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000 

WWUS20 KWNS 172349

SEL3

SPC WW 172349

MTZ000-180700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 563

NWS STORM PREDICTION CENTER NORMAN OK

545 PM MDT TUE JUN 17 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL MONTANA



EFFECTIVE THIS TUESDAY AFTERNOON AND WEDNESDAY MORNING FROM 545

PM UNTIL 100 AM MDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 100

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH OF

HAVRE MONTANA TO 45 MILES SOUTH OF LIVINGSTON MONTANA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU3).



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 558...WW 559...WW

560...WW 561...WW 562...



DISCUSSION...HIGH-BASED TSTM DEVELOPMENT WAS OCCURRING AHEAD OF

MID-LEVEL SHORT WAVE TROUGH IMPINGING UPON LARGE SCALE RIDGE

SITUATED ACROSS THE NRN ROCKIES. LIFT WITH THIS FEATURE WILL

CONTINUE TO FAVOR THE DEVELOPMENT OF STORMS ATOP WARM AND DEEPLY

MIXED BOUNDARY LAYER AIR MASS FROM SWRN TO NERN MT THROUGH TONIGHT.

BOTH DIRECTIONAL AND DEEP-LAYER SPEED SHEAR WILL CONTRIBUTE TO

UPDRAFT PERSISTENCE AND SOME STORM ROTATION WITH A FEW CELLS CAPABLE

OF PRODUCING LARGE HAIL. STEEP/DRY ADIABATIC SUB-CLOUD LAPSE RATES

WILL ALSO RESULT IN STRONG EVAPORATIONAL COOLING AND GREATER

POTENTIAL FOR LOCALLY DAMAGING TSTM DOWNDRAFTS.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400. MEAN STORM

MOTION VECTOR 26025.





...CARBIN

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