

979 

WWUS20 KWNS 142010

SEL2

SPC WW 142010

MTZ000-150200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 702

NWS STORM PREDICTION CENTER NORMAN OK

205 PM MDT FRI AUG 14 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHERN MONTANA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 205 PM UNTIL 800

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 85

STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES SOUTHEAST OF

LIVINGSTON MONTANA TO 50 MILES NORTH NORTHWEST OF LEWISTOWN

MONTANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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...STRONG FORCING...ASSOCIATED WITH UPPER TROUGH ENTERING

THE NRN ROCKIES...WAS SPREADING EWD INTO CENTRAL MT. AS THIS FEATURE

SHIFTS EWD...STORMS ARE EXPECTED TO INTENSIFY AND INCREASE IN

COVERAGE AS THEY ENCOUNTER A WARMING/DESTABILIZING AIR MASS AND DEEP

LAYER SHEAR AT 50 KT. THE ENVIRONMENT INITIALLY WILL SUPPORT

SUPERCELLS WITH PRIMARILY A HAIL THREAT. HOWEVER...STRONG LINEAR

FORCING ALOFT AND DEVELOPING SURFACE FRONT SHOULD ENHANCE THE

POTENTIAL FOR THE STORMS TO EVOLVE INTO A SQUALL LINE...AND AN

INCREASING POTENTIAL FOR DAMAGING WINDS.



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 25030.





...IMY

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