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WWUS20 KWNS 011910

SEL5

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IAZ000-NEZ000-SDZ000-020300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 455

NWS STORM PREDICTION CENTER NORMAN OK

210 PM CDT THU AUG 1 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  WESTERN IOWA

  NORTHEAST NEBRASKA

  SOUTHEAST SOUTH DAKOTA



* EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 210 PM UNTIL

  1000 PM CDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO 2

    INCHES IN DIAMETER POSSIBLE

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH

NORTHWEST OF YANKTON SOUTH DAKOTA TO 35 MILES EAST OF COLUMBUS

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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 454...



DISCUSSION...SEVERE STORMS --INCLUDING SUPERCELLS-- CONTINUE TO

DEVELOP THIS AFTERNOON NEAR THE INTERSECTION OF THE SYNOPTIC FRONT

AND AN OUTFLOW BOUNDARY OVER SERN SD INTO N-CNTRL AND NERN NEB.

THIS ACTIVITY IS FORMING WITHIN A MODERATELY UNSTABLE AIR MASS WHICH

COINCIDES WITH RELATIVELY STRONG DEEP-LAYER SHEAR.  THESE STORMS ARE

EXPECTED TO SPREAD SEWD ACROSS THE WATCH AREA THIS AFTERNOON INTO

EVENING WITH A RISK FOR LARGE HAIL AND DAMAGING WIND GUSTS.



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 32020.





...MEAD

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