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905 

WWUS20 KWNS 292048

SEL7

SPC WW 292048

IAZ000-ILZ000-300200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 437

NWS STORM PREDICTION CENTER NORMAN OK

350 PM CDT FRI JUN 29 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EAST CENTRAL AND SOUTHEAST IOWA

       NORTHWEST ILLINOIS



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 350 PM UNTIL 900

PM 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 45

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHWEST

OF OTTUMWA IOWA TO 45 MILES NORTHEAST OF BURLINGTON 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 435...WW 436...



DISCUSSION...A CLUSTER OF STORMS NEAR DSM IS EXPECTED TO SLOWLY

INTENSIFY THIS AFTERNOON IN ADVANCE OF A REMNANT MCV.  STRONG

INSTABILITY IS PRESENT IN ADVANCE OF THE STORMS WHERE SURFACE

HEATING IN CLOUD BREAKS WILL ALLOW ADDITIONAL DESTABILIZATION THIS

AFTERNOON.  MEANWHILE...THE CONVECTION WILL HAVE A CORRIDOR TO

SPREAD EWD/ESEWD ALONG AND IMMEDIATELY N OF AN OUTFLOW BOUNDARY

ACROSS WRN IL AND SE IA.  A FEW DAMAGING GUSTS AND LARGE HAIL WILL

BE POSSIBLE WITH THIS CONVECTION FOR THE NEXT FEW HOURS.



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 550. MEAN STORM

MOTION VECTOR 27030.





...THOMPSON

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