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855 

WWUS20 KWNS 130346

SEL5

SPC WW 130346

IDZ000-WAZ000-130900-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 575

NWS STORM PREDICTION CENTER NORMAN OK

850 PM PDT SUN JUL 12 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN IDAHO

       EASTERN WASHINGTON



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 850 PM UNTIL

200 AM PDT.



HAIL TO 2 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 50

STATUTE MILES EAST AND WEST OF A LINE FROM 95 MILES NORTH OF

SPOKANE WASHINGTON TO 30 MILES SOUTHWEST OF PULLMAN WASHINGTON.

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.



DISCUSSION...A CLUSTER OF HIGH-BASED THUNDERSTORMS WILL SPREAD

NORTHWARD THROUGH THE NIGHT ACROSS EASTERN WA AND INTO NORTHERN ID.

STRONG WINDS ALOFT AHEAD OF AN INTENSE UPPER TROUGH...COMBINED WITH

A DEEP MIXED BOUNDARY LAYER WILL PROMOTE A RISK OF LOCALLY DAMAGING

WINDS WITH THE STORMS.



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 400. MEAN STORM

MOTION VECTOR 20030.





...HART

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