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000 

WWUS20 KWNS 131445

SEL1

SPC WW 131445

NDZ000-132100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 591

NWS STORM PREDICTION CENTER NORMAN OK

945 AM CDT MON AUG 13 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN NORTH DAKOTA



EFFECTIVE THIS MONDAY MORNING AND AFTERNOON FROM 945 AM UNTIL 400

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 55

STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES NORTH

NORTHWEST OF DEVILS LAKE NORTH DAKOTA TO 85 MILES SOUTHEAST OF

JAMESTOWN NORTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH

SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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...LOW-MID LEVEL WAA/ASCENT DOWNSTREAM FROM A SHORTWAVE

TROUGH OVER WRN ND...AS EVIDENCED BY BROAD AREA OF MOISTENING IN

WATER VAPOR IMAGERY...WILL LIKELY SUPPORT CONTINUED ELEVATED

THUNDERSTORM DEVELOPMENT INTO THE AFTERNOON OVER ERN ND.  ELEVATED

CAPE OF 1000-2000 J/KG BASED ABOVE THE STRONG CAP NEAR 850 MB AND

EFFECTIVE BULK SHEAR IN EXCESS OF 40 KT WILL SUPPORT STORMS WITH

SUPERCELL STRUCTURES AND THE THREAT FOR LARGE HAIL.



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 500. MEAN STORM

MOTION VECTOR 28030.





...THOMPSON

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