006 
FXUS63 KILX 090535
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1135 PM CST TUE JAN 8 2013

.DISCUSSION...
ISSUED 900 PM CST TUE JAN 8 2013

A WEAK FRONTAL BOUNDARY IS POISED TO CLEAR THE AREA LATE TONIGHT
OR EARLY WEDNESDAY...WITH THE FRONT STILL LYING TO THE WEST OF
ILLINOIS. HOWEVER...THE FORCING ALOFT THAT WILL ACCOMPANY THE
FRONT IS PRETTY IMPRESSIVE. THE BEST WAA/ISENTROPIC LIFT AND JET
FORCING IS PROGGED TO IMPACT THE SOUTHEAST PORTION OF THE FORECAST
AREA LATE TONIGHT...ALTHOUGH MOST AREAS HAVE ALREADY SEEN A
BLANKET OF MID CLOUD DEVELOP OVERHEAD. IN ADDITION...SHOWERS ARE
ALREADY SPREADING NORTHEAST THROUGH MISSOURI WITH THE STRONGEST
FORCING.

PLAN TO UPDATE FORECAST TO INCREASE CLOUD COVER ACROSS THE ENTIRE
FORECAST AREA TONIGHT. ALSO PLAN TO ADD CHANCE POPS IN THE
SOUTHEAST INTO WEDNESDAY MORNING...ALTHOUGH AN INITIALLY DRY
AIRMASS SHOULD KEEP PRECIPITATION TOTALS LOW.

BAK
&&

.AVIATION...
ISSUED 1135 PM CST TUE JAN 8 2013

A WEAK FRONTAL BOUNDARY IS APPROACHING NORTHWEST ILLINOIS...AND
WILL BEGIN TO CROSS THE CENTRAL ILLINOIS TERMINALS IN THE NEXT FEW
HOURS. THE PASSAGE OF THIS BOUNDARY WILL RESULT IN SOUTHERLY WINDS
TURNING TOWARD THE WEST BY DAYBREAK WEDNESDAY. HIGH PRESSURE WILL
BUILD IN BEHIND THE FRONT LATER WEDNESDAY...WITH WINDS TRENDING
LIGHT/VARIABLE. VFR LEVEL CIGS ARE ANTICIPATED FOR THE NEXT
SEVERAL HOURS...BUT SKIES WILL CLEAR ON WEDNESDAY AS DRIER AIR
FILTERS IN BEHIND THE FRONT.

BAK
&&

.PREV DISCUSSION...
ISSUED 244 PM CST TUE JAN 8 2013
HIGH PRESSURE AXIS SLIDING OFF THE EAST COAST AND PLENTY OF
SOUTHERLY FLOW STREAMING WARM AIR INTO THE REGION. THOUGH THE DAY
STARTED SOMEWHAT CLOUDY...LLVL WAA OVERCAME THE LACK OF SUNSHINE
EARLY...THEN CLEARING SKIES HELPED BOOST TEMPS WELL INTO THE 40S.
FORECAST FOR THE NEXT COUPLE OF DAYS IS MORE OF THE SAME WHILE AN
UPPER LOW DIGS IN OVER THE SWRN US AND STARTS TO DEVELOP THE SFC
WAVE THAT WILL EVENTUALLY BRING THE NEXT SHOT AT RAIN THU/THU
NIGHT. MODELS HAVING A BIT OF TIMING ISSUES...THOUGH DOWN TO A FEW
HOURS DIFFERENCE AS OPPOSED TO THE 24 HR DIFFERENCES OF A COUPLE
DAYS AGO. THU/THUR NIGHT IS ON TRACK TO BE RATHER WET AS THE LOW
PRESSURE SYSTEM MOVES THROUGH THE CWA. FORECAST NOT ALTOGETHER
DIFFERENT FROM PREVIOUS RUN...BUT FRESHENED WITH NEW GUIDANCE. 

SHORT TERM...TONIGHT THROUGH WEDNESDAY...
VARIABLE CLOUDS IN THE OVERNIGHT COULD RESULT IN SOME DIFFICULT
OVERNIGHT LOWS. WARM AIR CONTINUING UP INTO THE REGION WILL KEEP
OVERNIGHT LOWS IN THE 30S. SOME CONCERN THAT THE WAVE SPINNING UP
OVER THE SOUTHERN PLAINS IS STARTING TO PUSH QUITE A BIT OF PRECIP
OUT AHEAD OF IT. TONIGHT...THE MAJORITY OF THE CWA IS BETWEEN
STRONGER DYNAMICS...WITH MOST MOISTURE TO THE SOUTH. FOR
NOW...KEEPING THE FORECAST DRY...BUT WILL NEED TO WATCH NORTHWARD
PROGRESSION. ECMWF AND GFS ARE PAINTING QPF OVER FAR SOUTHERN IL.
HAVE REPEATEDLY BEEN TOO QUICK WITH RAPID CHANGES. WILL DEFER TO
NAM IN SHORT TERM AND STAY DRY. TOMORROW MUCH LIKE
TODAY...UNSEASONABLY WARM SOUTHERLY WINDS AND VARIABLE
CLOUDINESS. STILL A BIT OF SNOW ON THE GROUND...LWV STILL LIKELY
TO BE THE COLD SPOT THROUGH TONIGHT AND POSSIBLY TOMORROW. EVERYWHERE
ELSE WILL SEE SOME INFLUENCE FROM THE SOUTHERLY WINDS AS
RADIATIONAL COOLING IS COUNTERED BY PRETTY CONSISTENT LLVL WAA.
TOMORROW HIGHS WILL BE A FEW DEGREES OVER TODAYS.

LONG TERM...THURSDAY THROUGH MONDAY...
WARMING TEMPS CONTINUE SLOWLY...WITH THURSDAY/FRIDAY TEMPS LIKELY TO
BE THE WARMEST INTO THE 40S AND LOWER 50S IN THE SOUTHEAST AHEAD
OF THE NEXT WAVE. NEXT SYSTEM STILL HAS ISSUES WITH THE
SOLUTIONS OF SPEED AND TRACK...THOUGH CONSIDERABLY LESS.  AT THIS
POINT...BEST CHANCES FOR RAIN AND ISO THUNDER THUR/THUR NIGHT.GFS
AND ECMWF HAVE CLEANED UP THE QPF A BIT ON THU/THU NIGHT...KEEPING
FRIDAY DRY. NOW POPS FOR THE SATURDAY SYSTEM A BIT OF A MESS.
BOTH MODELS NOW LIFTING A SFC LOW OVER UPPER MIDWEST/GREAT LAKES/THE
US/CAN BORDER...WITH A COLD FRONT FOR THE CONUS...AND VERY
DIFFERENT LOCATIONS FOR THE UPPER TROF AS IT MOVES THROUGH THE
STATES. KEEPING THE FORECAST RATHER CONSERVATIVE AND GENERIC WITH
THE GFS KEEPING THE SFC CONVERGENCE SOUTHEAST OF THE CWA...AND
ECMWF LAYING OUT THE BOUNDARY CLOSER TO CENTRAL ILLINOIS. BOTH
MODELS EJECT THE PARTIAL REMAINS OF THE DEEP SWRN LOW OUT ALONG
THE BOUNDARY ON SUN NIGHT...PROLONGING THE EXTENDED POPS. FOR THE
MOST PART...FAVORING SLOWER TRENDS WITH CUT OFF SYSTEM IN SW.

HJS


&&

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

$$