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557 

WWUS20 KWNS 211414

SEL5

SPC WW 211414

SDZ000-212100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 335

NWS STORM PREDICTION CENTER NORMAN OK

910 AM CDT FRI JUN 21 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  WESTERN AND CENTRAL SOUTH DAKOTA



* EFFECTIVE THIS FRIDAY MORNING AND AFTERNOON FROM 910 AM UNTIL

  400 PM CDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL DAMAGING WIND GUSTS LIKELY WITH A FEW SIGNIFICANT GUSTS

    TO 80 MPH POSSIBLE

  SEVERAL LARGE HAIL EVENTS WITH A FEW VERY LARGE HAIL EVENTS TO 3

    INCHES IN DIAMETER POSSIBLE

  A FEW TORNADOES POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 90

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES WEST

NORTHWEST OF RAPID CITY SOUTH DAKOTA TO 15 MILES EAST SOUTHEAST

OF HURON SOUTH DAKOTA.  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 333...WW 334...



DISCUSSION...SCATTERED INTENSE STORM DEVELOPMENT IS ALREADY UNDERWAY

NEAR THE BLACK HILLS.  CONVECTION IS EXPECTED TO CONTINUE TO

INCREASE IN COVERAGE AS A WEAK MID-LEVEL IMPULSE PROGRESSES

NORTHEASTWARD THROUGH THE NORTHERN HIGH PLAINS.  A GRADUAL UPSCALE

GROWTH INTO A SEVERE MESOSCALE CONVECTIVE SYSTEM APPEARS POSSIBLE

DURING THE AFTERNOON HOURS...IF NOT BEFORE...FOCUSED WITHIN A ZONE

OF ENHANCED LOWER/MID TROPOSPHERIC WARM ADVECTION EXTENDING IN

EAST-WEST FASHION ACROSS SOUTH DAKOTA...ON THE NORTHERN PERIPHERY OF

STRONGLY CAPPING ELEVATED MIXED LAYER AIR.  AS THIS OCCURS...THE

RISK FOR STRONG DAMAGING WIND GUSTS WILL BECOME MORE PROMINENT...IN

ADDITION TO THE THREAT FOR LARGE HAIL.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

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

MOTION VECTOR 27020.





...KERR

