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WWUS20 KWNS 040659

SEL5

SPC WW 040659

IAZ000-ILZ000-MOZ000-041400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 565

NWS STORM PREDICTION CENTER NORMAN OK

155 AM CDT WED AUG 4 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST IOWA

       PART OF NORTHERN AND CENTRAL ILLINOIS

       FAR NORTHEAST MISSOURI



EFFECTIVE THIS WEDNESDAY MORNING FROM 155 AM UNTIL 900 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 50

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST

NORTHWEST OF BURLINGTON IOWA TO 40 MILES EAST SOUTHEAST OF

MARSEILLES ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 564...



DISCUSSION...EVOLVING SHORT-SEGMENT BOWING SYSTEM OVER S-CNTRL IA IS

EXPECTED TO ACCELERATE EWD THIS MORNING ALONG IMMEDIATE COOL SIDE OF

SYNOPTIC BOUNDARY ALIGNED W-E ACROSS THE AREA.  STRENGTHENING WSWLY

LLJ WILL SERVE TO ENHANCE THE INFLUX OF A VERY MOIST AND UNSTABLE

AIR MASS INTO SYSTEM WHERE MLCAPE IS STILL AROUND 2000-3000 J/KG.

THIS INSTABILITY IN CONJUNCTION WITH 30-40 KT OF DEEP WLY SHEAR

SHOULD BE SUFFICIENT TO SUSTAIN SYSTEM EWD EARLY THIS MORNING WITH

DAMAGING WIND GUSTS BEING THE PRIMARY CONCERN.



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 27040.





...MEAD

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