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WWUS20 KWNS 080437

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SPC WW 080437

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 744

NWS STORM PREDICTION CENTER NORMAN OK

1135 PM CDT SUN AUG 7 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN IOWA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1135 PM UNTIL

500 AM CDT.



HAIL TO 0.5 INCH 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 45

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH OF

DENISON IOWA TO 30 MILES EAST SOUTHEAST OF SHENANDOAH IOWA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU4).



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 739...WW 740...WW

741...WW 742...WW 743...



DISCUSSION...ERN NEB BOW MCS EXPECTED TO CONTINUE MAINLY ESEWD...TO

PERHAPS SEWD WITH TIME...AS SYSTEM ENCOUNTERS REGION OF LESSER

SFC-BASED INSTABILITY/WEAKER LOW LVL FLOW E OF THE MO RVR.

NEVERTHELESS...RELATIVELY FAST SYSTEM MOVEMENT /AVERAGING ABOUT

40-45 KTS/...MODERATELY STRONG WNWLY MID LVL FLOW...AND PRESENCE OF

STRONG SLIGHTLY ELEVATED INSTABILITY/EML SUGGEST A CONTINUED THREAT

FOR LOCALLY DMGG WIND.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 30040.





...CORFIDI

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