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000 

WWUS20 KWNS 240058

SEL6

SPC WW 240058

MNZ000-NDZ000-240700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 686

NWS STORM PREDICTION CENTER NORMAN OK

750 PM CDT SUN SEP 23 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST MINNESOTA

       EASTERN NORTH DAKOTA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 750 PM UNTIL

200 AM CDT.



HAIL TO 1 INCH 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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHWEST OF

HALLOCK MINNESOTA TO 10 MILES EAST OF JAMESTOWN NORTH DAKOTA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 685...



DISCUSSION...TSTMS NOW FORMING BETWEEN MBG AND JMS IN N NCNTRL SD/SE

ND EXPECTED TO MOVE/DEVELOP NNE ALONG LEAD COLD FRONT ASSOCIATED

WITH EJECTING GRT BASIN UPR TROUGH.  SFC-BASED INSTABILITY HAS

PEAKED FOR THE DAY.  BUT DECOUPLING/STRENGTHENING SSWLY LLJ AND

ASSOCIATED MASS FLUX CHANGES SUGGEST THAT SE ND STORMS SHOULD REMAIN

STRONG THROUGH THE EVENING.  GIVEN 40 KT SSWLY DEEP SWLY SHEAR AND

POTENTIAL FOR EMBEDDED SUPERCELLS/SUSTAINED UPDRAFTS...ACTIVITY MAY

POSE A THREAT FOR HI WIND/MARGINALLY SVR HAIL AND PERHAPS A BRIEF

TORNADO.



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

TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.

A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM MOTION

VECTOR 22040.





...CORFIDI

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