

707 

WWUS20 KWNS 222140

SEL2

SPC WW 222140

MDZ000-OHZ000-PAZ000-WVZ000-230500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 672

NWS STORM PREDICTION CENTER NORMAN OK

540 PM EDT FRI JUL 22 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       FAR WESTERN MARYLAND

       EAST CENTRAL OHIO

       WESTERN AND CENTRAL PENNSYLVANIA

       NORTHERN WEST VIRGINIA



EFFECTIVE THIS FRIDAY AFTERNOON AND SATURDAY MORNING FROM 540 PM

UNTIL 100 AM 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 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES NORTH

NORTHEAST OF ALTOONA PENNSYLVANIA TO 40 MILES SOUTH SOUTHWEST OF

AKRON OHIO.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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 670...WW 671...



DISCUSSION...TSTM CLUSTERS EXPECTED TO CONTINUE FORMING WITH SFC

HEATING/WAA ALONG STALLED W-E BOUNDARY IN WRN/CNTRL PA...WITH

ADDITIONAL ASCENT POSSIBLY PROVIDED BY CIRCULATION ASSOCIATED WITH

CNTRL OH MCS.  STEEP LOW LVL LAPSE RATES /WITH SFC TEMPS IN THE 90S

TO AROUND 100 F/...COUPLED WITH MODEST DEEP WLY SHEAR AND POCKETS OF

HIGH PW WITH SIZABLE TEMP-DEW POINT SPREADS...SUGGEST POTENTIAL FOR

SMALL BOWING SEGMENTS/WET MICROBURSTS.



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 27025.





...CORFIDI

