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060 

WWUS20 KWNS 072224

SEL5

SPC WW 072224

MTZ000-NDZ000-SDZ000-WYZ000-080500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 515

NWS STORM PREDICTION CENTER NORMAN OK

420 PM MDT SAT SEP 7 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 SATURDAY AFTERNOON AND EVENING FROM 420 PM UNTIL

  1100 PM 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

    2.5 INCHES IN DIAMETER POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 140

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES EAST

NORTHEAST OF BAKER MONTANA TO 90 MILES SOUTH OF BUFFALO SOUTH

DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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.



&&



DISCUSSION...INITIALLY ISOLATED STG-SVR TSTMS OVER SERN MT ARE

BECOMING EMBEDDED WITHIN LARGER CLUSTER OF INTENSIFYING CONVECTION

ALONG/AHEAD OF ITS OUTFLOW BOUNDARY.  ITS AGGREGATE WIND/HAIL THREAT

SHOULD BE FOCUSED ESEWD WITHIN BAROCLINIC ZONE...ROUGHLY INVOF US-12

ACROSS NWRN SD AND SWRN ND.  ADDITIONAL SVR CONVECTION MAY FORM

ALONG OUTFLOW/CONVERGENCE BOUNDARIES EVIDENT IN VIS IMAGERY OVER

NERN WY...AND TRAILING FROM MT CLUSTER BACK INTO ROSEBUD COUNTY.

REF SPC MESOSCALE DISCUSSION 1851 FOR ADDITIONAL METEOROLOGICAL

DETAILS.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

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

MOTION VECTOR 28025.





...EDWARDS

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