ZCZC SPCSWOMCD ALL ACUS11 KWNS 190828 SPC MCD 190828 SDZ000-WYZ000-191000- MESOSCALE DISCUSSION 1068 NWS STORM PREDICTION CENTER NORMAN OK 0328 AM CDT FRI JUN 19 2015 AREAS AFFECTED...FAR SERN MT/FAR NERN WY/NORTHWEST SD CONCERNING...SEVERE THUNDERSTORM WATCH 312... VALID 190828Z - 191000Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 312 CONTINUES. SUMMARY...LOCALLY STRONG/DAMAGING WIND GUSTS WILL REMAIN THE PRIMARY SEVERE WEATHER THREAT AS A LINE OF STORMS...WITH EMBEDDED BOWING STRUCTURES AT TIMES...TRACKS TO THE EAST AFFECTING NORTHWEST SD THROUGH 10Z. LOCAL WFO SPATIAL EXTENSION MAY BE NEEDED ON THE EAST SIDE OF WW 312 /PRIMARILY INTO ZIEBACH COUNTY SD/. OTHERWISE...THE SEVERE WEATHER THREAT WILL CONTINUE TO DIMINISH WITH THE PASSAGE OF THE LINE OF STORMS. DISCUSSION...RECENT TRENDS /THROUGH 0810Z/ IN AREA WSR-88D DATA INDICATE THE NORTHERN EXTENT OF THE LINE OF STORMS...WITH A BOWING SIGNATURE IN NORTHERN BUTTE/SOUTHERN HARDING COUNTIES SD...WAS MOVING TO THE EAST AT 45 KT...WHILE THE SRN EXTENT OF THIS LINE OF THE MCS WAS MOVING MORE SLOWLY TO THE ESE AT 35 KT. THE NRN BOW STRUCTURE SHOULD REACH ZIEBACH COUNTY SD BY 0930Z...WITH LOCAL WFO AREAL EXTENSION OF WW 312 POSSIBLE FOR THIS COUNTY. OBJECTIVE ANALYSES INDICATE MUCAPE OF 2000-3000 J/KG ACROSS WRN SD WITH A 45-KT SLY LLJ PER UNR VAD MAINTAINING AN INFLUX OF THIS INSTABILITY INTO THE SRN EXTENT OF THE NRN HIGH PLAINS MCS EARLY THIS MORNING. GRADUAL VEERING OF THE LLJ DURING THE NEXT 4-5 HOURS WILL SUPPORT A CONTINUED EWD TRACK OF THE MCS ACROSS MAINLY NORTHWEST INTO PARTS OF CENTRAL SD. A WEAK MIDLEVEL IMPULSE AND ACCOMPANYING WLY 50-KT JETLET WILL SUSTAIN BULK SHEAR FOR STORM ORGANIZATION. ALTHOUGH RECENT HRRR RUNS SUGGEST THIS MCS WILL ADVANCE TO THE ESE ACROSS NORTH-CENTRAL SD BY 10-11Z...THE OVERALL SEVERE WEATHER THREAT SHOULD BEGIN TO DIMINISH AS THIS SYSTEM MOVES AWAY FROM THE INSTABILITY AXIS IN WESTERN SD. ..PETERS.. 06/19/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...ABR...UNR... LAT...LON 45580368 45710356 45750219 45360159 44830121 44100118 44100256 44110394 44410448 44940382 45280379 45580368 NNNN