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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 478

NWS STORM PREDICTION CENTER NORMAN OK

1255 PM EDT WED JUN 15 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN ALABAMA

       NORTHERN GEORGIA

       NORTHEAST MISSISSIPPI

       EXTREME WESTERN NORTH CAROLINA

       TENNESSEE



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL

800 PM EDT.



HAIL TO 2 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 70

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES SOUTHWEST

OF JACKSON TENNESSEE TO 65 MILES EAST SOUTHEAST OF KNOXVILLE

TENNESSEE.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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...BROKEN BANDS OF ELEVATED STORMS WILL PERSIST IN THE WAA

REGIME FROM NE AL/MIDDLE TN EWD...WITH A RISK FOR LARGE HAIL AND

ISOLATED DAMAGING GUSTS AS THE BOUNDARY LAYER WARMS.  FARTHER

W...SURFACE HEATING IS ERODING THE CAP...AND A MIDLEVEL TROUGH

CROSSING THE MS RIVER WILL SUPPORT ADDITIONAL STORM DEVELOPMENT

THROUGH THE AFTERNOON.  THE COMBINATION OF MLCAPE AOA 3000

J/KG...INITIALLY FROM MIDDLE TN/NRN AL WWD...AND 50 KT WLY MIDLEVEL

FLOW WILL SUPPORT ORGANIZED STORM CLUSTERS CAPABLE OF PRODUCING

DAMAGING WINDS AND LARGE HAIL.  THERE WILL BE SOME POTENTIAL FOR A

MORE CONCENTRATED SWATH OF DAMAGING WINDS ACROSS MIDDLE TN AND

ADJACENT AL/GA IF ENOUGH STORM MERGERS CAN PROMOTE UPSCALE GROWTH

INTO A LARGER CLUSTER/MCS LATER THIS AFTERNOON.



AVIATION...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 550. MEAN STORM

MOTION VECTOR 29035.





...THOMPSON

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