336 
FXUS62 KGSP 090440
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1240 AM EDT Sat Oct 9 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 TODAY/...
As of 12:30AM EDT Saturday:  Showers have been trending downward in 
strength and coverage, though some high-res models still show 
healthy convection into daybreak around I77.  With a decent respect 
for the observations, have cutback some on precipitation as well as 
chances for thunder through the morning.  

Lingering clouds and moisture should keep low temps seasonally mild 
overnight. 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 /TONIGHT 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 /06Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Considerable uncertainty as to how the
situation will play out overnight. The departure of light rain
to the east has left behind spotty low cloud decks at the IFR
and MVFR levels that are not presently affecting any terminals,
but that is expected to change this evening. A remnant low level
ENE flow should bring a return to widespread IFR ceilings by the
early morning hours that will affect most terminals. At KCLT, the
synoptic scale model guidance continues to suggest the redevelopment
of precip in the early morning hours, but this is only supported
by about half of the convection-allowing mesoscale models. Either
way, a restriction is likely at KCLT, and temporary LIFR conditions
are easily in the realm of possibilities. The passage of an upper
trof is not a clean one, and as a result, we keep an upslope flow
with plenty of lingering low level moisture that keeps a ceiling
restriction over the area well into Saturday. It won't be until
mid afternoon until some drier air tries to filter in from the
NW that we will start mixing out a ceiling restriction, and that
probably won't reach KCLT before the end of daylight. Wind will
stay mainly N to NE.

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 Sunday and heading into early next week.

&&

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

&&

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