour or two, although it will
largely track south of there. Otherwise, MVFR conditions will
prevail into mid afternoon, although an area of clearing is not
too far west of KPIA and will be spreading eastward through the
afternoon. Later on in the forecast period, northwest winds to
turn more southeast overnight, following the passage of an area of
high pressure. Strong low level winds will arrive on Friday
morning and mix down toward the surface, producing some gusts up
to 15-20 knots by mid to late morning. Some higher clouds around
8000 feet or so will move through overnight and exit Friday
morning, as a clipper system passes to our north.

&&

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

$$

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






000
FXUS63 KILX 271601
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1001 AM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 1000 AM CST THU NOV 27 2014

Have updated the forecast to significantly ramp up the PoP`s for
the next few hours from about Decatur northwest to Galesburg. An
area of light snow and flurries has been moving southeast out of
the Quad Cities. While significant accumulation is not
anticipated, the visibilities have been getting down to 1 to 2
miles at times which would imply more than just flurries, and
web cams around Peoria suggest a dusting of accumulation is
occurring in the heavier bands. The snow has been weakening as it
moves southeast through central Illinois, so have kept the
afternoon dry for now. Back edge of the cloud deck is along the
Illinois/Iowa border and slowly moving east, with the RAP guidance
continuing to indicate some gradual clearing from west to east
across our forecast area this afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dew points increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder air mass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder air mass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 557 AM CST THU NOV 27 2014

VFR conditions across the central Illinois terminals will quickly
degrade to MVFR this morning as a band of SC spreads in from the
northwest. Then, skies will scatter out this afternoon as a ridge
of high pressure begins to build into the area. However, mid/high
level VFR cigs will spread into the region tonight ahead of the
next weather disturbance. A period of 10-15 kt northwest winds
will exist to start the day, with a few gusts to 20 kts possible
into midday. Then, winds will trend light/variable as the ridge of
high pressure builds in for tonight.


&&

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

$$

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







000
FXUS63 KILX 271601
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1001 AM CST Thu Nov 27 2014

.UPDATE...
ISSUED AT 1000 AM CST THU NOV 27 2014

Have updated the forecast to significantly ramp up the PoP`s for
the next few hours from about Decatur northwest to Galesburg. An
area of light snow and flurries has been moving southeast out of
the Quad Cities. While significant accumulation is not
anticipated, the visibilities have been getting down to 1 to 2
miles at times which would imply more than just flurries, and
web cams around Peoria suggest a dusting of accumulation is
occurring in the heavier bands. The snow has been weakening as it
moves southeast through central Illinois, so have kept the
afternoon dry for now. Back edge of the cloud deck is along the
Illinois/Iowa border and slowly moving east, with the RAP guidance
continuing to indicate some gradual clearing from west to east
across our forecast area this afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dew points increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder air mass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder air mass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 557 AM CST THU NOV 27 2014

VFR conditions across the central Illinois terminals will quickly
degrade to MVFR this morning as a band of SC spreads in from the
northwest. Then, skies will scatter out this afternoon as a ridge
of high pressure begins to build into the area. However, mid/high
level VFR cigs will spread into the region tonight ahead of the
next weather disturbance. A period of 10-15 kt northwest winds
will exist to start the day, with a few gusts to 20 kts possible
into midday. Then, winds will trend light/variable as the ridge of
high pressure builds in for tonight.


&&

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

$$

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






000
FXUS63 KLOT 271600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1000 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

RC

//DISCUSSION...UPDATED 14Z...

BASED ON REGIONAL OBSERVATIONS...EXPECT PATCHY MVFR CIGS THROUGH
MID DAY/EARLY AFTERNOON FOLLOWED BY RISING BASES AND THEN
SCATTERING LATER THIS AFTERNOON. HAVE CARRIED TEMPO GROUPS AT THE
TAF SITES TO INDICATE LIKELY VARIATION FROM MVFR TO SCATTERING FOR
THE NEXT SEVERAL HOURS. OTHERWISE...THERE ARE OCCASIONAL FLURRIES
BUT THESE ARE NOT CAUSING ANY VSBY RESTRICTIONS EXCEPT IN AREAS
WHERE THERE IS EXISTING HZ/BR...WHICH SHOULD ALSO IMPROVE OVER THE
NEXT FEW HOURS.

FROM 12Z...

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ

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

* MEDIUM IN MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

* HIGH IN REMAINING ELEMENTS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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

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






000
FXUS63 KLOT 271600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1000 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

RC

//DISCUSSION...UPDATED 14Z...

BASED ON REGIONAL OBSERVATIONS...EXPECT PATCHY MVFR CIGS THROUGH
MID DAY/EARLY AFTERNOON FOLLOWED BY RISING BASES AND THEN
SCATTERING LATER THIS AFTERNOON. HAVE CARRIED TEMPO GROUPS AT THE
TAF SITES TO INDICATE LIKELY VARIATION FROM MVFR TO SCATTERING FOR
THE NEXT SEVERAL HOURS. OTHERWISE...THERE ARE OCCASIONAL FLURRIES
BUT THESE ARE NOT CAUSING ANY VSBY RESTRICTIONS EXCEPT IN AREAS
WHERE THERE IS EXISTING HZ/BR...WHICH SHOULD ALSO IMPROVE OVER THE
NEXT FEW HOURS.

FROM 12Z...

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ

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

* MEDIUM IN MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

* HIGH IN REMAINING ELEMENTS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1000 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

RC

//DISCUSSION...UPDATED 14Z...

BASED ON REGIONAL OBSERVATIONS...EXPECT PATCHY MVFR CIGS THROUGH
MID DAY/EARLY AFTERNOON FOLLOWED BY RISING BASES AND THEN
SCATTERING LATER THIS AFTERNOON. HAVE CARRIED TEMPO GROUPS AT THE
TAF SITES TO INDICATE LIKELY VARIATION FROM MVFR TO SCATTERING FOR
THE NEXT SEVERAL HOURS. OTHERWISE...THERE ARE OCCASIONAL FLURRIES
BUT THESE ARE NOT CAUSING ANY VSBY RESTRICTIONS EXCEPT IN AREAS
WHERE THERE IS EXISTING HZ/BR...WHICH SHOULD ALSO IMPROVE OVER THE
NEXT FEW HOURS.

FROM 12Z...

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ

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

* MEDIUM IN MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

* HIGH IN REMAINING ELEMENTS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271600
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1000 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

RC

//DISCUSSION...UPDATED 14Z...

BASED ON REGIONAL OBSERVATIONS...EXPECT PATCHY MVFR CIGS THROUGH
MID DAY/EARLY AFTERNOON FOLLOWED BY RISING BASES AND THEN
SCATTERING LATER THIS AFTERNOON. HAVE CARRIED TEMPO GROUPS AT THE
TAF SITES TO INDICATE LIKELY VARIATION FROM MVFR TO SCATTERING FOR
THE NEXT SEVERAL HOURS. OTHERWISE...THERE ARE OCCASIONAL FLURRIES
BUT THESE ARE NOT CAUSING ANY VSBY RESTRICTIONS EXCEPT IN AREAS
WHERE THERE IS EXISTING HZ/BR...WHICH SHOULD ALSO IMPROVE OVER THE
NEXT FEW HOURS.

FROM 12Z...

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ

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

* MEDIUM IN MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

* HIGH IN REMAINING ELEMENTS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271422
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
822 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

RC

//DISCUSSION...UPDATED 14Z...

BASED ON REGIONAL OBSERVATIONS...EXPECT PATCHY MVFR CIGS THROUGH
MID DAY/EARLY AFTERNOON FOLLOWED BY RISING BASES AND THEN
SCATTERING LATER THIS AFTERNOON. HAVE CARRIED TEMPO GROUPS AT THE
TAF SITES TO INDICATE LIKELY VARIATION FROM MVFR TO SCATTERING FOR
THE NEXT SEVERAL HOURS. OTHERWISE...THERE ARE OCCASIONAL FLURRIES
BUT THESE ARE NOT CAUSING ANY VSBY RESTRICTIONS EXCEPT IN AREAS
WHERE THERE IS EXISTING HZ/BR...WHICH SHOULD ALSO IMPROVE OVER THE
NEXT FEW HOURS.

FROM 12Z...

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ

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

* MEDIUM IN MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

* HIGH IN REMAINING ELEMENTS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271422
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
822 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

RC

//DISCUSSION...UPDATED 14Z...

BASED ON REGIONAL OBSERVATIONS...EXPECT PATCHY MVFR CIGS THROUGH
MID DAY/EARLY AFTERNOON FOLLOWED BY RISING BASES AND THEN
SCATTERING LATER THIS AFTERNOON. HAVE CARRIED TEMPO GROUPS AT THE
TAF SITES TO INDICATE LIKELY VARIATION FROM MVFR TO SCATTERING FOR
THE NEXT SEVERAL HOURS. OTHERWISE...THERE ARE OCCASIONAL FLURRIES
BUT THESE ARE NOT CAUSING ANY VSBY RESTRICTIONS EXCEPT IN AREAS
WHERE THERE IS EXISTING HZ/BR...WHICH SHOULD ALSO IMPROVE OVER THE
NEXT FEW HOURS.

FROM 12Z...

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ

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

* MEDIUM IN MVFR CIG TRENDS THROUGH EARLY AFTERNOON.

* HIGH IN REMAINING ELEMENTS.

RC

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 6 PM THURSDAY.

&&

$$

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 271158
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
558 AM CST Thu Nov 27 2014

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dewpoints increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder airmass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder airmass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 557 AM CST THU NOV 27 2014

VFR conditions across the central Illinois terminals will quickly
degrade to MVFR this morning as a band of SC spreads in from the
northwest. Then, skies will scatter out this afternoon as a ridge
of high pressure begins to build into the area. However, mid/high
level VFR cigs will spread into the region tonight ahead of the
next weather disturbance. A period of 10-15 kt northwest winds
will exist to start the day, with a few gusts to 20 kts possible
into midday. Then, winds will trend light/variable as the ridge of
high pressure builds in for tonight.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Bak






000
FXUS63 KILX 271158
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
558 AM CST Thu Nov 27 2014

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.

&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dewpoints increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder airmass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder airmass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 557 AM CST THU NOV 27 2014

VFR conditions across the central Illinois terminals will quickly
degrade to MVFR this morning as a band of SC spreads in from the
northwest. Then, skies will scatter out this afternoon as a ridge
of high pressure begins to build into the area. However, mid/high
level VFR cigs will spread into the region tonight ahead of the
next weather disturbance. A period of 10-15 kt northwest winds
will exist to start the day, with a few gusts to 20 kts possible
into midday. Then, winds will trend light/variable as the ridge of
high pressure builds in for tonight.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Bak







000
FXUS63 KLOT 271155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
555 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* SCATTERED FLURRIES OR LIGHT SNOW OVER THE NEXT SEVERAL
  HOURS...BUT WITH NO VIS RESTRICTION.

* MVFR CEILINGS RETURNING LATER THIS MORNING...LASTING THROUGH MID
  DAY.

RODRIGUEZ

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

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH FLURRIES/LIGHT SNOW AND VIS THIS MORNING.

* MEDIUM CONFIDENCE OF MVFR CEILINGS RETURNING...AND EXACT
  TIMING/DURATION.

RODRIGUEZ

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
555 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* SCATTERED FLURRIES OR LIGHT SNOW OVER THE NEXT SEVERAL
  HOURS...BUT WITH NO VIS RESTRICTION.

* MVFR CEILINGS RETURNING LATER THIS MORNING...LASTING THROUGH MID
  DAY.

RODRIGUEZ

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

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH FLURRIES/LIGHT SNOW AND VIS THIS MORNING.

* MEDIUM CONFIDENCE OF MVFR CEILINGS RETURNING...AND EXACT
  TIMING/DURATION.

RODRIGUEZ

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
555 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* SCATTERED FLURRIES OR LIGHT SNOW OVER THE NEXT SEVERAL
  HOURS...BUT WITH NO VIS RESTRICTION.

* MVFR CEILINGS RETURNING LATER THIS MORNING...LASTING THROUGH MID
  DAY.

RODRIGUEZ

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

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH FLURRIES/LIGHT SNOW AND VIS THIS MORNING.

* MEDIUM CONFIDENCE OF MVFR CEILINGS RETURNING...AND EXACT
  TIMING/DURATION.

RODRIGUEZ

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271155
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
555 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* SCATTERED FLURRIES OR LIGHT SNOW OVER THE NEXT SEVERAL
  HOURS...BUT WITH NO VIS RESTRICTION.

* MVFR CEILINGS RETURNING LATER THIS MORNING...LASTING THROUGH MID
  DAY.

RODRIGUEZ

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

LAKE EFFECT SNOW SHOWERS AS WELL AS MVFR CEILINGS HAVE SINCE
PUSHED EAST OF ALL OF THE TERMINALS...WITH THE EXCEPTION OF GYY
WHERE THESE ARE BOTH STILL OCCURRING. VFR CEILINGS IN PLACE FOR
THE REMAINDER OF THE TERMINALS...AS A PASSING MID LEVEL
DISTURBANCE IS HELPING TO PROVIDE SCATTERED FLURRIES OR LIGHT
SNOW. THESE FLURRIES/LIGHT SNOW WILL OCCUR OVER THE NEXT SEVERAL
HOURS...BUT WITH NO REAL VIS RESTRICTION OR ACCUMULATION EXPECTED.
UPSTREAM AND TO THE WEST/NORTHWEST OF THE TERMINALS...MVFR
CEILINGS STILL CURRENTLY RESIDE. STILL EXPECT THESE MVFR CEILINGS
TO PUSH EAST REACHING THE TERMINALS THIS MORNING...WITH LATEST
SHORT TERM GUIDANCE STILL SUPPORTING THIS. AM NOT TOO CONFIDENT
WITH EXACT TIMING OR DURATION...WITH THESE LOWER CEILINGS POSSIBLY
NOT ARRIVING UNTIL LATER THAN IN THE TAFS. CEILINGS WILL IMPROVE
LATER THIS AFTERNOON BEFORE SHIFTING TO THE EAST...LEAVING VFR
CONDITIONS FOR THE REMAINING FORECAST PERIOD. NORTHWEST WINDS WILL
INCREASE THROUGH THIS MORNING AND MID DAY...WITH LIGHTER WINDS
EXPECTED TONIGHT AS HIGH PRESSURE MOVES ACROSS THE REGION.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH FLURRIES/LIGHT SNOW AND VIS THIS MORNING.

* MEDIUM CONFIDENCE OF MVFR CEILINGS RETURNING...AND EXACT
  TIMING/DURATION.

RODRIGUEZ

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

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...SLIGHT CHANCE OF RAIN.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LIGHT SNOW LATE.

WEDNESDAY...SLIGHT CHANCE OF LIGHT SNOW.

RODRIGUEZ

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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

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000
FXUS63 KLOT 271025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
425 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
424 AM CST

FRONTAL BOUNDARY PUSHING DOWN THE LAKE EARLY THIS MORNING AND AS
THIS IS OCCURRING...NORTHWEST WINDS ARE RAPIDLY INCREASING UP TO
30 KT. THIS TREND WILL CONTINUE IN THE NEAR TERM WITH ALL AREAS
ACROSS THE OPEN WATERS OBSERVING NORTHWEST 30 KT WINDS TODAY.
ALTHOUGH IT DOES APPEAR TO BE BRIEF...OCCASIONAL GALE FORCE GUSTS
STILL APPEAR TO BE POSSIBLE TODAY AND SO HAVE CONTINUED THE
MENTION IN THE OPEN WATERS FORECAST. FOR THE NEARSHORE
TODAY...NORTHWEST WINDS WILL PREVAIL WITH THE STRONGEST LIKELY
OBSERVED IN THE INDIANA NEARSHORE. THIS IS ALREADY OCCURRING AND
SO HAVE STARTED THE SCA FOR INDIANA NOW AND THEN EXTENDED IT
FURTHER INTO TONIGHT...AS HIGHER WAVES WILL LINGER FOR MOST OF
TONIGHT. AFTER A BRIEF LULL IN SPEEDS TONIGHT AS HIGH PRESSURE
MOVES ACROSS THE REGION...WINDS WILL TURN TO THE SOUTHWEST AND
SOUTH ON FRIDAY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE OVER THE
LAKE AND NEARSHORE WATERS...WITH SPEEDS UP TO 30 KT LIKELY OVER
THE OPEN WATERS FRIDAY AND FRIDAY EVENING. THERE ONCE AGAIN
APPEARS TO BE A POSSIBILITY FOR SPEEDS APPROACHING GALE
FORCE...ESPECIALLY IN THE AFTERNOON AND EARLY EVENING OVER THE
ENTIRE LAKE. HAVE MADE MENTION OF GALE FORCE GUSTS ONCE AGAIN
DURING THIS TIME...BUT CONFIDENCE OF THESE HIGHER SPEEDS IS LOW.
WILL NEED TO MONITOR THESE PERIODS...WITH THE POSSIBILITY OF THESE
HIGHER SPEEDS BEING OBSERVED.

RODRIGUEZ

&&

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

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 270942
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
342 AM CST THU NOV 27 2014

.SHORT TERM...
337 AM CST

THROUGH FRIDAY...

THOSE DREAMING OF A WHITE THANKSGIVING WILL LIKELY NEED TO BE
DOWNWIND OF THE LAKE ALONG THE INDIANA AND MICHIGAN SHORES
TODAY...ALTHOUGH DURING THE PREDAWN HOURS THERE HAVE BEEN SEVERAL
STATIONS REPORTING PERSISTENT FLURRIES BUT NO ACCUMULATION ON THE
ILLINOIS SIDE AS WELL. AFTERNOON HIGHS LIKELY WILL TOP OUT A FEW
DEGREES COOLER THAN WHAT WOULD BE MORE TYPICAL FOR CHRISTMAS THAN
LATE NOVEMBER...SO EVEN IN AREAS THAT DO NOT RECEIVE SNOW IT WILL
STILL BE QUITE A COLD THANKSGIVING.

PERHAPS THE MOST WELCOME NEWS COMES ON FRIDAY INTO THE WEEKEND WHEN
TEMPERATURES SHOULD FINALLY CLIMB BACK INTO NORMAL RANGES...AND
LIKELY WELL ABOVE.  COLD NORTHERLY FLOW AHEAD OF AN APPROACHING HIGH
IS WHAT WILL BE KEEPING THE LID ON TEMPERATURES TODAY...BUT WINDS
TURN SOUTH BY FRIDAY AND START TO PUSH THE COLD AIR AWAY TO OUR
NORTHEAST AS THE HIGH DROPS INTO THE OHIO VALLEY.

LENNING

&&

.LONG TERM...
337 AM CST

FRIDAY NIGHT THROUGH THURSDAY...

WITH WEAK TO MODERATE WARM ADVECTION LATE FRIDAY INTO FRIDAY
NIGHT AND SATURDAY...TEMPERATURE TRENDS OVERNIGHT COULD BE FLAT TO
SLOWLY RISING. WARM ADVECTION THEN DEVELOPS IN EARNEST DURING THE
DAY SATURDAY AHEAD OF A CENTER OF LOW PRESSURE SLIDING ACROSS THE
NORTHERN CONUS AND INTO THE NORTHERN GREAT LAKES BY SATURDAY
NIGHT.

AS THE NORTHERN LAKES LOW LIFTS INTO ONTARIO AND QUEBEC ON
SUNDAY...A TRAILING COLD FRONT MAKES ITS WAY ACROSS THE LOCAL AREA.
ASIDE FROM THE AREAS GETTING LAKE EFFECT SNOW TODAY...THIS FRONTAL
PASSAGE LIKELY BRINGS THE BEST CHANCE OF PRECIPITATION OVER THE NEXT
FEW DAYS...AND RIGHT NOW THERE ONLY APPEARS TO BE A CHANCE OR SLIGHT
CHANCE...PRIMARILY IN THE SOUTHEAST PART OF THE AREA. THE ECMWF AND
NAM ARE SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS
FEATURE...SO BY LEANING TOWARD THOSE SOLUTIONS WE ALLOW AT LEAST THE
SOUTHERN PORTIONS OF THE AREA TO EXPERIENCE ANOTHER MILD LATE
NOVEMBER DAY BEFORE THE COLD AIR RETURNS FOR EARLY NEXT WEEK.

WITH QUASI ZONAL FLOW IN PLACE ALOFT NEXT WEEK AND A PROGRESSIVE
PATTERN AT THE SURFACE...THE SHARP POST FRONTAL COOLDOWN LATE SUNDAY
INTO MONDAY LIKELY WILL EVOLVE INTO ANOTHER BRIEF WARMUP ABOVE
FREEZING ON TUESDAY AND WEDNESDAY...THOUGH NOT AS WARM AS THIS
WEEKEND AND MAYBE NOT EVEN QUITE UP TO TYPICAL HIGHS.

LENNING

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
335 PM CST

A STALLED WEST-EAST FRONTAL BOUNDARY STRETCHED ACROSS NORTHERN LAKE
MICHIGAN WILL GET A GOOD PUSH SOUTH TONIGHT AS COLDER AIR SURGES IN
BEHIND DEPARTING LOW PRESSURE OVER CENTRAL ILLINOIS.  HIGH PRESSURE
OVER THE SOUTHERN CANADIAN PRAIRIE PROVINCES WILL HELP DRIVE THE
COLDER AIR SOUTH. WINDS WILL INCREASE QUICKLY BEHIND THE FRONT EARLY
THURSDAY FROM NORTH TO SOUTH... WITH A BRIEF PERIOD OF GALE FORCE
GUSTS IS EXPECTED. HIGH PRESSURE RIDGING THEN QUICKLY BUILDS EAST
ACROSS THE LAKE THURSDAY NIGHT ALLOWING WINDS AND WAVES TO THEN
QUICKLY SUBSIDE.  WINDS AND WAVES THEN QUICKLY INCREASE AGAIN FRIDAY
AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE HIGH AND AHEAD OF
DEEPENING LOW PRESSURE OVER THE PLAINS.

THIS LOW PRESSURE AREA WILL MOVE TO THE U.P. OF MICHIGAN BY EARLY
SUNDAY.  A COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE EAST ACROSS
THE LAKE DURING THE DAY SUNDAY... WITH BRISK NORTHWEST FLOW
INTENSIFYING BEHIND THE FRONT INTO MONDAY.

ED F

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL MIDNIGHT
     FRIDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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

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





000
FXUS63 KILX 270921
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
321 AM CST Thu Nov 27 2014

.SHORT TERM...(Today)
ISSUED AT 321 AM CST THU NOV 27 2014

08z/2am surface analysis shows clipper system tracking southeastward
through the Ohio River Valley, while high pressure builds into the
Northern Plains.  Accumulating snow associated with the clipper has
ended, leaving behind mostly cloudy and cold conditions.  Main
short-term forecast challenge will be timing the clearing trend
later today.  Current IR satellite imagery shows clouds blanketing
the region, with the back edge evident across southeast Minnesota
into north-central Iowa.  Based solely on satellite timing tools,
clearing would arrive in the Illinois River Valley between 15z
and 17z.  However, with continued deep-layer northwesterly flow
and very cold air aloft, think clouds may tend to re-develop along
the back edge of the main cloud area, thus slowing the overall
eastward progression of the clearing.  Negative Cu-rule values
support this theory, as does the latest HRRR.  As a result, have
decided to go with an overcast morning across the board, followed
by a slow northwest to southeast clearing this afternoon.  Some
locations along/east of I-57 will likely remain cloudy through the
entire day.  Due to the cloud cover and gusty northwesterly winds,
high temperatures will remain in the 20s across most of the area,
with a few lower 30s south of I-70.


&&

.LONG TERM...(Tonight through Wednesday)
ISSUED AT 321 AM CST THU NOV 27 2014

After chilly low temperatures in the teens tonight, a major
warming trend will get underway by the end of the week.  High
pressure will shift east of the region on Friday, allowing gusty
southerly winds to develop.  Despite partial sunshine and strong
WAA, warming trend will be mitigated by existing snow cover along
a Rushville...to Springfield...to Robinson line.  Have therefore
lowered highs across this area by 3-4 degrees, with readings
reaching the lower 40s.  Much warmer weather is expected
everywhere on Saturday as strong southerly flow continues.  Models
are showing a fetch of increasing low-level moisture from the
western Gulf of Mexico northward into central Illinois, with
surface dewpoints increasing from the lower 30s early in the day
to well into the 40s to near 50 degrees late.  Forecast soundings
are showing saturation below 850mb, which suggests increasing
low-level cloudiness.  Have therefore gone with a mostly cloudy
forecast with high temperatures reaching the lower to middle 50s.

Another warm day is expected on Sunday, although an approaching
cold front may trigger scattered showers across the central and
southern zones as the day progresses.  Front will drop into the Ohio
River Valley by Sunday night, with a colder airmass settling
southward early next week.  Model discrepancies still exist Sunday
night, with the ECMWF trying to develop some light precip
along/north of the boundary into the colder airmass.  Meanwhile, the
GFS keeps the light precip confined to areas along/south of the
front.  With no clear upper wave to support the post-frontal precip,
have opted to side with the GFS here, resulting in dry weather
across all but the far SE CWA where a few rain showers may linger.

After that, major model differences arise by the middle of next week
as all are in poor agreement concerning the evolution of a closed
upper low over the central Pacific.  00z Nov 27 GFS shows this
feature shearing eastward across the central CONUS, eventually
triggering overrunning precip across Illinois by
Wednesday/Thursday.  The ECMWF takes the low and gradually absorbs
it into a stronger low over the Gulf of Alaska, with a downstream
trough providing cool/dry weather to Illinois on
Wednesday/Thursday.  Meanwhile, the GEM keeps the low off the coast
of California the entire time and also features a cool/dry forecast
for Illinois.  With so much uncertainty, decided to make very few
changes to the going forecast beyond Monday.  For now will maintain
dry weather through Wednesday with a gradual warming trend.


&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 1147 PM CST WED NOV 26 2014

VFR CONDITIONS ARE STARTING OFF THE TAF PERIOD AT ALL SITES AS
RIDGING CLEARS OUT THE CLOUDS TEMPORARILY. CURRENTLY NOT EXPECTING
THE CLEARING TO LAST ALL NIGHT SINCE SOUNDINGS AND SATELLITE STILL
INDICATE LOW CLOUD COVER WILL MOVE BACK INTO THE TAF SITES
OVERNIGHT...RESULTING IN MVFR CONDITIONS. WINDS WILL SHIFT MORE TO
THE NORTH NORTHWEST OVERNIGHT AS THE LOW PRESSURE CLIPPER SYSTEM
CONTINUES TO MOVE EASTWARD. MVFR CIGS COULD LAST INTO THE EARLY
AFTERNOON TOMORROW...WITH LOW CIGS BECOMING SCATTERED AROUND 19Z.
VFR CONDITIONS SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...ALW







000
FXUS63 KLOT 270909
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 AM CST THU NOV 27 2014

.UPDATE...
650 PM CST

MONITORING AN AREA OF CONVERGENCE OVER CENTRAL/SOUTHERN LAKE
MICHIGAN THIS EVENING WHERE A NE-SW ORIENTED WEAK BAND IS FORMING.
LAKE TEMPS ARE AROUND 6 DEG C...BUT WITH 850 TEMPS DROPPING THROUGH
THE NEGATIVE SINGLE DIGITS AND FORECASTED TO DROP SOME MORE THIS
EVENING...THIS IS RESULTING SOME WEAK CAPE. INVERSION LEVELS ARE
NOT VERY HIGH...AROUND 5-6KFT...BUT THIS AREA OF CONVERGENCE MAY
LAST LONG ENOUGH TO ALLOW SOME OF THIS SNOW SHOWER ACTIVITY TO
SNEAK INTO NE ILLNOIS THIS EVENING. WITH THE MODEST LAKE
PARAMETERS IN PLACE...NOT EXPECTING THIS TO AMOUNT TO MUCH AS LOW
LEVEL WINDS WILL BEGIN TO SHIFT FROM NE TO N THAN NW...BUT COULD
SOME ADDITIONAL LIGHT SNOW SHOWERS/FLURRIES MID TO LATE EVENING
BEFORE THE CONVERGENCE AXIS SHIFTS INTO NW INDIANA. COULD SEE A
DUSTING CLOSE TO THE LAKE IN COOK COUNTY. MORE LIKELY TO SEE SOME
ACCUMULATION OVERNIGHT IN NW INDIANA WITH THE COMBINATION OF THE
WEAK SYNOPTIC FORCING AND THE LAKE EFFECT PROCESSES. CURRENT
FORECAST ONLY CALLS FOR A SMALL CHANCE OF ACCUMULATION IN PORTER
COUNTY...BUT ITS POSSIBLE THAT SOME LIGHT SNOW MAY SNEAK INTO LAKE
COUNTY INDIANA AS WELL.

KMD

&&

.SHORT TERM...
311 PM CST

THROUGH FRIDAY...

REST OF TODAY INTO THIS EVENING...

IN IMMEDIATE NEAR TERM...SNOW ASSOCIATED WITH CLIPPER IS LIKELY TO
REMAIN ALMOST COMPLETE SOUTHWEST OF CWA...BUT COULD BE CLOSE TO
FAR SOUTHWEST FOR A FEW HRS INTO EARLY EVENING WHERE MAINLY SLIGHT
POPS HAVE BEEN CARRIED.

TONIGHT THROUGH FRIDAY...

THE BIG STORY OVER THE NEXT FEW DAYS WILL BE A HUGE TEMPERATURE
SWING FROM ONE OF THE COLDEST THANKSGIVING DAYS ON RECORD TO HIGHS
POTENTIALLY WELL INTO THE 50S FOR MUCH OF THE AREA OVER THE
WEEKEND. HIGHLY AMPLIFIED PATTERN OVER THE CONUS TODAY...WITH A
150+ KT UPPER JET CARVING OUT CURRENT DEEP TROUGH OVER THE EASTERN
HALF. 12Z RAOB SAMPLED -17 C AT 850 MB AT INL TODAY AND THIS AIR
MASS WILL SURGE SOUTH TOWARD AREA FOR BRIEF BLAST OF ARCTIC AIR
THAT WILL ARRIVE LATE TONIGHT INTO THANKSGIVING MORNING. THERE
SHOULD BE ENOUGH LIFT AS SHEARED OUT VORT/TROUGH AXIS CROSSES THE
AREA TONIGHT FOR FLURRIES TO BE SQUEEZED OUT FOR MAINLY
NORTH/NORTHEAST CWA OVERNIGHT INTO VERY EARLY THURSDAY.

TEMPERATURES WILL LIKELY BE FALLING INTO MID TEENS-LOW 20S BY MID
THURSDAY MORNING...FOLLOWED BY ONLY MINOR RECOVERY INTO LOW
20S/AROUND 20 NORTHWEST TO UPPER 20S FAR SOUTHEAST. PARAMETERS FOR
LAKE EFFECT SNOW WILL BE QUITE FAVORABLE ON THURSDAY...BUT WEST-
NORTHWEST FLOW IS EXPECTED TO KEEP FOCUS TO THE EAST OF THE CWA.
HAVE ONLY LOW CHANCE POPS IN NORTHEAST PORTER COUNTY...BUT IT MAY
BE VERY CLOSE FOR THAT AREA BEING CLIPPED BY AT LEAST PERSISTENT
LIGHT LAKE SNOWS.

THERE SHOULD BE A PERIOD OF PARTLY CLOUDY SKIES THURSDAY EVENING
INTO THE FIRST PART OF THE NIGHT AS SFC HIGH CROSSES THE AREA.
THIS WOULD PROVIDE SEVERAL HOURS OF GOOD RADIATIONAL COOLING AND
POTENTIAL FOR UPPER SINGLE DIGITS TO LOW TEENS WEST AND NW OF
CHICAGO.

INCREASING MID/HIGH CLOUDS AND WAA THEN SHOULD RESULT IN RISING
TEMPS TOWARD DAYBREAK. ISENTROPIC ASCENT AND UPPER FORCING WILL
RESULT IN PRECIP BREAKING OUT MAINLY NORTH OF CWA ON
FRIDAY...THOUGH FAR NORTHEAST COULD BE CLIPPED WHERE I MAINTAINED
SLIGHT CHANCE POPS. CONTINUE TO SUSPECT THAT MODELS ARE TOO COLD
WITH TEMPS ON FRIDAY DUE TO TOO MUCH SNOW COVER...SO STAYED
SIMILAR TO PREVIOUS FORECAST WITH UPPER 30S-NEAR 40 FOR SOUTHEAST
2/3 OF CWA.

RC

&&

.LONG TERM...
311 PM CST

FRIDAY NIGHT THROUGH THURSDAY...

AS FLOW  RAPIDLY TURNS ZONAL ON FRIDAY NIGHT...ANY MINOR COOLING
IN THE EVENING WILL LIKELY BE FOLLOWED BY RISING TEMPERATURES
OVERNIGHT. THIS WILL OCCUR AS VERY MILD AIR MASS RAPIDLY ADVECTS
INTO AREA...WITH BOTH ECMWF AND GFS SUGGESTING LOW-MID TEENS
CELSIUS AT 850 BY LATE DAY SATURDAY. LOCAL CLIMO SUGGESTS AT LEAST
LOW-MID 50S FOR HIGHS ON SATURDAY AND PROBABLY WARMER EVEN WITH
SOME CLOUD COVER. GUIDANCE CONTINUES TO SLOW FROPA ON SUNDAY...SO
EVEN WARMER TEMPS SATURDAY NIGHT WILL PROVIDE CHANCE FOR SOUTHERN
CWA ESPECIALLY TO NEAR 60 DEGREES FOR HIGHS ON SUNDAY! LIGHT
RAIN MAY BREAK OUT AS FRONT CROSSES THE AREA BUT FORCING IS
LIMITED. MODIFIED ARCTIC AIR WILL OOZE BACK IN ON SUNDAY
NIGHT...WITH CHILLY CONDITIONS MONDAY AND TUESDAY UNDER EXPANSIVE
HIGH PRESSURE. OPERATIONAL AND ENSEMBLE GUIDANCE VARIES LARGELY
BEYOND THIS...SO STAYED CLOSE TO A CONSENSUS BLEND...YIELDING
CLOSE TO AVERAGE TEMPERATURES. PRECIP CHANCES WILL DEPEND ON HOW
CLOSE BAROCLINIC ZONE CAN GET TO OUR AREA...WITH A SIGNIFICANT
TEMPERATURE GRADIENT PERSISTING ACROSS THE MIDWEST BUT EITHER
NEARBY OR SHUNTED WELL SOUTH.

RC

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
335 PM CST

A STALLED WEST-EAST FRONTAL BOUNDARY STRETCHED ACROSS NORTHERN LAKE
MICHIGAN WILL GET A GOOD PUSH SOUTH TONIGHT AS COLDER AIR SURGES IN
BEHIND DEPARTING LOW PRESSURE OVER CENTRAL ILLINOIS.  HIGH PRESSURE
OVER THE SOUTHERN CANADIAN PRAIRIE PROVINCES WILL HELP DRIVE THE
COLDER AIR SOUTH. WINDS WILL INCREASE QUICKLY BEHIND THE FRONT EARLY
THURSDAY FROM NORTH TO SOUTH... WITH A BRIEF PERIOD OF GALE FORCE
GUSTS IS EXPECTED. HIGH PRESSURE RIDGING THEN QUICKLY BUILDS EAST
ACROSS THE LAKE THURSDAY NIGHT ALLOWING WINDS AND WAVES TO THEN
QUICKLY SUBSIDE.  WINDS AND WAVES THEN QUICKLY INCREASE AGAIN FRIDAY
AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE HIGH AND AHEAD OF
DEEPENING LOW PRESSURE OVER THE PLAINS.

THIS LOW PRESSURE AREA WILL MOVE TO THE U.P. OF MICHIGAN BY EARLY
SUNDAY.  A COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE EAST ACROSS
THE LAKE DURING THE DAY SUNDAY... WITH BRISK NORTHWEST FLOW
INTENSIFYING BEHIND THE FRONT INTO MONDAY.

ED F

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL MIDNIGHT
     FRIDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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 270909
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 AM CST THU NOV 27 2014

.UPDATE...
650 PM CST

MONITORING AN AREA OF CONVERGENCE OVER CENTRAL/SOUTHERN LAKE
MICHIGAN THIS EVENING WHERE A NE-SW ORIENTED WEAK BAND IS FORMING.
LAKE TEMPS ARE AROUND 6 DEG C...BUT WITH 850 TEMPS DROPPING THROUGH
THE NEGATIVE SINGLE DIGITS AND FORECASTED TO DROP SOME MORE THIS
EVENING...THIS IS RESULTING SOME WEAK CAPE. INVERSION LEVELS ARE
NOT VERY HIGH...AROUND 5-6KFT...BUT THIS AREA OF CONVERGENCE MAY
LAST LONG ENOUGH TO ALLOW SOME OF THIS SNOW SHOWER ACTIVITY TO
SNEAK INTO NE ILLNOIS THIS EVENING. WITH THE MODEST LAKE
PARAMETERS IN PLACE...NOT EXPECTING THIS TO AMOUNT TO MUCH AS LOW
LEVEL WINDS WILL BEGIN TO SHIFT FROM NE TO N THAN NW...BUT COULD
SOME ADDITIONAL LIGHT SNOW SHOWERS/FLURRIES MID TO LATE EVENING
BEFORE THE CONVERGENCE AXIS SHIFTS INTO NW INDIANA. COULD SEE A
DUSTING CLOSE TO THE LAKE IN COOK COUNTY. MORE LIKELY TO SEE SOME
ACCUMULATION OVERNIGHT IN NW INDIANA WITH THE COMBINATION OF THE
WEAK SYNOPTIC FORCING AND THE LAKE EFFECT PROCESSES. CURRENT
FORECAST ONLY CALLS FOR A SMALL CHANCE OF ACCUMULATION IN PORTER
COUNTY...BUT ITS POSSIBLE THAT SOME LIGHT SNOW MAY SNEAK INTO LAKE
COUNTY INDIANA AS WELL.

KMD

&&

.SHORT TERM...
311 PM CST

THROUGH FRIDAY...

REST OF TODAY INTO THIS EVENING...

IN IMMEDIATE NEAR TERM...SNOW ASSOCIATED WITH CLIPPER IS LIKELY TO
REMAIN ALMOST COMPLETE SOUTHWEST OF CWA...BUT COULD BE CLOSE TO
FAR SOUTHWEST FOR A FEW HRS INTO EARLY EVENING WHERE MAINLY SLIGHT
POPS HAVE BEEN CARRIED.

TONIGHT THROUGH FRIDAY...

THE BIG STORY OVER THE NEXT FEW DAYS WILL BE A HUGE TEMPERATURE
SWING FROM ONE OF THE COLDEST THANKSGIVING DAYS ON RECORD TO HIGHS
POTENTIALLY WELL INTO THE 50S FOR MUCH OF THE AREA OVER THE
WEEKEND. HIGHLY AMPLIFIED PATTERN OVER THE CONUS TODAY...WITH A
150+ KT UPPER JET CARVING OUT CURRENT DEEP TROUGH OVER THE EASTERN
HALF. 12Z RAOB SAMPLED -17 C AT 850 MB AT INL TODAY AND THIS AIR
MASS WILL SURGE SOUTH TOWARD AREA FOR BRIEF BLAST OF ARCTIC AIR
THAT WILL ARRIVE LATE TONIGHT INTO THANKSGIVING MORNING. THERE
SHOULD BE ENOUGH LIFT AS SHEARED OUT VORT/TROUGH AXIS CROSSES THE
AREA TONIGHT FOR FLURRIES TO BE SQUEEZED OUT FOR MAINLY
NORTH/NORTHEAST CWA OVERNIGHT INTO VERY EARLY THURSDAY.

TEMPERATURES WILL LIKELY BE FALLING INTO MID TEENS-LOW 20S BY MID
THURSDAY MORNING...FOLLOWED BY ONLY MINOR RECOVERY INTO LOW
20S/AROUND 20 NORTHWEST TO UPPER 20S FAR SOUTHEAST. PARAMETERS FOR
LAKE EFFECT SNOW WILL BE QUITE FAVORABLE ON THURSDAY...BUT WEST-
NORTHWEST FLOW IS EXPECTED TO KEEP FOCUS TO THE EAST OF THE CWA.
HAVE ONLY LOW CHANCE POPS IN NORTHEAST PORTER COUNTY...BUT IT MAY
BE VERY CLOSE FOR THAT AREA BEING CLIPPED BY AT LEAST PERSISTENT
LIGHT LAKE SNOWS.

THERE SHOULD BE A PERIOD OF PARTLY CLOUDY SKIES THURSDAY EVENING
INTO THE FIRST PART OF THE NIGHT AS SFC HIGH CROSSES THE AREA.
THIS WOULD PROVIDE SEVERAL HOURS OF GOOD RADIATIONAL COOLING AND
POTENTIAL FOR UPPER SINGLE DIGITS TO LOW TEENS WEST AND NW OF
CHICAGO.

INCREASING MID/HIGH CLOUDS AND WAA THEN SHOULD RESULT IN RISING
TEMPS TOWARD DAYBREAK. ISENTROPIC ASCENT AND UPPER FORCING WILL
RESULT IN PRECIP BREAKING OUT MAINLY NORTH OF CWA ON
FRIDAY...THOUGH FAR NORTHEAST COULD BE CLIPPED WHERE I MAINTAINED
SLIGHT CHANCE POPS. CONTINUE TO SUSPECT THAT MODELS ARE TOO COLD
WITH TEMPS ON FRIDAY DUE TO TOO MUCH SNOW COVER...SO STAYED
SIMILAR TO PREVIOUS FORECAST WITH UPPER 30S-NEAR 40 FOR SOUTHEAST
2/3 OF CWA.

RC

&&

.LONG TERM...
311 PM CST

FRIDAY NIGHT THROUGH THURSDAY...

AS FLOW  RAPIDLY TURNS ZONAL ON FRIDAY NIGHT...ANY MINOR COOLING
IN THE EVENING WILL LIKELY BE FOLLOWED BY RISING TEMPERATURES
OVERNIGHT. THIS WILL OCCUR AS VERY MILD AIR MASS RAPIDLY ADVECTS
INTO AREA...WITH BOTH ECMWF AND GFS SUGGESTING LOW-MID TEENS
CELSIUS AT 850 BY LATE DAY SATURDAY. LOCAL CLIMO SUGGESTS AT LEAST
LOW-MID 50S FOR HIGHS ON SATURDAY AND PROBABLY WARMER EVEN WITH
SOME CLOUD COVER. GUIDANCE CONTINUES TO SLOW FROPA ON SUNDAY...SO
EVEN WARMER TEMPS SATURDAY NIGHT WILL PROVIDE CHANCE FOR SOUTHERN
CWA ESPECIALLY TO NEAR 60 DEGREES FOR HIGHS ON SUNDAY! LIGHT
RAIN MAY BREAK OUT AS FRONT CROSSES THE AREA BUT FORCING IS
LIMITED. MODIFIED ARCTIC AIR WILL OOZE BACK IN ON SUNDAY
NIGHT...WITH CHILLY CONDITIONS MONDAY AND TUESDAY UNDER EXPANSIVE
HIGH PRESSURE. OPERATIONAL AND ENSEMBLE GUIDANCE VARIES LARGELY
BEYOND THIS...SO STAYED CLOSE TO A CONSENSUS BLEND...YIELDING
CLOSE TO AVERAGE TEMPERATURES. PRECIP CHANCES WILL DEPEND ON HOW
CLOSE BAROCLINIC ZONE CAN GET TO OUR AREA...WITH A SIGNIFICANT
TEMPERATURE GRADIENT PERSISTING ACROSS THE MIDWEST BUT EITHER
NEARBY OR SHUNTED WELL SOUTH.

RC

&&

.AVIATION...

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

* MVFR CEILINGS RETURNING LATER THIS MORNING.

* CHANCE FOR LIGHT SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

MVFR CEILINGS REMAIN OVER THE TERMINALS AT THIS HOUR...WITH THE
EXCEPTION OF RFD. EXPECT CLEARING TO OCCUR FOR THE REMAINING
TERMINALS OVER THE NEXT SEVERAL HOURS...BUT WITH GYY LIKELY
HOLDING ONTO THE CEILINGS AS AN AREA OF LAKE EFFECT CLOUDS AND SNOW
SHOWERS MOVES SOUTH DOWN THE LAKE. THESE SNOW SHOWERS AR CURRENTLY
CLIPPING THE ORD AND MDW TERMINALS BUT SHOULD ONLY LAST 1-2 HOURS
WITHOUT MUCH OF ANY VIS RESTRICTION. GYY WILL LIKELY OBSERVE A
PERIOD OF BETTER SNOWFALL WITH MORE PREVAILING MVFR VIS LIKELY.
THIS AREA OF LAKE EFFECT SNOW SHOWERS SHOULD REMAIN
PROGRESSIVE...EXITING GYY BY THE 9Z TIME FRAME. AFTER A PERIOD OF
VFR CONDITIONS THIS MORNING...UPSTREAM MVFR CEILINGS WILL LIKELY
MOVE BACK OVER THE TERMINALS WHILE SOME LIGHT SNOW SHOWERS ALSO
DEVELOP. DONT ANTICIPATE MUCH WITH THESE SHOWERS AS THEY SHOULD
REMAIN SCATTERED AND LIGHT...WHILE THE MVFR CEILINGS HOLD THROUGH
AT LEAST MID DAY. VFR CONDITIONS WILL THEN PREVAIL LATER THIS
AFTERNOON INTO THE EVENING AS HIGH PRESSURE BUILDS ACROSS THE
AREA. CURRENT NORTHWEST WINDS WILL REMAIN IN PLACE FOR
TODAY...INCREASING THROUGH MID AND LATE MORNING.

RODRIGUEZ

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

* MEDIUM HIGH CONFIDENCE OF MVFR CEILINGS RETURNING WITH MEDIUM
  CONFIDENCE OF EXACT TIMING AND DURATION.

* MEDIUM CONFIDENCE WITH SNOW SHOWERS LATER THIS MORNING.

RODRIGUEZ

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

FRIDAY...VFR. WX NIL.

SATURDAY...VFR. WX NIL.

SUNDAY...SLIGHT CHANCE -RA EARLY. VFR/WX NIL OVERNIGHT.

MONDAY...VFR. WX NIL.

TUESDAY...VFR/WX NIL EARLY. CHANCE RAIN OR FREEZING RAIN
OVERNIGHT.

KREIN

&&

.MARINE...
335 PM CST

A STALLED WEST-EAST FRONTAL BOUNDARY STRETCHED ACROSS NORTHERN LAKE
MICHIGAN WILL GET A GOOD PUSH SOUTH TONIGHT AS COLDER AIR SURGES IN
BEHIND DEPARTING LOW PRESSURE OVER CENTRAL ILLINOIS.  HIGH PRESSURE
OVER THE SOUTHERN CANADIAN PRAIRIE PROVINCES WILL HELP DRIVE THE
COLDER AIR SOUTH. WINDS WILL INCREASE QUICKLY BEHIND THE FRONT EARLY
THURSDAY FROM NORTH TO SOUTH... WITH A BRIEF PERIOD OF GALE FORCE
GUSTS IS EXPECTED. HIGH PRESSURE RIDGING THEN QUICKLY BUILDS EAST
ACROSS THE LAKE THURSDAY NIGHT ALLOWING WINDS AND WAVES TO THEN
QUICKLY SUBSIDE.  WINDS AND WAVES THEN QUICKLY INCREASE AGAIN FRIDAY
AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE HIGH AND AHEAD OF
DEEPENING LOW PRESSURE OVER THE PLAINS.

THIS LOW PRESSURE AREA WILL MOVE TO THE U.P. OF MICHIGAN BY EARLY
SUNDAY.  A COLD FRONT ASSOCIATED WITH THIS LOW WILL MOVE EAST ACROSS
THE LAKE DURING THE DAY SUNDAY... WITH BRISK NORTHWEST FLOW
INTENSIFYING BEHIND THE FRONT INTO MONDAY.

ED F

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL MIDNIGHT
     FRIDAY.

     SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...9 AM THURSDAY TO 6
     PM THURSDAY.

&&

$$

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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