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443 

WWUS20 KWNS 182358

SEL7

SPC WW 182358

CTZ000-MAZ000-NHZ000-RIZ000-CWZ000-190700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 647

NWS STORM PREDICTION CENTER NORMAN OK

755 PM EDT TUE SEP 18 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN AND EASTERN CONNECTICUT

       MASSACHUSETTS

       SOUTHERN NEW HAMPSHIRE

       RHODE ISLAND

       COASTAL WATERS



EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 755 PM

UNTIL 300 AM EDT.



HAIL TO 0.5 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 70

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

NORTHEAST OF WORCESTER MASSACHUSETTS TO 25 MILES EAST SOUTHEAST

OF GROTON CONNECTICUT.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 646...



DISCUSSION...LOW-TOPPED CONVECTIVE BAND IN THE NYC AREA EXPECTED TO

CONTINUE ENE INTO SRN NEW ENGLAND...DRIVEN MAINLY BY UPLIFT ALONG

EXISTING GUST FRONT...AND POSSIBLY BY SOME INCREASE IN UPR

DIVERGENCE ASSOCIATED WITH AMPLIFICATION OF NRN STREAM UPR TROUGH.

WHILE NO SIGNIFICANT LOW-LVL DESTABILIZATION APPEARS LIKELY IN WW

AREA...SUFFICIENT MOISTURE/UPLIFT SHOULD PERSIST TO POSE A RISK FOR

SPORADIC DMGG WIND AND POSSIBLY A BRIEF TORNADO GIVEN STRENGTH OF

LOW TO MID-LVL WIND FIELD AND PRESENCE OF EXISTING BAND OF

CONVECTION/STORMS.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 250. MEAN STORM

MOTION VECTOR 21035.





...CORFIDI

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