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874 

WWUS20 KWNS 090049

SEL7

SPC WW 090049

MTZ000-NDZ000-SDZ000-WYZ000-090700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 517

NWS STORM PREDICTION CENTER NORMAN OK

645 PM MDT SUN SEP 8 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  SOUTHEASTERN MONTANA

  SOUTHWESTERN NORTH DAKOTA

  NORTHWESTERN SOUTH DAKOTA

  NORTHEASTERN WYOMING



* EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 645 PM

  UNTIL 100 AM MDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL DAMAGING WIND GUSTS WITH A FEW SIGNIFICANT GUSTS TO 75

    MPH POSSIBLE

  SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO 3

    INCHES IN DIAMETER POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95

STATUTE MILES EAST AND WEST OF A LINE FROM 70 MILES SOUTH OF

RAPID CITY SOUTH DAKOTA TO 30 MILES EAST NORTHEAST OF BAKER

MONTANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



&&



OTHER WATCH INFORMATION...CONTINUE...WW 516...



DISCUSSION...BKN BAND OF TSTMS MOVING NEWD OVER NERN WY AND EXTREME

SERN MT IS BECOMING BETTER ORGANIZED WHILE MOVING INTO FAVORABLY

MOIST AND AT LEAST MARGINALLY BUOYANT BOUNDARY LAYER...INDICATING

THAT INITIALLY ISOLATED SVR THREAT MAY INCREASE IN DENSITY.  EXPECT

CONTINUING POTENTIAL FOR SVR HAIL...SUCH AS HAS BEEN OBSERVED WITH

CELL NEAR I-90 IN NERN WY...AND INCREASING WIND THREAT.  BARELY

SUB-SVR/48-KT GUST HAS BEEN MEASURED WITH APPARENTLY LESS-ORGANIZED

PORTION OF LINE S OF WW AREA -- AT TOR -- WITHIN PAST HALF HOUR.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 26030.





...EDWARDS

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