496
FXUS62 KGSP 250236
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
936 PM EST Sun Nov 24 2024

.SYNOPSIS...
High pressure will persist over the Atlantic Southeastern States
through Monday. A passing cold front brings a chance for brief
showers early Tuesday, followed by dry weather Wednesday. A second
front will bring more widespread rain for Thanksgiving Day
followed by much colder temperatures for the end of the week and
through the weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 932 PM Sunday: Another night of modest radiational cooling is
underway as the boundary layer has decoupled across much of the
area. Gradual airmass modification and at least some degree of
moisture recovery within weak southwest flow has resulted in higher
dewpoints. This will somewhat limit the magnitude of cooling, but
overnight lows should still bottom out in the mid 30s to low 40s.

Key Messages:

1) Dry and unseasonably warm today and Monday.

As of 200 PM EST Sunday: A broad region of westerly flow aloft and
high pressure dominate the southeast through Monday. Modest ridging
over the eastern portion of the CONUS starts to slide off the
coastline as an upper low forms across central Canada. By the end of
the near term, a weak cold front approaches the area from the north,
but doesn`t cross into the CWA until the next period. By Monday, an
uptick in moisture ahead of the front returns with the SW surface
winds, dewpoints steadily increasing Monday afternoon. The last few
days of unseasonably warm temperatures occur through the period
before a strong cool down into the preceding forecasts. Overall, dry
and warm to end the weekend and start the week.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 225 pm Sunday: Within quasi-zonal flow, a short wave trough
will lift from the Ohio Valley Monday night...to the northeast
quadrant of the country by Tuesday night. An attendant fast-moving
cold front and accompanying shower band will approach the southern
Appalachians early Tuesday, bringing likely-to-categorical rain
chances to the NC mountains by daybreak. However, with the upper
level support passing well north of the forecast area, the frontal
circulation is forecast to weaken over the high terrain such that
the frontal band will become increasingly disorganized as it crosses
the mountains...and chances for precip east/south of the Blue Ridge
will only be in the 20-30% range Tuesday morning. After a warm start
to the short term...with lows 15 degrees above normal, and highs
5-10 degrees above, transient post-frontal high pressure will supply
a brief cool down to near-normal temperatures Tue night and Wed.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 155 pm Sunday: A fast/low-amplitude quasi-zonal flow pattern
will be in place across much of the Conus at the start of the
extended, with the pattern expected to gradually amplify, as a
series of short wave troughs carve out a low-amplitude trough across
the East. The first of these waves is forecast to sweep across the
Southeast and Mid-Atlantic on Thanksgiving. However, notable
differences remain among the major global deterministic guidance
regarding the intensity/timing of this feature...as the ECMWF
continues to offer a weaker/faster and farther north scenario. As a
result, the ECMWF would suggest weaker forcing/lighter precip for
our forecast area...with the event winding down by Thu afternoon...
while the GFS (with a decent amount of support from the Canadian)
suggests a more strongly forced event that would just be getting
started during the afternoon. Nevertheless, model signals are such
that likely PoPs are warranted across the entire area during the
daylight hours on Thanksgiving, with categorical PoPs largely
confined to the mountains at this point. A brief period of northwest
flow showers...with an eventual transition to snow showers is
expected before the moisture depletes Thu night/Friday. The
remainder of the extended will be generally dry and quite cool, with
temperatures expected to average 5-10 degrees below normal.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: VFR conditions will prevail at all terminals
through the TAF period. Scattered high cirrus clouds will continue
to stream overhead through the overnight into tomorrow, but of no
impact. Light to calm winds overnight will increase to 5-10kts out
of the southwest during the day tomorrow. A couple gusts will be
possible across the Upstate at KGSP, KGMU and KAND.

Outlook: A weak cold front may bring scattered rain showers and
associated restrictions on Tuesday. Dry high pressure briefly
returns Wednesday. A more significant storm system may bring
widespread rain and restrictions on Thursday.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...CP/TW
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...TW