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WWUS20 KWNS 151750

SEL2

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ILZ000-KYZ000-MOZ000-160200-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 142

NWS STORM PREDICTION CENTER NORMAN OK

1250 PM CDT FRI APR 15 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WESTERN AND SOUTHERN ILLINOIS

       WESTERN KENTUCKY

       EASTERN MISSOURI



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL

900 PM CDT.



TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTH SOUTHWEST OF

PADUCAH KENTUCKY TO 70 MILES NORTH NORTHWEST OF ALTON ILLINOIS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU2).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 140...WW 141...



DISCUSSION...TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG COLD

FRONT AND WITHIN DRY SLOT OF INTENSE MID TO UPPER-LEVEL CYCLONE.

DAYTIME HEATING...BOUNDARY LAYER DEWPOINTS IN THE 50S AND 500 MB

TEMPERATURES OF AROUND -20 C WILL RESULT IN A STEEP LAPSE RATE

ENVIRONMENT WITH MLCAPE VALUES APPROACHING 1000-1500 J/KG.  WHEN

COUPLED WITH A VERTICALLY VEERING WIND PROFILE...SETUP WILL FAVOR

THE DEVELOPMENT OF SUPERCELLS CAPABLE OF TORNADOES AND LARGE HAIL.



AVIATION...TORNADOES AND 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

350. MEAN STORM MOTION VECTOR 21035.





...MEAD

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