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641 

WWUS20 KWNS 022012

SEL0

SPC WW 022012

MTZ000-030300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 340

NWS STORM PREDICTION CENTER NORMAN OK

210 PM MDT SAT JUN 2 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH-CENTRAL AND EASTERN MONTANA



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 210 PM UNTIL

900 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 95

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES NORTH

NORTHWEST OF BOZEMAN MONTANA TO 25 MILES NORTH OF BAKER 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...TSTMS ARE EXPECTED TO INCREASE IN BOTH COVERAGE AND

INTENSITY ACROSS PARTS OF CNTRL...SRN AND ERN MT THROUGH THE LATE

AFTERNOON AND INTO THE EVENING. MID/UPPER LEVEL HEIGHT FALLS WILL

ACT TO SUPPRESS RIDGE AXIS ACROSS THE REGION WITH SUBSEQUENT LARGE

SCALE ASCENT ACTING ON A MOIST AND WEAKLY UNSTABLE AIRMASS

SUFFICIENT TO RESULT IN SCATTERED VIGOROUS CONVECTION. DEEP-LAYER

SHEAR SHOULD ALLOW FOR UPDRAFT PERSISTENCE AND SOME ORGANIZATION

WITH CELLS AND/OR SHORT LINE SEGMENTS POSING A THREAT FOR SEVERE

HAIL AND HIGH WINDS. STORMS MAY CONGEAL ACROSS PORTIONS OF ERN MT

DURING THE EVENING WITH WIND POTENTIAL POSSIBLY INCREASING OVER

THESE AREAS.



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 400. MEAN STORM

MOTION VECTOR 25025.





...CARBIN

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