[LeArc] Forecast Discussion : MLI@ 8/11/02 3:11:57 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 112014
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
313 PM CDT SUN AUG 11 2002

STRONG SHORTWAVE ROTATING OVER SOUTHERN ALBERTA AT MIDDAY WILL CARVE 
OUT DEEP UPPER TROUGH OVER N CENTRAL CONUS EARLY THIS WEEK AND SEND 
A VIGORUS COLD FRONT THROUGH FORECAST AREA. CHALLENGE CONTINUES TO 
BE POPS FROM TONIGHT THROUGH TUESDAY AS AIRMASS AHEAD OF WAVE HAS 
PLENTY OF MOISTURE TO WORK WITH. 

SCATTERED THUNDERSTORMS HAVE BROKEN OUT OVER THE PAST HOUR MAINLY 
ALONG WEAK WARM FRONTAL BOUNDARY FROM OTM TO IOW AT 19Z. MESOSCALE 
BOUNDARY APPARENT ON 88D CURVING SE FROM IOW TO NEAR GBG AND LIFTING 
NORTH. THESE LIKELY BEING AIDED BY NOSE OF HIGHER H85 MOISTURE... 
WITH H85 DEWPOINTS ABOVE 10 C NEAR MCI AT 12Z...AND WEAK MID LEVEL 
VORT MAX BEST SHOWN BY ETA INTO EASTERN IA THIS AFTERNOON. MAIN 
SYNOPTIC WARM FRONT WELL TO THE NORTH ACROSS CENTRAL MN AND NRN WI 
ATTACHED TO LOW OVER WESTERN SD AT 19Z. WITH ON-GOING TSRA AND 
SUBTLE BOUNDARY LIFTING THROUGH WARM UNSTABLE AIRMASS...WILL KEEP 
CURRENT SCATTERED POPS GOING TONIGHT...ALTHOUGH LOW LEVEL JET THAT 
ASSISTED SCATTERED CONVECTION EARLY THIS MORNING WILL LIKELY HAVE 
BIGGER IMPACT WELL TO NORTH. 

12Z MODELS ALL SIMILAR AND CONTINUED RUN TO RUN TREND OF SLOWING 
SYSTEM DOWN WITH FROPA NOW NOT INDICATED UNTIL 12Z TUESDAY. AT UPPER 
LEVELS...THEY ARE IN CLOSE AGREEMENT. AVN LIKELY TOO SLOW WITH 
FRONTAL PASSAGE AND LINGERING PRECIP OVER AREA THROUGH TUESDAY 
EVENING. WENT CLOSER TO ETA COMPROMISE AND LEFT TUESDAY EVENING DRY 
FOR NOW. 

IN NEARER TERM...BOUNDARIES LEFT OVER FROM OVERNIGHT CONVECTION AND 
ANY UPSTREAM MCS WILL BE MAIN FOCUS FOR AFTERNOON TSRA MONDAY AS 
FRONT NOT ANTICIPATED IN WEST UNTIL EVENING. WILL KEEP LIKELY POPS 
GOING IN WEST WITH HIGH SCATTERED CENTRAL AND SOUTH. SHOULD WARM 
NICELY WITH SURFACE SW FLOW...BUT AMOUNT OF CLOUD COVER WILL BE 
CRITICAL. GUIDANCE HIGHS TOO COOL AND STAYED SEVERAL DEG ABOVE. 
LOCALLY HEAVY RAIN AND SOME SEVERE THREAT CONTINUES WITH MONDAY 
NIGHT FROPA AND WILL KEEP WORDING IN ZONES...ALTHOUGH BEST SEVERE 
RISK WILL BE ON IA SIDE DUE TO DIURNAL TIMING. UPPER LEVEL TROUGH 
DOES NOT PASS UNTIL LATE TUESDAY AND WILL KEEP POST FRONTAL RAIN 
POTENTIAL GOING TUESDAY WITH TEMPERATURES HELD TO LOWER 70S.

IN EXTENDED...SLOWING OF CENTRAL CONUS TROUGH HAS DELAYED TIMING OF 
NEXT SIGNIFICANT SHORTWAVE UNTIL FRIDAY IN MEDIUM RANGE GUIDANCE AND 
THUS REMOVED POPS FROM THURSDAY. RETURN FLOW BRINGS WARM FRONT AND 
PRECIP CHANCES FOR FRIDAY...FOLLOWED BY COLD FRONT IN SAT 
NIGHT/EARLY SUNDAY TIME FRAME. WITH NOT ENOUGH CONFIDENCE ON 
TIMING...HAVE CHANCE POPS FRIDAY THROUGH SUNDAY. TEMPERATURES 
TRENDED UPWARD SOME...BUT STILL KEPT MAINLY BELOW GUIDANCE FOR 
HIGHS. 

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

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