-- Discussion containing changed information from previous version are highlighted. --
418
FXUS62 KGSP 091047
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
647 AM EDT Wed Jul 9 2025

.SYNOPSIS...
Hot and humid conditions will cool closer to normal late this
week with numerous afternoon and evening showers and thunder-
storms expected each day. Temperatures increase again over the
weekend and early next week as an upper ridge amplifies. Diurnal
showers and thunderstorms will continue each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 640 AM Wednesday: Mountain valley fog, and patchy fog
elsewhere, will dissipate quickly this morning.

Overall a much better chance of convection today with a moist,
unstable air mass over the area. Dewpoints will mix out somewhat
this afternoon, but not nearly to the extent of yesterday. This will
lead to SBCAPE in the 2000 J/kg range. Weak height falls are
expected as a short wave approaches the area. Surface forcing will
be improved by an old outflow boundary moving in from the west. With
less mixing, LFC`s will be lower leading to thicker CAPE profiles
than the last few days despite meager lapse rates. Bulk shear
romaines 20 kts or less, with higher values north of our area. DCAPE
and sfc delta thet-e values are also lower than the past few days
due to deeper moisture, but they won`t be eliminated. CAMs are in
general agreement of convection initiating over the mountains and
moving south and east across the area. A consolidating cold pool
could help storms become semi-organized as they cross the area. All
of this to say severe thunderstorms are possible with damaging winds
in wet microbursts the main threat. That said, there is some large
hail potential as well given the thicker CAPE profiles. Guidance is
also consistent on better heavy rain potential to our east; however,
with the high PW values and somewhat organized convection, there will
be an isolated flash flood threat. Some of the CAMs show merging
convection from the mountains and convection moving NE along the sea
breeze which moves well inland from the coast. This could slow
convection down and potentially lead to some training cells. Given
the uncertainty of timing and location of this potential, will hold
off on any watches at this time. Highs will be few degrees above
normal today, so even with less dewpoint mixing, heat index values
remain below 105.

Convection lingers into the evening then dissipates or moves east of
the area around midnight. Mountain valley fog is expected once
again, and areas of low clouds and fog will be more likely
elsewhere. Lows will be near to slightly above normal.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 1:25 AM EDT Wednesday: The short-term fcst picks up at 12z on
Thursday with broad upper ridging to our east and west. The large-
scale upper pattern won`t change much thru the period, with numerous
weak upper impulses translating over our area on Thursday and Friday.
At the sfc, we will remain under the western periphery of the Bermuda
High. This will keep moist, SWLY, low-lvl flow over our area thru the
period. We can expect active weather each day with sct to numerous
showers and thunderstorms each afternoon and evening. The persistent
SWLY low-level flow and favorable storm-motion vectors suggest a con-
tinued risk for isolated areas of excessive rainfall and localized
flooding each day. Model profiles continue to support some strong to
severe storms each day as well. High temperatures on Thursday should
remain near-normal with highs topping out a few degrees above-normal
on Friday. Heat indices should remain below Advisory criteria thru the
period.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 1:15 AM EDT Wednesday: The extended period picks up at 12z on
Saturday and is expected to remain active thru the period. Our area
will remain on the western periphery of the broad, subtropical Bermuda
High and broad, weak high pressure to our west and north. A couple of
low pressure systems will lift up and over the Great Lakes region thru
the period, but any frontal boundaries associated with these systems
are expected to wash out/dissipate as they approach our area. Our area
will remain under moist, SWLY low-level flow thru the weekend. Early
next week, low-level winds could take on a weak NLY component, but they
will likely be light and vrb for much of the time. Aloft, numerous weak
shortwaves will move across the OH and TN valleys and over the central
and southern Appalachians over the weekend and early next week. This
energy aloft will help support above-climo PoPs over the mtns and near-
climo PoPs outside the mtns each afternoon/evening. Towards the end of
the period, diurnal PoPs increase to likely across most of our CWA. At
this time, there doesn`t appear to be a significant severe wx threat any
particular day, with isolated strong to severe thunderstorms possible
each day. With the persistent moist airmass in place, the bigger threat
will likely be excessive rainfall from thunderstorms that could produce
localized flooding. Otherwise, high temperatures are expected to remain
about a category above normal thru most of the period. Dewpts are fcst
to remain low enough to keep heat indices below Heat Advisory criteria,
although some values between 100 and 105 degrees are possible over our
southern Upstate and Piedmont zones each day.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
At KCLT and elsewhere: Mountain valley fog, and patchy fog
elsewhere, dissipates quickly this morning. A better chance of
convection today with a moist, unstable air mass and boundary
interaction. Have gone with a mix of TEMPO and PROB30 to indicate
the best times for convective coverage. Low clouds and fog are more
likely overnight. Generally MVFR cigs drop to IFR or even LIFR. Vsby
restrictions a little more fickle, so put MVFR to IFR at the
normally more foggy locations. Light S to SW wind this morning,
picks up speed during the day, then turns NW behind the convection
at KAVL and light and variable elsewhere. There will be some
potential for strong thunderstorm outflows, so expect variable
flight conditions and strong gusts near storms.

Outlook: Typical summertime weather is expected into the
weekend, with scattered to numerous thunderstorms mainly in the
afternoon/evening and fog and/or low stratus possible each morning.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...JPT
NEAR TERM...RWH
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...RWH