MESOSCALE DISCUSSION 1206
   NWS STORM PREDICTION CENTER NORMAN OK
   1252 PM CDT THU JUN 18 2009
   
   AREAS AFFECTED...SERN ND / NERN SD / W-CNTRL MN
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 181752Z - 181915Z
   
   THE THREAT FOR A FEW SEVERE STORMS IS EXPECTED TO INCREASE THIS
   AFTERNOON AND CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE
   WW.
   
   A RATHER COMPLEX SURFACE PATTERN HAS EVOLVED TODAY OWING TO THE
   PRESENCE OF MULTIPLE BOUNDARIES REMNANT FROM NOCTURNAL TSTM
   ACTIVITY.  BUT...IT APPEARS THAT SYNOPTIC SURFACE LOW WAS LOCATED
   OVER N-CNTRL SD AS OF 17Z WITH ATTENDANT WARM FRONT EXTENDING
   GENERALLY EWD INTO W-CNTRL MN /N OF A ABR-ATY-AXN LINE/.  BASED ON
   CURRENT SURFACE OBSERVATIONS AND 12Z MODEL GUIDANCE...THE AXIS OF
   RICHER BOUNDARY LAYER MOISTURE AND RESULTANT STRONGER INSTABILITY
   WILL REMAIN ALONG WARM FRONT INTO THIS AFTERNOON WITH MLCAPE OF
   1000-2000 J/KG.
   
   THUS FAR...MOST CONCENTRATED AREA OF TSTM DEVELOPMENT HAS BEEN
   S-CNTRL ND WITHIN ZONE OF DEEP ASCENT N OF SURFACE LOW. 
   HOWEVER...WITH TIME THIS ACTIVITY MAY BEGIN TO DEVELOP EWD ALONG OR
   JUST N OF WARM FRONT.  LOW-LEVEL SHEAR IS NOT PARTICULARLY
   STRONG...BUT THE PRESENCE OF THE MOIST/LOW LCL AIR MASS COUPLED WITH
   SUFFICIENT DEEP-LAYER SHEAR FOR SUPERCELLS SUGGESTS SOME TORNADO
   THREAT IN ADDITION TO HAIL AND DAMAGING WINDS.
   
   ..MEAD.. 06/18/2009
   
   
   ATTN...WFO...DLH...MPX...FGF...ABR...BIS...
   
   LAT...LON   45559941 46029977 46889911 47179795 47199644 47159569
               46899478 46439465 46049478 45519516 45569636 45349818
               45559941