[LeArc] Forecast Discussion : MLI@ 9/21/02 2:30:23 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 210738
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
239 AM CDT SAT SEP 21 2002

NW HUDSON BAY UPPER LOW WITH LONG WAVE TROUGH EXTENDING SOUTH INTO N 
CENTRAL CONUS TO DOMINATE THROUGH FORECAST WITH CLIPPER LIKE 
SHORTWAVES IN NW FLOW BRINGING POTENTIAL FOR RAIN TO CWFA ABOUT 
EVERY 48 HOURS. MAIN SHORTWAVE THAT IMPACTED AREA PAST COUPLE DAYS 
SEEN ON ANALYSIS AND SATELLITE IMAGERY PUSHING INTO GREAT LAKES. 
ANOTHER EXTENDED S FROM MAIN VORTEX INTO NW MN WITH WEAK 
EXTENSION BEST SEEN AROUND H7 EXTENDING SW INTO CENTRAL NEB NEB AT 
00Z. MORE SIGNIFICANT NEXT UPSTREAM SYSTEM WAS 140 KT H3 JET 
PUNCHING INTO WESTERN MT WITH EXIT REGION PRODUCING -RA OVER 
BAROCLINIC ZONE IN SW SD. FORECAST CHALLENGES CENTER AROUND CHANCES 
FOR -RA WITH SHORTWAVES AND ALSO HOW COLD TEMPERATURES WILL GO INTO 
NEXT WEEK WITH EACH ASSOCIATED COLD FRONT. 

MODELS INITIALIZED HEIGHTS A BIT TOO HIGH OVER SD AND AT H85 ETA 
AND NGM INITIALIZED TEMPERATURES A FEW DEGREES TOO WARM IN SAME 
AREA. OTHERWISE MODEL SOLUTIONS SIMILAR WITH SURFACE AND MID LEVEL 
FEATURES NEXT 36 HOURS...WITH NGM MOST NOTABLY A BIT SLOWER WITH 
SPEED OF SURFACE FRONT AND UPPER WAVE. AVN AND ETA HAD DECENT HANDLE 
ON 06Z FRONTAL LOCATION AND THUS BLEND FOLLOWED...WHICH PUSHES FRONT 
E-SE OF CWA...FROM N CENTRAL IL TO NE MO BY 18Z. CLOUDS ASSOCIATED 
WITH JET LEVEL DIVERGENCE OVER SD WILL MOVE INTO NW ZONES BY LATE 
MORNING AND THEN OVERSPREAD ALL OF CWA BY AFTERNOON...FOLLOWING MID 
LEVEL RH FIELDS. H85 TEMPERATURES SUPPORT HIGHS IN 70 TO 75 DEGREE 
RANGE. WITH AT LEAST HALF DAY SUNSHINE AND LOOKING AT TRAJECTORY 
TEMPS FROM FRIDAY...WILL NOT STRAY FAR FROM MIDDLE RANGE OF MOS. 
TONIGHT...MID LEVEL FORCING FROM SHORTWAVE AND JET ENTRANCE REGION 
WILL SUPPORT ENOUGH LIFT FOR SCATTERED -RA. ETA QPF HAD DECENT 
HANDLE ON PRECIP AREAS THIS MORNING AND SOLUTION FOR TONIGHT LOOKS 
REASONABLE. WITH INITIALLY DRY LOW LEVEL AIRMASS NOT CONFIDENT 
ENOUGH FOR LIKELY MET AND MAV POPS AND WILL STICK WITH 40 TO 50 
PERCENT RANGE FOR MEASUREABLE RAIN.  

SUNDAY LOOKS COOLER WITH SURFACE HIGH TO W AND H85 COLD AIR 
ADVECTION TO LIMIT HIGHS TO 60S. NEXT SHORTWAVE AND SURFACE FRONT 
PUSHES THROUGH MONDAY...BUT MAIN FORCING PASSES TO NORTH AND WILL 
KEEP DRY FORECAST. MEDIUM RANGE MODELS STILL IN DISAGREEMENT WITH 
TIMING OF NEXT WAVE IN LATE WED/THURSDAY TIMEFRAME. WILL KEEP 
CURRENT DRY FORECAST GOING. NEWEST FMR GUIDANCE TRENDING EVEN COLDER 
WITH TEMPERATURES THAN PREVIOUS RUN. THIS TREND ALREADY HANDLED WELL 
IN PREVIOUS PACKAGE LOWS AND WILL NOT MAKE ANY MAJOR CHANGES.   

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

DLS