MESOSCALE DISCUSSION 1374
   NWS STORM PREDICTION CENTER NORMAN OK
   0436 PM CDT MON JUN 29 2009
   
   AREAS AFFECTED...WRN SD AND WRN NEB
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 292136Z - 292300Z
   
   AN ISOLATED THREAT OF LARGE HAIL AND DAMAGING WINDS WILL EXIST
   DURING THE AFTERNOON AND EVENING OVER WRN SD AND WRN NEB. AT THIS
   TIME...A WW DOES NOT APPEAR NECESSARY.
   
   SUBJECTIVE SURFACE ANALYSIS INDICATES THE PRESENCE OF WEAK LOW
   PRESSURE OVER WRN/CENTRAL SD...WHICH IS ACTING TO FOCUS LOW LEVEL
   CONVERGENCE AND A NW TO SE ORIENTED THERMAL GRADIENT. TEMPERATURES
   ACROSS THE REGION HAVE WARMED INTO THE 90S...AND ARE ACCOMPANIED BY
   UPPER 40S TO LOW 50S DEWPOINTS. THESE SURFACE CONDITIONS...COMBINED
   WITH STEEP MID LEVEL LAPSE RATES /AOA 7.5-8.0 C PER KM/...AS
   INDICATED BY RUC FORECAST SOUNDINGS AND 18Z LBF RAOB...ARE
   CONTRIBUTING TOWARD A MODERATELY UNSTABLE ENVIRONMENT /MLCAPE VALUES
   APPROACHING 2000 J PER KG OVER WRN SD/.
   
   STRONG BOUNDARY LAYER DESTABILIZATION COMBINED WITH AN APPROACHING
   UPPER LEVEL IMPULSE EMBEDDED WITHIN A S/W RIDGE OVER THE REGION IS
   FAVORING SCATTERED THUNDERSTORM DEVELOPMENT OVER WRN PORTIONS OF SD.
   LOW LEVEL SSELY WINDS VEERING TO 30 KT/S OF WNWLY FLOW IN THE
   MID/UPPER LEVELS WILL CONTRIBUTE TOWARD SUFFICIENT EFFECTIVE BULK
   SHEAR FOR ORGANIZED MULTICELLS AND PERHAPS BRIEF SUPERCELL
   STRUCTURES. LOW LEVEL FLOW IS FAIRLY WEAK...WHICH MAY HAMPER THE
   DEVELOPMENT OF PERSISTENT UPDRAFT ROTATION. HOWEVER...THE FAVORABLE
   CAPE/LAPSE RATES COMBINED WITH MODEST VERTICAL WIND SHEAR WILL
   PROMOTE LARGE HAIL AND DAMAGING WINDS WITH THE STRONGER UPDRAFT
   CORES. THESE STORMS MAY EVENTUALLY DRIFT SE INTO PORTIONS OF WRN NEB
   DURING THE EVENING...WITH SOME POTENTIAL FOR UPSCALE GROWTH INTO A
   LOOSELY ORGANIZED MCS.
   
   ..GARNER.. 06/29/2009
   
   
   ATTN...WFO...ABR...LBF...UNR...CYS...
   
   LAT...LON   45350363 45830268 45560121 42789987 41760050 41860367
               45350363