WATCHES: Severe Thunderstorm Watch Number 631

WWUS20 KWNS 281754
SEL1
SPC WW 281754
IDZ000-UTZ000-WYZ000-290000-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 631
NWS STORM PREDICTION CENTER NORMAN OK
1155 AM MDT SAT AUG 28 2010

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

PARTS OF SOUTHEAST IDAHO
NORTHERN UTAH
MUCH OF WESTERN WYOMING

EFFECTIVE THIS SATURDAY MORNING AND EVENING FROM 1155 AM UNTIL
600 PM MDT.

HAIL TO 2 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 70
STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTHWEST OF
CODY WYOMING TO 45 MILES EAST SOUTHEAST OF DUGWAY UTAH. 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.

DISCUSSION...STORMS EXPECTED TO DEVELOP RAPIDLY ACROSS THE WATCH AS
AIR MASS HAS BECOME MDTLY UNSTABLE WITH LITTLE REMAINING CONVECTIVE
INHIBITION. WITH 40-50 KT OF SHEAR...STEEP MID LEVEL LAPSE RATES
AND MLCAPES AOA 1200 J/KG...SEVERE THUNDERSTORMS INCLUDING POSSIBLE
SUPERCELLS ARE LIKELY. PRIMARY THREAT WILL BE STRONG/DAMAGING WINDS
ENHANCED BY THE EXISTING GRADIENT WINDS ALONG WITH LARGE HAIL.
SEVERE THREAT WILL BE GREATEST WITH ANY SUPERCELL THAT DEVELOPS
INCLUDING POSSIBILITY OF A BRIEF TORNADO.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 23035.

...HALES

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