FXUS63 KILX 271141
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
541 AM CST FRI NOV 27 2009

.DISCUSSION...
ISSUED 225 AM CST FRI NOV 27 2009

LOW CLOUDS WERE SLOW TO ERODE ACROSS THE CWA...CURRENTLY REMAINING
IN PLACE EAST OF A PEORIA TO MATTOON LINE. SOME HIGH CLOUDS WERE 
DROPPING SOUTHEAST ACROSS THE WESTERN CWA...SKIRTING THE RIDGE
THAT IS CURRENTLY BUILDING EAST ACROSS THE MID-MISSISSIPPI VALLEY.
TEMPERATURES WERE FAIRLY UNIFORM EARLY THIS MORNING DESPITE THE
VARYING AMOUNTS OF CLOUDS...GENERALLY A FEW DEGREES EITHER SIDE OF
30. 

MAIN FORECAST ISSUE FOR TODAY INVOLVES A FRONTAL PASSAGE ON
SUNDAY...AND ANY PRECIPITATION ASSOCIATED WITH IT. NO MAJOR
DIFFERENCES WERE NOTED IN THE MODELS THROUGH 84 HOURS. 

SHORT TERM...TODAY THROUGH MONDAY...

CURRENT STRATOCUMULUS DECK IS APPROXIMATED WELL BY THE RUC MODEL
925-850 MB HUMIDITY PLOT. USING THIS APPROACH...THE CLOUDS SHOULD
BE ERODING QUITE A BIT OVER THE NEXT FEW HOURS...WITH SIGNS OF
THIS ALREADY SHOWING UP ACROSS SOUTHERN WISCONSIN. OTHERWISE...
SCATTERED HIGH CLOUDS WILL PASS ACROSS THE AREA...BUT MOSTLY
SUNNY SKIES SHOULD DOMINATE THE CWA BY EARLY AFTERNOON.

UPPER RIDING OVER THE CENTRAL CONUS WILL FLATTEN AS THE WEEKEND
PROGRESSES. THE ASSOCIATED SURFACE RIDGE WILL PUSH EAST ACROSS THE
STATE THROUGH TONIGHT...WITH A FRONTAL BOUNDARY DEVELOPING OVER
THE PLAINS AND UPPER MIDWEST. THIS FRONT IS EXPECTED TO BE NEAR
THE I-55 CORRIDOR BY 12Z SUNDAY. INITIAL ARRIVAL OF THIS FRONT IS
EXPECTED TO BE DRY...WITH PRECIPITATION THREAT INCREASING AS THE
FRONT PUSHES THROUGH THE FORECAST AREA THROUGH MID-AFTERNOON. AS A
RESULT...HIGHEST POPS ON SUNDAY WILL BE ACROSS THE SOUTHEAST
CWA...PEAKING IN THE LIKELY POP RANGE SUNDAY NIGHT. MUCH OF THIS
WILL BE IN THE FORM OF RAIN...BUT BUFKIT SOUNDINGS SUPPORT A
POTENTIAL SWITCHOVER TO SNOW ACROSS THE NORTHERN CWA SUNDAY
NIGHT...ALTHOUGH POPS IN THIS AREA ARE FAIRLY LOW. DRY WEATHER
WILL RETURN ON MONDAY AS HIGH PRESSURE RIDGING BUILDS EAST TOWARD
THE OHIO VALLEY.

A NICE WARM UP IS EXPECTED THROUGH SATURDAY...AS 850 MB
TEMPERATURES RISE TO NEAR 13C BY SATURDAY MORNING. SOUTH HALF OF
THE CWA EXPECTED TO REACH NEAR 60 DEGREES FOR SATURDAY HIGHS. THIS
WILL BE THE WARMEST DAY OF THE FORESEEABLE FUTURE.

LONG TERM...TUESDAY THROUGH THURSDAY...

EXTENDED MODELS HAVING SOME DIFFICULTIES WITH DETERMINING THE
AMOUNT OF DIGGING THAT WILL TAKE PLACE WITH A SHORTWAVE IN THE
NORTHERN JET STREAM. THE GFS IS ABOUT 12-18 HOURS FASTER THAN THE
ECMWF IN BRINGING A FRONT THROUGH THE AREA TUESDAY NIGHT OR
WEDNESDAY MORNING...WITH THE ECMWF MUCH MORE AGGRESSIVE IN DIGGING
AN UPPER TROUGH FURTHER SOUTH OVER THE PLAINS BY THURSDAY
MORNING. DIFFERENCES BECOME MORE GLARING BY THE END OF THE
WEEK...SOMETHING THAT LATER SHIFTS WILL HAVE TO SORT OUT.

GEELHART
&&

.AVIATION...
ISSUED 541 AM CST FRI NOV 27 2009

QUIET/VFR CONDITIONS EXPECTED...FOR THE MOST PART...ACROSS THE
CENTRAL ILLINOIS TERMINALS THROUGH THE 12Z TAF PERIOD. THE
POSSIBLE EXCEPTION IS THE POTENTIAL FOR A FEW HOURS OF 1500 FT
MVFR CIGS AT KBMI/KCMI THIS MORNING ON THE BACK SIDE OF DEPARTING
LOW PRESSURE OVER THE EASTERN GREAT LAKES. OTHERWISE...A RIDGE OF
HIGH PRESSURE WILL BUILD THROUGH THE REGION...PROVIDING MINIMAL
CLOUD COVER AND LIGHT/VARIABLE WINDS.

BAK
&&

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

$$