[LeArc] Forecast Discussion : MLI@ 8/19/02 2:12:20 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 190712
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
212 AM CDT MON AUG 19 2002

BUSY MORNING WITH ELEVATED THUNDERSTORMS THAT DEVELOPED RAPIDLY 
BETWEEN 9 PM AND MIDNIGHT...BETWEEN THE SURFACE AND 850MB 
BOUNDARIES...AND ARE MOVING ACROSS CWA AT A STEADY RATE. SURFACE 
BOUNDARY AS OF 06Z POSITIONED BETWEEN KMCI...TO JUST NORTH OF 
KIRK...TO NEAR KVYS.  THERE IS A SURFACE WAVE IN SW CORNER OF CWA... 
WHICH SHOULD MOVE NORTHEAST ALONG FRONT OVER NEXT FEW HOURS.  
THE FLASH FLOOD THREAT WILL INCREASE AFTER THE THE SURFACE LOW 
SHIFTS EAST...AS TSTMS HAVE BEEN CONSISTENT IN AN EAST-WEST BAND 
ACROSS SRN IA...AND EXPECT THIS TO SHIFT EAST INTO THE SOUTHERN 
PARTS OF THIS CWA.  

MAIN FORECAST CONCERN THIS PACKAGE INCLUDE LINGERING PRECIPITATION 
IN THE MORNING...AND TUESDAY NIGHT/WEDNESDAY PRECIPITATION.

00Z MODELS APPEAR TO HAVE INITIALIZED FAIRLY WELL...WITH THE AVN  
APPEARING TO HAVE THE BEST HANDLE ON THE CURRENT SITUATION...THOUGH 
MODELS HAVE TOO MUCH PRECIPITATION BETWEEN 00Z AND 06Z SOUTH OF THE 
FRONT...WHERE LITTLE IF ANYTHING HAS OCCURRED AT ALL.  FEEL AVN ALSO 
ENDS PRECIPITATION REASONABLY WELL THIS MORNING...WITH THE ETA TOO 
DRY.  AVN BRINGS SURFACE HIGH FURTHER SOUTH INTO REGION TONIGHT... 
DRIVING FRONT TO SRN MO.  THIS IS ACTUALLY SIMILAR TO ETA POSITION 
BY 00Z TUE.  MODELS AGAIN DIVERGE BY TUESDAY EVENING...WITH THE 
CONVECTION DEVELOPING ALONG THE WARM FRONT THAT LIFTED ACROSS THE 
PLAINS DURING THE DAY.  AVN APPEARS TO BE SUFFERING FROM CONVECTIVE 
FEEDBACK...AND MISTRUST THIS SOLUTION WITH ITS VERY FAST...VERY 
STRONG 500MB SHORTWAVE THAT SEEMS FISHY.  PREFER ETAS SLOWER... 
WEAKER...AND MORE REASONABLE LOOKING SOLUTION. SO...WILL BE GOING 
WITH A MIX OF THE TWO MODELS FOR THIS FORECAST.  

TODAY...AS PRECIPITATION TO THE NORTHWEST OF MAIN TSTM BAND HAS BEEN 
MAINLY SHOWERY.  WHILE THERE ARE PLENTY OF LOW TO MID CLOUDS...NO 
DRIZZLE HAS BEEN REPORTED IN THIS AREA.  WILL ADJUST MORNING WORDING 
TO SHOWERS/SPRINKLES WORDING...BUT OTHERWISE GOING TIMING FITS IN 
WELL WITH THINKING DISCUSSED ABOVE.  WITH NORTHEAST FLOW...AND MOST 
OF THE MORNING UNDER CLOUDS...DONT EXPECT TEMPS TO RECOVER MUCH 
DURING THE DAY.  PREFER MAV/FWC TEMPS...WHICH ARE VERY SIMILAR.  

TONIGHT...LIGHT WINDS UNDER RIDGE...RECENT SIGNIFICANT RAINFALL... 
AND CLEARING SKIES SHOULD ALLOW FOG TO DEVELOP.  HOWEVER...DONT 
EXPECT CONDITIONS TO GET TOO LOW...SO WILL JUST GO WITH PATCHY LIGHT 
FOG FOR NOW.  LATER SHIFTS CAN DECIDE IF FOG WILL BE MORE 
SIGNIFICANT.  GOING TEMPS IN THE MID TO UPPER 50S REASONABLE.

TUESDAY REMAINS QUIET...WITH RETURN FLOW BEGINNING TO KICK IN SO 
TEMPS SHOULD RISE QUITE NICELY.  THERE MAY BE SOME CIRRUS DEBRIS 
FROM CONVECTION FURTHER WEST...BUT OTHERWISE PLENTY OF SUNSHINE.  

TUESDAY NIGHT/EARLY WEDENSDAY...AS DISCUSSED ABOVE...QUITE A BIT OF 
UNCERTAINTY ON WHEN/WHERE MCS WILL DEVELOP...SO CHANCE POPS AS IN 
GOING FORECAST REASONABLE.  WILL REFINE TIMING TO DELAY A LITTLE IN 
THE EVENING...AND DRAG OVER INTO WEDNESDAY MORNING.  WEDNESDAY HIGH 
TEMPS QUESTIONABLE WITH POSSIBLE DEBRIS FROM MCS TO KEEP THINGS COOL 
DESPITE STRONG WAA IN WARM SECTOR SOUTH OF FRONT.  WILL INCREASE 
RANGE A LITTLE ACROSS CWA...THOUGH NOT AS MUCH AS MAV TEMPS.  

EXPECT TO MAKE LITTLE/NO CHANGES TO EXTENDED PERIODS.

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

LRE