MESOSCALE DISCUSSION 1804
   NWS STORM PREDICTION CENTER NORMAN OK
   1250 PM CDT SUN JUL 31 2011
   
   AREAS AFFECTED...PORTIONS ERN/NRN SD...S-CENTRAL/SERN ND...WRN MN.
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 311750Z - 312015Z
   
   CONDITIONAL SVR THREAT DEVELOPING ACROSS WW AREA DURING NEXT 2-3
   HOURS...IN REGIME OF VERY STG MLCAPE AND WEAKENING CINH.  ANY
   SUSTAINED CONVECTION MAY BECOME SVR RATHER QUICKLY WITH SUPERCELL
   EVOLUTION LIKELY.
   
   SFC MESOANALYSIS SHOWS COLD FRONT FROM ERN UPPER MI WSWWD ACROSS NRN
   WI...BECOMING QUASISTATIONARY OVER MSP AREA THEN WARM FRONT WSWWD
   ACROSS CENTRAL SD TO BLACK HILLS.  WARM FRONT APPEARS TO BE
   REDEVELOPING NWD INTO INITIALLY SECONDARY BOUNDARY--MANIFEST WELL IN
   MOISTURE GRADIENT FROM MSP AREA WNWWD ACROSS NERN SD TO NEAR BIS. 
   PRIND COMBINED BOUNDARY WILL BECOME MORE IMPORTANT FEATURE FOR
   FOCUSING CONVECTIVE POTENTIAL AS IT MOVES NWD OVER CENTRAL/ERN ND
   AND WRN MN DURING REMAINDER AFTERNOON.
   
   TWO AREAS OF CONVECTION ARE EVIDENT ATTM IN VIS/REFLECTIVITY
   IMAGERY--ONE INVOF ND/SD LINE BETWEEN JMS-ABR WITH LITTLE
   MOVEMENT...ANOTHER JUST E OF HON-MHE LINE MOVING E ABOUT 15 KT.
   MODIFIED FCST SOUNDINGS SUGGEST EACH AREA OF CONVECTION INITIALLY IS
   ROOTED IN ELEVATED INFLOW PARCELS.  THIS IDEA IS SUPPORTED BY CLOUD
   CHARACTER EVIDENT IN VIS IMAGERY AND BY EARLY-PHASE CELL MOTIONS
   MORE CONSISTENT WITH LACK OF BOUNDARY-LAYER CONTRIBUTION TO
   AMBIENT/STEERING CURRENTS.  HOWEVER...0-1 KM LAYER ACROSS THIS
   REGION IS DESTABILIZING WITH CONTINUED/STG SFC DIABATIC
   HEATING...RESULTING IN REDUCTION OF CAPPING DESPITE SLOWLY
   INCREASING HEIGHTS ALOFT.  POTENTIAL FOR SUSTAINED GROWTH APPEARS
   GREATEST WITH NORTHERN CONVECTION...UNDER WHICH SFC BOUNDARY WILL
   FOCUS LOW-LEVEL LIFT TO REDUCE CINH IN ADDITION TO STG SFC HEATING. 
   AIR MASS S OF BOUNDARY WILL REMAIN CHARACTERIZED BY SFC DEW POINTS
   70S F...LEADING TO POTENTIALLY EXTREME BUOYANCY WITH MLCAPE
   3500-5000 J/KG.  THOUGH SFC WINDS WILL REMAIN WEAK...BOUNDARY WILL
   OFFER ENHANCED VORTICITY/SRH TO ANY CONVECTION THAT CAN DEVELOP/MOVE
   ALONG IT...AMIDST EFFECTIVE SHEAR MAGNITUDES 45-55 KT.
   
   ..EDWARDS.. 07/31/2011
   
   
   ATTN...WFO...MPX...FGF...FSD...ABR...BIS...
   
   LAT...LON   43559752 44399875 46710158 47120140 47120037 46869884
               46119653 45259465 43909473 43489684 43559752