Post by Nws Olney Maryland on Jun 12, 2011 13:45:34 GMT -5
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 467
NWS STORM PREDICTION CENTER OLNEY MD
150 PM EDT SUN JUN 12 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
DISTRICT OF COLUMBIA
NORTHERN DELAWARE
MARYLAND
A SMALL PART OF NORTHWEST NORTH CAROLINA
SOUTHEAST PENNSYLVANIA
VIRGINIA
THE EASTERN WEST VIRGINIA PANHANDLE
COASTAL WATERS
EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 150 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 95
STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES EAST OF
HARRISBURG PENNSYLVANIA TO 55 MILES SOUTH OF LYNCHBURG VIRGINIA.
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.
DISCUSSION...THUNDERSTORMS ARE STRENGTHENING ALONG THE COLD FRONT IN
PA...AND ADDITIONAL DEVELOPMENT IS BEGINNING FARTHER TO THE S/SW
OVER THE HIGHER TERRAIN AND IN THE OPEN WARM SECTOR. STRONG SURFACE
HEATING IS SUPPORTING MLCAPE VALUES OF 1500-2000 J/KG...WHILE
VERTICAL SHEAR IS SUFFICIENT FOR ORGANIZED CLUSTERS FROM NRN VA INTO
PA. FARTHER S...THE ENVIRONMENT IS MORE FAVORABLE FOR PULSE TYPE
SEVERE STORMS WITH DAMAGING DOWNBURSTS...GIVEN THE WEAKER VERTICAL
SHEAR AND STEEP LOW-LEVEL LAPSE RATES. DAMAGING WINDS WILL BE THE
MAIN SEVERE THREAT...THOUGH MARGINALLY SEVERE HAIL WILL ALSO BE
POSSIBLE IN THE STRONGER STORMS.
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 500. MEAN STORM
MOTION VECTOR 30025.
SEVERE THUNDERSTORM WATCH NUMBER 467
NWS STORM PREDICTION CENTER OLNEY MD
150 PM EDT SUN JUN 12 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
DISTRICT OF COLUMBIA
NORTHERN DELAWARE
MARYLAND
A SMALL PART OF NORTHWEST NORTH CAROLINA
SOUTHEAST PENNSYLVANIA
VIRGINIA
THE EASTERN WEST VIRGINIA PANHANDLE
COASTAL WATERS
EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 150 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 95
STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES EAST OF
HARRISBURG PENNSYLVANIA TO 55 MILES SOUTH OF LYNCHBURG VIRGINIA.
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.
DISCUSSION...THUNDERSTORMS ARE STRENGTHENING ALONG THE COLD FRONT IN
PA...AND ADDITIONAL DEVELOPMENT IS BEGINNING FARTHER TO THE S/SW
OVER THE HIGHER TERRAIN AND IN THE OPEN WARM SECTOR. STRONG SURFACE
HEATING IS SUPPORTING MLCAPE VALUES OF 1500-2000 J/KG...WHILE
VERTICAL SHEAR IS SUFFICIENT FOR ORGANIZED CLUSTERS FROM NRN VA INTO
PA. FARTHER S...THE ENVIRONMENT IS MORE FAVORABLE FOR PULSE TYPE
SEVERE STORMS WITH DAMAGING DOWNBURSTS...GIVEN THE WEAKER VERTICAL
SHEAR AND STEEP LOW-LEVEL LAPSE RATES. DAMAGING WINDS WILL BE THE
MAIN SEVERE THREAT...THOUGH MARGINALLY SEVERE HAIL WILL ALSO BE
POSSIBLE IN THE STRONGER STORMS.
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 500. MEAN STORM
MOTION VECTOR 30025.