000 
FXUS63 KILX 222015
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
215 PM CST SUN FEB 22 2009

.DISCUSSION...
ISSUED 215 PM CST SUN FEB 22 2009

MAIN CONCERN THIS PACKAGE WILL BE HOW QUICKLY TEMPS WARMUP THIS
WEEK...FOLLOWED BY TIMING AND TYPE OF PCPN WITH THE NEXT SYSTEM
EXPECTED TO MOVE THROUGH THE AREA WED NIGHT THROUGH THUR NIGHT. 

SHORT-TERM MODELS WERE IN GOOD AGREEMENT WITH OVERALL PATTERN. THE
ONLY DIFFERENCES SEEN WERE WITH LOW TEMPS FOR TONIGHT AND TOMORROW
NIGHT. THE LONG-TERM MODELS CONTINUE THE ZONAL FLOW-TYPE PATTERN
THROUGH THE PERIOD WITH A WEAK TROUGH MOVING THROUGH MIDDLE OF THE
WEEK. HOWEVER...ON THE SFC THERE IS SOME DIFFERENCES ON THE TIMING
OF A FRONT THAT IS FORECAST TO DROP THROUGH THE STATE. 12Z ECMWF
IS MUCH QUICKER THAN THE GFS...WHICH IS A CHANGE FROM THE 00Z RUN.
THIS MAY BE THE CASE IN A FAST ZONAL FLOW...SO WILL LEAN TOWARD A
COMPROMISE BETWEEN THE TWO FOR THIS FORECAST. 

SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT

HIGH PRSS RIDGE WEST OF THE AREA THIS AFTERNOON WILL SLOWLY MOVE
EAST TONIGHT AND THEN BE OVER THE CWA BY TOMORROW AFTERNOON. THIS
WILL KEEP SKIES MOSTLY CLEAR AND PROVIDE LIGHTER WINDS. HI PRSS
MOVES EAST TOMORROW NIGHT ALLOWING SOUTHERLY WINDS TO RETURN TO
THE REGION FOR THE REST OF THE PERIOD. THESE SOUTHERLY WINDS WILL
BRING WAA AND INCREASED MOISTURE BACK TO THE CWA...WELL AHEAD OF
THE NEXT SYSTEM. THIS NEXT SYSTEM WILL SLOWLY DEVELOP AND DROP A
COLD FRONT TO AN WISC/IOWA LINE BY WED EVENING. WITH TWO DAYS OF
SOUTHERLY WINDS...THERE SHOULD BE SUFFICIENT MOISTURE FOR PCPN IN
THE WARM SECTOR FOR WED NIGHT. GFS AND ECWMF HAVE VERY LIGHT QPF
AND WITHOUT AN OBVIOUS FOCUS WILL GO WITH ONLY CHANCE POPS FOR WED
NIGHT FOR NOW. WITH US BEING IN THE WARM SECTOR AND WE SHOULD
STILL HAVE COLD TEMPS ALOFT...LAPSE RATES SHOULD BE HIGH ENOUGH TO
SUPPORT THUNDERSTORMS.

WITH MOSTLY CLEAR SKIES...LOW DEWPOINTS...AND LIGHT WINDS...EXPECT
TEMPS TONIGHT TO BE LOWER THAN GUIDANCE SO HAVE UNDERCUT MET AND
MAV BY AS MUCH AS 5 DEGREES. POTENTIAL FOR LOWER TEMPS IN SNOW
COVERED AREAS AS WELL. THEN TEMPS WILL GRADUALLY WARM THROUGH THE
PERIOD AS HIGH PRSS MOVES EAST OF STATE. WAA COULD BEGIN MONDAY
NIGHT SO BELIEVE LOWS WILL BE MONDAY EVENING AND THEN REMAIN
STEADY OR SLOWLY RISE INTO TUE MORNING. STRONGEST WAA NOT EXPECTED
UNTIL TUESDAY AND INTO WED.

LONG TERM...THURSDAY THROUGH SUNDAY

FRONT WILL MOVE THROUGH THE AREA SOMETIME ON THURSDAY AND WITH
CONTINUED SOUTHERLY WAA AND MOISTURE ADVECTION BELIEVE SHOWERS AND
POSSIBLE THUNDERSTORMS WILL BE LIKELY DURING THE DAY. MODELS ALSO
INDICATE A SFC WAVE RIDING ALONG THE FRONT PROVIDING ADDITIONAL
DYNAMICS IN THE AREA. PCPN CHANCES WILL CONTINUE INTO THUR NIGHT
AS FRONT MOVES THROUGH THE CWA. AS COLDER AIR ADVECTS INTO THE
REGION BEHIND THE FRONT EXPECT PCPN TO CHANGE FROM RAIN TO SNOW.
THIS NEXT COOL HIGH PRSS WILL PUSH THE FRONT INTO THE SOUTHEASTERN
US LEAVING US DRY FOR THE REMAINDER OF THE PERIOD...FRIDAY THROUGH
SUNDAY. 

TEMPS WILL REMAIN WARM FOR THUR AHEAD OF THE FRONT BUT THEN COOL
AS THE NEXT COOL HIGH PRSS AREA BUILDS INTO THE AREA. EXPECTING
CLOUDY AND COOL CONDITIONS FOR FRIDAY...BUT STILL NEAR NORMAL IN
THE MIDDLE TO UPPER 30S. AS HIGH PRSS SITS OVER THE AREA FOR NEXT
WEEKEND...EXPECT TEMPS TO WARM BACK UP BY SUNDAY. MEX GUIDANCE
LOOKS A LITTLE WARM FOR FRIDAY...BUT OK FOR THE WEEKEND.

AUTEN
&&

.AVIATION...
ISSUED 1133 AM CST SUN FEB 22 2009

QUIET AVIATION WEATHER EXPECTED THROUGH THE ENTIRE 18Z TAF PERIOD.
NORTHWESTERLY WINDS OF BETWEEN 10 AND 15KT WILL DIMINISH TO 5KT OR
LESS AND BECOME NORTH/NORTHEAST TONIGHT INTO MONDAY MORNING AS
HIGH PRESSURE MOVES OVERHEAD. ASIDE FROM FEW-SCT DIURNAL CU WITH
BASES AROUND 2500FT THIS AFTERNOON...SKIES WILL REMAIN CLEAR
THROUGH 18Z MON.

BARNES
&&

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

$$