Wednesday, July 21, 2010

WATCHES: Severe Thunderstorm Watch Number 510

WWUS20 KWNS 212026
SEL0
SPC WW 212026
SDZ000-220300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 510
NWS STORM PREDICTION CENTER NORMAN OK
330 PM CDT WED JUL 21 2010

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

CENTRAL AND SOUTHEAST SOUTH DAKOTA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 330 PM UNTIL
1000 PM CDT.

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 60
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 5 MILES WEST
NORTHWEST OF PHILIP SOUTH DAKOTA TO 15 MILES EAST OF SIOUX FALLS
SOUTH DAKOTA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

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...

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INTENSIFY AND TRACK
EAST-SOUTHEASTWARD ALONG BAROCLINIC ZONE ACROSS WATCH AREA THROUGH
THE AFTERNOON AND EARLY EVENING. INCREASING INSTABILITY ALONG AND
SOUTH OF BOUNDARY...COUPLED WITH FAVORABLE DEEP LAYER VERTICAL
SHEAR...WILL SUPPORT A RISK OF ISOLATED SEVERE STORMS/SUPERCELLS
CAPABLE OF DAMAGING WINDS AND LARGE HAIL.

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 28030.


...HART

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