WATCHES: Severe Thunderstorm Watch Number 267

WWUS20 KWNS 122012
SEL7
SPC WW 122012
MTZ000-130400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 267
NWS STORM PREDICTION CENTER NORMAN OK
210 PM MDT SAT MAY 12 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

WESTERN AND CENTRAL MONTANA

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 210 PM UNTIL
1000 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 105
STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES WEST
SOUTHWEST OF BOZEMAN MONTANA TO 75 MILES NORTHEAST OF GREAT FALLS
MONTANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

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...DEEP MOIST CONVECTION CONTINUES TO INCREASE OVER HIGHER
TERRAIN ACROSS W-CENTRAL/SWRN MT EARLY THIS AFTERNOON...LIKELY AIDED
BY SUBTLE SHORTWAVE TROUGHS ROTATING NEWD INTO THE NRN ROCKIES. AIR
MASS IS DESTABILIZING AHEAD OF THIS ACTIVITY OVER LOWER ELEVATIONS
WHERE MLCAPE AROUND 1500 J/KG AND WEAK CINH IS ALREADY IN PLACE.
SHEAR WILL REMAIN MORE THAN ADEQUATE FOR SUPERCELLS...AND POSSIBLY
SMALL LINES AS ACTIVITY BUILDS UPSCALE AND MOVES NEWD THROUGH THE
EVENING. LARGE HAIL AND ISOLATED DAMAGING WINDS CAN BE EXPECTED
WITH STRONGER STORMS.

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 500. MEAN STORM
MOTION VECTOR 22025.

..EVANS

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