

696 

WWUS20 KWNS 171724

SEL9

SPC WW 171724

MEZ000-NHZ000-NYZ000-VTZ000-180100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 489

NWS STORM PREDICTION CENTER NORMAN OK

125 PM EDT TUE JUL 17 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN MAINE

       NEW HAMPSHIRE

       NORTHERN NEW YORK

       VERMONT



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 125 PM UNTIL

900 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 60

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

OF WATERTOWN NEW YORK TO 40 MILES EAST SOUTHEAST OF BERLIN NEW

HAMPSHIRE.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 488...



DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY THIS AFTERNOON AHEAD OF COLD FRONT ADVANCING SEWD INTO THE

REGION.  THE COMBINATION OF STEEPENING MIDLEVEL LAPSE RATES FROM THE

W AND BOUNDARY LAYER DEWPOINTS IN THE 60S WILL YIELD MLCAPE VALUES

APPROACHING 1000-1500 J/KG.  WHEN COUPLED WITH A STEADILY

STRENGTHENING WLY...DEEP-LAYER WIND FIELD...SETUP WILL SUPPORT

SUPERCELLS AND BOWING STRUCTURES CAPABLE OF DAMAGING WINDS...LARGE

HAIL...AND PERHAPS A TORNADO.



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 32030.





...MEAD

