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000
ACUS11 KWNS 180327
SWOMCD
SPC MCD 180326
NEZ000-SDZ000-MTZ000-WYZ000-180430-

MESOSCALE DISCUSSION 0674
NWS STORM PREDICTION CENTER NORMAN OK
1026 PM CDT FRI MAY 17 2013

AREAS AFFECTED...NE WYOMING..SE MONTANA...WRN AND CENTRAL SOUTH
DAKOTA

CONCERNING...SEVERE THUNDERSTORM WATCH 167...169...

VALID 180326Z - 180430Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
167...169...CONTINUES.

SUMMARY...ISOLATED STRONG/SVR TSTMS CONTINUE TO PERSIST/DEVELOP
ACROSS PORTIONS OF ERN WYOMING AND NRN NEBRASKA. AN ISOLATED
HAIL/WIND THREAT MAY PERSIST FOR THE NEXT FEW HOURS...AT LEAST
ACROSS WRN NEBRASKA.

DISCUSSION...AT 03 UTC...A BROAD WAA REGIME WAS HELPING TO MAINTAIN
SEVERAL CLUSTERS OF TSTMS ACROSS PORTIONS OF WW167/WW169. EMBEDDED
IN THIS WAA REGIME STRONG/SVR TSTMS WERE ONGOING ACROSS NERN WYOMING
/WESTIN AND CROOK COUNTIES/ AND NWRN NEBRASKA /CHERRY AND GRANT
COUNTIES/. THE LARGE SCALE ENVIRONMENT IN WHICH THESE STORMS ARE
DEVELOPING/MAINTAINING IS CHARACTERIZED BY MUCAPE VALUES BETWEEN
500-1000 J/KG AND DEEP LAYER SHEAR AOA 35 KTS. GIVEN THE CONTINUED
MAINTENANCE/DEVELOPMENT OF TSTMS IN SUCH A FAVORABLE
ENVIRONMENT...THE SVR THREAT MAY PERSIST PAST THE EXPIRATION OF
WW167 /04 UTC/. A LOCAL EXTENSION MAY BE REQUIRED.

FARTHER E...ACROSS PORTIONS OF WW169...EARLIER CONVECTION HAS
ACCELERATED EWD...WEAKENED...AND SHOULD EXIT WW169 IN THE NEXT 1-2
HRS. UNLESS OBSERVATIONAL TRENDS SUGGEST AN UPTICK IN CONVECTIVE
INTENSITY...OR THE DEVELOPMENT/INTENSIFICATION OF NEW CONVECTION
WW169 COULD BE CANCELLED EARLY AS CONVECTION MOVES TO THE EAST.

..MARSH.. 05/18/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FSD...OAX...ABR...LBF...UNR...CYS...BYZ...

LAT...LON   44970598 45079872 42819812 41190226 42610488 44970598