FXUS63 KILX 021155
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
555 AM CST WED DEC 2 2009

.DISCUSSION...
ISSUED 310 AM CST WED DEC 2 2009

00Z SHORT RANGE MODELS ARE IN BETTER AGREEMENT WITH DEALING WITH
DEEPENING LOW PRESSURE NEAR THE LA COAST MOVING NNE ACROSS THE
OHIO VALLEY AND INTO THE EASTERN GREAT LAKES THROUGH DAWN THU.
FORECAST CONCERN IS PRECIPITATION TIMING/CHANCES AND TYPE TODAY
AND TONIGHT. UNDERCUT SIMILAR GUIDANCE HIGHS A FEW DEGREES THU/FRI 
AS UPPER LEVEL TROF DIGS INTO THE MIDWEST BRINGING THE COLDEST AIR
OF THE SEASON TO IL. 

09Z/3 AM SURFACE MAP SHOWS 999 MB LOW PRESSURE NEAR THE LA GULF
COAST WHILE A WEAKER 1004 MB LOW PRESSURE WAS OVER THE KEWEENAW
PENINSULA OF UPPER MI WITH ITS COLD FRONT EXTENDING INTO FAR NW IL
AND NW MO. RAIN SHIELD WAS MOVING NORTHWARD ACROSS AR/TN INTO
SOUTHERN KY EARLY THIS MORNING. MID/HIGH CLOUDS INCREASED DURING
THE NIGHT ACROSS IL. TEMPS WERE IN THE LOW TO MID 30S WITH
DEWPOINTS IN THE UPPER 20S AND LOWER 30S AND LIGHT TO CALM WINDS.
ALOFT A DEEPENING 547 DM 500 MB LOW WAS OVER CENTRAL TX WHILE A
NORTHERN STREAM UPPER LEVEL TROF WAS OVER THE NORTHERN PLAINS.
UPPER LEVEL RIDGES WERE OFF THE WEST COAST AND FROM FL SE. 

SHORT TERM...TODAY THROUGH FRIDAY NIGHT.

MODELS DEEPEN LOW PRESSURE FROM LA GULF COAST NNE INTO NORTH
CENTRAL KY NEAR LOUISVILLE BY SUNSET AND TO NEAR BUFFALO NY BY
SUNRISE THU. RAIN SHIELD TO SPREAD NORTHWARD ACROSS SE IL THIS
MORNING AND TOWARD THE IL RIVER VALLEY THIS AFTERNOON. AREAS NW OF
THE IL RIVER LIKE BY GALESBURG WILL NOT SEE MUCH PRECIPITATION OUT 
OF THIS STORM SYSTEM. INCREASING NORTHERLY WINDS DURING THE DAY TO
USHER IN COLDER AIR AND HIGHS IN THE LOW TO MID 40S WILL BE
SLIPPING DURING THE AFTERNOON AS PRECIPITATION MOVES IN. MODELS
HAVE TRENDED A BIT SLOWER WITH COLDER AIR MOVING IN SO CHANGEOVER
TO SNOW DELAYED A BIT AS WELL. HAVE A MIX OF LIGHT SNOW/RAIN
DEVELOPING DURING THE AFTERNOON ACROSS THE IL RIVER VALLEY. THEN
EAST TO I-55 CORRIDOR EARLY THIS EVENING AND TOWARD I-57 CORRIDOR
LATE THIS EVENING AND TO THE WABASH RIVER DURING EARLY OVERNIGHT.
HAVE JUST A COUPLE TENTH INCHES OF SNOW POSSIBLE FROM DECATUR WEST
THIS EVENING. MODELS CONTINUE TO DIMINISH PRECIPITATION QUICKLY
OVERNIGHT WITH JUST 20-30% CHANCES OF PRECIPITATION AS LOW PRESSURE
QUICKLY PULLS AWAY FROM IL INTO THE EASTERN GREAT LAKES BY DAWN THU.

MODELS HAVE TRENDED SLOWER BRINGING IN THE COLDER AIR THU AND
BUMPED UP HIGHS A FEW DEGREES WITH FRI BEING THE COLDEST DAY
(WITH 850 MB TEMPS DOWN TO MINUS 12-14C) THOUGH STILL BELOW
SIMILAR GUIDANCE HIGHS BY A FEW DEGREES BOTH DAYS. HAVE MOSTLY
CLOUDY SKIES WITH CHANCE OF FLURRIES THU AND MAINLY FROM I-74
NORTH FRI WITH UPPER LEVEL TROF DIGGING INTO THE GREAT LAKES.

LONG TERM...SATURDAY THROUGH WEDNESDAY.

UPPER LEVEL TROF GRADUALLY LIFTS OUT OF IL THIS WEEKEND WITH TEMPS
SLOWLY MODIFYING CLOSER TO NORMAL EARLY NEXT WEEK. DRY CONDITIONS
EXPECTED SAT THROUGH MON ACROSS THE AREA WITH CANADIAN HIGH
PRESSURE SETTLING INTO THE EASTERN STATES. GFS AND ECMWF MODELS
ARE QUICKER RETURNING LIGHT QPF FROM WARM AIR ADVECTION PATTERN
BY MON BUT FEEL AIR MASS WILL BE TOO DRY FOR LIGHT SNOW
THEN...MAYBE JUST MORE CLOUDS AND CHANCE OF FLURRIES. STORM SYSTEM
EJECTING NE FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY MIDDLE
OF NEXT WEEK WITH BRING NEXT BEST CHANCE OF PRECIPITATION. 

HUETTL 
&&

.AVIATION...
ISSUED 555 AM CST WED DEC 2 2009

TWO STORM SYSTEMS WILL PASS IN THE VICINITY OF THE CENTRAL
ILLINOIS TERMINALS THROUGH THE 12Z TAF PERIOD. THE FIRST SYSTEM IS
CURRENTLY CENTERED OVER THE GREAT LAKES WITH A TRAILING COLD FRONT
JUST PUSHING INTO WESTERN ILLINOIS. THE SECOND SYSTEM IS CURRENTLY
CENTERED OVER THE LOWER MISSISSIPPI VALLEY AND IS EXPECTED TO TRACK
NORTHEAST ACROSS THE OHIO VALLEY. VARIABLE WINDS WILL TREND
NORTHERLY AND BECOME STRONGER AS THE COLD FRONT PUSHES THROUGH
THIS MORNING.

VFR CONDITIONS WILL PREVAIL INTO THIS AFTERNOON OR EARLY EVENING.
RAIN...SNOW AT KPIA...WILL BEGIN TO BREAK OUT THIS AFTERNOON OR
EVENING AS THE SECOND STORM SYSTEM PASSES BY. CIGS/VSBYS EXPECTED
TO DETERIORATE TO MVFR AS PRECIPITATION DEVELOPS. THE PRECIPITATION
WILL CHANGE OVER TO SNOW THIS EVENING BEFORE ENDING... THOUGH MVFR
CONDITIONS ARE LIKELY TO PERSIST THROUGH THE TAF VALID TIME.

BAK
&&

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

$$