103
FXUS62 KGSP 111027
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
627 AM EDT Thu Jun 11 2026

.WHAT HAS CHANGED...
Updated the aviation discussion.

&&

.KEY MESSAGES...
1. Mainly diurnal convection into the weekend.
2. Hot and humid conditions develop today and continue into
the weekend.

&&

.DISCUSSION...
Key message 1: Mainly diurnal convection into the weekend.

Mountain valley fog, and patchy fog elsewhere, dissipates after
daybreak leaving mostly sunny skies. An upper ridge slowly builds
into the area today with a shortwave dropping down the east side of
the ridge across the mountains and northern tier. The air mass will
be very unstable and the wave should help initiate convection over
the mountains and I-40 corridor. Outside of the mountains, high
LFC`s and a lack of forcing will limit initiation and actually help
dissipate convection as it moves out of the mountains, the I-40
corridor being the exception. Shear is light but high dCAPE and sfc
delta theta-e values will lead to a severe downburst threat for
storms that become strong enough. The heavy rain threat is limited
due to the overall drier airmass.

The upper ridge reasserts itself on Friday creating even higher
LFC`s. However, a shortwave barrels into the ridge and an old MCS
boundary moves into the mountains during the afternoon. CAM guidance
shows convection initiating along this boundary with good coverage
over the mountains. Even with the poor conditions outside of the
mountains, forcing will be enough to overcome that over the NC
foothills and Piedmont bringing scattered late afternoon and early
evening convection there. The forcing weakens to the west with only
an isolated chance over the western Upstate and NE GA. The
atmosphere is again very unstable with light shear. High dCAPE and
sfc delta theta-e values continue as well. Severe storm chances will
be better given the semi-organized nature of the convection. This
has prompted SPC to introduce a Slight chance of severe over the NC
mountains, foothills, and I-40 corridor with a Marginal chance south
of there to the I-85 corridor. The semi-organization will lead to a
better chance of locally heavy rainfall, especially over the
mountains.

Convective chances diminish on Saturday with warmer mid-level temps
limiting instability and lapse rates.

A series of shortwaves knock down the ridge and cross the area
bringing zonal flow early next week and a trough by mid week. This
brings weak frontal systems into the area and increasing chances of
convection.


Key message 2: Hot and humid conditions develop today and continue
into the weekend.

The upper ridge building over the area will lead to increasing heat
into the weekend. Highs in the lower 90s will be common outside of
the mountains today with mid 90s on Friday. Even the warmer mountain
valleys will see highs around 90 on Friday. Highs drop a few degrees
for the weekend, but lower 90s will again be common outside of the
mountains. Confidence is increasing on these hot temps; however,
confidence remains low on the dewpoints which will be what
determines the resultant heat index. Right now, we have the heat
index approaching 100 south of I-85 today, but they may very well
remain below 100 if dewpoints mix out more than expected. Friday is
the hottest day with the potential for for heat index values to
eclipse 100 over the I-77 and I-85 corridors. Right now, it appears
the heat index will be less than 105, but if temps or dewpoints end
up a little higher, than a Heat Advisory would be needed. Heat index
values will be near 100 again on Saturday and Sunday with the
slightly cooler temps.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Mountain valley fog hasn`t reached KAVL and
may not before dissipating. The same with lake fog at KAND. KHKY has
VLIFR fog which should dissipate before 14Z. Otherwise, low VFR
stratocu lifts to high based Cu by afternoon. Guidance shows diurnal
convection should be limited to the mountains and foothills, so
PROB30s at KAVL and KHKY. Mountain valley fog expected again
overnight. Light SW or light and variable wind this morning picks up
from the SW, N at KAVL, during the day, going back light overnight.

Outlook: Diurnal convection and associated restrictions are expected
into early next week. Mtn valley fog and low stratus will be
possible each morning.

&&

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

&&

$$

RWH