211
FXUS62 KGSP 221727
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
127 PM EDT Sun Sep 22 2024

.SYNOPSIS...
High pressure will linger across the region through the weekend
helping keep temperatures above normal. A more moist airmass will
spread over the area on Monday and linger through at least mid-week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 125 PM EDT: An upper ridge axis to our west will become
centered over the Appalachians by the end of the period. Cumulus is
developing across the area but mostly sunny skies will remain for
the bulk of the day. Another hot and relatively muggy day, with max
temps expected to average almost 10 degrees above climo. Moderate
destabilization, with forecast soundings indicating an uncapped
environment will create some potential for spotty diurnal convection
late in the day...especially across the western half of the area,
where 20-30 PoPs are advertised. Any convection should diminish by
late evening, although some activity originating from a frontal zone
across the Ohio Valley could wander toward the southern Appalachians
toward daybreak Monday. Min temps will be 5-10 degrees above normal.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 3:05 AM EDT Sunday: The short-term fcst picks up at 12z on
Monday with broad upper ridging still in place over the Southeast.
The upper ridge is expected to linger over our area thru the period,
though it does get suppressed by an embedded upper trof that rides
up and over the ridge from the SW on Tuesday. At the sfc, a complex
low will develop over the Ohio River Valley and move a broad area
of deeper moisture SE and down the spine of the Appalachians and
into our fcst area as the period begins early Monday. This moisture
is expected to linger for the rest of the period and spread further
SE early Tuesday. By the end of the period early Wednesday, another
low will spin up over the Ohio River Valley and bring another cold
front to our doorstep from the west. As for the sensible fcst, I
bumped up precip chances across our northern zones for both Monday
and Tuesday afternoon/evening. In addition to showers, we could also
see some thunderstorms as some amount of instability will be present
over the fcst area during the afternoon/evening. High temperatures
will moderate on Monday and Tuesday under increased cloud cover,
yet still remain above climatology across most of the CWA.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 3:15 AM EDT Sunday: The extended fcst picks up at 12z on
Wednesday with upper ridging still lingering over the far SE
CONUS as broad upper trofing amplifies over the central CONUS.
The operational models appear to be coming into better agreement
wrt the evolution of the upper trof during the first part of
the period. The majority of the long-range guidance has a fair-
ly large upper low spinning off the backside of the trof over
the central CONUS on Wednesday, while the trof itself continues
to translate eastward with the trof axis passing to our north
early Thursday. On Friday, another large upper low is expected
to quickly dive southward and over the New England area as the
above-mentioned upper low lingers just to our west. Beyond this
point, it is difficult to predict how these lows will interact
with each other, but most of the guidance has the central CONUS
upper low remaining to our west thru the weekend. At the sfc,
a low pressure system will lift north over the eastern Great
Lakes and move another cold front into our fcst area later on
Wednesday. It`s looking increasingly likely that the front will
stall out over our area while broad high pressure remains well
to our NW for Thursday and Friday. At the same time, a robust
tropical low from the Gulf of Mexico will track north and over
our area as early as Friday. We will need to see how consistent
the long-range guidance is over the next few days with this sys-
tem before we can have much confidence wrt how it will impact
our area.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere: VFR cumulus this afternoon with isolated
convection generally along and west of I-26. Chance still too low
for TAF mention. MVFR then IFR stratocu moves SW across the area
late this evening and overnight. Have it for the NC sites, where fog
may also develop at KAVL and KHKY. There is a chance the cloud deck
makes it to KGSP/KGMU, but that is more uncertain so put FEW MVFR
for now. Vsby should improve quickly after daybreak, but cigs will
take longer to go VFR. Scattered convection expected during the
afternoon, so have PROB30 at KAVL where it starts sooner and KCLT
wit the longer TAF period. Light N to NE wind becomes through the
overnight becomes light S on Monday.

Outlook: A weak cold front will slowly approach from the west this
week before tracking over the area on Thursday. Chances for diurnal
showers and thunderstorms will increase Monday and remain elevated
through at least Thursday. A tropical cyclone may move into the SE
late in the week. Mountain valley fog/low stratus may develop each
morning around daybreak.

&&

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

&&

$$

SYNOPSIS...JPT
NEAR TERM...JDL/RWH
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...RWH