WATCHES: Severe Thunderstorm Watch Number 717

WWUS20 KWNS 192234
SEL7
SPC WW 192234
IAZ000-MNZ000-MOZ000-NEZ000-SDZ000-200700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 717
NWS STORM PREDICTION CENTER NORMAN OK
535 PM CDT WED AUG 19 2009

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

WESTERN AND CENTRAL IOWA
SOUTHWEST MINNESOTA
NORTHERN MISSOURI
EASTERN NEBRASKA
FAR SOUTHEAST SOUTH DAKOTA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND THURSDAY MORNING FROM 535
PM UNTIL 200 AM 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 85
STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH
NORTHWEST OF FAIRMONT MINNESOTA TO 20 MILES SOUTH SOUTHEAST OF
BEATRICE NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

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 713...WW 714...WW
715...WW 716...

DISCUSSION...TSTMS...INCLUDING A FEW SUPERCELLS/SUSTAINED
STORMS...EXPECTED TO INCREASE IN NUMBER/STRENGTH ALONG AND AHEAD OF
INTENSIFYING MID MO VLY COLD FRONT ASSOCIATED WITH AMPLIFYING UPR
TROUGH. SEASONABLY STRONG DEEP WIND FIELD AND PRESENCE OF STEEP MID
LVL LAPSE RATES ATOP PW VALUES AOA 1,50 INCHES TOGETHER SUGGEST
POTENTIAL FOR SVR HAIL AND...WITH TIME...POSSIBLE UPSCALE GROWTH
INTO ONE OR MORE MCSS WITH A THREAT FOR HIGH WIND.

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.

...CORFIDI

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