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000 

WWUS20 KWNS 251827

SEL1

SPC WW 251827

IAZ000-ILZ000-MOZ000-260100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 231

NWS STORM PREDICTION CENTER NORMAN OK

130 PM CDT FRI APR 25 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN IOWA

       WESTERN INTO NORTHERN ILLINOIS

       CENTRAL INTO NORTHEASTERN MISSOURI



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 130 PM UNTIL 800

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 70

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES WEST

NORTHWEST OF ROCKFORD ILLINOIS TO 50 MILES EAST OF COLUMBIA

MISSOURI.  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...LINE OF THUNDERSTORMS IS EXPECTED TO INCREASE EARLY

THIS AFTERNOON AND DEVELOP ENEWD ACROSS WW ALONG STRONG SURFACE COLD

FRONT NOW MOVING INTO ERN IA/CENTRAL MO.  STRONG ASCENT AND MARGINAL

INSTABILITY SHOULD SUPPORT BROKEN LINE OF STORMS...WITH SUFFICIENT

SHEAR FOR SMALL LINES AND A FEW SUPERCELLS.  PRIMARY SEVERE THREAT

WILL BE MARGINAL SEVERE HAIL INITIALLY...ALTHOUGH POTENTIAL FOR

DAMAGING WINDS AND EVEN A BRIEF TORNADO WILL LIKELY INCREASE THROUGH

THE LATE AFTERNOON.



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 400. MEAN STORM

MOTION VECTOR 25035.





...EVANS

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