489 
FXUS62 KGSP 082151
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
551 PM EDT Fri Oct 8 2021

.SYNOPSIS...
Upper level low pressure moves into the Great Lakes today but 
periods of widespread showers and locally heavy rainfall are still 
possible. Moisture lingers over the area Saturday as a surface low 
pressure center moves north along the Carolina Coast. Dry high 
pressure builds in on Sunday and remains in place through next week 
with warming temperatures.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 530 PM...The remaining shower activity has split into two
separate camps. To the east of the Charlotte metro area, steadier
rain associated with forcing lifting out of the upper trof axis
was exiting the forecast area. Meanwhile...scattered showers
were developing mainly over the higher terrain where clearing has
allowed for sfc-based CAPE underneath the upper trof to the tune
of 1500 J/kg. Won't rule out some isolated flooding, and there
is some ongoing minor flooding that could be exacerbated if any
thunderstorms develop in the wrong spots.

Rain and thunder will begin to end from west to east across
the region this evening as upper system ejects northeastward,
and surface winds become more northerly.  Rain and clouds will
keep temperatures seasonally mild again tonight. Depending on how
shallow the boundary layer can get, may see some patchy dense fog
in spots, but overall low stratus clouds are more favored.

Finally some drier weather will begin to take hold, at least across
the western portions of the area, on Saturday. A developing low
off the Carolina coast will continue to wrap moisture around
into the NC Piedmont, which could keep it mostly cloudy with
spotty showers. Probably not enough instability or forcing for
thunder. Further west, less cloud cover should allow temps to warm
to near normal Saturday afternoon.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 100 PM Friday: The beginning portion of the short-term will
bring much needed changes to the overall forecast. A surface low
off of the North Carolina coast will gradually lift northward and
shift the low-level flow from easterly to northeasterly Saturday
night. This will produce a low-level subsidence inversion and
dissipate most of the activity across the CFWA, with the exception
of a few lingering showers in the far eastern zones. The surface
low will struggle to develop tropical features due to the closed
upper low over the Florida Peninsula. This feature will be in the
vicinity of the Outer Banks Sunday and will more or less keep the
CFWA mostly dry. The ECMWF is keen on keeping some sort of precip
in the area, but height rises will begin to the filter in from the
west during the day and most of the model guidance allows the CFWA
to remain mostly capped with the additional subsidence. The upper
ridge will begin to take control the overall weather pattern by
early next week with a warming trend in store. Fingers crossed for 
drier weather! Hoping the 12Z ECMWF run is just out to lunch since 
it is the outlier that keeps the area relatively active through a 
decent portion of the forecast period. Otherwise, mostly dry weather 
and high temperatures to be a few degrees above normal, while lows 
end up 5-10 degrees above normal both Sunday and Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 200 PM Friday: The overall synoptic pattern will be controlled
by the aforementioned upper ridge through much of the period. A
potent shortwave trough will push through the Midwest and Upper
Great Lakes that could provide enough support for a few isolated
showers to develop over the mountains Tuesday. The upper ridge
continues to set up shop over the East Coast through the rest of
the extended. Broad upper trough to the west will begin to push
the upper ridge offshore by day 6 and 7 and encroach the region
with an attendant cold front. In this scenario, the pattern will
begin to change from the unseasonably warm weather the CFWA will
experience during the medium range with temperatures expected to
be ~5-10 degrees above normal for both highs and lows through the
middle part of next week.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: The more widespread -RA and embedded heavier
showers is slowly shifting to the east, but additional isolated
to scattered showers will continue to develop across the area
thru the aftn. The convection will then become mostly confined to
the NC Piedmont tonight, warranting continued mention of -SHRA at
KCLT thru the evening. There are some breaks in the clouds across
the west, but overall CIGS should stay MVFR, except breaking out
to VFR at KAVL and KAND at times into this evening. Then expect
low stratus to fill back in across the area, with IFR to LIFR
cigs possible. Patchy fog is possible, but not expected to be
widespread at this time. Stratus should improve across the Upstate
and KAVL Saturday morning, as some drier air filters in from the
north. However, Atlantic moisture will wrap around low off the
Carolina coast and may continue to keep KCLT in some lower CIGS
possibly well into the aftn, with spotty -SHRA possible. Winds
will be generally 5-10 kts out of the NE, but lighter and more
variable at KAVL.

Outlook: Finally, some drier air will try to work in from the
west over the weekend. However, low-level moisture may linger,
keeping a chance of low cigs and fog returning from the east
Saturday night into Sunday morning. This may occur again Sunday
night, at least across portions of the NC Piedmont. But otherwise,
should be dry and VFR heading into early next week.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...CAC
NEAR TERM...ARK/PM
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...ARK