[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 211725
SWOMCD
SPC MCD 211724 
VAZ000-NCZ000-SCZ000-211930-

MESOSCALE DISCUSSION 2069
NWS STORM PREDICTION CENTER NORMAN OK
1224 PM CDT SAT AUG 21 2004

AREAS AFFECTED...ERN NC...SERN VA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 211724Z - 211930Z

GRADUAL DEVELOPMENT OF STRONG-SEVERE TSTMS IS EXPECTED OVER NEXT FEW
HOURS ACROSS COASTAL PLAIN OF NC AND SERN VA.  VERTICAL SHEAR IS
INCREASING FROM W-E AND BECOMING MORE FAVORABLE FOR SUPERCELLS AS
WELL AS BOW ECHOES.  MAIN THREAT WILL BE DAMAGING WIND...THOUGH
OCCASIONAL HAIL AND A TORNADO OR TWO ARE ALSO POSSIBLE.  WW MAY BE
REQUIRED IN NEXT COUPLE HOURS.

1630Z VIS IMAGERY INDICATES 50-60 NM WIDE MIDLEVEL CLOUD DECK FROM
LOWER POTOMAC BASIN SWWD ALONG E EDGE OF PIEDMONT IN NC.  STRONGEST
HEATING IS OCCURRING E OF THIS BOUNDARY...WHICH ALSO COINCIDES WITH
A SUBTLE CONFLUENCE LINE IN SFC WINDS. 
AIR MASS ACROSS THIS AREA HAS DESTABILIZED RAPIDLY AND SHOULD
CONTINUE TO DO SO FOR ANOTHER FEW HOURS OUTSIDE CONVECTIVE AREAS. 
TEMPS IN UPPER 80S AND LOW 90S F...COMBINED WITH 70S F SFC DEW
POINTS...CONTRIBUTE TO MLCAPE APCHG 3000 J/KG. 30-35 KT WINDS IN
900-700 MB LAYER CONTRIBUTE TO ENHANCED LOW LEVEL SHEAR ACROSS THIS
REGION...ESPECIALLY OVER NERN NC/SERN VA WHERE STRENGTHING MIDLEVEL
FLOW ALSO WILL AID DEEP-LAYER SHEAR.  MAIN WEAKNESS IS WITH
CONVERGENCE AMIDST BROAD FETCH OF SWLY BOUNDARY LAYER FLOW. 
HOWEVER...MODIFIED RAOBS AND RUC SOUNDINGS INDICATE CAP IS NEARLY
GONE...SO STORMS MAY INITIATE ON SUBTLE FOCI SUCH AS CONFLUENCE
LINE...BAY/SEA BREEZES OR HORIZONTAL ROLLS.  CONVECTION IS
DEVELOPING ATTM ALONG SERN NC SE BREEZE...AND THIS TREND MAY EXTEND
NWD WITH TIME.

..EDWARDS.. 08/21/2004

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...AKQ...MHX...RAH...ILM...

33877854 34247912 34727929 35097869 35747780 36477700
37597714 37917644 37847542 36967562 35887551 35237615
34687687 

WWWW