

576 

WWUS20 KWNS 272021

SEL4

SPC WW 272021

NYZ000-OHZ000-PAZ000-LEZ000-280400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 424

NWS STORM PREDICTION CENTER NORMAN OK

420 PM EDT SUN JUN 27 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN NEW YORK

       EAST-CENTRAL AND NORTHEASTERN OHIO

       NORTHWESTERN PENNSYLVANIA

       LAKE ERIE



EFFECTIVE THIS SUNDAY AFTERNOON FROM 420 PM UNTIL MIDNIGHT 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 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 15 MILES SOUTHWEST

OF MANSFIELD OHIO TO 55 MILES EAST SOUTHEAST OF BUFFALO NEW YORK.

 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU4).



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 423...



DISCUSSION...SVR THREAT FCST TO SHIFT/EXPAND EWD FROM WW 423 AND

FROM SRN ONT REGION ACROSS FAVORABLY UNSTABLE AIR MASS...UNDER SRN

RIM OF FAVORABLE WLYS ALOFT AND RELATED DEEP-LAYER SHEAR...DURING

REMAINDER AFTERNOON INTO EVENING.  REF SPC MESOSCALE DISCUSSION 1147

FOR INITIAL FCST DETAILS.



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 27030.





...EDWARDS/THOMPSON

