

157 

WWUS20 KWNS 161741

SEL7

SPC WW 161741

CTZ000-MAZ000-NYZ000-PAZ000-VTZ000-170000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 587

NWS STORM PREDICTION CENTER NORMAN OK

140 PM EDT THU JUL 16 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME NORTHWEST CONNECTICUT

       EXTREME WESTERN MASSACHUSETTS

       CENTRAL AND EASTERN NEW YORK

       EXTREME NORTHEAST PENNSYLVANIA

       WESTERN VERMONT



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 140 PM UNTIL

800 PM 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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES NORTH OF

SARANAC LAKE NEW YORK TO 25 MILES WEST OF POUGHKEEPSIE NEW YORK.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...SCATTERED THUNDERSTORMS ARE DEVELOPING IN CENTRAL NY

NEAR THE INTERSECTION OF A DIFFUSE COLD FRONT AND THE LAKE BREEZE

ALONG THE S SHORE OF LAKE ONTARIO...WHILE ADDITIONAL DEVELOPMENT IS

EXPECTED THIS AFTERNOON BOTH N AND S OF THIS AREA ALONG THE FRONT.

SURFACE TEMPERATURES ARE WARMING INTO THE UPPER 70S TO LOWER 80S

WITH DEWPOINTS IN THE MID 60S...RESULTING IN MLCAPE VALUES OF

1000-1500 J/KG.  SUBTLE MID LEVEL SPEED MAXIMA WILL CROSS THIS AREA

NEAR THE FRONT DURING THE AFTERNOON AND CONTRIBUTE TO AN ENVIRONMENT

OF DEEP WLY BULK SHEAR OF 35-40 KT...WHICH WILL BE SUFFICIENT FOR

ORGANIZED STORMS/SUPERCELLS...ESPECIALLY WHERE SHEAR IS ENHANCED

SOME BY TERRAIN-INDUCED LOW-LEVEL SLY FLOW.  A FEW DAMAGING GUSTS

AND MARGINALLY SEVERE HAIL WILL BE THE MAIN THREATS THROUGH THE

AFTERNOON/EVENING.



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 27025.





...THOMPSON

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