[LeArc] Forecast Discussion : MLI@ 1/30/03 3:39:34 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 300948
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
347 AM CST THU JAN 30 2003

PRECIPITATION TYPE AND COVERAGE TONIGHT AND EARLY FRIDAY MAIN 
CHALLENGE AS STRONG WAVE PUSHING INTO BC MOVES THROUGH...THEN EVEN 
MORE IMPRESSIVE SYSTEM CONCERN FOR SUNDAY/MONDAY.

SURFACE RIDGE AXIS THAT MOVED OVER WED HAS SHIFTED TO AXIS FROM  
GREAT LAKES TO EASTERN KS. SIGNIFICANT STRATUS TRAPPED UNDER RIDGE 
CONTINUES TO SOUTHEAST...WHILE HIGHER SC DEVELOPED IN H85 WARM AIR 
ADVECTION TO COVER MOST OF FORECAST AREA EARLY THIS MORNING. WEAK 
MID LEVEL WAVE SEEN ON WATER VAPOR EVEN PRODUCING -SN OVER CENTRAL 
IA...THANKS DMX FOR HEADS UP...AND WILL ADD FEW FLURRIES FOR EARLY 
MORNING PERIOD. EXPECT SOME PARTIAL CLEARING IN SOUTH THIS MORNING 
AS PROFILERS SHOW SOME DRIER AIR TRYING TO NUDGE IN FROM S. MOSTLY 
CLOUDY WILL SUFFICE BY AFTERNOON ENTIRE AREA AS HIGHER CLOUDS STREAM 
IN FROM W AND UPGLIDE DEVELOPS ON ISENTROPIC SURFACES. MODELS HAVE 
SIGNIFICANT DIFFERENCES WITH QPF AS SHORTWAVE PASSES THROUGH 
TONIGHT. ALL HAVE SURFACE WAVE TO NORTH WITH COLD FRONT AFTER 12Z 
FRIDAY. HOWEVER...QPF VARIES SIGNIFICANTLY WITH AVN/UK SHOWING 
WIDESPREAD COVERAGE DEVELOPING BY 06Z...WHILE META RUNS FROM BOTH 
00Z AND 06Z INDICATED MORE NARROW OMEGA AND QPF ALONG AND EAST MISS 
RIVER DEVELOPING AFTER 06Z. WITH DECENT UPPER DIVERGENCE AND MID 
LEVEL QG FORCING...MAIN FACTOR WILL BE SATURATION PROCESS. 
ISENTROPICS SHOW BEST CONDENSATION PRESSURE DEFECITS OCCURRING IN 
NORTH. WENT ALONG WITH COMPROMISE...WITH GFS COVERAGE...BUT AMOUNTS 
SKEWED DOWNWARD CLOSER TO META. AS FOR PRECIP TYPE...CRITICAL 
THICKNESS VALUES AND MODEL SOUNDINGS SUPPORT MAIN IDEA IN GOING 
FORECAST WITH MAINLY RAIN IN FAR SOUTH AND MIX IN CENTRAL...WITH 
CHANGE OVER TO SNOW TOWARD MORNING OVER ALL BUT FAR SOUTH. IN 
NORTH...MAINLY SNOW EVENT WITH SOME SLEET POSSIBLY MIXED IN AT 
ONSET. SURFACE TEMPERATURES STILL A WILD CARD AND WILL COUNT ON 
ENOUGH WARMING TO PREVENT SIGNIFICANT ZR EVENT AND HOLD OFF ON 
ADVISORY. WILL BE A QUICK SHOT OF FORCING IN NORTH TO LIMIT SNOWFALL 
AMOUNTS TO 1 TO 2 INCHES. WILL KEEP FLURRIES GOING FOR FRIDAY 
MORNING...AS H5 SHORTWAVE QUICKLY PASSES TO EAST.  

GFS HAS SLOWED SYSTEM IN SUNDAY/MONDAY TIMEFRAME TO MORE CLOSELY 
AFREE WITH UK AND ECMWF. PATH OF SURFACE LOW INIDATED BY GFS ACROSS 
MO INTO CENTRAL IL MORE FAVORABLE SNOW FOR CWFA SNOW EVENT. MADE 
ONLY MINOR CHANGES WITH TIMING AND PRECIP TYPE. OTHERWISE LITTLE 
CHANGES TO EXTENDED WITH BIG WARMUP AHEAD OF SYSTEM SATURDAY. 

COORDINATED WITH ARX...THANKS.

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

DLS