[LeArc] Forecast Discussion : MLI@ 12/8/02 1:38:41 PM

[Richard R. Sample]

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


FXUS63 KDVN 081953
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
153 PM CST SUN DEC 8 2002

SURFACE HIGH CENTERED NEAR FARGO AT 18Z ON TRACK TO SETTLE ACROSS 
FORECAST AREA OVERNIGHT. ONLY THIN CI IN SOUTH ASSOCIATED WITH 
SOUTHERN STREAM SYSTEM AND EFFECTS TONIGHT SHOULD BE MINIMAL. 
FORECAST CHALLENGE IS TEMPERATURES THROUGH SHORT TERM...THEN LATE 
WEEK CHANCES FOR PRECIPITATION. 

MODELS ALL BRING HIGH ABOUT OVERHEAD 06Z TONIGHT...THEN SHIFT TO 
EAST BY SUNRISE WITH WARM AIR ADVECTION ALREADY KICKING IN AT THE 
H85 LEVEL. LOOKING AT UPSTREAM MINS FROM THIS MORNING UNDER THE 
HIGH...RADIATIONAL COOLING AND LIGHT WINDS RESULTED IN RANGE OF 
ABOUT 5 TO 10 OVER NON-SNOW COVERED AREAS. 12Z GUIDANCE HAS 
CORRECTED MINS UPWARD SIGNIFICANTLY AND WILL ADJUST IN GRIDS CLOSEST
TO FWC...EXCEPT IN NORTH...WHERE KEPT A BIT BELOW. 

LOW LEVEL SOUTHWEST FLOW WILL BRING MUCH MILDER TEMPERATURES MONDAY 
THROUGH WEDNESDAY AS UPPER FLOW BECOMES MORE ZONAL. GUIDANCE HAS HAD 
DIFFICULTY...TRENDING TOO COOL WITH MAX TEMPERATURES PAST FEW DAYS 
AND BELIEVE THIS TREND WILL CONTINUE. WILL CONTINUE NEARLY A 
CATEGORY ABOVE GUIDANCE THROUGH WED WITH HIGHS IN 40S AND KEEP LOWS 
MAINLY IN 40S. 

MEDIUM RANGE MODELS CONTINUE TO HAVE SIGNIFICANT DIFFERENCES WITH 
UPPER TROUGH DEVELOPING OVER ROCKIES THURSDAY AND MOVING NORTHEAST 
TO SOUTHERN GREAT LAKES BY SATURDAY. GFS CONTINUES MOST AGGRESSIVE 
WITH CUT OFF CIRCULATION. EXPERIENCE SHOWS MODELS TYPICALLY BRING 
ONSET OF PRECIP TOO FAST AND EVEN MRF KEEPS FORCING TOO FAR SOUTH TO 
IMPACT HERE UNTIL THURSDAY EVENING...SO DELAYED SNOW CHANCES UNTIL 
THURSDAY NIGHT AND EXTENDED INTO SATURDAY. WITH ALL MODELS SHOWING 
UPPER LOW IN VICINITY...CONFIDENCE OF PRECIP SOMEWHERE IN CWA IS 
HIGH...BUT NOT ENOUGH TO BUMP UP TO LIKELY. GFS SHOWS POSSIBILITY OF 
SYSTEM STARTING OUT WITH MIXED OR FREEZING PRECIP THURSDAY NIGHT 
WITH POSSIBLE OVERRUNNING SITUATION...BUT WAY TOO EARLY TO DETERMINE
SPECIFICS AND WILL KEEP SNOW WORDING.   

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

DLS