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WWUS20 KWNS 102017

SEL5

SPC WW 102017

IDZ000-MTZ000-ORZ000-110300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 265

NWS STORM PREDICTION CENTER NORMAN OK

215 PM MDT THU MAY 10 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL IDAHO

       PARTS OF SOUTHWEST AND SOUTH CENTRAL MONTANA

       SMALL PART OF NORTHEAST OREGON



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 215 PM UNTIL

900 PM MDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 10 MILES WEST

SOUTHWEST OF BAKER OREGON TO 35 MILES NORTHEAST OF BILLINGS

MONTANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 264...



DISCUSSION...THUNDERSTORMS EXPECTED TO INCREASE BOTH IN NUMBER AND

INTENSITY ACROSS THE WATCH AREA REMAINDER OF AFTERNOON.  THIS IS IN

RESPONSE TO APPROACH OF MID LEVEL WIND MAX FROM OREGON ENHANCING

SHEAR COUPLED WITH STEEP LAPSE RATES AND ADEQUATE INSTABILITY.

PRIMARY THREAT WILL  BE LARGE HAIL AND WIND DAMAGE...PARTICULARLY

ASSOCIATED WITH STORMS THAT EVOLVE INTO LINE SEGMENTS.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM

MOTION VECTOR 24035.





...HALES

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