FXUS63 KILX 291142
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
542 AM CST SUN NOV 29 2009

.DISCUSSION...
ISSUED 330 AM CST SUN NOV 29 2009

FORECAST CONCERN IS CHANCES OF RAIN TODAY INTO TONIGHT ESPECIALLY
OVER EASTERN IL. THEN ADDRESSING NEXT WEATHER SYSTEM WED/THU AS
COLDER AIR FILTERS INTO IL DURING THE 2ND HALF OF THE WEEK. 00Z
SHORT RANGE MODELS ARE IN FAIR AGREEMENT. BUT MODELS DIVERGE WITH
HANDLING WX SYSTEM WED/THU WITH GFS AND ECMWF TRENDING FURTHER SE
WITH STRONG STORM SYSTEM WED/WED NIGHT AND WHILE GEM AND SREF
MODELS ARE FURTHER NW WITH QPF INTO SE HALF OF IL WED NIGHT. WILL
USE A BLEND BETWEEN THE FURTHER SE GFS/ECMWF AND FURTHER NW
GEM/SREF MODELS FOR WED/THU SYSTEM. 

09Z/3 AM SURFACE MAP SHOWS A COLD FRONT EXTENDING FROM NW IL/MO 
INTO SE KS WITH WEAK 1007 MB LOW PRESSURE IN SE IA AND PRESSING
SLOWLY SE TOWARD GALESBURG. MOSTLY CLEAR SKIES EAST OF THE IL RIVER 
WHILE CLOUDS INCREASING WEST OF THE IL RIVER. MILD TEMPS WERE IN
THE 40S WITH AREAS FROM SPRINGFIELD SW AROUND 50F. ALOFT A 549 DM
500 MB LOW WAS OVER SOUTHERN CA WHILE NORTHERN STREAM TROF OVER
THE DAKOTAS/MN. UPPER LEVEL RIDGE WAS OFF THE WEST COAST AND
ACROSS THE SE STATES.

SHORT TERM...TODAY THROUGH TUESDAY NIGHT.

MODELS LIFT WEAK LOW PRESSURE FROM SE IA NE INTO SE LOWER MI BY
18Z/NOON PULLING THE COLD FRONT SE INTO CENTRAL IL AND TO NEAR
LAWRENCEVILLE BY 00Z/6 PM. JUST A SLIGHT CHANCE OF SHOWERS
DEVELOPING DURING THIS MORNING WITH CHANCES OF SHOWERS INCREASING
THIS AFTERNOON EAST OF I-55 WITH LIKELY CHANCES FROM I-57 EAST.
CHANCES OF RAIN WILL DIMINISH OVER EASTERN IL DURING THIS EVENING
WITH MOST AREAS DRY OVERNIGHT AS THE RAIN SHIFTS SE OF IL WITH THE
COLD FRONT MOVING SE ACROSS KY. WITH SLOWER ARRIVAL OF COLD FRONT
THAN EARLIER EXPECTED...INCREASED HIGHS BY A FEW DEGREES TODAY
INTO THE UPPER 40S NW OF THE IL RIVER TO THE MID 50S IN SE IL. 

UPPER LEVEL TROF THAT MOVES ACROSS IL TONIGHT QUICKLY EXITS EAST
OF IL MON WHILE HIGH PRESSURE OVER THE PACIFIC NW MOVES INTO THE
MID MS VALLEY AND DECREASES CLOUDS OVER CENTRAL/SE IL LATER
TONIGHT INTO MON MORNING WITH MOSTLY SUNNY SKIES BY MON AFTERNOON.
COOLER HIGHS MON IN THE MID TO UPPER 40S WHICH IS CLOSE TO NORMAL
FOR LATE NOV. 

HIGH PRESSURE DRIFTS OVER THE SE STATES TUE WITH RETURN SOUTH FLOW
OF MILDER AIR BACK INTO IL AHEAD OF THE NEXT APPROACHING WX SYSTEM
AND COLD FRONT. HIGHS TUE BACK IN THE LOW TO MID 50S WITH AMPLE
SUNSHINE. 

LONG TERM...WEDNESDAY THROUGH SATURDAY.

EXTENDED MODELS/ENSEMBLES CONTINUE TO SHOW LARGE CUTOFF UPPER
LEVEL LOW IN SOUTHERN CA MOVING EAST ACROSS THE SOUTHERN STATES
INTO MID WEEK KEEPING ITS BEST MOISTURE SOUTH AND EAST OF IL.
NORTHERN STREAM SHORT WAVE TROF DIGS INTO THE MIDWEST AND GREAT
LAKES WED/THU. DOES NOT APPEAR TO PHASE OVER IL SO BEST CHANCES OF
PRECIPITATION LOOKS TO STAY SOUTH AND EAST OF IL. HAVE CHANCE OF
LIGHT RAIN/SNOW MAINLY SE HALF WED AFTERNOON/WED NIGHT AND JUST
SLIGHT CHANCES OF LIGHT SNOW SHOWERS THU WITH UPPER LEVEL TROF
NEARBY. COLDER AIR TO USHER IN WITH HIGHS WED IN THE LOW TO MID
40S. THEN IN THE MID TO UPPER 30S THU-SAT WITH SE IL NEAR 40F.

HUETTL
&&

.AVIATION...
ISSUED 542 AM CST SUN NOV 29 2009

A COLD FRONT WILL MOVE THROUGH THE CENTRAL ILLINOIS TERMINALS
TODAY. HOWEVER...IT WILL DO SO WITHOUT TOO MUCH FANFARE DUE TO IT
HAVING LIMITED MOISTURE TO WORK WITH. EXPECT A MVFR CLOUD DECK TO
DEVELOP OVER THE TERMINALS DURING THE NEXT FEW HOURS AS THE FRONTAL
ZONE MOVES THROUGH. THE QUESTION IS HOW MUCH...IF ANY
PRECIPITATION DEVELOPS ALONG OR JUST BEHIND THE FRONT. AT THIS
POINT...KDEC AND KCMI SEEM THE MOST LIKELY TO SEE RAINFALL AS
THERE WILL BE MORE TIME FOR DEEPER MOISTURE TO WORK NORTHEAST
ALONG THE FRONT. SO...INCLUDED AFTERNOON VCSH AT KDEC AND KCMI...
THOUGH THE PRECIPITATION WILL MORE LIKELY END UP BEING DRIZZLE IF
IT OCCURS. DRIER LOW LEVEL AIR WILL SLOWLY WORK IN BEHIND THE
FRONT OVERNIGHT AND SHOULD GRADUALLY ALLOW CIGS TO SCATTER OUT.
HOWEVER...FORECAST SOUNDINGS SUGGEST KBMI AND KCMI MAY HOLD ONTO
CIGS THROUGH THE NIGHT. SOUTHWEST WINDS WILL SWING NORTHWEST TO
DAY WITH FROPA...AND GENERALLY RANGE FROM 10-15KTS.

BAK
&&

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

$$