

000 

WWUS20 KWNS 180036

SEL1

SPC WW 180036

IAZ000-MNZ000-SDZ000-180600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 671

NWS STORM PREDICTION CENTER NORMAN OK

740 PM CDT MON SEP 17 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST IOWA

       MUCH OF MINNESOTA

       SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 740 PM UNTIL

100 AM 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 65

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

HIBBING MINNESOTA TO 45 MILES EAST SOUTHEAST OF YANKTON SOUTH

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...SCATTERED THUNDERSTORMS ARE LIKELY TO STRENGTHEN THIS

EVENING ALONG SURFACE COLD FRONT FROM CENTRAL/NORTHERN MN INTO

EASTERN SD.  THESE STORMS WILL ORGANIZE AND SPREAD NORTHEASTWARD

INTO EASTERN MN AND NORTHWEST IA BY MIDNIGHT.  MODERATE INSTABILITY

IS IN PLACE OVER THIS REGION...ALONG WITH STRENGTHENING LOW/MID

LEVEL WIND FIELDS.  THIS WILL SUPPORT A RISK OF SUPERCELLS

EARLY...TRANSITIONING INTO MULTICELL CLUSTERS.  LARGE HAIL AND

DAMAGING WINDS ARE POSSIBLE IN STRONGER CELLS.



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 23035.





...HART

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