DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 270103
SWODY1
SPC AC 270059

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CDT SAT SEP 26 2009

VALID 270100Z - 271200Z

...NO SVR TSTM AREAS FORECAST...

...ERN GA AND SRN SC...
A LINE OF STRONG THUNDERSTORMS CURRENTLY ONGOING IN ERN GA IS
LOCATED ON THE NRN EDGE OF MODERATE INSTABILITY. AHEAD OF THE
LINE...THE 00Z SOUNDING FROM CHARLESTON SC SHOWS A SFC DEWPOINT IN
THE MID 70S F...OVER 2000 J/KG OF MUCAPE AND A PRECIPITABLE WATER
VALUE AROUND 2.25 INCHES. THIS SHOULD SUPPORT THE CONVECTION EWD
ACROSS THE REMAINDER OF SC LATE THIS EVENING INTO THE OVERNIGHT
PERIOD. HOWEVER...THE SOUNDING SHOWS WEAK LOW-LEVEL FLOW AND A
MARGINAL VERTICAL SHEAR PROFILE FOR ORGANIZED CONVECTION. IF THE
LINE CAN REMAIN INTACT...A FEW DAMAGING WIND GUSTS MAY OCCUR IN SRN
SC LATE THIS EVENING OR OVERNIGHT.

...ERN NC...
AN UPPER-LEVEL TROUGH OVER THE MID-MS VALLEY WILL MOVE EWD INTO THE
OH AND TN VALLEYS TONIGHT AS A MID-LEVEL CIRCULATION EVIDENT ON
WATER VAPOR DRIFTS NEWD ALONG THE COAST OF NC. THUNDERSTORMS LOCATED
IN THE NRN PART OF THE CIRCULATION WILL MOVE NEWD ACROSS THE OUTER
BANKS THIS EVENING WITH THE ACTIVITY ENDING TEMPORARILY ACROSS SRN
NC. AHEAD OF THE UPPER-LEVEL TROUGH...SOUTHWEST FLOW AND MOISTURE
ADVECTION WILL INCREASE ACROSS ERN NC. A VERY MOIST AIRMASS EXISTS
AS FAR NORTH AS WILMINGTON NC WHERE THE SFC DEWPOINT IS CURRENTLY IN
THE LOWER 70S F. THIS AIRMASS SHOULD ADVECT NEWD ACROSS MUCH OF THE
NC COAST DURING THE OVERNIGHT PERIOD HELPING TO GRADUALLY
DESTABILIZE THE ENVIRONMENT. AS LARGE-SCALE ASCENT INCREASES FROM
THE WEST...THUNDERSTORMS SHOULD REDEVELOP ALONG THE WRN EDGE OF
MOISTURE IN THE IMMEDIATE COASTAL AREAS IN THE 09Z TO 12Z TIMEFRAME.
FORECAST SOUNDINGS EARLY SUNDAY MORNING SHOW STRONG LOW-LEVEL
SHEAR...ABUNDANT LOW-LEVEL MOISTURE AND LOW LCL HEIGHTS SUGGESTING A
MARGINAL TORNADO THREAT WILL EXIST WITH ANY ROTATING STORMS THAT CAN
DEVELOP INLAND. STRONG GUSTY WINDS WILL ALSO BE POSSIBLE AS WELL.
HOWEVER...MODEL FORECASTS SUGGEST MOST OF THE CONVECTION WILL REMAIN
OFFSHORE.

..BROYLES.. 09/27/2009

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