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984 

WWUS20 KWNS 042151

SEL7

SPC WW 042151

IAZ000-ILZ000-MOZ000-050500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 427

NWS STORM PREDICTION CENTER NORMAN OK

455 PM CDT SAT JUN 4 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       FAR SOUTHEAST IOWA

       CENTRAL ILLINOIS

       FAR NORTHEAST MISSOURI



EFFECTIVE THIS SATURDAY AFTERNOON FROM 455 PM UNTIL MIDNIGHT 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 55 MILES WEST OF

BURLINGTON IOWA TO 20 MILES NORTH NORTHEAST OF BLOOMINGTON

ILLINOIS.  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 426...



DISCUSSION...TSTMS HAVE RECENTLY DEVELOPED ALONG W-E ORIENTED FRONT

WHERE TEMPERATURES OF 85-95 F AND DEWPOINTS OF AROUND 7O F ARE

CONTRIBUTING TO MLCAPE VALUES OF 3000-3500 J/KG.  DEEP LAYER SHEAR

IS NOT PARTICULARLY STRONG...BUT SUFFICIENT FOR ORGANIZED MULTICELL

CLUSTERS CAPABLE OF DAMAGING WINDS AND HAIL.



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 28025.





...MEAD

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