[LeArc] Forecast Discussion : MLI@ 6/19/02 3:04:42 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 190804
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 AM CDT WED JUN 19 2002

LINE OF CONVECTION FIRING AGAIN JUST TO WEST IN CENTRAL IOWA TONIGHT 
MATCHES WELL WITH SOUTHERN END OF GUIDANCE H5 VORT LOBE AND 
SHORTWAVE EXTENDING S FROM CENTRAL MN. INITIAL FORECAST CHALLENGE IS 
HANDLING OF THIS LINE AND ON-GOING WEAK SHOWERS IN CWFA IN FIRST 
PERIOD...THEN THUNDERSTORM POPS LATER TODAY THROUGH END OF WEEK. 

00Z UPPER ANALYSIS SHOWED UPPER RIDGE FROM TX TO GREAT LAKES. 
UPSTREAM TROUGHING WAS OVER SW CAN/NORTHERN US ROCKIES WITH VORT 
SEEN ON WV IMAGERY MOVING ALONG NW MT BORDER. ETA INITIALIZED THIS 
WAVE TOO FAR WEST...BUT BY 06Z ALL SHORT TERM MODELS HAD GOOD HANDLE 
ON FEATURE. AT H85...SUPSICIOUSLY DRY OUN SOUNDING UNDER SUBSIDENCE 
INVERSION STUCK OUT AND WAS INITIALIZED IN MODELS WITH DRY PUNCH 
INTO CWFA LATER THIS MORNING BEFORE MOISTURE RETURNS. ETA AND AVN 
HAD DECENT HANDLE ON SURFACE FEATURES AT 06Z WITH LOW OVER NE CO 
WITH FRONT NE INTO EASTERN ND. WILL FOLLOW ETA AVN COMPROMISE WITH 
H5 HIGH BUILDING JUST TO SOUTH OVER NEXT SEVERAL DAYS AND FRONT 
SAGGING SOUTHEAST AND BISECTING FORECAST AREA LATE THURSDAY/THURSDAY 
NIGHT FOR BEST CHANCE OF SHRA/TSRA THIS WEEK.   

IN SHORT TERM...CONVECTION OVER CENTRAL IA SHOULD DECREASE IN 
INTENSITY AS IT ENTERS CWFA THIS MORNING ACORDING TO MSAS ANALYSIS 
INDICATING SURFACE MOISTURE DIVERGENCE AND RISING LI/S. WILL ADD 
SCATTERED SHOWERS AND FEW TSRA TO IA N OF I-80 THIS MORNING AND 
SPRINKLES EARLY OVER REMAINDER TO HANDLE N-S LINE OF --SHRA CROSSING 
RIVER AT THIS TIME. REMAINDER OF DAY SHOULD BE DRY WITH LACK OF 
FOCUS FOR FURTHER CONVECTION AND INCREASING CIN. EXCEPTION WILL BE 
IN NW...WHERE WEAK MID LEVEL QG FORCING TOWARD 00Z WILL ENCOUNTER 
STEEPENING MID LEVEL LAPSE RATES AND LOW LEVEL INSTABILITY AND WILL 
GO WITH SLIGHT CHANCE AFTERNOON AND 30 PERCENT POPS FOR OVERNIGHT.
SURFACE FRONT DROPS THROUGH THURSDAY AND THURSDAY NIGHT WITH 
BAROCLINIC ZONE AT H85 FOR BETTER FOCUS FOR ORGANIZED CONVECTION 
AND HAVE INCREASED POPS TO 40 PERCENT FOR ENTIRE AREA WITH TOO MUCH 
UNCERTAINTY ON LOCATION AND TIMING OF FRONT TO FURTHER PINPOINT 
HIGHEST POPS. FRONT LINGERS AND WEAKENS IN FAR SOUTH ON FRIDAY AND 
WILL KEEP LOW POPS IN FOR POSSIBLE DECAYING MCS IN MORNING AND 
SCATTERED AFTERNOON CONVECTION WITH MESOSCALE BOUNDARIES WITH BEST 
POPS IN SOUTH. NO HUGE DIFFERENCES IN MOS GUIDANCE OVER NEXT SEVERAL 
DAYS...WITH A COUPLE DEG C WARMUP AT H85 MIXING DOWN TO MID TO UPPER 
80S FOR TODAY AND THURSDAY WITH FRIDAY SLIGHTLY COOLER. 

NO MAJOR CHANGES TO EXTENDED AND WILL KEEP WEEKEND DRY...IGNORING 
LATEST AVN QPF PLACEMENT OVER CWFA THAT IS UNDER UPPER LEVEL HIGH.  
 
.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

DLS