[LeArc] Forecast Discussion : MLI@ 5/24/02 2:49:04 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 240747
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
246 AM FRI MAY 24 2002

COLD FRONT ACCOMPANIED BY SHOWERS AT 07Z HAD PUSHED OUT OF NE ZONES.
MAIN FORECAST CHALLENGE IS RAIN CHANCES TONIGHT AND SATURDAY WITH 
HEAVY RAIN AND FLOODING POTENTIAL IN SOUTHERN ZONES. 

AT 06Z SATELLITE WV IMAGERY SHOWED UPPER LOW OVER N CENTRAL UT WITH 
RIDGE OVER SE CONUS AND RESULTING SW FLOW FROM NV INTO IL. TONGUE OF 
H85 MOISTURE WITH DEWPOINTS OVER 10 C EXTENDED UP TO NRN IL AT 00Z. 
EMBEDDED SHORTWAVES IN SW FLOW MOVING ALONG SURFACE FRONT RESULTING 
IN MCCS OVER OK AND KS...WHICH WILL CONTINUE TO PROPAGATE E-NE INTO 
MO.

INITIAL CONCERN IS NECESSITY FOR POPS THIS MORNING AS DECAYING MCS 
MAY BRUSH FAR SOUTH. SHORT TERM MODELS ARE IN AGREEMENT WITH FRONT 
PROGRESSING TO KDTW TO KLBB LINE BY 12Z...WHICH MAY BE A LITTLE 
FAST. WILL TRIM BACK POPS TO DAY TO CHANCE IN MORNING FOR SE...THEN 
SHORTWAVE RIDGING ALOFT AND LOW TO MID LEVEL DRYING AND SURFACE 
RIDGE OVER NORTHERN PLAINS EDGING EAST WILL KEEP THINGS DRY TODAY. 
WILL SEE PLENTY OF HIGH LEVEL CONVECTIVE DEBRIS CLOUDS THROUGH 
MIDDAY...THEN EXPECT FILTERED SUNSHINE AND SUFFICIENT H5-H7 LAPSE 
RATES WILL CAUSE SC TO FILL IN DURING AFTERNOON AS HINTED BY META 
SOUNDINGS WILL PROVIDE MOSTLY CLOUDY SKIES. THIS...AND N-NE SURFACE 
WINDS WILL KEEP TEMPERATURES DOWN AND WILL GO CLOSER TO COOLER FWC 
GUIDANCE IN UPPER 50S TO LOWER 60S.

NEXT WAVE OF RAIN DEVELOPS TONIGHT AS UPPER DIVERGENCE 
DEVELOPS AHEAD OF ROCKIES H5 SHORTWAVE AND PUSHES LOW PRESSURE WAVE 
NE ALONG STALLED FRONT. MODELS DISAGREE ON TIMING OF THIS WAVE AND 
PLACEMENT OF QPF. AVN AND UKMET IN SOMEWHAT AGREEMENT WITH WAVE 
MOVING THROUGH MIDDAY SATURDAY TO END RAIN CHANCES WITH ETA AND NGM 
A BIT SLOWER. ALL ARE CONSIDERABLY SLOWER WITH FEATURE AND KEEP RAIN 
GOING LATER SATURDAY THAN PREVIOUS RUNS. WILL FAVOR AVN/UKMET 
SOLUTION AND EXTEND CATEGORICAL RAIN AND THUNDERSTORMS INTO MIDDAY 
SATURDAY IN EAST AND LIKELY FOR WESTERN ZONES. 

HEAVY RAIN OVER AREAS THAT WERE SATURATED THURSDAY STILL A CONCERN. 
PRECIPITABLE H20 VALUES OF 1.25 TO 1.5 INCHES UNDER AREA OF STRONG 
UPPER DIVERGENCE AND MID SHORTWAVE FORCING WILL RESULT IN WIDESPREAD 
THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY MORNING...WITH MAIN FOCUS 
ALONG AND NE OF LOW THAT TRACKS TO W OF PIA BY 18Z. MODEL QPFS 
SUGGEST POTENTIAL FOR 1 TO 1.8 INCH AMOUNTS OVER SOUTHERN THIRD 
CWFA. WITH QPF CENTERS ALL OVER THE PLACE AND FRONTAL POSITION 
SOMEWHAT UNCERTAIN...WILL NOT ISSUE ANY FLOODING HIGHLIGHTS THIS 
MORNING AND CONTINUE WITH ESF/HYDROLOGIC OUTLOOK AND LET DAY SHIFT 
FURTHER ASSESS SITUATION.     

REST OF WEEKEND UNDER ZONAL FLOW WITH NEXT CHANCE OF RAIN IN WEST 
MONDAY NIGHT AS RETURN FLOW AT LOW LEVEL DEVELOPS AHEAD OF NEXT 
SHORTWAVE ARRIVING FROM SW. AFTER QUICK LOOK AT LATEST MRF...WILL 
REFINE EXTENDED TO REMOVE TSRA CHANCES FOR WEDNESDAY...OTHERWISE 
LITTLE CHANGES ANTICIPATED.   

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

DLS