956
FXUS62 KGSP 180039
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
839 PM EDT Mon Aug 17 2026

.WHAT HAS CHANGED...
The Severe Thunderstorm Watch has been expanded to include portions
of the North Carolina Piedmont and South Carolina Upstate, valid
through 10 PM this evening.

The aviation forecast was updated for the 00z TAF issuance.

&&

.KEY MESSAGES...
1. Hot and humid conditions persist most of this week, with little
relief until this weekend.
2. Slight Risk for Severe Weather across western North Carolina
this evening. More seasonally-typical diurnal convection continues
for most of the week.

&&

.DISCUSSION...
Key message 1: Hot and humid conditions persist most of this week,
with little relief until this weekend.

Hot and muggy conditions currently ongoing with temperatures
getting well into the mid and upper 90s this afternoon with
dewpts in the upper 60s and low 70s. We decided not to issue a
Heat Advisory for Tuesday as temperatures and dewpts will be
slightly lower compared to the past few days.

Otherwise, broad subtropical ridge will meander over the southern
CONUS over the next few days before the center of the ridge retro-
grades to the southwest CONUS and subtle height falls move in from
the northwest over the CWA. A deep closed low will move across the
central Canadian Providences and set up shop over the Hudson Bay
and northern Quebec by Tuesday and Wednesday, which will send
multiple rounds of shortwave troughs across the region starting
around Thursday once this feature becomes more established. This
will help bring small relief to the region later this week before
an actual cold front makes its way into the region by this weekend
into early next week, helping to potentially knock temperatures
back down a few ticks below normal as a result.


Key message 2: Slight Risk for Severe Weather across western North
Carolina this evening. More seasonally-typical diurnal convection
continues for most of the week.

Convective initiation will be a little later than the typical
start time during peak heating as a very weak frontal boundary
advances across Tennessee this afternoon and moves into the region
overnight tonight. The environment through the evening timeframe
will be primed for severe weather potential ahead of the front with
20-25 kts of deep layer shear, 2500-3500 J/kg of SBCAPE, 1000+
J/kg DCAPE, and decent dry layer in the mid-levels to go along
with steep level lapse rates. CAMs vary as far as how to handle
the coverage for convection as most initiate scattered storms
over east Tennessee and push across the border over the North
Carolina mountains some time after 21Z. With just enough shear,
some of the convection can become loosely organized and would be
the mostly likely culprit for damaging wind gusts. The question
will be how far east can this activity be maintained once it slips
off the terrain into the Piedmont zones later in the evening,
likely after 8 pm. In this case, the environment will lose some
of its steam, but some of the CAMs are killing the activity a
little sooner than we should anticipate as the dewpoints are
mixing out more than what`s actually happening in real time. The
main area of concerns will be across the North Carolina mountains,
foothills, and Piedmont (mainly west of I-77) from 4pm-8pm. Still
can`t rule out severe weather across northeast Georgia and Upstate
South Carolina after 6pm, but the conditional threat is lower as
coverage will be more isolated in these regions.

After today, the atmosphere becomes more suppressed as the
cold front shifts south of the area and any feature that can
provide forcing for ascent will be absent Tuesday and Wednesday,
leading to mostly just some ridgetop convection across the
mountains. Conditions become more favorable for an uptick in
convection by Thursday into the weekend with shortwave troughs
traversing across the southeastern CONUS, but specific details
are in question this far out.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR conditions should prevail outside of
any showers and thunderstorms this evening. There is currently a
line of robust thunderstorms associated with a cold front moving
eastward out of the NC mtns. Over the next few hrs, the activity
is expected to weaken as it moves further east, but it remains
unclear exactly how much it will weaken. As such, I have a TEMPO
for TSRA until 01z at KAVL, one at KHKY until 02z, and TEMPOs at
the Upstate terminals until 04z. For KCLT, I went with a PROB30
for TSRA from 01 to 03z as the convection is expected to weaken
the further east it moves. I can`t rule out some restrictions along
the TN/NC border overnight, but more than likely KAVL will remain
VFR. Nonetheless, depending on the extent of the cloud cover, the
mtn valleys could see some fog/low stratus develop overnight and
into the morning. Otherwise, conditions should remain mostly dry
tomorrow with no mention of showers or storms and few to sct VFR
clouds. Winds should remain N of W in the wake of the front. They
will become more NLY later tomorrow morning and pick up in speed
a bit.

Outlook: Isolated showers and thunderstorms will be possible on
Wednesday, mainly over the mtns. Increased chances for showers
and thunderstorms is expected Thursday and into the weekend. Low
stratus and fog will be possible each morning, especially in the
mtn valleys.

&&

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

&&

$$

CAC/JPT