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951 

WWUS20 KWNS 252159

SEL0

SPC WW 252159

MTZ000-260700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 430

NWS STORM PREDICTION CENTER NORMAN OK

400 PM MDT MON JUN 25 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN MONTANA



EFFECTIVE THIS MONDAY AFTERNOON AND TUESDAY MORNING FROM 400 PM

UNTIL 100 AM MDT.



HAIL TO 2.5 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 75

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

SOUTHWEST OF CUT BANK MONTANA TO 15 MILES NORTH NORTHEAST OF

SIDNEY 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.



OTHER WATCH INFORMATION...CONTINUE...WW 426...WW 427...WW

428...WW 429...



DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY ACROSS THE WATCH AREA LATE THIS AFTERNOON INTO TONIGHT AS

LARGE-SCALE FORCING STRENGTHENS AHEAD OF A MIDLEVEL JET STREAK

PROPAGATING NNEWD THROUGH THE NRN INTERMOUNTAIN REGION.  AIR MASS

ALONG TO THE N OF WNW-ESE ORIENTED SURFACE FRONT IS QUITE MOIST FOR

THE ELEVATION WITH MLCAPE VALUES APPROACHING 1500-3000+ J/KG.  WHEN

COUPLED WITH 35-50 KT OF EFFECTIVE BULK SHEAR...SETUP WILL FAVOR

SUPERCELLS AND BOWING STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING

WINDS.  A TORNADO IS ALSO POSSIBLE.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 26020.





...MEAD

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