MESOSCALE DISCUSSION 0671
   NWS STORM PREDICTION CENTER NORMAN OK
   0738 PM CDT SAT MAY 21 2016

   AREAS AFFECTED...ERN MT....NERN WY

   CONCERNING...SEVERE THUNDERSTORM WATCH 188...189...

   VALID 220038Z - 220145Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   188...189...CONTINUES.

   SUMMARY...THE THREAT FOR DMGG WINDS AND ISOLATED INSTANCES OF LARGE
   HAIL CONTINUES ACROSS SVR TSTM WATCHES 188 AND 189.

   DISCUSSION...A BROKEN LINE OF TSTMS HAS EVOLVED ALONG OUTFLOW
   BOUNDARY/COLD FRONT ACROSS ERN MT INTO NERN WY. DMGG WINDS HAVE
   LIKELY BECOME THE DOMINANT THREAT ACROSS THESE AREAS...MAXIMIZED
   NEAR/W OF KGGW WHERE THE NWRN SEGMENT OF CONVECTION IS ORIENTED
   PERPENDICULAR TO THE DEEP-LAYER FLOW. RECENT RADAR TRENDS ALSO
   SUPPORT THE POTENTIAL FOR VERY STRONG WINDS ACROSS THIS AREA. LARGE
   HAIL ALSO REMAINS POSSIBLE WITHIN STRONGER CONVECTIVE
   CORES...INCLUDING THE LONGER-LIVED SUPERCELL CLUSTER APPROACHING
   KGGW...BUT THIS THREAT HAS BECOME MORE LOCALIZED DUE TO THE
   CONVECTIVE MODE EVOLUTION. THE 00Z GGW RAOB SAMPLED AN UNSTABLE AIR
   MASS CHARACTERIZED BY STEEP LOW-MIDLEVEL LAPSE RATES AND MODERATELY
   STRONG NEARLY UNIDIRECTIONAL DEEP-LAYER FLOW...FAVORABLE FOR
   MAINTAINING A SVR THREAT THROUGH 03Z...DESPITE THE IMMINENT LOSS OF
   DIURNAL HEATING.

   ..ROGERS.. 05/22/2016


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

   LAT...LON   49130441 45900404 43570519 43500594 43900657 45530675
               47120699 47900793 48270838 48980857 49130441