

034 

WWUS20 KWNS 051849

SEL9

SPC WW 051849

NDZ000-SDZ000-060200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 729

NWS STORM PREDICTION CENTER NORMAN OK

1250 PM MDT FRI AUG 5 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN NORTH DAKOTA

       NORTHWESTERN SOUTH DAKOTA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL

800 PM MDT.



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 100

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES SOUTHEAST

OF BISMARCK NORTH DAKOTA TO 25 MILES WEST NORTHWEST OF BUFFALO

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

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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.



DISCUSSION...ASCENT AHEAD OF A LEAD MID-LEVEL IMPULSE WILL SPREAD

ENE ACROSS THE WRN DAKOTAS THROUGH THIS EVENING.  TSTMS WILL

CONTINUE TO GROW UPSCALE IN INTENSITY...BOTH ALONG THE TRACK OF THE

IMPULSE...AND EWD ALONG/N OF THE OUTFLOW BOUNDARY ALONG THE SD/ND

BORDER.  AIR MASS DOWNSTREAM WILL RECOVER WITH SBCAPES TO 3000 J/KG

AND EFFECTIVE SHEAR SUFFICIENT FOR SUPERCELLS.  SVR WIND GUSTS AND

LARGE HAIL CAN BE EXPECTED AS STORMS PROGRESS EWD INTO WRN ND AND

NWRN SD THROUGH THIS 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 24035.





...RACY

