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021 

WWUS20 KWNS 092255

SEL9

SPC WW 092255

IAZ000-ILZ000-WIZ000-100600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 689

NWS STORM PREDICTION CENTER NORMAN OK

545 PM CDT SUN AUG 9 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN IOWA

       NORTHWEST INTO CENTRAL ILLINOIS

       FAR SOUTHERN WISCONSIN



EFFECTIVE THIS SUNDAY AFTERNOON AND MONDAY MORNING FROM 545 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 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES SOUTHWEST

OF CEDAR RAPIDS IOWA TO 15 MILES SOUTHEAST OF ROCKFORD ILLINOIS.

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.



OTHER WATCH INFORMATION...THIS SEVERE THUNDERSTORM WATCH REPLACES

SEVERE THUNDERSTORM WATCH NUMBER 682. WATCH NUMBER 682 WILL NOT

BE IN EFFECT AFTER 545 PM CDT. CONTINUE...WW 684...WW 685...WW

686...WW 687...WW 688...



DISCUSSION...STRONG TO SEVERE THUNDERSTORMS WILL REMAIN ACTIVE

MOVING GENERALLY ENEWD ACROSS WW INTO THE EARLY MORNING HOURS AS

SSWLY LLJ STRENGTHENS INTO ERN IA THIS EVENING.  AIR MASS REMAINS

VERY MOIST AND UNSTABLE WITH SUFFICIENT DEEP LAYER SHEAR FOR

ORGANIZATION INTO LINES/CLUSTERS.  MOST LIKELY SEVERE THREAT SHOULD

BE FROM DAMAGING WINDS WITH BOW ECHOES PERSISTING ALONG AND JUST

NORTH OF STALLED SURFACE BOUNDARIES.  VERY HEAVY RAINFALL AND

ISOLATED LARGE HAIL WILL BE ADDITIONAL HAZARDS.



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 26035.





...EVANS

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