[LeArc] Forecast Discussion : MLI@ 12/5/02 3:02:43 PM

[Richard R. Sample]

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


FXUS63 KDVN 052116
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
316 PM CST THU DEC 5 2002

SATELLITE IMAGERY SHOWS LOW CLOUDS AND FLURRIES ASSOCIATED WITH WEAK 
SURFACE TROUGH HAD PUSHED EAST OF FORECAST AREA EARLY THIS 
AFTERNOON. PERSISTENT NW FLOW PATTERN CONTINUES WITH FLOW OVER 
WESTERN CONUS RIDGE WITH PERIODIC SHORTWAVES MAINLY IMPACTING GREAT 
LAKES THROUGH WEEKEND. MAIN FORECAST CHALLENGE IS TEMPERATURES.

NO SIGNIFICANT DIFFERENCES IN MODELS NOTED. SURFACE HIGH OVER OK AT 
18Z SLIDES EAST WITH RIDGE AXIS EDGING NORTH INTO EASTERN IA/NW IL 
BY 12Z. 18Z SURFACE ANALYSIS INDICATED ANOTHER WEAK SURFACE TROUGH 
UNDER MID LEVEL SHORTWAVE SEEN ON WATER VAPOR FROM UPPER MI TO W 
CENTRAL MN. WILL GO ALONG WITH MODEL CONSENSUS WITH LOW CLOUDS AND 
FLURRIES STAYING TO NORTHEAST THIS EVENING AS FEATURE NUDGES INTO 
THE HIGH. WILL BE IDEAL RADIATIONAL COOLING CONDITIONS TONIGHT WITH 
CLEAR SKIES AND DRY AIR ALOFT. AS WAS CASE LAST NIGHT...SNOW COVERED 
AREAS WILL BE MUCH COLDER THAN SURROUNDING SURFACES. WILL GO ABOUT 1 
CATEGORY BELOW GUIDANCE...CLOSE TO ZERO IN SNOW FIELD FROM DUBUQUE 
AREA EAST TO FREEPORT. OVER REMAINDER OF AREA...WENT JUST BELOW 
GUIDANCE IN 5 TO 10 RANGE.  

WARM AIR ADVECTION KICKS IN FRIDAY AFTERNOON AT H85...BUT AFTER COLD 
START WITH LIMITED MIXING THROUGH MUCH OF DAY DUE TO WEAK RIDGE 
STARTING OUT OVERHEAD...GOING ON COOL SIDE OF GUIDANCE WITH RANGE OF 
UPPER 20S NORTH TO MID 30S SOUTH LOOKS REASONABLE. ANOTHER FAST 
MOVING WAVE MOVES THROUGH LATE FRIDAY NIGHT...BUT SEE INSUFFICIENT
MOISTURE FOR MORE THAN FEW CLOUDS. MAIN IMPACT WILL BE TEMPERATURES 
STAYING WARMER WITH LOWS MAINLY IN 20S. AN EVEN WEAKER WAVE PUSHES 
THROUGH SATURDAY NIGHT WITH LITTLE IMPACT AND HAVE REMOVED WEEKEND 
FLURRIES. 

NEXT WEEK...PATTERN BEGINS TO SHIFT TO MORE ZONAL WITH SOUTHERN 
STREAM STAYING ACTIVE AND GRADUALLY SHIFTING NORTH. LATEST UK AND 
GFS SUGGESTS ACTIVE SOUTHERN STREAM SYSTEMS WILL STAY TOO FAR SOUTH 
UNTIL LATE WEEK AND KEPT FORECAST DRY. DID RAISE MAXS TO HIGH END 
AND SLIGHTLY ABOVE GFS MOS AS AGREE WITH DMX ON GUIDANCE RECENT COOL 
TREND AND PER TRENDS SEEN IN INTERSITE COMPARISON TO SURROUNDING 
GRIDS. 

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

DLS