MESOSCALE DISCUSSION 1080
   NWS STORM PREDICTION CENTER NORMAN OK
   0102 AM CDT SAT JUN 20 2015

   AREAS AFFECTED...SRN AND CENTRAL INTO ERN SD

   CONCERNING...SEVERE THUNDERSTORM WATCH 315...

   VALID 200602Z - 200700Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 315
   CONTINUES.

   SUMMARY...A FAST...ESEWD-MOVING BOW ECHO WILL REMAIN CAPABLE OF
   PRODUCING SEVERE WIND GUSTS OF 60-80 MPH THROUGH ABOUT 07-08Z AS IT
   ADVANCES THROUGH THE EASTERN EXTENT OF WW 315 AT AROUND 50 KT. 
   GIVEN A  RECENT EWD TRAJECTORY WITH THE PORTION OF THE BOW IN
   STANLEY/JONES COUNTIES...A FEW COUNTIES ON THE NORTHEAST EXTENT OF
   THIS WW HAVE BEEN ADDED THROUGH COORDINATION WITH WFO ABR.  FURTHER
   COUNTY EXTENSION MAY BE NEEDED INTO PARTS OF ERN SD OR A NEW WW
   COULD BE REQUIRED.

   DISCUSSION...A FAST /NOW PRIMARILY/ ESEWD-MOVING BOW STRUCTURE IS
   SPREADING ACROSS THE CORRIDOR OF STRONGEST RESIDUAL INSTABILITY
   /MUCAPE UP TO 3000 J PER KG/.  THIS COUPLED WITH A 50-KT SSWLY LLJ
   EXTENDING INTO THIS FORWARD-PROPAGATING MCS AND A 50+ KT WLY LOWER-
   TO MID- TROPOSPHERIC JET /BETWEEN 4-7 KM AGL PER KUDX VAD/ WILL
   CONTINUE TO RESULT IN STRONG/DAMAGING SEVERE WINDS AS WAS RECENTLY
   OBSERVED AT KPIR WITH 53 KT AT 0538Z.

   A MORE STABLE AIR MASS WITH EWD EXTENT INTO SWRN MN AND RELATIVELY
   STRONG CAP WITH EWD EXTENT AS WELL SHOULD RESULT IN SOME WEAKENING
   TREND AFTER 07-08Z.  THIS TREND IS GENERALLY BEING OBSERVED WITH A
   WEAKENING OF UPDRAFTS PER 9-KM CAPPI.

   ..PETERS/MEAD.. 06/20/2015


   ATTN...WFO...FSD...ABR...UNR...

   LAT...LON   43370162 44050132 44690012 44879845 44769726 44329715
               43599706 43169724 42949745 43079828 43170043 43370162