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WWUS20 KWNS 132035

SEL0

SPC WW 132035

MTZ000-140400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 740

NWS STORM PREDICTION CENTER NORMAN OK

235 PM MDT SUN SEP 13 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF EASTERN MONTANA



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 235 PM UNTIL

1000 PM MDT.



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 90

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH OF

GLASGOW MONTANA TO 30 MILES SOUTH OF MILES CITY MONTANA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU0).



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...COLD UPPER LOW CONTINUES MOVING NNWWD THRU CENTRAL MT

WITH A 35-40KT SLY LOW LEVEL JET ERN MT.  AIR MASS CONTINUES TO

DESTABILIZE ERN MT AND WITH 40-50KT OF DEEP LAYER

SHEAR...STRONG/SEVERE THUNDERSTORMS EXPECTED TO DEVELOP NEXT 1-2

HOURS.  INITIALLY STORMS WILL FORM ECENTRAL MT THEN MOVE N/NEWD THRU

THE EVENING.  POTENTIAL FOR ISOLATED SUPERCELLS WHICH WILL ENHANCE

THREAT OF BOTH LARGE HAIL AND BRIEF TORNADOES.



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 18030.





...HALES

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