[LeArc] Forecast Discussion : MLI@ 6/26/02 2:10:19 PM

[learc@mailman.qth.net]

The following weather message is provided by McDonough County E.S.D.A.


FXUS63 KDVN 261907
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
207 PM CDT WED JUN 26 2002

SURFACE FRONT AT 18Z WAS FROM CENTRAL UPPER MI THROUGH FAR NE IA 
SOUTHWEST TO NEAR OMA. THIS IS MUCH SLOWER THAN YESTERDAYS MODELS 
HAD FORECAST AND THUS FORECAST CHALLENGE IS MAINLY SHORT TERM WITH 
SEVERE POTENTIAL AND POPS IN FIRST PERIOD. THEN FOCUS ON 
TEMPERATURES THROUGH WEEKEND.

CONVECTIVE COMPLEX ASSOCIATED WITH A COUPLE OUTFLOWS FROM OVERNIGHT 
STORMS THAT COVERGED OVER EASTERN IA HAD EXITED TO SE EARLY THIS 
AFTERNOON. ASSOCIATED CI DEBRIS SHIELD HOLDING TEMPERATURES DOWN 
OVER MOST OF CWFA. THINNING CLOUDS TO WEST SHOULD ALLOW RAPID 
WARMING AND DESTABILIZATION IN IA ZONES THIS AFTERNOON. MESOSCALE 
BOUNDARY VISIBLE ON SATELLITE IMAGERY FROM CENTRAL TO NE IA WAS 
INTERSECTING WITH THE SYNOPTIC FRONT AND ASSISTING SEVERE CONVECTION 
ALREADY SEEN IN FAR NE AND SW IA. WITH FROPA DELAYED...SEVERE 
POTENTIAL LOOKS HIGHER THAN EARLIER EXPECTED. 18Z SURFACE PRESSURE 
FALLS CENTER EAST OF QUAD CITIES INDICATES FRONT AND CURRENT SEVERE 
STORMS IN NE IA SHOULD BUILD SE THIS AFTERNOON. ANTICIPATE HIGHEST 
SEVERE WIND AND HAIL RISK LATE THIS AFTERNOON OVER MAINLY IA ZONES 
NORTH OF I-80...WITH SOME CONTINUING INTO EVENING ALONG FRONT INTO 
NW IL AND FAR NE MO.  PER SPC MCD... WATCH MAY BE ISSUED AND WILL 
WAIT UNTIL LAST MINUTE FOR SEVERE WORDING.

MODELS IN SOMEWHAT AGREEMENT WITH FRONT LAYING OUT FROM ABOUT 
FREEPORT TO IOWA CITY BY 00Z. NGM HAD BEST QPF PLACEMENT FOR MORNING 
CONVECTION...THEN MODELS SHOW GREATER VARIABILITY BY 00Z AND 06Z. 
ETA HAD FARTHEST NORTH PLACEMENT OF SIGNIFICANT INTO NW IL THROUGH 
12Z AND THIS LOOKS REASONABLE LOOKING AT UPPER QG FORCING AND 
DELAYED TIMING FROM PREVIOUS FORECASTS. WILL THUS GO WITH LIKELY 
POPS TONIGHT FOR ENTIRE AREA EXCEPT NW OF CID-DBQ LINE...WHERE POST 
FRONTAL SHOWERS SHOULD END BEFORE MIDNIGHT. 

NW FLOW ALOFT AND HIGH PRESSURE BUILDS AT SURFACE THURSDAY WITH 
DRIER AND MUCH COOLER AIRMASS. MIXING TO H85 WOULD PRODUCE LOWER 80S 
AND WILL GO CLOSE MOS GUIDANCE. UPPER LEVEL RIDGE BUILDS EASTWARD 
WITH HIGH CENTERED OVER CWFA BY EARLY SATURDAY. THIS SUPPORTS 
WARMING TREND AND CAPPED ENVIRONMENT THROUGH REST OF WEEK INTO 
WEEKEND AND WILL TREND TOWARD WARMER END OF GUIDANCE. FOR 
EXTENDED...MEDUIM RANGE MODELS NOT IN MUCH AGREEMENT WITH TIMING OF 
SHORTWAVES ALONG SOUTHERN EDGE OF WESTERLIES FROM SUNDAY INTO EARLY 
NEXT WEEK. MONDAY NOW LOOKS DRY AND WILL REMOVE TSRA CHANCES...BUT 
CONTINUE FOR TUESDAY INTO WEDNESDAY FOR PORTIONS OF CWFA.

IA...NONE.
IL...NONE.
MO...NONE.

DLS