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196 

WWUS20 KWNS 042100

SEL6

SPC WW 042100

IAZ000-ILZ000-KSZ000-MOZ000-NEZ000-050400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 256

NWS STORM PREDICTION CENTER NORMAN OK

355 PM CDT FRI JUN 4 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       FAR SOUTHERN IOWA

       WEST CENTRAL ILLINOIS

       NORTHEAST KANSAS

       NORTHERN MISSOURI

       FAR SOUTHEASTERN NEBRASKA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 355 PM UNTIL

1100 PM CDT.



HAIL TO 2.5 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 55

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

NORTHEAST OF QUINCY ILLINOIS TO 20 MILES SOUTHWEST OF BEATRICE

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 254...WW 255...



DISCUSSION...CONVERGENCE WAS INCREASING ALONG FRONTAL ZONE/TROUGH

LOCATED NEAR THE MO/IA BORDER. AS STORMS BEGIN TO DEVELOP...THE

COMBINATION OF VERY STRONG INSTABILITY AND DEEP LAYER SHEAR AT 40-50

KT WILL LIKELY RESULT IN RAPID SUPERCELL DEVELOPMENT DURING THE NEXT

HOUR OR SO. THE PRIMARY THREAT IS EXPECTED TO BE VERY LARGE HAIL. A

BRIEF TORNADO IS POSSIBLE...THOUGH WEAK LOW LEVEL SHEAR SUGGESTS THE

THREAT IS LOW. LATER THIS EVENING...THE STORMS MAY CONGEAL INTO A

LINE SEGMENT OR TWO...AND IF THIS HAPPENS...THE THREAT FOR WIND

DAMAGE WILL INCREASE.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 30025.





...IMY

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