

000 

WWUS20 KWNS 102043

SEL2

SPC WW 102043

NDZ000-SDZ000-110300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 582

NWS STORM PREDICTION CENTER NORMAN OK

340 PM CDT FRI AUG 10 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH CENTRAL NORTH DAKOTA

       NORTH CENTRAL SOUTH DAKOTA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 340 PM UNTIL

1000 PM 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 45

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH

NORTHWEST OF JAMESTOWN NORTH DAKOTA TO 35 MILES SOUTH SOUTHWEST

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

SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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 579...WW 580...WW 581...



DISCUSSION...CONVECTION IS BEGINNING TO DEVELOP ALONG A NE-SW

SURFACE BOUNDARY ACROSS SRN ND/NRN SD.  SURFACE OBSERVATIONS AND

MODIFIED MODEL SOUNDINGS SUGGEST THAT THE CAP IS WEAKENING ALONG

THIS CORRIDOR...AND THAT SUPERCELL DEVELOPMENT WILL BE POSSIBLE THE

NEXT FEW HOURS GIVEN EFFECTIVE BULK SHEAR IN EXCESS OF 40 KT AND

MLCAPE OF 1500-3000 J/KG.  TEMPERATURE-DEWPOINT SPREADS NEAR 30 F

SUGGEST THAT THE TORNADO THREAT WILL BE LIMITED IN SD...WITH A

SLIGHTLY GREATER THREAT FOR AN ISOLATED TORNADO ALONG THE FRONT IN

ND.  STILL...LARGE HAIL AND DAMAGING WINDS WILL BE THE PRIMARY

THREATS 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 550. MEAN STORM

MOTION VECTOR 26025.





...THOMPSON

