[LeArc] Forecast Discussion : MLI@ 2/16/03 3:32:07 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 160941
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
341 AM CST SUN FEB 16 2003

LAST OF SNOW FROM DEPARTING STORM ENDED AROUND 07Z AT MQB. LOW AT 
SURFACE WAS MOVING INTO NW AR WITH PRESSURE GRADIENT RELAXING AND 
WINDS DIMINISHING OVER ALL BUT FAR SE CWFA. RIDGE AXIS AT SURFACE 
EXTENDED SW ONTARIO ACROSS NW IA WITH CLEARING SKIES OVER EAST 
CENTRAL IA INTO NW IL. SATELLITE AND PROFILERS INDICATE UPPER TROUGH 
AXIS CURRENTLY MOVING ACROSS EASTERN IA ALONG BACK EDGE OF CLOUDS.
MAIN FORECAST CHALLENGE IS TEMPERATURES IN SHORT TERM AS RIDGE 
SLIDES OVER AREA AND SETS UP IDEAL RADIATIONAL COOLING EVENT. 

NO SIGNIFICANT DIFFERENCE IN MODEL FEATURES RELEVANT TO CWA THROUGH 
MONDAY AND MODEL BLEND USED. TODAY...CONTINUED COLD AIR ADVECTION IN 
NE FLOW AND SNOW COVER WILL LIMIT HIGHS TO LOWER AND MID 20S... 
CLOSEST TO MAV NUMBERS. TONIGHT RIDGE AT SURFACE AND ALOFT WITH DEEP 
DRY LAYER AND FRESH SNOW COVER WILL SET STAGE FOR TEMPERATURE PLUNGE.
GUIDANCE DOES NOT PICK UP ON THIS WELL. A LOOK AT UPSTREAM METARS 
SHOWS TEMPS ALREADY BELOW ZERO WITH DEWPOINTS WELL BELOW ZERO AT 09Z 
UNDER RIDGE AXIS. HAVE LOWERED MINS A COUPLE CATEGORIES BELOW MOS 
WITH SINGLE DIGITS ABOVE TO AROUND ZERO. NORTHERN STREAM SHORTWAVE 
WITH SURFACE TROUGH APPROACHING WESTERN IA LATE IN DAY MONDAY WITH 
GRADUAL BACKING LOW LEVEL FLOW. DESPITE LOTS OF STRONGER FEBRUARY 
SUNSHINE...COLD START AND SNOW COVER SHOULD LIMIT TEMPERATURES 
CLOSER TO COOLER MAV NUMBERS. 

THROUGH MOST OF WEEK ALL MODELS HAVE SPLIT FLOW PATTERN WITH SYSTEMS 
PASSING TOO FAR NORTH OR SOUTH TO BRING PRECIP TO CWFA. REMOVED 
CHANCES FOR MIDWEEK PRECIP AS SHORTWAVE AND SURFACE TROUGH PASS TOO 
FAR TO NORTH WITH VERY WEAK LIFT AND MOISTURE LACKING. NO 
SIGNIFICANT CHANGES TO GOING TEMPERATURE GRIDS WITH SNOW COVER 
LIMITING DEGREE OF WARMUP WITH MAINLY ZONAL FLOW. LONG WAVE TROUGH 
PUSHES THROUGH TOWARD SATURDAY WITH SIGNIFICANT WEEKEND COOL DOWN 
AND WINDY FRONTAL PASSAGE STILL INDICATED BY MODEL CONCENSUS AND 
LEFT LATE WEEK POPS AND PRECIP ESSENTIALLY INTACT IN GRIDS.  

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

$$
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