WATCHES: Severe Thunderstorm Watch Number 457

WWUS20 KWNS 031937
SEL7
SPC WW 031937
MTZ000-040200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 457
NWS STORM PREDICTION CENTER NORMAN OK
135 PM MDT TUE JUL 3 2012

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

NORTHEAST MONTANA

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 135 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 95
STATUTE MILES EAST AND WEST OF A LINE FROM 60 MILES NORTH
NORTHEAST OF GLASGOW MONTANA TO 80 MILES WEST SOUTHWEST OF
GLENDIVE 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...THUNDERSTORMS WILL FORM ALONG A COLD FRONT PROGRESSING
EWD FROM CENTRAL INTO ERN MT...WITH THE GREATER STORM
COVERAGE/INTENSITY EXPECTED ACROSS NE MT THIS AFTERNOON. AN
INCREASE IN LOW-LEVEL MOISTURE FROM THE SE AND STRONG DAYTIME
HEATING...BENEATH STEEP LAPSE RATES...HAS BOOSTED MLCAPE TO AOA 2000
J/KG AND WEAKENED CONVECTIVE INHIBITION ALONG THE FRONT. DEEP-LAYER
VERTICAL SHEAR WILL BE SUFFICIENT FOR EMBEDDED SUPERCELLS WITH THE
RISK FOR LARGE HAIL...THOUGH A PRIMARILY MODE EVOLUTION WILL SUPPORT
THE POTENTIAL FOR DAMAGING WINDS THROUGH THIS EVENING.

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 500. MEAN STORM
MOTION VECTOR 26030.


...THOMPSON

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