MESOSCALE DISCUSSION 0348
   NWS STORM PREDICTION CENTER NORMAN OK
   0126 PM CDT TUE MAR 31 2009
   
   AREAS AFFECTED...ERN SD / NWRN IA / SWRN AND N-CNTRL MN
   
   CONCERNING...HEAVY SNOW 
   
   VALID 311826Z - 312100Z
   
   HEAVIER SNOWFALL RATES /IN EXCESS OF 1 INCH PER HR/ WILL GRADUALLY
   WANE DURING THE AFTN HRS /18-21Z/ ACROSS MUCH OF N-CNTRL MN/ERN SD. 
   SNOWFALL RATES GENERALLY BELOW 1 INCH/HR WILL DEVELOP EWD INTO PARTS
   OF SWRN MN 20-00Z.
   
   TRENDS IN RADAR MOSAIC SHOW A GRADUAL WEAKENING IN REFLECTIVITIES
   ACROSS MUCH OF ERN SD WITH A WELL DEVELOPED DRYSLOT EVIDENT VIA
   RADAR/WATER VAPOR IMAGERY OVER THE SRN HALF OF MN INTO WRN WI
   SPREADING NWD.  DEEP CLOSED LOW INVOF SD/MN/IA BORDER WITH ATTENDANT
   992 MB SURFACE LOW WILL SLOWLY MIGRATE NEWD AS SYSTEM CONTINUES TO
   BECOME MORE NEGATIVELY-TILTED WITH TIME.  WITH WARM MOIST CONVEYER
   BECOMING MORE REMOVED WITH ITS SSE-NNW AXIS SHIFTING EWD TOWARDS
   LAKE MICH AWAY FROM CLOSED LOW...A LESS FOCUSED WAA TONGUE WILL
   PENETRATE INTO NRN MN WITH SNOWFALL RATES CORRESPONDINGLY EXPECTED
   TO WEAKEN.  THIS IS MIRRORED WITH GPS/PW DATA INDICATING THIS MOIST
   FETCH MOVING EWD OVER CNTRL WI AS OF 18Z.  
   
   LATEST RADAR IMAGERY SHOWS HEAVIER N-S BAND OF SNOW LOCATED OVER ERN
   SD...WITH THIS LIKELY TO PERSIST IN THE NEAR TERM AS MID-LEVEL
   FRONTOGENESIS IS MAINTAINED BEFORE WEAKENING ACROSS THE AREA. 
   FURTHER E OVER PARTS OF SWRN MN IN THE 20-00Z PERIOD...FORECAST
   SOUNDINGS SHOW PROFILES MOISTEN/DEEPEN WITH TIME AS INCREASING DCVA
   /ENHANCED UVV/S ASSOCIATED WITH CYCLONE OVERSPREAD THE REGION.
   
   ..SMITH.. 03/31/2009
   
   
   ATTN...WFO...DLH...MPX...FGF...FSD...ABR...
   
   LAT...LON   45689123 46179373 46179526 45489618 45009595 44639457
               44039430 43669477 42919565 43019741 43439808 44269814
               45849709 47319505 47579225 47389127 46729041 45689123