

000 

WWUS20 KWNS 080037

SEL7

SPC WW 080037

IAZ000-ILZ000-080500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 667

NWS STORM PREDICTION CENTER NORMAN OK

740 PM CDT MON JUL 7 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EAST CENTRAL IOWA

       NORTHWEST ILLINOIS



EFFECTIVE THIS MONDAY NIGHT FROM 740 PM UNTIL MIDNIGHT CDT.



HAIL TO 1.5 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 40

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

NORTHWEST OF CEDAR RAPIDS IOWA TO 55 MILES EAST SOUTHEAST OF

DUBUQUE IOWA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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 663...WW 664...WW

665...WW 666...



DISCUSSION...MERGING CONVECTIVE CLUSTERS HAVE EVOLVED INTO AN

EXTENSIVE LINE OF STRONG/SEVERE STORMS FROM E/NE IA INTO SRN WI.

THE MORE RECENT MERGERS HAVE OCCURRED OVER E CENTRAL IA...AND THIS

CONVECTION WILL MOVE INTO A REGION OF STRONG INSTABILITY AND 30-40

KT LOW-LEVEL FLOW /PER THE 00Z DVN SOUNDING/.  BOWING SEGMENTS WITH

DAMAGING WINDS WILL BE THE MAIN SEVERE THREAT...ALONG WITH LARGE

HAIL IN THE STRONGER STORMS.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 28035.





...THOMPSON

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