MESOSCALE DISCUSSION 0662
   NWS STORM PREDICTION CENTER NORMAN OK
   0151 PM CDT SAT MAY 22 2010
   
   AREAS AFFECTED...PORTIONS OF WRN/CENTRAL SD AND ND
   
   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 
   
   VALID 221851Z - 222015Z
   
   A TORNADO WATCH IS LIKELY FOR PORTIONS OF THE WRN/CENTRAL DAKOTAS BY
   MID AFTERNOON.
   
   AT 18Z...WEAK AREAS OF LOW PRESSURE WERE LOCATED IN ERN MT AND SWRN
   SD...WITH A WEAK FRONT/TROUGH CONNECTING THE TWO LOW PRESSURE
   SYSTEMS. FROM THE LOW IN SRN SD...A WARM FRONT STRETCHED EWD THROUGH
   THE CENTRAL PORTIONS OF THE STATE. AN ISOLATED SEVERE STORM WAS
   LOCATED IN NRN ND IN REGION OF STRONG LOW LEVEL JET/WARM ADVECTION.
   THE UPDRAFT OF THIS STORM IS SITUATED AROUND 850 MB AND GIVEN THE
   STABLE BOUNDARY LAYER...HAIL WILL BE THE PRIMARY THREAT AS IT MOVES
   NEWD.
   
   HOWEVER...WATER VAPOR IMAGERY AND MODEL GUIDANCE SHOW AN UPPER WAVE
   AND JET MAX WILL BE MOVING NEWD FROM WY INTO THE WRN DAKOTAS LATER
   THIS AFTERNOON. THESE FEATURES SHOULD AID IN CONVECTION DEVELOPING
   OVER THE HIGHER TERRAIN OF NERN WY AND THEN SPREADING INTO THE
   WRN/CENTRAL DAKOTAS LATER THIS AFTERNOON/EVENING. THE AIR MASS EAST
   AND SOUTH OF THE PRE-MENTIONED FRONTS WAS VERY UNSTABLE WITH MLCAPES
   NEAR 3000 J/KG. THIS INSTABILITY PLUS EFFECTIVE SHEAR AROUND 60 KT
   WILL BE VERY FAVORABLE FOR INTENSE SUPERCELLS. THOUGH VERY LARGE
   HAIL IS EXPECTED TO BE THE PRIMARY THREAT...THE MOISTENING BOUNDARY
   LAYER AND STRONG LOW LEVEL SHEAR...ESPECIALLY NEAR THE WARM
   FRONT...WHICH WILL BE LIFTING SLOWLY NWD TOWARD THE SD/ND
   BORDER..WILL SUPPORT TORNADOES. EXTENSIVE CLOUDS AND WEAKER
   INSTABILITY WILL PERSIST NORTH OF WARM FRONT AND THOUGH THIS MAY
   LIMIT THE NWD EXTENT OF SEVERE WEATHER SOMEWHAT...ELEVATED
   SUPERCELLS WITH LARGE HAIL ARE ALSO EXPECTED NORTH OF THE WARM
   FRONT.
   
   ..IMY.. 05/22/2010
   
   
   ATTN...WFO...ABR...BIS...UNR...
   
   LAT...LON   44629996 43740082 43680217 44410294 46180377 47360322
               47820222 47960101 47799945 47029891 45899929 44629996