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WWUS20 KWNS 092041

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 567

NWS STORM PREDICTION CENTER NORMAN OK

440 PM EDT THU AUG 9 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME NORTHERN KENTUCKY

       SOUTHERN AND EASTERN OHIO

       EXTREME WESTERN PENNSYLVANIA

       EXTREME NORTHERN WEST VIRGINIA AND THE NORTHERN WEST VIRGINIA

PANHANDLE



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 440 PM UNTIL

1000 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 40

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 115 MILES WEST

SOUTHWEST OF ATHENS OHIO TO 10 MILES EAST NORTHEAST OF PITTSBURGH

PENNSYLVANIA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...STORMS WILL LIKELY INCREASE IN COVERAGE ALONG A SURFACE

CONFLUENCE BAND ACROSS OH...IN ADVANCE OF A LEAD SHORTWAVE TROUGH

MOVING EWD FROM INDIANA TO OH.  SURFACE HEATING TO THE SE OF THE

CONFLUENCE BAND HAS BOOSTED MLCAPE TO NEAR 1500 J/KG...WHILE

EFFECTIVE BULK SHEAR IS BECOMING FAVORABLE FOR ORGANIZED MULTICELL

CLUSTERS AND MARGINAL SUPERCELL STRUCTURES.  DAMAGING WINDS AND

LARGE HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS FOR THE NEXT

FEW HOURS.



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 27020.





...THOMPSON

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