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310 

WWUS20 KWNS 131608

SEL4

SPC WW 131608

ALZ000-GAZ000-NCZ000-TNZ000-132300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 464

NWS STORM PREDICTION CENTER NORMAN OK

1105 AM CDT TUE JUL 13 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF NORTHERN ALABAMA

       MUCH OF NORTHERN GEORGIA

       FAR WESTERN NORTH CAROLINA

       PART OF SOUTHERN MIDDLE AND SOUTHEAST TENNESSEE



EFFECTIVE THIS TUESDAY MORNING AND EVENING FROM 1105 AM UNTIL 600

PM 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 NORTH AND SOUTH OF A LINE FROM 45 MILES WEST

SOUTHWEST OF HUNTSVILLE ALABAMA TO 85 MILES EAST OF ROME GEORGIA.

 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU4).



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.



DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY THIS AFTERNOON IN ADVANCE OF MIDLEVEL TROUGH PROGRESSING

EWD ACROSS THE REGION.  WHILE MIDLEVEL LAPSE RATES ARE NOT

PARTICULARLY STEEP...THE PRESENCE OF A HOT AND HUMID AIR MASS WILL

BOOST MLCAPE VALUES TO 2000-2500 J/KG LATER TODAY.  THIS INSTABILITY

COMBINED WITH A BELT OF 35-45 KT WLY MIDLEVEL FLOW ATTENDING SHORT

WAVE TROUGH WILL RESULT IN AN ENVIRONMENT FAVORABLE FOR

FORWARD-PROPAGATING CONVECTIVE CLUSTERS/BANDS WITH THE THREAT FOR

DAMAGING WINDS.



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 27030.





...MEAD

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