MESOSCALE DISCUSSION 0673
   NWS STORM PREDICTION CENTER NORMAN OK
   0728 PM CDT FRI MAY 17 2013
   
   AREAS AFFECTED...NE WYOMING..SE MONTANA...WRN AND CENTRAL SOUTH
   DAKOTA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 167...
   
   VALID 180028Z - 180200Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 167
   CONTINUES.
   
   SUMMARY...TSTMS ARE EXPECTED TO PERSIST FOR THE NEXT FEW HOURS
   ACROSS PORTIONS OF WRN SOUTH DAKOTA AND ERN WYOMING...WITH LARGE
   HAIL AND ISOLATED DAMAGING WINDS THE PRIMARY CONCERNS.
   ADDITIONALLY...A NEW WW MAY BE REQUIRED DOWNSTREAM OF WW167 ACROSS
   PORTIONS OF CENTRAL SOUTH DAKOTA WITHIN THE HOUR.
   
   DISCUSSION...AT 00 UTC...A CLUSTER OF TSTMS WAS ONGOING ACROSS
   PORTIONS OF SWRN SOUTH DAKOTA AND NWRN NEBRASKA. THESE TSTMS WERE
   MOVING ENE AND LOCATED IN AN ENVIRONMENT CHARACTERIZED BY DEEP-LAYER
   SHEAR AOA 35 KTS AND MLCAPE VALUES AROUND 1000 J/KG. THIS
   ENVIRONMENT SHOULD PERSIST THROUGH THE NEXT FEW HOURS AND SUPPORT AN
   ONGOING SVR THREAT. FARTHER E...THE ENVIRONMENT APPEARS TO BE
   CONDUCIVE FOR THE MAINTENANCE OF THE ONGOING TSTMS AS THEY MOVE ENE
   OUT OF WW167. FURTHERMORE...RECENT RADAR TRENDS SUGGEST THE
   POSSIBILITY OF A DEVELOPING MCV ACROSS BENNETT AND JACKSON COUNTIES
   IN SOUTH DAKOTA WHICH SHOULD HELP MAINTAIN TSTM INTENSITY...AT LEAST
   IN THE SHORT TERM. THIS WOULD SUGGEST THE NEED FOR A NEW WW
   DOWNSTREAM OF WW167. THE PRIMARY CONCERN WITH ANY NEW WATCH WOULD
   CONTINUE TO BE LARGE HAIL AND ISOLATED DAMAGING WIND GUSTS.
   
   TO THE NW...ACROSS NE WYOMING AND WEST-CENTRAL SOUTH DAKOTA...TSTMS
   ARE EXPECTED TO PERSIST FOR THE NEXT FEW HOURS. ALTHOUGH THE
   ENVIRONMENT IS NOT AS FAVORABLE HERE AS TO THE SOUTHEAST...IT SHOULD
   REMAIN CONDUCIVE FOR THE CONTINUATION OF AN ISOLATED SVR
   THREAT...WITH LARGE HAIL AND ISOLATE DAMAGING WIND GUSTS THE PRIMARY
   CONCERNS.
   
   ..MARSH/GUYER.. 05/18/2013
   
   
   ATTN...WFO...FSD...ABR...BIS...LBF...UNR...CYS...BYZ...
   
   LAT...LON   45000595 46120383 44990139 43869906 43029897 42720141
               43060305 43830530 45000595