MESOSCALE DISCUSSION 1855
   NWS STORM PREDICTION CENTER NORMAN OK
   1100 PM CDT SAT SEP 07 2013

   AREAS AFFECTED...EXTREME SERN MT/FAR NERN WY/A SMALL PORTION OF SRN
   ND/NORTHWEST AND N CENTRAL SD

   CONCERNING...SEVERE THUNDERSTORM WATCH 515...

   VALID 080400Z - 080500Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 515
   CONTINUES.

   SUMMARY...A CLUSTER OF THUNDERSTORMS CONTINUES ACROSS PARTS OF SRN
   ND/NWRN SD AND ADJACENT AREAS...WITH ISOLATED SEVERE THREAT ONGOING
   -- PARTICULARLY WITH A CELL NOW CROSSING SERN PERKINS COUNTY.  WHILE
   THE OVERALL SEVERE THREAT HAS WANED AND WILL CONTINUE TO DO
   SO...THREAT MAY PERSIST FOR A COUPLE MORE HOURS WITH THIS STORM AS
   IT MOVES EWD ACROSS N CENTRAL SD.

   DISCUSSION...LATEST RADAR LOOP SHOWS THE SEVERE STORM CROSSING SERN
   PERKINS COUNTY WHICH WILL SHIFT ACROSS NRN ZIEBACH COUNTY OVER THE
   NEXT HALF HOUR.  THIS STORM HAS PRODUCED SEVERAL REPORTS OF
   SEVERE/DAMAGING WINDS IN THE PAST HALF HOUR OR SO...AND EXPECT THIS
   THREAT TO CONTINUE AS THE STORM CROSSES INTO NRN ZIEBACH COUNTY.

   WHILE VERY ISOLATED SEVERE RISK PERSISTS ACROSS AREAS ADJACENT TO
   THE LARGER CONVECTIVE CLUSTER...EXPECT PRIMARY SEVERE RISK TO REMAIN
   ACROSS N CENTRAL SD -- WHERE THE AXIS OF MOST UNSTABLE AIR PERSISTS
   PER LATEST OBJECTIVE ANALYSIS.  THOUGH THE THREAT SHOULD DIMINISH
   SLOWLY WITH TIME...WW MAY NEED TO BE EXTENDED LOCALLY IN TIME -- AND
   POSSIBLY AREA -- TO COVER ANY THREAT WHICH MAY PERSIST BEYOND THE
   SCHEDULED 05Z EXPIRATION OF WW 515.

   ..GOSS.. 09/08/2013


   ATTN...WFO...ABR...BIS...UNR...BYZ...

   LAT...LON   44220553 45580451 46060351 46430103 45179845 44739859
               44629944 44630023 44420122 44220553