MESOSCALE DISCUSSION 0679
   NWS STORM PREDICTION CENTER NORMAN OK
   0524 PM CDT SAT MAY 18 2013
   
   AREAS AFFECTED...SRN NORTH DAKOTA...CNTRL AND NORTH CNTRL SOUTH
   DAKOTA
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 182224Z - 182330Z
   
   PROBABILITY OF WATCH ISSUANCE...60 PERCENT
   
   SUMMARY...TSTMS ARE EXPECTED TO CONTINUE TO DEVELOP THROUGH THE
   AFTERNOON AND INTO THE EVENING ACROSS SRN NORTH DAKOTA...SWD INTO
   CNTRL SOUTH DAKOTA. LARGE HAIL AND ISOLATED DAMAGING WIND GUSTS WILL
   BE POSSIBLE WITH THE STRONGER STORMS. A WW MAY BECOME NECESSARY
   LATER THIS AFTERNOON OR EVENING.
   
   DISCUSSION...BROAD ASCENT IS OVERSPREADING PORTIONS OF THE NRN HIGH
   PLAINS IN CONJUNCTION WITH A SUBTLE SHORT-WAVE TROUGH EJECTING NNE
   TO THE EAST OF A LARGER-SCALE CYCLONE ACROSS THE WRN CONUS. THIS
   ASCENT SHOULD ACT TO WEAKEN CINH ALLOWING FOR THE DEVELOPMENT OF
   TSTMS ACROSS SRN NORTH DAKOTA AND CNTRL SOUTH DAKOTA. THE
   ENVIRONMENT ACROSS THIS AREA IS CHARACTERIZED BY MUCAPE AOA 1000
   J/KG AND EFFECTIVE BULK SHEAR AOA 30 KTS WHICH IS SUPPORTIVE OF
   SUPERCELLS. ADDITIONALLY...STRONG/SVR TSTMS TO THE SW /ACROSS WW172/
   MAY EVENTUALLY MOVE INTO THIS AREA. AS SUCH A WW MAY BECOME
   NECESSARY LATER THIS AFTERNOON...WITH LARGE HAIL AND ISOLATED
   DAMAGING WIND GUSTS AS THE PRIMARY THREATS.
   
   ..MARSH/CORFIDI.. 05/18/2013
   
   
   ATTN...WFO...FGF...FSD...ABR...BIS...UNR...
   
   LAT...LON   45010111 45920200 45960400 47060397 47530331 47760217
               47730086 47629934 46869818 45949798 44659868 43749966
               43910108 45010111