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WWUS20 KWNS 142000

SEL2

SPC WW 142000

MTZ000-WYZ000-150300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 642

NWS STORM PREDICTION CENTER NORMAN OK

155 PM MDT THU JUL 14 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND EASTERN MONTANA

       A SMALL PORTION OF FAR NORTHERN WYOMING



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 155 PM UNTIL

900 PM 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 85

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH OF

GLASGOW MONTANA TO 60 MILES SOUTH SOUTHWEST OF BILLINGS 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...APPROACHING UPPER TROUGH AND SPEED MAX ARE EXPECTED TO

INCREASE THUNDERSTORM COVERAGE OVER CENTRAL MT THE NEXT FEW

HOURS...WITH THE STORMS SPREADING NEWD INTO ERN MT DURING THE

EVENING HOURS. SUFFICIENT DEEP LAYER SHEAR AND INSTABILITY EXISTS

FOR SUPERCELLS WITH VERY LARGE HAIL AND WIND DAMAGE. THE WIND DAMAGE

THREAT MAY INCREASE DURING THE EVENING ACROSS PORTIONS OF NERN MT AS

HIGH RESOLUTION MODELS SUGGEST STORMS EVOLVING INTO A WIND PRODUCING

MCS.



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 450. MEAN STORM

MOTION VECTOR 24025.





...IMY

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