692
FXUS62 KGSP 162230
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
630 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 600 PM EDT Monday...

Key Messages:

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

2) Better Coverage of Diurnal Showers and Thunderstorms Today with
Similar Coverage Possible Tomorrow

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

The bulk of the convection is beginning to shift to the I-77
corridor, with just isolated to scattered activity elsewhere across
the CWFA. Will continue to see convection popping up until sunset,
then things should wane this evening. Overall, the forecast is on
track. Blended in the latest CONSShort PoPs to show the decreasing
trend in the western half of the CWFA. Temps are in good shape,
except where convection has overturned the atmosphere and brought
temps down.

Otherwise...despite 2,500-3,500 J/kg of SBCAPE expected today
per the SPC mesoanalysis, DCAPE is expected to remain less than
800 J/kg through peak heating (most areas will only see up to
500 J/kg of DCAPE), the severe threat will once again remain
low today.  Confidence is higher that we could see a few strong,
sub-severe storms develop through sunset. Activity will gradually
wane near/after sunset with the loss of daytime heating.

There is more concern regarding the locally heavy rainfall/isolated
flash flooding threat through early this evening. The SPC
mesoanalysis page shows roughly 2" PWATs in place across the CWA
this afternoon, which is above the 90th percentile for this time of
year. So, any convection that develops will be capable of producing
locally heavy rainfall. The 3 hour probability match mean (PMM) on
the 12Z HREF shows areas of 2.0-2.5 inches along and north of I-40
for this afternoon and 3 hour flash flood guidance shows similar
values. So, isolated flash flooding will be a concern if we end
up exceeding flash flood guidance, mainly for locations along and
north of I-40. This does not omit the rest of the forecast area
from the locally heavy rainfall/isolated flash flooding threat
as it is difficult to pinpoint exactly where the heaviest rain
will fall and cause flooding issues this time of year due to this
being pulse convective season. With any hydro/flash flooding issues
expected to remain isolated, opted to not issue a Flood Watch at
this time as we try to reserve our Flood Watches for higher impact
and/or more widespread flood events.

Highs east of the mountains will climb into the upper 80s to lower
90s each afternoon, 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 /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Scattered SHRA and TSRA have developed across
mainly the NC mountains and northern SC Upstate this afternoon.
Chances will continue to gradually blossom through the early evening
hours, especially at KAVL and KHKY. Thus, maintained TEMPOs for TSRA
and associated restrictions. Went with PROB30s elsewhere as
confidence is lower on whether a storm will track directly over the
terminal as it`s hard to pinpoint exactly where pulse convection
will develop this time of year. VFR cu field has developed this
afternoon and will linger through early this evening before
diminishing around sunset with the loss of daytime heating. Will
keep SCT to BKN VFR cloud cover in place through late tonight. The
NC terminals will have the best chance to see patchy fog and low
stratus develop overnight into early Tuesday morning, especially any
terminals that receive heavy rainfall today. KHKY and KAVL have the
best chance to see IFR to MVFR cigs/vsbys develop so have introduced
TEMPOs at these terminals for restrictions. KCLT may see MVFR cigs
develop around daybreak. Any fog/stratus that develops should lift
shortly after daybreak Tuesday morning. Another round of SHRA/TSRA
will develop Tuesday afternoon/evening so Went with VCSH at KAVL and
a PROB30 at KCLT towards the end of the TAF period as these sites
are most likely to see activity develop. Maintained dry conditions
elsewhere as activity should hold off until after the 18Z TAF
period. Wind direction will be primarily SW east of the mountains
with low-end wind gusts possible each afternoon across the
terminals, especially across the SC Upstate. Wind direction will be
VRB through tonight at KAVL before picking up out of the S/SW after
daybreak Tuesday. VFR cu and cirrus will return Tuesday afternoon.

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...AR