121
FXUS62 KGSP 100642
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
242 AM EDT Mon Aug 10 2026

.WHAT HAS CHANGED...
A downward adjustment was made to Heat Index this afternoon and
Tuesday afternoon, so Heat Advisory criteria is unlikely to be
met. An uptick in organized severe weather potential is noted
for Tuesday. Temperatures were raised for next weekend, so hot
and humid conditions may persist well into next week. Updated the
aviation discussion for the 06Z TAFs.

&&

.KEY MESSAGES...
1. Mainly isolated to scattered mainly diurnal convection will
continue each day through the week, with some potential for
isolated pulse severe storms that produce damaging wind gusts
and localized excessive rainfall. Organized severe weather will
be a possibility Tuesday afternoon and evening.
2. Hot and humid for the next seven days at least. Some
Piedmont/Upstate locations could see daily afternoon heat index
between 98-103 each afternoon beginning today.

&&

.DISCUSSION...
Key message 1: Mainly isolated to scattered mainly diurnal convection
will continue each day through the week, with some potential for
isolated pulse severe storms that produce damaging wind gusts and
localized excessive rainfall. Organized severe weather will be a
possibility Tuesday afternoon and evening.

Coverage of storms is expected to be less across the region this
afternoon/evening as a weak WNW flow takes over with a shallow upper
trof moving off the East Coast and mid-level dry air moves in. The
HRRR and FV3 are unimpressed with the amount of deep convection
this afternoon and the precip prob fcst reflects this. The RAP has
more modest sfc-based CAPE, perhaps in the 2000-2500 J/kg range this
afternoon, and slightly better but still weak shear. The change is
the introduction of mid-level dry air, which would be more favorable
for strong outflows in the storms that manage to develop. A few
strong/severe pulse storms is a decent bet, even if the coverage is
less than the past few days. The flash flood threat also appears
to be a bit less as the precipitable water drops this afternoon
and the better flow should keep storms moving slowly along.

Tuesday and Wednesday look similar at this time in our forecast,
with limited coverage of storms mostly over the mountains, but I
suspect the precip probs are too low. As we get into the middle part
of the week, there remains some possibility that we will get into
an MCS track. Now that we are getting closer and some of the CAMs
give us a look into Tuesday afternoon, confidence in something more
organized has ticked upward, especially if the HRRR is correct. The
environment across the fcst area is shown by the RAP to be conducive
to an MCS crossing the mtns, though it might be more directed at
the Virginias and not the Carolinas. However, we could conceivably
get some organized storms dropping down across the NW Piedmont
along an outflow boundary. Be that as it may, confidence remains
low for now. The trend in the GFS toward bringing the upper ridge
farther eastward might nudge the MCS track too far to the northeast
to affect our region, especially as we get later in the week.


Key message 2: Hot and humid for the next seven days at least. Some
Piedmont/Upstate locations could see daily afternoon heat index
between 98-103 each afternoon beginning today.

The axis of a broad upper trof, probably the remnant of what was to
our west for several days last week, will migrate off the East Coast
by this afternoon and heights will start to rise while veering the
flow around to more WNW. A weak downslope flow and drier air aloft
should allow for temps to climb a few degrees higher than yesterday,
thus beginning a period of above normal temperatures that looks like
it will persist through the entire forecast period. Some mixing
out of the dewpoint is likely in the afternoon, probably more so
than the model blend indicates so a downward adjustment was made,
which should keep the Heat Index below 103 for today in all but
isolated spots. A similar downward adjustment to the dewpoint
was made Tuesday afternoon based on the pattern and experience,
which should keep the Heat Index out of advisory range. It will be
seasonally hot though, with highs five degrees above normal and into
the middle 90s most places outside the mtns. We come under a more
NW flow aloft by mid-week and it would appear that dewpoint will
be less likely to mix out, so the heat might slowly build each day
and reach a peak Thursday or Friday. Those two days have the best
chances for getting up to 105 on the Heat Index. As to next weekend,
the models have trended toward a more pronounced eastward drift
of an upper anticyclone from the srn Plains to the lower MS Valley
and Southeast by Saturday and Sunday. Unfortunately, that means the
cool-down shown by previous runs next weekend is much less likely,
and the heat might persist well into the following week.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: The deep convection has finally fallen
apart, but some patches of light rain persist along with extensive
convective debris cloudiness. The mtns have cleared off enough to
allow for the development of low stratus in the valleys, and this
should continue for the next few hours. Thus, restrictions look
like a good bet for KAVL by 08Z at the latest. As per the last few
nights, suspect conditions will be highly variable again between
VFR and LIFR with vis and ceiling. KHKY also has good chance
at restrictions. Elsewhere, some fog will be possible at KGSP
and KCLT because precip fell this past evening, so that will be
monitored. After the morning restrictions mix out...VFR. The flow
should be more westerly than the past few days, and not quite as
favorable for storm coverage. So, PROB30s should suffice over the
mtns and Upstate for this afternoon. By mid-evening, the convection
should die off and we do it all over again tonight.

Outlook: Isolated-to-scattered diurnal showers and thunderstorms
with associated flight restrictions are expected through
the week. Patchy fog and low stratus is possible each morning,
especially in the mtn valleys and anywhere that received significant
rainfall the previous afternoon/evening.

&&

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

&&

$$

PM