

080 

WWUS20 KWNS 011925

SEL6

SPC WW 011925

IDZ000-MTZ000-020400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 456

NWS STORM PREDICTION CENTER NORMAN OK

125 PM MDT THU AUG 1 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHEAST IDAHO

  WESTERN AND CENTRAL MONTANA



* EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 125 PM UNTIL

  1000 PM MDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL LARGE HAIL EVENTS 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 80

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 55 MILES NORTH

NORTHWEST OF SALMON IDAHO TO 40 MILES NORTHEAST OF BILLINGS

MONTANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 454...WW 455...



DISCUSSION...HEATING ALONG THE HIGH TERRAIN COUPLED WITH INCREASED

FORCING FOR ASCENT/DCVA ATTENDANT TO A SHORT-WAVE TROUGH APPROACHING

THE REGION FROM THE SW WILL YIELD AN INCREASE IN STORM COVERAGE AND

INTENSITY THIS AFTERNOON.  WHILE THE ENVIRONMENT IS NOT OVERLY

MOIST...THE PRESENCE OF STEEP LOW TO MIDLEVEL LAPSE RATES AND AMPLE

VERTICAL SHEAR WILL SUPPORT SUPERCELLS AND BOWING STRUCTURES CAPABLE

OF DAMAGING WINDS AND LARGE HAIL.



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 450. MEAN STORM

MOTION VECTOR 26025.





...MEAD

