Tornado Watch out

SEL7
 
  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