MESOSCALE DISCUSSION 1051
   NWS STORM PREDICTION CENTER NORMAN OK
   0332 PM CDT WED JUN 17 2015

   AREAS AFFECTED...PORTIONS OF SERN MT...NRN WY...WRN SD...AND FAR
   NWRN NEB

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 172032Z - 172230Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...THUNDERSTORMS WILL LIKELY INCREASE IN COVERAGE THIS
   AFTERNOON INTO EARLY THIS EVENING...WITH AN ATTENDANT THREAT FOR
   STRONG WIND GUSTS...LARGE HAIL...AND A COUPLE TORNADOES. WATCH
   ISSUANCE IS POSSIBLE BY 21-22Z.

   DISCUSSION...CONVECTIVE ACTIVITY IS EXPECTED TO INCREASE IN COVERAGE
   THIS AFTERNOON INTO EARLY THIS EVENING...AS HEATING ALONG HIGHER
   TERRAIN AND LOW-LEVEL CONVERGENCE ALONG A CONFLUENCE
   BOUNDARY/QUASI-STATIONARY FRONT WORK IN CONCERT WITH WEAK FORCING
   FOR ASCENT ALOFT. SUFFICIENT HEATING AND SFC DEW POINTS GENERALLY IN
   THE 50S HAVE YIELDED MLCAPE AROUND 500-1500 J/KG...AS FAIRLY STEEP
   MID-LEVEL LAPSE RATES SURMOUNT THE REGION. WITH A CORRIDOR OF
   ENHANCED WLY FLOW OVERHEAD...EFFECTIVE SHEAR OF 40-50 KTS WILL
   PROMOTE UPDRAFT ORGANIZATION IN MORE VIGOROUS CELLS. HIGHER MOMENTUM
   FLOW IN THE CLOUD-BEARING LAYER AND A WELL MIXED BOUNDARY LAYER WILL
   OFFER A STRONG WIND POTENTIAL...WHILE UPDRAFT ROTATION AND MID-LEVEL
   CAPE WILL SUPPORT A LARGE HAIL THREAT. ADDITIONALLY...BACKED
   LOW-LEVEL FLOW IN THE VICINITY OF THE CONFLUENCE BOUNDARY AND SOME
   INCREASE IN MOISTURE ACROSS ERN PORTIONS OF THE MCD MAY FAVOR A
   TORNADO OR TWO LATE THIS AFTERNOON INTO THIS EVENING. AS
   SUCH...WATCH ISSUANCE BY 21-22Z IS POSSIBLE.

   ..PICCA/KERR.. 06/17/2015


   ATTN...WFO...LBF...UNR...CYS...BYZ...RIW...TFX...

   LAT...LON   44420284 43850204 43270206 42900230 42790332 42840419
               44620817 45070906 45790981 46391006 46690987 46820898
               46400723 45870598 45010415 44420284