

479 

WWUS20 KWNS 101750

SEL0

SPC WW 101750

VAZ000-CWZ000-110000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 490

NWS STORM PREDICTION CENTER NORMAN OK

150 PM EDT SAT AUG 10 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  SOUTH CENTRAL AND SOUTHEAST VIRGINIA

  COASTAL WATERS



* EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 150 PM UNTIL

  800 PM EDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH LIKELY

  A FEW LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 40

STATUTE MILES EITHER SIDE OF A LINE FROM 60 MILES WEST SOUTHWEST

OF RICHMOND VIRGINIA TO 40 MILES EAST NORTHEAST OF NORFOLK

VIRGINIA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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...STRONG/SEVERE STORM APPROACHING RICHMOND HAS TAKEN ON A

BOW ECHO SHAPE SUGGESTING INCREASING POTENTIAL TO PRODUCE DAMAGING

WINDS.  ADDITIONAL STORMS ARE EXPECTED TO DEVELOP OVER SOUTH CENTRAL

AND SERN VA WITHIN A VERY MOIST AND UNSTABLE ENVIRONMENT /MLCAPE

AROUND 2500 J PER KG.  AREA VAD WIND PROFILE DATA INDICATE 30-40 KT

WESTERLY FLOW ABOVE 3-4 KM WHICH WILL PROVIDE SUFFICIENT SHEAR FOR

ORGANIZED MULTICELL STORMS AND OCCASIONAL BOW ECHOES.  DAMAGING WIND

IS EXPECTED TO BE THE PRIMARY THREAT INTO THE EVENING.



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 550. MEAN STORM

MOTION VECTOR 27025.





...WEISS

