450
FXUS62 KGSP 170204
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1004 PM EDT Mon Jun 16 2025

.SYNOPSIS...
Hot and humid with daily chances for showers and thunderstorms
through Thursday. A cold front pushes across the area early
Friday, bringing a reduction in rain chances lasting through the
weekend. Although humidity looks lower this weekend, temperatures
will trend hotter.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 945 PM EDT Monday...

Key Messages:

1) Hot and Muggy, Especially East of the Mountains, with Above
Normal Temps Expected

2) Similar Coverage of Diurnal Showers and Thunderstorms Tomorrow

3) Severe Threat Remains Low but Isolated Flash Flooding Remains
Possible with any Storms that Develop through the Near Term


A cluster of storms has developed between Spartanburg and
Charlotte, where there is still over 2000 J/kg of MUCAPE and
enhanced convergence along outflow boundaries. This activity should
gradually weaken as it drifts eastward, but we could see lingering
convection near the boundary for the next 2-3 hours. There is also
an uptick of mainly showers and general thunderstorms across the
NC mountains. Not really seeing anything that should keep this
activity going into the night. So with all that said, tweaked PoPs
to capture the radar trends, then have them gradually decrease
late evening into the overnight.

Otherwise...our marginal flash flood threat is winding down as we
lose coverage of deeper convection. The main concern will be west
of Charlotte along this stalled outflow boundary over the next
couple hours. Partly cloudy overnight with fog and low stratus
likely developing in the mountain valleys and across portions of
the NC foothills and Piedmont before daybreak Tuesday.

Highs east of the mountains will climb into the upper 80s to
lower 90s, with heat indices climbing into mid to upper 90s and
lower 100s. Lows tonight will only drop into the 60s and 70s
making for another muggy night. Low stratus and patchy fog may
develop again overnight into daybreak Tuesday (especially for any
locations that receive heavy rainfall) but should lift quickly
after sunrise. Another day of diurnal convection can be expected on
Tuesday with the severe threat remaining low but with the locally
heavy rainfall/isolated flash flooding threat continuing.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of midday Mon, key messages:

1. Conditions will be somewhat less favorable for diurnal showers and
thunderstorms Wednesday compared to the previous day, so
chances/coverage should trend downward.

2. Approach of an upper trough and cold front imply coverage will
tick upward again Thursday, especially over the NC mountains.

3. Temperatures remain slightly above normal both days with typical
June humidity.

A compact shortwave trough is progged to be centered west of the
southern Appalachians Tuesday evening, primarily over central KY/TN.
Although model consensus is for it to fill and/or track northeastward
from there overnight, enhanced SW`ly flow will continue into our NC
mountains and some showers/storms could regenerate; PoPs persist most
of the night. A weak convergence axis associated with the trough does
appear to shift over the mountains during the day Wed.  Despite
similar CAPE and lapse rates, the mid to upper levels are subtly
drier and thus less conducive to deep updrafts.  The convergence axis
seems to help overcome that over the mountains, but not for the
Piedmont. While PoPs overall trend downward, they remain in likely
range over the mountains, and slight-chance to low chance most other
areas. Where storms do form, some training cannot be ruled out, so a
localized flash flood threat will persist, although decreased PWATs
will mitigate rates. Drier air aloft may increase storms` damaging
wind potential. With shear is likely to fall in the 20-25 kt range
over much of the area so multicell storms would be favored over pulse
storms, but damaging wind can`t be ruled out. No SPC risk contour in
our area as of this writing.

Sfc low will track thru the eastern Great Lakes region late Wed night
into Thu morning. Associated cold front and synoptic trough axis will
move across the Cumberland Plateau Thu, reaching the TN/NC border Thu
evening. Prefrontal convergence potentially will enhance convective
coverage compared to Wed, so PoPs are higher and persist longer into
Thu evening. Shear will improve a little bit in the faster midlevel
flow around the trough, with the mean closer to 25 kt in our north
and some ensemble members showing 30+ kt. The SPC Day 4 outlook,
issued overnight Sun night, depicts a 15% risk area centered in the
Mid-Atlantic, extending into the NC Piedmont ahead of the shortwave,
reflecting the slightly better shear but arguably moreso the
increased coverage. Damaging wind still would appear the most likely
threat. PWATs do increase again, but with storms moving a little
faster the threat of heavy rain probably will remain isolated.
Antecedent soil conditions will have had more time to deteriorate
where heavy rain repeats from day to day.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 200 PM Mon, key messages:

1. In the wake of a cold front, atmospheric moisture is likely to
decrease Friday, but probably will build back gradually over the
weekend.  Convective coverage likely will be reduced in this period
compared to in the middle of the week.

2. Temperatures will trend warmer Saturday and Sunday, potentially 6-8
degrees above normal by Sunday. Despite relatively low humidity, heat
impacts are possible in some areas.

Drier air looks increasingly likely to have sensible weather effects
in our CWA by Friday, following the cold fropa. The major
deterministic models and Euro/NAEFS ensembles suggest PWATs fall
below climo. In terms of dewpoint, most guidance members depict
values a few degrees lower Friday than in the midweek period, and
there is more spread among members on the low side of the mean,
suggesting some potential for a midafternoon dip via mixing.
Although that accordingly suggests lower CAPE, there appears
insufficient subsidence to produce a capping inversion, so a 20-30%
PoP is still warranted for most of the area. Upper anticyclone does
center over the area Saturday and linger Sunday, so the potential for
capping would appear higher those days, although surface moisture
does begin to build back as airmass modifies. Similar 20-30% PoP
distribution continues thru the weekend.

Friday will be slightly cooler over parts of the area via the fresh
post-frontal airmass, but trend warmer Saturday and Sunday via the
modification and light southerly flow. Aftn maxes will reach the
mid-90s over most of the Piedmont by Sunday, with the Little TN and
French Broad valleys flirting with 90 both days. Dewpoints will be
manageable and largely in the upper 60s across the Piedmont, but
areas southeast of I-85 are likely to have heat index above 100
Sunday, if not Saturday, in some cases the first period of heat
concern this year.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Still scattered convection in the
mountains and around KCLT at 00z issuance. Storm may impact KCLT
in the first hour of the TAF, then things should trend down thru
the evening. Some lingering VFR-level clouds overnight, with
mountain valley fog and low stratus possible late tonight thru
daybreak Tuesday. Both KAVL and KHKY had rainfall at the terminal
and have best chance of some restrictions. Have tempo for both
sites. Confidence too low elsewhere. Convection on Tuesday looks
to favor the mountains, but still expect scattered TSRA in the
Piedmont too. Will go with PROB30 at all sites during the typical
aftn to early evening hours. Winds will be out of the SW thru the
period, except VRB around TS.

Outlook: Isolated to scattered showers and thunderstorms are
expected each afternoon/evening through Thursday. Drier conditions
return behind a cold front Friday into Saturday. Fog and/or low
stratus will be possible each morning.

&&

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

&&

$$

SYNOPSIS...Wimberley
NEAR TERM...AR/ARK
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...ARK