WATCHES: Severe Thunderstorm Watch Number 511

WWUS20 KWNS 212047
SEL1
SPC WW 212047
MTZ000-WYZ000-220400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 511
NWS STORM PREDICTION CENTER NORMAN OK
250 PM MDT WED JUL 21 2010

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

SOUTHEAST MONTANA
CENTRAL AND NORTHEASTERN WYOMING

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 250 PM UNTIL
1000 PM MDT.

HAIL TO 2 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 EAST AND WEST OF A LINE FROM 60 MILES SOUTHEAST OF
ROCK SPRINGS WYOMING TO 10 MILES EAST NORTHEAST OF BROADUS
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 507...WW 508...WW
509...WW 510...

DISCUSSION...SCATTERED THUNDERSTORMS HAVE DEVELOPED ALONG THE BIG
HORN MTNS...AND FARTHER SOUTHWEST ACROSS CENTRAL WY. THESE STORMS
ARE IN AN ENVIRONMENT OF STEEP LAPSE RATES AND SUFFICIENT
INSTABILITY FOR STRONG UPDRAFTS. FAVORABLE VERTICAL SHEAR WILL
PROMOTE ORGANIZED/SUPERCELL STORMS CAPABLE OF LARGE HAIL AND
DAMAGING WINDS THROUGH THE EVENING.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 27030.

...HART

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