[LeArc] Forecast Discussion : MLI@ 12/7/02 1:59:03 PM

[Richard R. Sample]

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


FXUS63 KDVN 072011
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
210 PM CST SAT DEC 7 2002

RATHER ILL-DEFINED COLD FRONT AT 18Z SLOWLY PUSHING INTO FAR 
SOUTHERN WI AND NORTHERN IA. DRY W-NW FLOW ALOFT PROVIDING PLENTY OF 
SUNSHINE AND WIDESPREAD TEMPERATURES ABOVE FREEZING. VISIBLE 
SATELLITE IMAGERY SHOWS SNOW COVER NEARLY GONE FROM FAR NORTHERN 
ZONES AS A RESULT. FORECAST CHALLENGE IS TEMPERATURES THROUGH SHORT 
TERM WITH NO CHANCE OF PRECIPITATION UNTIL LARGE SCALE CHANGES TAKE 
PLACE LATER IN THE WEEK. 

NO MODEL PREFERENCE FOR SHORT TERM AND BLEND OF MAINLY ETA AND GFS 
USED. SHORTWAVE IN FLOW AROUND HUDSON BAY REGION POLAR VORTEX SEEN 
ON WATER VAPOR MOVING INTO N DAKOTA WILL HELP NUDGE THE SURFACE COLD 
FRONT SOUTH ACROSS ENTIRE FORECAST AREA BY AROUND 09Z. WITH LACK OF 
CONVERGENCE ALONG FRONT AND ALMOST NIL QG FORCING...EXPECTING ONLY 
SCATTERED MID LEVEL POST FRONTAL CLOUDS INTO SUNDAY MORNING. LOW 
LEVEL COLD AIR DOES NOT REALLY KICK IN UNTIL AFTER SUNRISE... 
ESPECIALLY ACROSS SOUTH. USING SURFACE TRAJECTORY METHOD AND 
EXPECTING LOW LEVEL FLOW TO REMAIN SOMEWHAT COUPLED...WENT CLOSER TO 
WARMER ETA GUIDANCE WITH LOWER 20S SOUTH AND AROUND 15 NORTH. 
COLDEST TEMPERATURES AT H85...AROUND -13 C BRUSHES FAR NORTH SUNDAY 
AND WITH LOW LEVEL COLD ADVECTION THROUGH THE DAY...HIGHS SHOULD 
REACH ONLY INTO 20S. MAV APPEARS TO BE OVERCOMPENSATING FOR LIMITED 
SNOW COVER IN NORTH WITH UPPER TEENS DBQ EASTWARD AND WILL STICK 
WITH LOWER 20S THERE. SUNDAY NIGHT SETTING UP TO BE NEARLY COLDEST 
OF SEASON SO FAR WITH SURFACE HIGH SETTLING OVERHEAD. WENT IN 
MIDDLE ROAD OF GUIDANCE RANGE WITH AROUND ZERO NORTH TO ABOUT 8 IN 
SOUTH. 

GRADUAL MODERATION IN TEMPERATURES OCCURS MONDAY AND TUESDAY AS 
WESTERN UPPER RIDGE BREAKS DOWN WITH UNDERCUTTING SOUTHERN STREAM 
BECOMING MORE ACTIVE. GFS MOS APPEARS TO BE UNDERESTIMATING DEGREE 
OF WARMING...ESPECIALLY TUE AND WED AND WENT SOMEWHAT ABOVE. GFS 
STILL FASTEST AND MOST NORTHERLY WITH UPPER LOW COMING OUT OF SW 
CONUS THURSDAY AND FRIDAY...ESPECIALLY 12Z RUN PUSHING ENERGY INTO 
AREA EARLY THURSDAY. WILL KEEP SNOW CHANCES GOING FOR LATE WEEK AND 
INTRODUCE SAT AS DRY WITH SYSTEM MOST LIKELY EAST OF REGION BY 
THEN.    

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

DLS