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WWUS20 KWNS 271753

SEL7

SPC WW 271753

MTZ000-NDZ000-SDZ000-WYZ000-280100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 227

NWS STORM PREDICTION CENTER NORMAN OK

1155 AM MDT MON MAY 27 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  SOUTHEAST MONTANA

  SOUTHWEST NORTH DAKOTA

  WESTERN AND CENTRAL SOUTH DAKOTA

  NORTHEAST WYOMING



* EFFECTIVE THIS MONDAY MORNING AND EVENING FROM 1155 AM UNTIL

  700 PM MDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL LARGE HAIL EVENTS LIKELY WITH A FEW VERY LARGE HAIL

    EVENTS TO 2 INCHES IN DIAMETER POSSIBLE

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 110

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH

NORTHEAST OF MILES CITY MONTANA TO 75 MILES SOUTH SOUTHWEST OF

PHILIP SOUTH DAKOTA.  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.



&&



DISCUSSION...TSTMS ONGOING OVER WRN SD ARE EXPECTED TO INCREASE IN

COVERAGE AND INTENSITY THIS AFTERNOON WITH A SECOND AREA OF STORMS

ALSO LIKELY TO STRENGTHEN AHEAD OF VORTICITY MAXIMUM MOVING THROUGH

SERN MT/NERN WY.  GIVEN THE PRESENCE OF STEEP LAPSE RATES...MODERATE

INSTABILITY...AND MODERATELY STRONG VERTICAL SHEAR...THE POTENTIAL

WILL EXIST FOR SUPERCELLS AND BOWING STRUCTURES CAPABLE OF LARGE

HAIL AND DAMAGING WIND GUSTS.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 25020.





...MEAD

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