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105 

WWUS20 KWNS 081420

SEL7

SPC WW 081420

ARZ000-ILZ000-KYZ000-MOZ000-TNZ000-082100-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 267

NWS STORM PREDICTION CENTER NORMAN OK

920 AM CDT FRI MAY 8 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       PARTS OF NORTHEAST ARKANSAS

       PARTS OF SOUTHERN ILLINOIS

       WESTERN KENTUCKY

       SOUTHEAST MISSOURI

       MUCH OF WESTERN AND MIDDLE TENNESSEE



EFFECTIVE THIS FRIDAY MORNING AND AFTERNOON FROM 920 AM UNTIL 400

PM CDT.



TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 105 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST OF WEST PLAINS

MISSOURI TO 35 MILES EAST SOUTHEAST OF CLARKSVILLE TENNESSEE.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU7).



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 266...



DISCUSSION...A MATURE VERY INTENSE DERECHO IS MOVING VERY RAPIDLY

ALONG THERMAL/INSTABILITY GRADIENT ACROSS MID MS VLY INTO TN AND

LOWER OH VALLEYS.  WITH A VERY MOIST UNSTABLE AIR MASS AND STRONG

VEERING SHEAR PROFILES...EMBEDDED TORNADIC SUPERCELLS WILL CONTINUE

TO BE ASSOCIATED WITH THE DERECHO ALONG WITH WIDESPREAD DAMAGING

WINDS.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 90 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

650. MEAN STORM MOTION VECTOR 27055.





...HALES

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