WATCHES: Severe Thunderstorm Watch Number 409

WWUS20 KWNS 172102
SEL9
SPC WW 172102
SDZ000-WYZ000-180400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 409
NWS STORM PREDICTION CENTER NORMAN OK
305 PM MDT SUN JUN 17 2007

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

WESTERN SOUTH DAKOTA
NORTHEASTERN WYOMING

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 305 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 55
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTH
SOUTHWEST OF GILLETTE WYOMING TO 60 MILES NORTH NORTHEAST OF
PHILIP SOUTH DAKOTA. FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

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 407...WW 408...

DISCUSSION...SEVERE THUNDERSTORMS EXPECTED TO INCREASE ACROSS WW
THROUGH THE EVENING AHEAD OF STRONG MID/UPPER LEVEL TROUGH AND
ASSOCIATED MID LEVEL JET. SHEAR AND INSTABILITY WILL FAVOR
SUSTAINED SEVERE STORMS WITH PRIMARY THREATS OF LARGE HAIL AND
DAMAGING WINDS.

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 25030.

..EVANS

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