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WWUS20 KWNS 242053

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SPC WW 242053

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 439

NWS STORM PREDICTION CENTER NORMAN OK

255 PM MDT THU JUL 24 2014



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHEAST MONTANA

  WESTERN NORTH DAKOTA



* EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 255 PM UNTIL

  900 PM MDT.



* PRIMARY THREATS INCLUDE...

  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2.5

    INCHES IN DIAMETER POSSIBLE

  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

  A TORNADO OR TWO POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 80 MILES WEST

SOUTHWEST OF GLASGOW MONTANA TO 70 MILES EAST OF WILLISTON NORTH

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

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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...STORMS ARE EXPECTED TO INCREASE OVER NORTHEAST MT THIS

AFTERNOON IN RESPONSE TO DYNAMIC FORCING FOR ASCENT IN ADVANCE OF A

STRONG UPPER LOW/SHORT WAVE TROUGH MOVING ENEWD ACROSS SWRN CANADA

AND THE NRN ROCKIES.  THE ENVIRONMENT OVER NERN MT IS WARM/MOIST AND

UNSTABLE WITH SURFACE DEW POINTS NEAR 60 AND CAPE TO 2000 J/KG.

STRONG WSWLY FLOW ALOFT/DEEP LAYER SHEAR WILL SUPPORT SUPERCELL

DEVELOPMENT WITH POTENTIAL FOR VERY LARGE HAIL AND DAMAGING WIND

GUSTS.  THERE IS POTENTIAL FOR A SHORT BOWING LINE TO DEVELOP WITH

TIME AS COLD POOLS MAY CONSOLIDATE DURING THE EVENING HOURS.



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 500. MEAN STORM

MOTION VECTOR 24035.





...WEISS

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