Friday, April 15, 2011

April 15: Tornado Watch #4


URGENT - IMMEDIATE BROADCAST REQUESTED
   TORNADO WATCH NUMBER 143
   NWS STORM PREDICTION CENTER NORMAN OK
   210 PM CDT FRI APR 15 2011
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   TORNADO WATCH FOR PORTIONS OF 
   
          NORTHEAST ARKANSAS
          MISSOURI BOOTHEEL
          NORTHERN MISSISSIPPI
          WESTERN TENNESSEE
   
   EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 210 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 90 STATUTE
   MILES EAST AND WEST OF A LINE FROM 50 MILES NORTHEAST OF
   DYERSBURG TENNESSEE TO 40 MILES SOUTH SOUTHEAST OF OXFORD
   MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
   ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).
   
   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...WW 142...
   
   DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
   INTENSITY THIS AFTERNOON ALONG COLD FRONT AS DEEP ASCENT IN EXIT
   REGION OF MID AND UPPER-LEVEL JET STREAKS MOVES INTO THE REGION. 
   THE COMBINATION OF STRONG DAYTIME HEATING...BOUNDARY LAYER DEWPOINTS
   OF 55-60 F AND COOLING MIDLEVEL TEMPERATURES WILL SUPPORT FURTHER
   AIR MASS DESTABILIZATION WITH MLCAPE VALUES APPROACHING 1000-1500
   J/KG.  WHEN COUPLED WITH VERTICALLY-VEERING WIND
   PROFILES...ENVIRONMENT WILL BE SUPPORTIVE OF SUPERCELLS AND BOWING
   STRUCTURES WILL A RISK FOR TORNADOES...LARGE HAIL AND DAMAGING
   WINDS.
   
   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
   400. MEAN STORM MOTION VECTOR 24030.

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