792 
FXUS63 KLSX 211854
AFDSTL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
1245 PM CST TUE JAN 21 2003
  
BAND OF SNOW CONTINUES ACROSS NEB AT THIS TIME WITH GRI VARYING 
BETWEEN 1 AND 3 MILES DURING THE MORNING.  THE ETA AND GFS SHOW 
FAVORABLE FRONTAL SCALE FORCING ACROSS THAT REGION.  BOTH MODELS 
FORECAST AREA OF FORCING TO SLIDE ACROSS THE AREA ON WED.  THE GFS 
HAS BEEN VERY CONSISTENT SINCE SUN WITH THIS FEATURE.  COULD BE A 
REPEAT OF SAT WITH A DUSTING TO AN INCH OF SNOW ACROSS MUCH OF THE 
CWA.  THE QPF FROM BOTH MODELS IS FAIRLY SIMILAR.  THE SHORT WAVE 
WITH THIS SYSTEM DEEPENS SIGNIFICANTLY WED NIGHT.  ETA AND GFS 
FORECAST A 80-100 METER HEIGHT FALL CENTER OVER NW IL WED EVENING 
DROPPING TO 240 METERS BY THU MORNING.  MODELS ARE CONSISTENT IN 
BRINGING -22C 850 TEMPS INTO NE MO BY THU MORNING WITH 35-40 
KTS.        
 
HUGE ARCTIC HIGH SETTLES INTO THE AREA BY THU EVENING AND IS 
FORECAST TO SLIDE TO THE S OF THE AREA BY FRI MORNING.  STRONG WAA 
FORECAST TO RETURN BY ETA AND GFS BY FRI MORNING WHICH SHOULD BRING 
CLOUDS BACK IN.  MAV TEMPS FOLLOWED FAIRLY CLOSELY FOR FRI MORNING 
LOWS.  THE GFS IS MORE AGGRESSIVE WITH SHORT WAVE FOR FRI WITH 
DECENT AREA OF SYNOPTIC SCALE FORCING FORECAST.

IN THE EXTENDED PERIOD, THE GFS, UKMET AND ECMWF ALL FORECAST A 
BROAD NWLY FLOW FROM VANCOUVER ISLAND INTO THE SERN U.S. SAT 
MORNING. ANOTHER SHORT WAVE IS FORECAST TO DROP DOWN ACROSS THE 
REGION ON SAT BY THE GFS.  THE 12Z GFS UPDATE FOR SUN MORNING 
FORECASTS A DEEPER TROF ACROSS MO THAN THE 00Z RUN.  500 HEIGHTS ARE 
FORECAST TO INCREASE INTO THE MIDWEST EARLY NEXT WEEK WITH 10C 850 
TEMP FORECAST INTO WRN MO BY TUE MORNING.  AFTER AN ARCTIC BLAST WED 
NIGHT AND THU, TEMPS SHOULD WARM UP ABOVE AVERAGE FOR EARLY NEXT 
WEEK.     
 
.STL...NONE