Black Mountain, North Carolina Weather Forecast Discussion

087
FXUS62 KGSP 232320
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
720 PM EDT Tue Sep 23 2025
.SYNOPSIS...
Scattered showers and thunderstorms return Wednesday afternoon into
Wednesday night, mainly across the mountains and the North Carolina
Foothills. Shower and thunderstorm chances increase for the entire
forecast area Thursday ahead of a cold front, lingering into Friday
behind the front. Highs remain well above normal through Wednesday
before much cooler highs return Thursday into the weekend, with
shower and thunderstorms chances lingering through the weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 720 PM EDT Tuesday: Made some minor tweaks to PoPs based on
the latest KGSP radar loops. Otherwise, showers (and the occasional
thunderstorm) continue tracking ENE across the northern NC mountains
and northern Foothills this evening. Activity should gradually wane
through sunset with mostly dry conditions returning.
For tonight, after the short wave passes, the flow aloft will be
nearly flat as an upper anticyclone remains stretched out to our S
and two upper low centers over the central High Plains and Upper
Great Lakes essentially keep a very positively tilted upper ridge
axis to our N. A few showers may develop at times along the NC/TN
border overnight and an increase in moisture and cloud cover might
keep the mountain valley fog at bay again, as it did this morning.
Low temps are expected to be warm, running 8-11 degrees above
normal.
Not much change is expected Wednesday as the high Plains upper low
pivots eastward to the Ozarks and mid-MS Valley regions. This will
back the flow aloft around to something more SW during the day,
which should essentially keep shower activity stuck over the higher
terrain. Looks like the warmest day yet, though, with high temps on
the order of 9-12 degrees above normal. Nowhere near a record,
though.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 105 PM EDT Tuesday: An upper low spins over the Great Lakes on
Thursday then opens and moves off the New England coast Friday. A
trough stretches southwest of the low across the OH and lower MS
River valleys. A strong short wave dives into this trough and closes
off into an upper low over the Mid-South. This low moves into the
Middle TN Valley on Friday. Our area will be in SW flow ahead of
these systems with short waves moving through the flow and across
the area. At the surface, broad SW flow will be in place ahead of a
cold front that moves into the area late in the day. There will be
enough forcing and moisture for categorical PoP over the mountains,
with likely PoP spreading eastward into the evening. The question is
how much heating can take place. If heating is limited, instability
will be as well limiting any severe storm potential. If decent
heating can take place, then moderate instability would be possible.
This combined with 30 to 40 kts of shear would lead to the potential
for some severe storms with damaging winds the main threat. SPC
currently has our area in a Marginal risk which matches these
parameters. Right now, it appears that rainfall amounts will be in
the "much needed" category, mainly an inch or less for all but
portions of the mountains near the TN border. As the front crosses
the area Friday, moisture and forcing remain elevated but
instability will be weak. Thunderstorms are expected but the severe
potential will be much lower. Rainfall again generally less than an
inch. Highs are expected to be near normal for all but the I-77
corridor and south of I-85 in the Upstate and NE GA where they will
be around 5 degrees above normal. All areas will be near to slightly
below normal on Friday. Lows will be above normal both days.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 125 PM EDT Tuesday: The TN Valley upper low slowly moves into
the Carolinas by Sunday. The low then retrogrades to the Lower MS
Valley by Tuesday as an anti-cyclone builds over the top of it
across the Midwest, with the pattern taking on the look of a Rex
Block. Friday`s cold front stalls along the Carolina coast Saturday
through Monday with a series of low pressure waves moving northward
along it. The front then moves offshore Tuesday. There looks to be
enough moisture rotating around the developing easterly flow from
the low pressure waves and high pressure building in from the north,
for mainly scattered diurnal convection Saturday through Monday.
Precip chances then drop to slight chance on Tuesday as drier air
begins working in. Moderate QPF is possible Saturday with lighter
amounts through the rest of the period. Highs start out a few
degrees below normal Saturday then remain around normal through the
end of the period. Lows start out slightly above normal then remain
around normal through the end of the period.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: VFR and dry for most terminals through the
00Z TAF period, with the exceptions being KAVL and KHKY. KAVL may
see mountain valley fog and low stratus develop overnight into
daybreak Wednesday but confidence is low with upper cloud cover
expected to limit radiational cooling. Thus, maintained the TEMPO
for IFR restrictions from 10-13Z this TAF update. Showers may
develop again at KAVL Wednesday afternoon and evening, possibly
reaching KHKY. Could not rule out TSRA entirely but confidence is
low. Thus, went with PROB30s for -SHRA at KAVL and KHKY tomorrow
from 20Z-24Z. Cloud bases will gradually lower Wednesday
afternoon/evening but should remain VFR. Could see some VFR cu
develop again during peak heating hours Wednesday as well. Winds
will generally be light and VRB to calm this evening into tonight,
favoring at S/SW direction at times. Wind direction will primarily
be S/SW on Wednesday with speeds ranging from ~4-9 kts. Could not
rule out a few isolated low-end gusts Wednesday afternoon but
confidence is low.
Outlook: Shower and thunderstorm chances, as well as associated
restrictions, increase for all terminals Thursday into Friday in
association with a cold front. Shower and thunderstorm chances may
stick around through the weekend. Mountain valley fog and low
stratus are possible each morning.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...AR
NEAR TERM...AR/PM
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...AR

NWS GSP Office Area Forecast Discussion