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WWUS20 KWNS 171730

SEL3

SPC WW 171730

INZ000-KYZ000-TNZ000-180100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 683

NWS STORM PREDICTION CENTER NORMAN OK

1230 PM EST MON DEC 17 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHERN INDIANA

       WESTERN...CENTRAL...AND EASTERN KENTUCKY

       MIDDLE TENNESSEE



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 1230 PM UNTIL

800 PM EST.



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 90

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH OF

LEXINGTON KENTUCKY TO 25 MILES SOUTH OF NASHVILLE TENNESSEE.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU3).



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...SHOWERS/TSTMS ARE BEGINNING TO FORM ALONG AND E OF

SSW-NNE CONFLUENCE ZONE NOW OVER WRN KY/TN. ACTIVITY LIKELY IS BEING

FOSTERED BY SFC HEATING AND MID LVL COLD ADVECTION/ASCENT DOWNSTREAM

FROM LEAD UPR IMPULSE NOW OVER SE MO...AND UPSTREAM DISTURBANCE IN

WRN MO. AMPLE DEEP SHEAR IS PRESENT FOR SUPERCELLS AND SUSTAINED

STORMS WITH SVR HAIL AND POSSIBLY LOCALLY DMGG WIND. A TORNADO OR

TWO CANNOT BE RULED OUT...ESPECIALLY WITH ANY LONGER-LIVED DISCRETE

STORMS IN SRN HALF OF WW...BUT RELATIVELY WEAK/VEERED LOW-LVL FLOW

SHOULD LIMIT SUCH THREAT.



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 400. MEAN STORM

MOTION VECTOR 26035.





...CORFIDI

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