

944 

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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