MESOSCALE DISCUSSION 1120
   NWS STORM PREDICTION CENTER NORMAN OK
   0207 PM CDT TUE JUN 18 2013

   AREAS AFFECTED...ERN CO...ERN WY...EXTREME WRN NEB AND SERN MT

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 181907Z - 182100Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...STORMS MAY POSE A RISK FOR ISOLATED DAMAGING WIND AND
   LARGE HAIL AS THEY SPREAD EWD OFF THE HIGHER TERRAIN INTO THE HIGH
   PLAINS OF ERN CO...ERN WY AND SERN MT. TRENDS ARE BEING MONITORED
   FOR A POSSIBLE SEVERE THUNDERSTORM WATCH.

   DISCUSSION...OROGRAPHIC FORCING INDUCED BY DIABATIC WARMING OVER THE
   MOUNTAINS HAS RESULTED IN THE DEVELOPMENT OF NUMEROUS STORMS FROM
   THE CNTRL THROUGH NRN ROCKIES. TEMPERATURES ARE CLIMBING INTO THE
   80S WITH LOW-MID 50S DEWPOINTS AND STEEP LAPSE RATES PROMOTING
   MLCAPE FROM 1500-2000 J/KG. DEEPLY MIXED BOUNDARY LAYERS WITH 30+ F
   TEMPERATURE-DEWPOINT SPREADS SUPPORT RELATIVE HIGH BASED STORMS.
   THIS REGION RESIDES WITHIN AN UPPER RIDGE AXIS WITH GENERALLY WEAK
   WINDS ALOFT. HOWEVER...BELT OF SLIGHTLY STRONGER FLOW AND UP TO
   25-30 KT 0-6 KM SHEAR RESIDE OVER NRN WY...SERN MT AND SRN CO. THIS
   SUGGESTS THE DOMINANT MODES SHOULD BE MULTICELLULAR AND STORMS MAY
   EVENTUALLY EVOLVE INTO CLUSTERS SUPPORTED BY COLD POOL MERGERS AS
   ACTIVITY MOVES OFF THE HIGHER TERRAIN. ISOLATED DAMAGING WIND AND
   LARGE HAIL WILL BE POSSIBLE THROUGH MID EVENING.

   ..DIAL/THOMPSON.. 06/18/2013


   ATTN...WFO...UNR...PUB...BOU...CYS...BYZ...RIW...

   LAT...LON   45580695 43560618 41180539 38510481 38470319 40790326
               45200465 45580695