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834 

WWUS20 KWNS 022158

SEL6

SPC WW 022158

MDZ000-PAZ000-VAZ000-WVZ000-030300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 136

NWS STORM PREDICTION CENTER NORMAN OK

600 PM EDT SUN MAY 2 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL MARYLAND

       SOUTH CENTRAL PENNSYLVANIA

       NORTHERN VIRGINIA

       EASTERN PANHANDLE OF WEST VIRGINIA



EFFECTIVE THIS SUNDAY EVENING FROM 600 PM UNTIL 1100 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 40

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST

SOUTHWEST OF MARTINSBURG WEST VIRGINIA TO 55 MILES EAST OF

HAGERSTOWN MARYLAND.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 134...WW 135...



DISCUSSION...LOOSE CLUSTER OF STORMS WILL PROGRESS EWD FROM WV TO

NRN VA/MD AND S CENTRAL PA THE NEXT FEW HOURS.  THOUGH MIDLEVEL

LAPSE RATES ARE NOT PARTICULARLY STEEP...A WARM/MOIST BOUNDARY LAYER

IS CONTRIBUTING MLCAPE VALUES OF 1000-1500 J/KG.  THIS

INSTABILITY...AND EFFECTIVE BULK SHEAR OF 60-70 KT...WILL SUPPORT

SUPERCELLS WITH A LOCALLY ENHANCED THREAT FOR DAMAGING WINDS AND

MARGINALLY SEVERE HAIL.



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 450. MEAN STORM

MOTION VECTOR 26035.





...THOMPSON

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