WATCHES: Severe Thunderstorm Watch Number 581

WWUS20 KWNS 062101
SEL1
SPC WW 062101
MTZ000-070300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 581
NWS STORM PREDICTION CENTER NORMAN OK
305 PM MDT FRI AUG 6 2010

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

LARGE PART OF CENTRAL AND SOUTHWEST MONTANA

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 305 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 130
STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES EAST
SOUTHEAST OF DILLON MONTANA TO 25 MILES EAST NORTHEAST OF HAVRE
MONTANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

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 579...WW 580...

DISCUSSION...THUNDERSTORMS ARE INCREASING ACROSS THE HIGHER TERRAIN
OF SWRN MT AHEAD OF A WEAK S/WV TROUGH. WITH STEEP LAPSE RATES ALONG
WITH 30-40KT OF SHEAR...POTENTIAL WILL INCREASE FOR DAMAGING
DOWNBURST WINDS AS STORMS DEVELOP/PROPAGATE ENEWD ACROSS THE LOWER
ELEVATIONS WHERE T/TD SPREADS ARE AROUND 40F.

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 500. MEAN STORM
MOTION VECTOR 26030.

...HALES

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