MESOSCALE DISCUSSION 1564
   NWS STORM PREDICTION CENTER NORMAN OK
   0543 PM CDT SAT JUL 21 2007
   
   AREAS AFFECTED...WRN THROUGH N CNTRL ND
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 212243Z - 220045Z
   
   WRN ND IS BEING MONITORED FOR THUNDERSTORM DEVELOPMENT. PRIMARY
   UNCERTAINTY IS WHETHER OR NOT STORMS WILL INITIATE. HOWEVER...IF
   STORMS DEVELOP THEY WILL BE CAPABLE OF PRODUCING ISOLATED LARGE HAIL
   AND DAMAGING WIND. TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.
   
   EARLY THIS EVENING A COLD FRONT STRETCHES FROM SERN SASKATCHEWAN
   SWWD THROUGH NERN MT. PRE-FRONTAL TROUGH EXTENDS FROM A WEAK SURFACE
   LOW OVER WRN ND SWD THROUGH SWRN ND AND WRN SD. WARM FRONT EXTENDS
   SEWD FROM THE LOW THROUGH SWRN ND AND CNTRL SD. LOW LEVEL DEWPOINTS
   IN THE UPPER 60S HAVE ADVECTED NWD THROUGH PRE-FRONTAL WARM SECTOR
   BENEATH 8+ MID LEVEL LAPSE RATES. THIS HAS CONTRIBUTED TO MLCAPE
   FROM 3500 TO 4000 J/KG OVER WRN AND CNTRL ND. WV IMAGERY SHOWS A
   SHORTWAVE TROUGH EJECTING NEWD INTO SASKATCHEWAN WITH WEAK FORCING
   AND LIMITED CONVERGENCE FARTHER SE ALONG BOUNDARIES OVER WRN AND
   NWRN ND. HOWEVER...LATEST OBJECTIVE ANALYSIS SUGGESTS CONVECTIVE
   INHIBITION MAY HAVE WEAKENED SUFFICIENTLY FOR STORMS TO INITIATE
   ALONG FRONT OR PRE-FRONTAL TROUGH OVER PARTS OF WRN ND. SOME
   BOUNDARY LAYER CUMULUS IS DEVELOPING VICINITY OF THE FRONT AND
   PRE-FRONTAL TROUGH OVER NWRN AND WRN ND. DEEP SHEAR OF 30-40 KT WILL
   SUPPORT SUPERCELL STRUCTURES IF STORMS MANAGE TO DEVELOP WITH
   ISOLATED DAMAGING WIND AND LARGE HAIL THE MAIN THREATS.
   
   ..DIAL.. 07/21/2007
   
   
   ATTN...WFO...BIS...
   
   47360070 47120248 47930349 48840380 48900146 48310038