MESOSCALE DISCUSSION 0321
   NWS STORM PREDICTION CENTER NORMAN OK
   0912 AM CDT SUN MAR 24 2013
   
   AREAS AFFECTED...CNTRL IL
   
   CONCERNING...HEAVY SNOW 
   
   VALID 241412Z - 241715Z
   
   SUMMARY...SNOW WITH RATES OF 1-2 IN/HR WILL OVERSPREAD CNTRL IL
   THROUGH LATE MORNING...WITH SIMILAR SNOW RATES FORECAST TO PERSIST
   INTO THE AFTERNOON.
   
   DISCUSSION...SHORT-RANGE DETERMINISTIC GUIDANCE...INCLUDING
   HIGH-RESOLUTION WRF ENSEMBLE OUTPUT...APPEAR TOO AGGRESSIVE WITH
   DAMPENING THE HEAVY SNOW POTENTIAL ACCOMPANYING THE BAND OF
   ISENTROPIC ASCENT ATTENDANT TO THE WARM CONVEYOR BELT CURRENTLY
   CROSSING THE MS RIVER. SFC OBSERVATIONS AND RADAR DATA INDICATE
   HEAVY SNOW ALREADY APPROACHING THE MS RIVER AS OF AROUND 14Z WITH
   THE N/S-ORIENTED WARM-CONVEYOR-RELATED PRECIPITATION BAND...WITH
   OCCASIONAL INSTANCES OF SLEET.
   
   WITH THE DOWNSTREAM ILX 12Z RAOB INDICATING AN ANTECEDENT DEEP AND
   NEARLY SATURATED PROFILE BELOW THE 600-MB LEVEL...IT WILL TAKE VERY
   LITTLE ADDITIONAL ASCENT/MOISTENING FOR THE PRECIPITATION TO BE
   MAINTAINED INTO CNTRL IL. ACCORDINGLY...HEAVY SNOW WILL BECOME
   INCREASINGLY LIKELY IN CNTRL IL BETWEEN 1430Z AND 1530Z. TRENDS IN
   WATER VAPOR IMAGERY REGARDING THE TRACK OF THE ATTENDANT MID-LEVEL
   CYCLONE SUGGEST THAT SIMILAR PRECIPITATION RATES WILL BE MAINTAINED
   INTO THE AFTERNOON...AS THE DRY SLOT REMAINS TO THE S...AND HEAVY
   SNOW WITHIN THE DEFORMATION ZONE/COLD CONVEYOR BELT EVENTUALLY
   OVERSPREADS THE AREA LATER IN THE DAY. AN ISOLATED LIGHTNING STRIKE
   OR TWO WILL BE POSSIBLE WITH THE MOST INTENSE SNOWFALL RATES OWING
   TO WEAK ELEVATED BUOYANCY.
   
   ..COHEN.. 03/24/2013
   
   
   ATTN...WFO...ILX...LSX...DVN...
   
   LAT...LON   39508829 38958849 38888931 39849070 40399042 40538931
               40188857 39508829