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019 

WWUS20 KWNS 312111

SEL5

SPC WW 312111

NDZ000-SDZ000-WYZ000-010400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 555

NWS STORM PREDICTION CENTER NORMAN OK

415 PM CDT SAT JUL 31 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF SOUTHWEST NORTH DAKOTA

       MUCH OF WESTERN SOUTH DAKOTA

       PARTS OF NORTHEAST WYOMING



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 415 PM UNTIL

1100 PM CDT.



HAIL TO 2.5 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 70 MILES NORTHEAST OF

LEMMON SOUTH DAKOTA TO 85 MILES WEST SOUTHWEST OF RAPID CITY

SOUTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 552...WW 553...WW 554...



DISCUSSION...SCATTERED STRONG/SEVERE THUNDERSTORMS WILL DEVELOP IN

AREA OF LOW LEVEL CONVERGENCE AND MDT INSTABILITY.  WITH STEEP LAPSE

RATES DAMAGING WINDS ALONG WITH LARGE HAIL WILL BE ASSOCIATED WITH

MOST INTENSE STORMS.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 26025.





...HALES

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