

517 

WWUS20 KWNS 241643

SEL5

SPC WW 241643

MDZ000-NCZ000-VAZ000-CWZ000-250000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 355

NWS STORM PREDICTION CENTER NORMAN OK

1240 PM EDT TUE MAY 24 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST MARYLAND

       NORTHERN NORTH CAROLINA

       CENTRAL AND EASTERN VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 1240 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 100

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES WEST

NORTHWEST OF PATUXENT RIVER MARYLAND TO 30 MILES SOUTHEAST OF

ROCKY MOUNT NORTH CAROLINA.  FOR A COMPLETE DEPICTION OF THE

WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 352...WW 353...WW 354...



DISCUSSION...NOCTURNAL MCS CURRENTLY EMERGING FROM THE BLUE RIDGE

HAS SHOWN A RAPID INCREASE IN STORM COVERAGE AND INTENSITY ALONG

ERN/SRN PERIPHERY OF SYSTEM COLD POOL.  AMBIENT INFLOW AIR MASS HAS

WARMED INTO THE 80S.  WHEN COUPLED WITH BOUNDARY LAYER DEWPOINTS IN

THE 60S...ENVIRONMENT HAS BECOME MODERATELY UNSTABLE WITH MLCAPE

VALUES OF 1000-2000 J/KG.  GIVEN 40-50 KT WLY FLOW OBSERVED IN THE

700-500 MB LAYER /PER REGIONAL VAD DATA/...SETUP WILL FAVOR

ORGANIZED STORM MODES INCLUDING LINE SEGMENTS AND SUPERCELLS CAPABLE

OF DAMAGING WINDS AND 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 500. MEAN STORM

MOTION VECTOR 28035.





...MEAD

