

240 

WWUS20 KWNS 212335

SEL3

SPC WW 212335

CTZ000-MAZ000-MEZ000-NHZ000-NYZ000-PAZ000-RIZ000-VTZ000-CWZ000-22050

0-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 513

NWS STORM PREDICTION CENTER NORMAN OK

730 PM EDT WED JUL 21 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN CONNECTICUT

       MUCH OF MASSACHUSETTS

       SOUTHWEST MAINE

       SOUTHERN NEW HAMPSHIRE

       PART OF SOUTH-CENTRAL INTO EASTERN NEW YORK

       PART OF CENTRAL AND EASTERN PENNSYLVANIA

       NORTHERN RHODE ISLAND

       SOUTHERN VERMONT

       COASTAL WATERS



EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 730 PM

UNTIL 100 AM 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 EAST

NORTHEAST OF PORTSMOUTH NEW HAMPSHIRE TO 30 MILES NORTHWEST OF

ALTOONA PENNSYLVANIA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 507...WW 508...WW

509...WW 510...WW 511...WW 512...



DISCUSSION...MULTIPLE BANDS OF STRONG/SEVERE TSTMS ARE EXPECTED TO

PROGRESS EWD/SEWD ACROSS THE NERN U.S. TONIGHT IN ADVANCE OF A

STRONG VORTICITY MAXIMUM AND ASSOCIATED MIDLEVEL JET STREAK

CURRENTLY MOVING THROUGH THE LOWER GREAT LAKES.  THOUGH EARLIER

STORMS HAVE STABILIZED THE AIR MASS IN SOME LOCATIONS...LARGE

POCKETS OF MODERATE INSTABILITY /I.E. MLCAPE OF 1000-1500 J PER KG/

STILL EXISTS.  WHEN COUPLED WITH 40-50 KT OF DEEP-LAYER

SHEAR...ENVIRONMENT WILL CONTINUE TO SUPPORT ORGANIZED STORMS

INCLUDING SUPERCELLS AND BOWS FOR THE NEXT FEW HOURS.  DAMAGING

WINDS AND HAIL WILL REMAIN THE PRIMARY HAZARDS.



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 29030.





...MEAD

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