[LeArc] Forecast Discussion : MLI@ 10/21/02 2:45:39 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 210754
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
245 AM CDT MON OCT 21 2002

CHALLENGING FORECAST WITH PHASING ISSUES. OVERALL...STRONG SIGNALS
OF STORM SYSTEM MID-LATE WEEK WITH FORCING 
OF SYNOPTIC SCALE...UNLIKE THAT WHICH WE HAVE SEEN YET THIS FALL 
SEASON. 

06Z SURFACE ANALYSIS SHOWS LOW PRESSURE OVER NORTHWEST IA WITH 
COLD FRONT TRAILING THROUGH NE. UPPER AIR ANALYSIS SHOWS STRONG H85 
BAROCLINIC ZONE ACROSS UPPER MIDWEST. POLAR VORTEX IN
EASTERN CANADA WITH SHORTWAVE DIVING SOUTH ACTING ON TIGHT THERMAL
GRADIENT TO PRODUCE BANDS OF HEAVY SNOW ACROSS MN. 

NEAR TERM...SURFACE LOW PRESSURE TO PASS OVER NORTHEAST IA TONIGHT
SUPPORTED BY LATEST PRESSURE FALLS. SURFACE LOW TO DRAG
COLD FRONT THROUGH REGION. AHEAD OF FRONT EXPECT DECENT WARMING WITH
TRAJECTORIES AND LLVL THICKNESS FIELDS SUPPORTIVE 
OF MAXES CLOSER TO BLEND OF FWC/MET GUIDANCE...ESPECIALLY IN THE SOUTH
HALF WHERE MORE SUNSHINE TO BE FOUND. LACK OF FORCING AND MOISTURE 
SUPPORTS NIL POPS PRE-FRONTAL...AND LITTLE IF ANY POST-FRONTAL PCPN
THOUGH CAN/T RULE OUT SPRINKLES OR SOME -DZ WITH
COLD ADVECTION LOW CLOUDS. LOWS TONIGHT CLOSER TO MAV GUIDANCE.

BEYOND TONIGHT...FORECAST BECOMES QUITE COMPLEX AND CHALLENGING. 
MODELS SUGGEST PHASING OF NORTHERN AND SOUTHERN STREAM SYSTEMS...WITH STRONG 
SIGNALS OF SURFACE LOW DEVELOPING ALONG TIGHT BAROCLINIC ZONE. 
BEST GUESS ATTIM IS DEVELOPMENT IN CENTRAL PLAINS WITH SYSTEM LIFTING E/NE 
ALONG TIGHT THERMAL GRADIENT INTO OHIO VALLEY. LOTS OF UNCERTAINTY ON 
EXACT TRACK AND TIMING BUT WOULD EXPECT NEXT FEW RUNS TO CLARIFY THIS. 
WHAT THIS ALL MEANS IS PCPN LIKELY OVER REGION WED-THU TIMEFRAME...WITH 
SNOW LOOKING LIKELY MAINLY IN AREAS ALONG AND NORTH OF HIGHWAY 20...
WITH RAIN/SNOW MIX SOUTH TO ABOUT I-80 CORRIDOR OR SO. JUST A QUESTION 
OF HOW MUCH SNOW. TIME WILL TELL. WILL CONTINUE MENTION IN HWO OF STORM SYSTEM
MIDWEEK WITH POTENTIAL SNOWFAL. TEMPS ON THE WAY DOWN AFTER TODAY...AND
MAY NOT GET OUT OF 30S IN NORTH ON WED WITH CLOUDS/PCPN. AS SURFACE WAVE LIFTS 
E/NE IT SHOULD PUMP WARMER AIR NORTHWARD SO WOULD ANTICIPATE 
AT SOME POINT PCPN TO GO TO ALL RAIN IN NORTH...SWITCHING BACK ON TAIL END.



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