Post by Nws Olney Maryland on Feb 25, 2011 12:31:59 GMT -5
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 19
NWS STORM PREDICTION CENTER NORMAN OK
1220 PM EST FRI FEB 25 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
DISTRICT OF COLUMBIA
DELAWARE
THE EASTERN SHORE OF MARYLAND
SOUTHERN NEW JERSEY
EXTREME SOUTHEAST PENNSYLVANIA
NORTHEAST VIRGINIA
COASTAL WATERS
EFFECTIVE THIS FRIDAY AFTERNOON FROM 1220 PM UNTIL 400 PM EST.
WIDELY SCATTERED DAMAGING WINDS TO 70 MPH
ISOLATED TORNADOES
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65
STATUTE MILES EAST AND WEST OF A LINE FROM PHILADELPHIA
PENNSYLVANIA TO 5 MILES WEST SOUTHWEST OF PATUXENT RIVER
MARYLAND. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).
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...LOW-TOPPED CONVECTION IS GRADUALLY INCREASING WITHIN
THE MIDLEVEL DRY SLOT...JUST IN ADVANCE OF AN EJECTING MIDLEVEL
TROUGH AND A SURFACE COLD FRONT. SURFACE HEATING IN THE DRY SLOT
AND RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE MID 50S WILL SUPPORT
SBCAPE NEAR 500 J/KG...WHILE STRONG WINDS JUST ABOVE THE SURFACE
WILL FAVOR MOMENTUM TRANSFER TO THE GROUND AND DAMAGING WIND
POTENTIAL WITH THE STRONGER LINE SEGMENTS/CELLS. ADDITIONALLY...THE
STRONG LOW-LEVEL SHEAR COULD SUPPORT ROTATING STORMS...AND AN
ISOLATED TORNADO CANNOT BE RULED OUT THIS AFTERNOON.
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 300. MEAN STORM
MOTION VECTOR 27045.
......MILLER/BURRUS
SEVERE THUNDERSTORM WATCH NUMBER 19
NWS STORM PREDICTION CENTER NORMAN OK
1220 PM EST FRI FEB 25 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
DISTRICT OF COLUMBIA
DELAWARE
THE EASTERN SHORE OF MARYLAND
SOUTHERN NEW JERSEY
EXTREME SOUTHEAST PENNSYLVANIA
NORTHEAST VIRGINIA
COASTAL WATERS
EFFECTIVE THIS FRIDAY AFTERNOON FROM 1220 PM UNTIL 400 PM EST.
WIDELY SCATTERED DAMAGING WINDS TO 70 MPH
ISOLATED TORNADOES
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65
STATUTE MILES EAST AND WEST OF A LINE FROM PHILADELPHIA
PENNSYLVANIA TO 5 MILES WEST SOUTHWEST OF PATUXENT RIVER
MARYLAND. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).
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...LOW-TOPPED CONVECTION IS GRADUALLY INCREASING WITHIN
THE MIDLEVEL DRY SLOT...JUST IN ADVANCE OF AN EJECTING MIDLEVEL
TROUGH AND A SURFACE COLD FRONT. SURFACE HEATING IN THE DRY SLOT
AND RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE MID 50S WILL SUPPORT
SBCAPE NEAR 500 J/KG...WHILE STRONG WINDS JUST ABOVE THE SURFACE
WILL FAVOR MOMENTUM TRANSFER TO THE GROUND AND DAMAGING WIND
POTENTIAL WITH THE STRONGER LINE SEGMENTS/CELLS. ADDITIONALLY...THE
STRONG LOW-LEVEL SHEAR COULD SUPPORT ROTATING STORMS...AND AN
ISOLATED TORNADO CANNOT BE RULED OUT THIS AFTERNOON.
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 300. MEAN STORM
MOTION VECTOR 27045.
......MILLER/BURRUS