

000 

WWUS20 KWNS 081856

SEL8

SPC WW 081856

MDZ000-OHZ000-PAZ000-WVZ000-090200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 568

NWS STORM PREDICTION CENTER NORMAN OK

255 PM EDT WED AUG 8 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME WESTERN MARYLAND

       CENTRAL AND SOUTHERN OHIO

       SOUTHWEST PENNSYLVANIA

       NORTHERN WEST VIRGINIA



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 255 PM UNTIL

1000 PM EDT.



HAIL TO 1 INCH 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 45

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST OF

DAYTON OHIO TO 80 MILES EAST NORTHEAST OF ELKINS WEST VIRGINIA.

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...SEVERAL BANDS OF THUNDERSTORMS ARE DEVELOPING FROM WRN

OH INTO SWRN PA...WITHIN VERY WARM AND MOIST LOW LEVEL AIR MASS

WHERE TEMPERATURES ARE IN THE LOW 90S AND DEW POINTS IN THE LOW 70S.

 DESPITE WARM MID LEVEL TEMPERATURES/MODEST MID LEVEL LAPSE

RATES...LIFTING OF HIGH THETA-E PARCELS IS RESULTING IN MLCAPE OF

1500-2500 J/KG.  WLY/WNWLY MID LEVEL WINDS OF 30-40 KT ARE

CONTRIBUTING TO DEEP LAYER SHEAR OF 30-35 KT IN THE LOWEST 6 KM

WHICH WILL ENHANCE STORM ORGANIZATION AND INTENSITY.  STORMS ARE

LIKELY TO SLOWLY INTENSIFY DURING THE NEXT SEVERAL HOURS WITH THREAT

FOR DAMAGING WIND GUSTS AND MARGINALLY SEVERE HAIL.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.

A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION

VECTOR 28020.





...WEISS

