MESOSCALE DISCUSSION 1171
   NWS STORM PREDICTION CENTER NORMAN OK
   0746 AM CDT THU JUN 25 2015

   AREAS AFFECTED...SERN MT / NERN WY / WRN SD

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 251246Z - 251415Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AND
   INTENSITY THIS MORNING WITH THE PRIMARY HAZARD BEING LARGE HAIL. 
   THIS THREAT SHOULD REMAIN FAIRLY ISOLATED INITIALLY...THOUGH THE
   SEVERE STORMS MAY BECOME MORE NUMEROUS LATER THIS
   MORNING...POTENTIALLY NECESSITATING A WATCH.

   DISCUSSION...A GENERAL INCREASE IN TSTM ACTIVITY HAS BEEN OBSERVED
   DURING THE PAST HOUR OVER CNTRL MT /E OF LWT/ WITH OTHER STORMS
   PERSISTING SW OF GCC IN NERN WY.  THE FORMER STORMS SIGNAL THE
   LEADING EDGE OF STRONGER HEIGHT FALLS/DCVA ASSOCIATED WITH A
   SHORT-WAVE TROUGH TRANSLATING THROUGH CNTRL MT.  DOWNSTREAM 12Z
   SOUNDINGS AT RIW AND RAP SAMPLED A RELATIVELY MOIST LOW-LEVEL AIR
   MASS SURMOUNTED BY 700-500-MB LAPSE RATES OF 7.5-8.5 C/KM...YIELDING
   MUCAPE OF 1000-1500 J/KG.

   LATEST MODEL GUIDANCE REMAINS CONSISTENT IN SUGGESTING THAT STORMS
   SHOULD INCREASE IN COVERAGE AND INTENSITY OVER THE DISCUSSION AREA
   THIS MORNING AS THE FORCING FOR ASCENT ASSOCIATED WITH THE
   SHORT-WAVE TROUGH OVERSPREADS A PROGRESSIVELY MORE UNSTABLE AIR
   MASS.  EFFECTIVE BULK SHEAR OF 40+ KT WILL SUPPORT ORGANIZED STORM
   MODES INCLUDING SUPERCELLS WITH THE PRIMARY HAZARD BEING LARGE HAIL.
   WHILE A WATCH IS NOT ANTICIPATED IN THE NEXT COUPLE OF HOURS...ONE
   COULD BE REQUIRED LATER THIS MORNING.

   ..MEAD.. 06/25/2015


   ATTN...WFO...UNR...CYS...BYZ...RIW...

   LAT...LON   43050405 43120560 43670640 44590697 45470704 46160621
               46260539 46110444 45930403 45630308 44970264 44110230
               43340291 43050405