

147 

WWUS20 KWNS 251640

SEL8

SPC WW 251640

NYZ000-LEZ000-LOZ000-260000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 508

NWS STORM PREDICTION CENTER NORMAN OK

1240 PM EDT THU JUN 25 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN INTO PART OF UPSTATE NEW YORK

       LAKE ERIE

       LAKE ONTARIO



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1240 PM UNTIL

800 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 90

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

SOUTHEAST OF JAMESTOWN NEW YORK TO 55 MILES NORTH NORTHEAST OF

WATERTOWN NEW YORK.  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...CLUSTER OF INTENSE THUNDERSTORMS OVER ONTARIO WILL

CONTINUE ESEWD INTO WRN NY THIS AFTERNOON WHERE AIR MASS IS ALREADY

MODERATELY UNSTABLE.  ADDITIONAL DEVELOPMENT COULD OCCUR INTO THE

ST. LAWRENCE VALLEY WITH SUBTLE SURFACE TROUGH INTERACTING WITH

INSTABILITY AXIS.  SHEAR WILL BE SUFFICIENT FOR ORGANIZATION INTO

LINES/CLUSTERS AS STORMS SHIFT EAST THROUGH THE DAY.  LARGE HAIL AND

DAMAGING WINDS ARE EXPECTED WITH THE STRONGER STORMS.



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 500. MEAN STORM

MOTION VECTOR 28025.





...EVANS

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