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561 

WWUS20 KWNS 211723

SEL5

SPC WW 211723

CTZ000-MAZ000-NHZ000-NYZ000-PAZ000-VTZ000-220100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 795

NWS STORM PREDICTION CENTER NORMAN OK

125 PM EDT SUN AUG 21 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTH CENTRAL AND NORTHEAST CONNECTICUT

       WESTERN MASSACHUSETTS

       MUCH OF NEW HAMPSHIRE

       CENTRAL AND EASTERN NEW YORK

       NORTHEAST PENNSYLVANIA

       MUCH OF VERMONT



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 125 PM UNTIL 900

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 95

STATUTE MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH

NORTHWEST OF MONTPELIER VERMONT TO 30 MILES SOUTH OF MONTICELLO

NEW YORK.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 794...



DISCUSSION...THUNDERSTORMS ARE ONGOING ALONG A PRE-FRONTAL TROUGH

NEAR THE HUDSON VALLEY.  THE STRONGER SURFACE HEATING IS OCCURRING

DOWNSTREAM FROM THESE STORMS FROM NH INTO WRN MA...AND THE

COMBINATION OF INCREASING INSTABILITY AND VERTICAL SHEAR THROUGH THE

AFTERNOON WILL FAVOR A CONTINUED RISK FOR DAMAGING WINDS AND LARGE

HAIL.  FARTHER W...CLOUDS HAVE LIMITED SURFACE HEATING ACROSS

CENTRAL NY...BUT CLOUD BREAKS COULD EVENTUALLY ALLOW SUFFICIENT

DESTABILIZATION FOR AN INCREASING SEVERE RISK AS THE STORMS ALONG

THE SYNOPTIC COLD FRONT MOVE EWD FROM WRN INTO CENTRAL NY LATER THIS

AFTERNOON.  ALSO...AN ISOLATED TORNADO CANNOT BE RULED OUT ALONG THE

HUDSON VALLEY WHERE SEMI-DISCRETE STORMS AND STRONGER LOW-LEVEL

SHEAR WILL CO-EXIST.



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 27035.





...THOMPSON

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