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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 471

NWS STORM PREDICTION CENTER NORMAN OK

320 PM EDT THU JUL 5 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH CENTRAL KENTUCKY

       EXTREME WESTERN NORTH CAROLINA

       MIDDLE AND EASTERN TENNESSEE



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 320 PM UNTIL

1100 PM EDT.



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 75

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHWEST OF

LONDON KENTUCKY TO 15 MILES EAST OF CHATTANOOGA TENNESSEE.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU1).



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 469...WW 470...



DISCUSSION...A LARGE CLUSTER OF SEVERE STORMS ACROSS ERN KY WILL

CONTINUE TO DEVELOP SWD/SWWD INTO A HOT/DEEPLY MIXED AIR MASS ACROSS

TN...WHERE MODERATE INSTABILITY IS PRESENT.  THE THERMODYNAMIC

ENVIRONMENT IS FAVORABLE FOR DAMAGING DOWNBURSTS...AS WELL AS LARGE

HAIL NEAR SEVERE LIMITS.  THE SEVERE THREAT IS EXPECTED TO PERSIST

UNTIL LATE EVENING WHEN THE BOUNDARY LAYER BEGINS TO STABILIZE.



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 550. MEAN STORM

MOTION VECTOR 02025.





...THOMPSON

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