

208 

WWUS20 KWNS 080154

SEL4

SPC WW 080154

NEZ000-SDZ000-080700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 674

NWS STORM PREDICTION CENTER NORMAN OK

855 PM CDT FRI AUG 7 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTH CENTRAL NEBRASKA

       CENTRAL SOUTH DAKOTA



EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 855 PM

UNTIL 200 AM CDT.



HAIL TO 3 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 60

STATUTE MILES EAST AND WEST OF A LINE FROM MULLEN NEBRASKA TO 25

MILES NORTHEAST OF PIERRE SOUTH DAKOTA.  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 672...WW 673...



DISCUSSION...LARGE SUPERCELL MAY CONTINUE ESEWD ALONG SURFACE FRONT

INVOF LOW CENTER FOR A FEW MORE HOURS GIVEN INFLUX OF VERY UNSTABLE

AIR AND STRONG DEEP LAYER SHEAR.  ADDITIONAL CLUSTERS OF STORMS

SHOULD SPREAD EWD ACROSS N-CENTRAL NEB/S-CENTRAL SD.  LARGE

HAIL...INCLUDING ISOLATED VERY LARGE STONES WITH PERSISTENT

SUPERCELLS...ALONG WITH DAMAGING WINDS WILL BE PRIMARY THREATS.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 27035.





...EVANS

