868
FXUS62 KGSP 060109
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
909 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 145 PM Sat: Still expecting a rather quiet Saturday for this
time of year. NE`ly low level flow continues between dry high
pressure centered east of New Jersey and developing TS Chantal
off the GA/SC coast. Vertical profiles feature little moisture
above the PBL and dewpoints should mix out to some degree this
afternoon. Hi-res models depict a subsidence inversion capping off
diurnal convection, and this is further supported by morning ACARS
soundings depicting inversion over CLT even stronger than what the
HRRR showed. Thus PoPs are forecast to be below slight-chance in
all zones this afternoon/evening.

The 15z NHC advisory maintained a similar track to the previous
cycle, although slightly faster forward motion is depicted, and
the track inland is very slightly further west. 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. Precip potential has ticked slightly higher east of I-77
owing to the more inland track, increasing confidence that rain
bands will reach that area, still highlighted by WPC Marginal
Risk ERO. That said, the heaviest rain still looks to fall to our
east. The SPC Day 2 risk area did add a 2% tornado contour on the
east side of the track, also still to our east. A few rumbles of
thunder are possible Sunday aftn near I-77 but deeply saturated
tropical profiles keep CAPE relatively low. 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 /00Z 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...Wimberley
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...JRK