279 
FXUS63 KILX 221844
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
144 PM CDT SUN JUN 22 2003

LATEST SURFACE ANALYSIS HAD STRONG HIGH PRESSURE CENTERED NEAR 
INDIANAPOLIS. MEANWHILE...LOW PRESSURE WAS CENTERED NEAR HASTINGS NE
WITH A NEARLY STATIONARY BOUNDARY EXTENDING NNE INTO MINNESOTA AND A 
WARM FRONT EXTENDING SE TOWARD MISSISSIPPI. MAIN CONCERNS THROUGH 
THE SHORT TERM REVOLVE AROUND SLIGHT PRECIPITATION CHANCE LATE 
TONIGHT AND MONDAY AS WELL AS TEMPERATURES (THE WARMEST OF THE 
SEASON).

12Z MODELS IN GOOD AGREEMENT...WITH THE ETA SEEMING TO HAVE THE BEST 
HANDLE ON POTENTIAL MCS DEVELOPMENT. GUIDANCE TEMPERATURES CLOSE AND 
REASONABLE...SO WILL NOT STRAY FAR.

TONIGHT AND MONDAY...INCREASINGLY WARM AND MOIST AIR WILL CONTINUE 
TO BUILD INTO THE REGION ON THE BACK SIDE OF AN UPPER/SURFACE RIDGE 
AXIS. HOWEVER...DUE TO A BLOCKING UPPER LOW DOWNSTREAM ALONG THE 
ATLANTIC COAST...THE RIDGE AND ASSOCIATED DRIER AIR DO NOT WANT TO 
BUDGE TOO QUICKLY. SO...THE BIG QUESTION IS...WILL WE GET ANY 
SHOWERS/STORMS IN CENTRAL ILLINOIS DURING THE PERIOD? A MCS SHOULD 
INITIATE (OR BE ONGOING) TONIGHT NEAR THE NE/KS/MO BORDER...WHERE A 
50+ KNOT LOW LEVEL JET AND SHARP THETA E RIDGE WILL BE IMPINGING
ON A SURFACE WARM FRONT. WHILE DEEP LAYER WINDS WILL BE FROM THE 
SSW...THICKNESS PATTERN AND CORFIDI VECTORS SUGGEST A SLOW SE 
PROPAGATION TO THE MCS. THE SLOW PROPAGATION COMBINED WITH THE 
ENTRENCHED DRY AIR OVERHEAD WILL KEEP CWA DRY TONIGHT. WILL HOLD 
ONTO A LOW CHANCE OF PRECIPITATION ACROSS THE EXTREME NW PORTION OF 
THE FORECAST AREA MONDAY TO CATCH ANY REMNANTS FROM DECAYING MCS. 
HOWEVER...REMAINDER OF FORECAST AREA WILL BECOME INCREASINGLY CAPPED 
AND REMAIN DRY AS A RESULT.

MONDAY NIGHT THROUGH WEDNESDAY...MCS INITIATION MONDAY NIGHT WILL
OCCUR ACROSS THE NORTHERN MISSISSIPPI VALLEY AND REMAIN WELL NORTH 
OF THE FORECAST AREA. OTHERWISE...AS THE RIDGE AXIS CONTINUES TO 
MAKE ITS SLOW MOVE EAST...THE AIRMASS OVERHEAD WILL BECOME 
INCREASINGLY WARM AND HUMID. MODEL SOUNDINGS SUGGEST A CAP WILL 
REMAIN IN PLACE ACROSS THE REGION...WITH NO FORCING MECHANISM 
EXPECTED TO BREAK THE CAP. SO...WILL CONTINUE WITH A DRY FORECAST 
THROUGH THE PERIOD.

THURSDAY THROUGH SUNDAY...MODELS FINALLY IN BETTER AGREEMENT TODAY 
REGARDING OUR MAIN LONG TERM CONCERN...WHICH IS THE PASSAGE OF AN 
UPPER TROF/COLD FRONT FOR THE SECOND HALF OF THIS WEEK. THE 
CONSENSUS IS THAT THE FRONT WILL MOVE INTO FORECAST AREA AFTER 12Z 
THURSDAY AND EXIT THE STATE BY 12Z FRIDAY. WILL MAINTAIN CHANCE OF 
SHOWERS/STORMS THURSDAY WITH FROPA...LINGERING CHANCES INTO FRIDAY 
WITH THE UPPER TROF STILL NEARLY OVERHEAD (OR IN CASE THE FRONT 
HANGS UP). RIDGING BUILDS BACK IN FOR THE WEEKEND AND INTO NEXT 
WEEK...SO WILL GO DRY THEN. TEMPERATURES SHOULD AVERAGE NEAR NORMAL 
THROUGH THE PERIOD.

.ILX...NONE.

$$

BAK