MESOSCALE DISCUSSION 1064
   NWS STORM PREDICTION CENTER NORMAN OK
   0457 PM CDT THU JUN 18 2015

   AREAS AFFECTED...N-CNTRL INTO S-CNTRL AND SERN MT / NERN WY

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 182157Z - 190030Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...ISOLATED STORMS ARE FORECAST TO DEVELOP WITHIN THE NEXT
   SEVERAL HOURS WITH THE INITIAL STORMS FORMING PREFERENTIALLY OVER
   THE HIGHER TERRAIN.  THE WIDELY-SPACED STORMS WILL BE CAPABLE
   PRIMARILY OF LARGE TO VERY LARGE HAIL AND SEVERE WIND GUSTS.

   DISCUSSION...SUBJECTIVE SURFACE MESOANALYSIS PLACES A MOIST AXIS
   EXTENDING NWWD FROM THE N-CNTRL HIGH PLAINS INTO THE NRN HIGH PLAINS
   AND SURFACE DEWPOINTS RANGE FROM NEAR 50 ON THE MT/ALBERTA BORDER TO
   THE UPPER 50S IN NERN WY.  STRONG HEATING COUPLED WITH THE
   APPRECIABLE LOW-LEVEL MOISTURE ARE CONTRIBUTING TO MODERATE BUOYANCY
   /1000-2000 J PER KG MLCAPE/ PER OBJECTIVE ANALYSIS.  SATELLITE
   IMAGERY SHOWS A BROKEN CIRRUS CANOPY ACROSS THE NRN ROCKIES INTO THE
   NRN HIGH PLAINS WITHIN A LARGELY ZONAL FLOW REGIME.

   AREA VAD WIND DATA SHOW ELY LOW-LEVEL WINDS VEERING MARKEDLY TO WLY
   AND INCREASING TO 50-60 KT IN THE 4-6 KM AGL LAYER.  AS A
   RESULT...STRONG EFFECTIVE SHEAR /50-70 KT/ WILL SUPPORT THE
   POTENTIAL FOR SUPERCELLS.  DESPITE MODEL GUIDANCE SHOWING ONLY
   SPARSE TO ISOLATED STORM COVERAGE THIS EVENING...IF STORMS MANAGE TO
   DEVELOP AND BECOME SUSTAINED...THE STORMS WILL LIKELY POSE A LARGE
   TO VERY LARGE HAIL AND SEVERE WIND GUST THREAT.  

   A CONDITIONAL SUPERCELL TORNADO RISK IS POSSIBLE DURING THE EVENING
   OVER SERN MT AND NERN WY WHERE FORECAST SOUNDINGS SHOW ENLARGING
   HODOGRAPHS AND WHERE THE RICHEST LOW-LEVEL MOISTURE IS FORECAST.

   ..SMITH/WEISS.. 06/18/2015


   ATTN...WFO...UNR...BYZ...GGW...RIW...TFX...

   LAT...LON   44080615 44640745 45080962 45511138 47311216 48801198
               48971040 48500928 47010881 45060537 44320535 44080615