WATCHES: Severe Thunderstorm Watch Number 563

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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