

691 

WWUS20 KWNS 180157

SEL7

SPC WW 180157

MTZ000-SDZ000-WYZ000-180700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 317

NWS STORM PREDICTION CENTER NORMAN OK

800 PM MDT TUE JUN 17 2014



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  SOUTHEAST MONTANA

  WESTERN SOUTH DAKOTA

  NORTHEAST WYOMING



* EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 800 PM

  UNTIL 100 AM MDT.



* PRIMARY THREATS INCLUDE...

  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2.5

    INCHES IN DIAMETER POSSIBLE

  ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

  A TORNADO OR TWO POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 50

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES WEST

NORTHWEST OF BAKER MONTANA TO 65 MILES SOUTH OF RAPID CITY 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.



&&



OTHER WATCH INFORMATION...THIS SEVERE THUNDERSTORM WATCH REPLACES

TORNADO WATCH NUMBER 311. WATCH NUMBER 311 WILL NOT BE IN EFFECT

AFTER 800 PM MDT. CONTINUE...WW 313...WW 314...WW 315...



DISCUSSION...SCATTERED SUPERCELLS WILL PERSIST FOR SEVERAL MORE

HOURS ACROSS WRN SD AND VICINITY...ALONG A GENERAL NW-SE AXIS OF

CONVERGENCE.  THE 00Z RAPID CITY SOUNDING SHOWED VERY STRONG

BUOYANCY/STEEP LAPSE RATES WITH A SUPERCELL WIND PROFILE...WHICH

WILL CONTINUE TO SUPPORT A RISK FOR ISOLATED VERY LARGE HAIL.  IN

THE SHORT TERM...A TORNADO CANNOT BE RULED OUT BEFORE THE BOUNDARY

LAYER STABILIZES.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 32010.





...THOMPSON

