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000 

WWUS20 KWNS 231845

SEL1

SPC WW 231845

OHZ000-PAZ000-WVZ000-240100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 641

NWS STORM PREDICTION CENTER NORMAN OK

245 PM EDT THU AUG 23 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND EASTERN OHIO

       WESTERN PENNSYLVANIA

       NORTHERN WEST VIRGINIA PANHANDLE



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 245 PM UNTIL

900 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 105

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES EAST

NORTHEAST OF YOUNGSTOWN OHIO TO 25 MILES SOUTH OF WHEELING WEST

VIRGINIA.  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 640...



DISCUSSION...STORMS CONTINUE TO DEVELOP AND INTENSIFY RAPIDLY OVER

WRN PA...AND VISIBLE SATELLITE IMAGERY SHOWS NEW CONVECTION

DEVELOPING WWD ALONG AN OLD OUTFLOW BOUNDARY INTO OH.  AIR MASS IS

VERY MOIST AND UNSTABLE WITH DEW POINTS IN THE LOW-MID 70S

CONTRIBUTING TO MLCAPE OF 2000-3000 J/KG.  MODERATE WESTERLY WINDS

ALOFT OF 25-35 KT WILL BE SUPPORTIVE OF ORGANIZED STORMS WITH

PRIMARY THREATS OF DAMAGING DOWNBURSTS AND LARGE HAIL.



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 26025.





...WEISS

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