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000 

WWUS20 KWNS 271651

SEL5

SPC WW 271651

NYZ000-PAZ000-LOZ000-280000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 555

NWS STORM PREDICTION CENTER NORMAN OK

1250 PM EDT FRI JUL 27 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND EASTERN NEW YORK

       CENTRAL PENNSYLVANIA

       LAKE ONTARIO



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL

800 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 80

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH

NORTHWEST OF SARANAC LAKE NEW YORK TO 15 MILES WEST OF HAGERSTOWN

MARYLAND.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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...SLOW-MOVING UPPER TROUGH/LOW WILL CONTINUE TO PROVIDE

DEEP-LAYER ASCENT ACROSS A VERY WARM/MOIST AND INCREASINGLY UNSTABLE

AIR MASS FROM PA NWD ACROSS NY THIS AFTERNOON. RESULTING INCREASE IN

TSTM COVERAGE WILL COINCIDE WITH POCKETS OF MODEST /20-30KT/ MID

LEVEL FLOW AND EFFECTIVE SHEAR VALUES SUPPORTIVE OF ROBUST

MULTICELLULAR STORMS. PRIMARY SEVERE HAZARD FROM THIS ACTIVITY IS

EXPECTED TO BE SCATTERED DAMAGING DOWNBURST WINDS WITH MARGINAL HAIL

ALSO POSSIBLE IN A FEW STORMS.



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 500. MEAN STORM MOTION

VECTOR 21025.





...CARBIN/IMY

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