

000 

WWUS20 KWNS 161730

SEL8

SPC WW 161730

DCZ000-DEZ000-MDZ000-NJZ000-NYZ000-PAZ000-VAZ000-WVZ000-CWZ000-17000

0-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 278

NWS STORM PREDICTION CENTER NORMAN OK

130 PM EDT WED MAY 16 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DISTRICT OF COLUMBIA

       DELAWARE

       MARYLAND

       NEW JERSEY

       EXTREME SOUTHERN NEW YORK AND WESTERN LONG ISLAND

       EASTERN PENNSYLVANIA

       CENTRAL AND NORTHERN VIRGINIA

       A SMALL PART OF THE EASTERN WEST VIRGINIA PANHANDLE

       COASTAL WATERS



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 130 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 90

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

NORTHWEST OF NEWARK NEW JERSEY TO 50 MILES SOUTHWEST OF

WASHINGTON DISTRICT OF COLUM.  FOR A COMPLETE DEPICTION OF THE

WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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 277...



DISCUSSION...AIR MASS WILL CONTINUE TO BECOME MODERATE TO MARGINALLY

UNSTABLE ACROSS WW THIS AFTERNOON WITH STRONG SURFACE HEATING.  THIS

WILL OCCUR AHEAD OF SURFACE COLD FRONT NOW MOVING ACROSS ERN PA AND

THE CENTRAL APPALACHIANS...WHICH WILL MOVE EWD TOWARDS THE ATLANTIC

COAST THROUGH THE EARLY EVENING.  APPEARS LOW-TOPPED LINES OF

STORMS...INCLUDING A FEW BOW ECHOES...WILL EVOLVE AHEAD OF THIS

FRONT UNDER STRONG WLY FLOW ALOFT.  STEEP LOW LEVEL LAPSE RATES DUE

TO ABUNDANT AFTERNOON HEATING AND 40+ KT WLY FLOW JUST ABOVE THE

SURFACE SHOULD ENHANCE THE THREAT OF DAMAGING WINDS.



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 400. MEAN STORM

MOTION VECTOR 27035.





...EVANS

