440
FXUS62 KGSP 060251
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1051 PM EDT Sat Jul 5 2025

.SYNOPSIS...
Tropical cyclone Chantal will move into and across the coastal plain
of the Carolinas through Sunday night.  Hot and more humid
conditions will return on Monday and linger through midweek
featuring daily afternoon and evening shower and thunderstorm
chances.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 1045 PM Saturday: Conditions remain quiet and dry across
the forecast area this evening. Attention now turns to Tropical
Storm Chantal, which is forecast to make landfall along the South
Carolina coast later tonight before turning north and then northeast
across the Carolinas on Sunday and Sunday night.

There remains significant uncertainty regarding the potential
for a narrow heavy rain band to organize on the northern side
of the circulation as the system moves inland. Most model
guidance continues to favor this axis remaining well east of the
forecast area, but a small subset of high-resolution models -
including the 12Z Hires ARW and several 12Z REFS ensemble
members - suggest a longer-sustained band farther to the west
that could clip the eastern portions of the forecast area,
particularly near the I-77 corridor. These solutions have
already verified too far west and appear to be suffering from
convective feedback, as many also deepen the low post-landfall
in concert with the organizing rain band, a scenario not
supported by the broader consensus or the latest trends. More
recent 18Z and early 00Z guidance have trended eastward with the
heavy rainfall axis. Confidence remains very low in any
impactful rainfall west of the I-77 corridor, but we will
continue to closely monitor short-term trends overnight for
signs of rainband organization and an expansion farther west
than currently forecast.

Our eastern zones remain on the western periphery of the storm`s
circulation but direct impacts still look minimal. Most likely winds
will remain well below tropical storm criteria although frequent
gusts to around 20 mph are expected in our eastern zones by the
wee hours Sunday and continuing thru the day; there would appear
potential for an occasional gust up to around 25 mph particularly
Sunday morning. Abundant low cloud cover is expected in that area
from early morning thru most of the day, so fcst max temps are held
into the lower to mid 80s there. In the western half of the area,
max temps will be near normal, but perhaps trend slightly warmer
in the French Broad and Little TN Valleys owing to downslope NE
flow off the ridges.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 1245 PM Saturday: The northerly pressure gradient between a
filling Chantal and weakening sfc ridge will continue to loosen
Sunday night giving way to the onset of SW flow, albeit weak at
first, through a deeper layer on Monday.  The heat returns on
Monday, featuring Piedmont lower to mid 90s along with a return to
more typical diurnal tstm chances regionwide.  Upper heights atop
the SE CONUS creep upward on Tuesday, and within the continued WAA
flow, Piedmont maximums will boost into the middle 90s with apparent
temperatures potentially in the lower 100s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 115 PM Saturday: In response to Ohio/Miss Valley energy
rippling eastward, upper ridging atop the region will start to break
down on Wednesday.  But the hot and humid air will linger one more
day featuring middle 90s again in the Piedmont.  For the rest of the
workweek, temperatures will fall back closer to the July climo as
flatter flow/subtle troughiness develops acrs the Eastern CONUS.
The latter half of the period is shaping up be an active one with
the potential for daily showers and tstms to become numerous each
day given seasonably high, if not above normal PWAT values within a
long period of moderate WSW flow.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Tropical Storm Chantal is forecast to make
landfall along the SC coast tonight and then turn northward across
the Carolinas, passing 50-150 miles east of CLT Sunday night. The
pressure gradient between Chantal and high pressure centered along
the Blue Ridge will keep winds elevated in the 5-10 kt range for
much of the night across most terminals. Forecast soundings show
the potential for occasional gusts just under 20 kt, particularly
within the first few hours after sunset and again late tonight. AVL
and HKY, however, will be located closer to the ridge axis where
a weaker pressure gradient will allow for winds to become light
(under 5 kt).

For CLT: MVFR CIGs are expected to develop as early as 09Z at CLT,
but most likely will hold off until around 12Z or 13Z. Forecast
trends provide greater confidence for the leading edge of showers
from Chantal to reach CLT during the day Sunday. Onset timing
is most likely between 14Z-17Z. There is still quite a bit of
uncertainty regarding the potential for a rainband to organize
on the poleward side of the circulation, and if it does, how far
west can it set up. Most model solutions that support the scenario
keep the axis of heavy rain east of CLT, but there are some western
outlier solutions that bring it to CLT, resulting in several hours
of low visibilities in IFR or worse. Added a PROB30 for IFR in
the 00Z TAFs between 18Z-21Z to hint at the possibility of this
happening, but that approach might be a bit aggressive compared
to the support from CAM ensembles. NE winds of 10-15 kt with
gusts in the 18-22 kt range are possible during the day - but the
strongest winds are expected to occur in the morning. Rain chances
quickly taper off between 21-00Z. Low clouds may redevelop after
sunset. Added prevailing MVFR restrictions the last few hours of
the 30-h TAF, but there is a potential for CIGs to tank quicker
than advertised, perhaps to IFR by 06Z.

Elsewhere, while rain showers may extend as far west as AVL-
GSP-GMU, impacts should be minimal. Prevailing VFR is forecast
outside of CLT although there is a hint of CIGs approaching MVFR
at KHKY after 12Z with the addition of a SCT030 deck. Winds
will be similar to CLT with forecast speeds only a few knots
lower.

Outlook: Models generally indicate a stratus deck to develop Sunday
night-Monday morning to vary degrees. The western extent of the
stratus deck will depend on how far inland the afternoon rainfall
and tropical maritime layer advances on the backside of Chantal`s
circulation. Typical summer weather returns Monday and much of
next week, with scattered SHRA/TSRA mainly in the afternoons
and evenings, and fog and/or low stratus possible each morning,
mainly in valleys or where heavy rain falls the previous afternoon.

&&

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

&&

$$

SYNOPSIS...CSH
NEAR TERM...JK/Wimberley
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...JK