650
FXUS62 KGSP 101040
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
640 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, and possibly Wednesday.
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, and possibly Wednesday.

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. Note that the SPC Day 2
Severe Outlook has a Marginal Risk cutting down across the northern
mountains/northern foothills/NW Piedmont. The new Day 3 supports
the notion of an MCS track pointed at us for Wednesday. 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 /12Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Variable low clouds and fog pose the threat
for flight restrictions at the terminals near bodies of water early
this morning. After the morning restrictions mix out...prevailing
VFR at all terminals. 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