MESO: Mesoscale Discussion 1747

ACUS11 KWNS 261932
SWOMCD
SPC MCD 261931
VAZ000-NCZ000-262100-

MESOSCALE DISCUSSION 1747
NWS STORM PREDICTION CENTER NORMAN OK
0231 PM CDT THU AUG 26 2010

AREAS AFFECTED...PORTIONS OF WRN AND CNTRL VA...FAR N CNTRL NC

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 261931Z - 262100Z

STORMS MAY MOVE EWD OFF OF THE APPALACHIAN MTNS OF WRN VA...AND POSE
A THREAT FOR ISOLATED DAMAGING WIND GUSTS AND MARGINALLY SVR HAIL AS
THEY ENTER PORTIONS OF CNTRL VA AND N CNTRL NC. THE
MARGINAL/ISOLATED NATURE OF THE THREAT WILL PRECLUDE A WW.

WEAK S/W TROUGH IS OBSERVED IN WV IMAGERY MOVING EWD ACROSS THE
MID/UPR OH VALLEY REGION AND INTO THE APPALACHIAN MTNS. THIS FEATURE
IS ACCOMPANIED BY A WEAK SURFACE COLD FRONT LOCATED OVER NRN
VA...WITH ZONE OF CONFLUENCE EXTENDING SWD ACROSS WRN VA.
THUNDERSTORMS HAVE DEVELOPED ALONG THE CONFLUENCE ZONE DURING THE
LAST FEW HRS AND ARE BEGINNING TO APPROACH PORTIONS OF CNTRL
VA...WHERE TEMPERATURES HAVE WARMED INTO THE 80S F...WHICH IS AIDING
IN THE DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES /AROUND 8.5 C PER
KM BASED ON OBJECTIVE ANALYSIS GUIDANCE/. RUC FORECAST SOUNDINGS
ACROSS THE REGION INDICATE A WARM NOSE RESIDES AT AROUND 600
MB...WHICH IS RESULTING IN GENERALLY WEAK MID-LEVEL LAPSE RATES.
HOWEVER...COMBINATION OF STRONG BOUNDARY LAYER DESTABILIZATION AND
SURFACE DEWPOINTS IN THE MID 60S F IS CONTRIBUTING TOWARD MUCAPE
VALUES AROUND 1000-1500 J/KG. THIS INSTABILITY MAY ALLOW A COUPLE OF
STORMS TO MAINTAIN SOME VIGOR AS THEY MOVE E TOWARD CNTRL VA AND
PERHAPS N CNTRL NC...WITH EFFECTIVE BULK SHEAR VALUES AROUND 20-30
KT SUGGESTING MULTICELL STORM TYPES WILL BE OBSERVED. A FEW OF THESE
THUNDERSTORMS MAY POSE A RISK OF DAMAGING WIND GUSTS GIVEN THE STEEP
LOW-LEVEL LAPSE RATE ENVIRONMENT...WHILE HAIL SIZE WILL GENERALLY BE
LIMITED TO SUB-SVR DUE TO WEAK MID-LEVEL LAPSE RATES.

..GARNER.. 08/26/2010

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

ATTN...WFO...AKQ...LWX...RAH...RNK...

LAT...LON 36898079 38217908 38437786 37757741 36517793 35987882
36168046 36898079

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