

321 

WWUS20 KWNS 312239

SEL7

SPC WW 312239

KSZ000-NEZ000-SDZ000-010500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 647

NWS STORM PREDICTION CENTER NORMAN OK

540 PM CDT FRI JUL 31 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF NORTHWEST KANSAS

       MUCH OF CENTRAL AND NORTHEAST NEBRASKA

       PARTS OF SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS FRIDAY AFTERNOON FROM 540 PM UNTIL MIDNIGHT CDT.



HAIL TO 2 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 70

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES SOUTHEAST OF

GOODLAND KANSAS TO 35 MILES NORTH OF YANKTON SOUTH DAKOTA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU7).



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 644...WW 645...WW 646...



DISCUSSION...THUNDERSTORMS INCREASING ALONG/AHEAD OF COLD FRONT FROM

ERN SD SWWD INTO SWRN NEB.  WITH STEEP LAPSE RATES AND 30-40KT OF

SHEAR...SUFFICIENT INSTABILITY AVAILABLE FOR SEVERE INCLUDING LARGE

HAIL AND DAMAGING WINDS AS STORMS MOVE DEVELOP E/SE THROUGH THE

EVENING.



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 28025.





...HALES

