MESOSCALE DISCUSSION 1239
   NWS STORM PREDICTION CENTER NORMAN OK
   0243 PM CDT THU JUN 21 2007
   
   AREAS AFFECTED...SWRN ND...NWRN SD
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 211943Z - 212115Z
   
   CORRECTED FOR AREAS AFFECTED
   
   THE SEVERE WEATHER THREAT MAY INCREASE INVOF COMPACT MID-LEVEL
   IMPULSE AND SEVERAL SURFACE BOUNDARIES DRAPED ACROSS THE NRN HIGH
   PLAINS. MODERATE INSTABILITY/DEEP-LAYER SHEAR WOULD BE SUFFICIENT
   FOR SUPERCELLS. ALTHOUGH EXPECTED CONVECTIVE EVOLUTION AND COVERAGE
   ARE UNCERTAIN ATTM...A SEVERE TSTM WATCH ISSUANCE IS POSSIBLE LATER
   THIS AFTERNOON.
   
   RECENT SATELLITE IMAGERY DEPICTS A COMPACT MID-LEVEL CIRCULATION
   CROSSING INTO SWRN ND/NWRN SD FROM SERN MT. A FEW TSTMS HAVE
   DEVELOPED OVER THE PAST HOUR ACROSS WIBAUX COUNTY MT AND GOLDEN
   VALLEY COUNTY ND. S/SE OF THIS ACTIVITY...SEVERAL SURFACE WIND
   SHIFTS WERE NOTED OWING TO RATHER ILL-DEFINED OUTFLOW BOUNDARIES
   FROM EARLIER CONVECTION TODAY. THIS HAS RESULTED IN A COMPLEX
   SURFACE PATTERN AND LENDS SIGNIFICANT UNCERTAINTY INTO WHERE/WHEN
   ADDITIONAL TSTMS WILL DEVELOP. ALTHOUGH MID/UPPER-LEVEL CLOUDINESS
   HAS SLOWED SURFACE HEATING...POCKETS OF STRONGER HEATING SHOULD
   MAINTAIN MODERATE INSTABILITY ACROSS THE AREA THROUGH LATE
   AFTERNOON. VEERING WINDS WITH HEIGHT WOULD BE SUFFICIENT FOR UPDRAFT
   ROTATION WITH LARGE HAIL AS THE PRIMARY SEVERE THREAT INITIALLY.
   
   ..GRAMS.. 06/21/2007
   
   
   ATTN...WFO...ABR...BIS...UNR...BYZ...GGW...
   
   47000212 46330089 45540036 45080041 44660095 44400180
   44290292 45080362 46030408 46920460 47670506 47950476
   47670336