

332 

WWUS20 KWNS 302238

SEL2

SPC WW 302238

ALZ000-TNZ000-310500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 642

NWS STORM PREDICTION CENTER NORMAN OK

540 PM CDT THU JUL 30 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF NORTHERN AND CENTRAL ALABAMA

       PARTS OF SOUTHERN MIDDLE TENNESSEE



EFFECTIVE THIS THURSDAY AFTERNOON FROM 540 PM UNTIL MIDNIGHT CDT.



HAIL TO 1.5 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 60

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

SOUTHEAST OF TUSCALOOSA ALABAMA TO 45 MILES NORTH OF HUNTSVILLE

ALABAMA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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 639...WW 640...WW 641...



DISCUSSION...SQUALL LINE WITH EMBEDDED BOWS MOVING RAPIDLY ENEWD

ACROSS NRN MS INTO AL.  WITH A VERY MOIST AND UNSTABLE AIR MASS

COUPLED WITH 30-35 KT OF SHEAR...POTENTIAL FOR DAMAGING WINDS WILL

CONTINUE ACROSS THE WATCH.  ISOLATED SUPERCELLS ALSO POSSIBLE ALONG

AND AHEAD OF THE LINE WITH A THREAT OF BRIEF TORNADOES.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 24035.





...HALES

