950
FXUS62 KGSP 300005
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
805 PM EDT Fri May 29 2026

.WHAT HAS CHANGED...
Updated the aviation discussion for the 00Z TAFs.

&&

.KEY MESSAGES...
1. The potential for locally heavy rainfall and isolated flash
flooding returns tonight into Saturday. Briefly cooler and drier
on Sunday before rain returns Monday.
2. Dry and cooler than normal weather is expected Tuesday through
at least Thursday. Slightly warmer with low chance of diurnal
convection Friday.

&&

.DISCUSSION...
Key message 1: The potential for locally heavy rainfall and isolated
flash flooding returns tonight into Saturday. Briefly cooler and
drier on Sunday before rain returns Monday.

Shortwave over the lower MS Valley will shift toward the Carolinas
through tonight, promoting development of SW flow above the boundary
layer, resulting in warm upglide over the stalled front. PWATs trend
back upward via the associated moisture flux with values at or above
1.75" by early Saturday morning (~150% of normal) over GA/SC if not
the southern tier of NC zones, and though lapse rates are
accordingly weak aloft, most model runs show at least a couple
hundred joules of MUCAPE, with potential for even higher values over
the SW CWA. Wind speeds through the column remain pretty weak,
suggesting slow storm motion, and MBE vectors are small so
backbuilding also would appear likely. As noted on previous forecast
cycles, CAM convective response with rainfall rates concerning for a
flash flood threat is isolated; the REFS 3-hr PMM shows similar
coverage of 2-3" totals from individual storms compared to the past
few runs, and values for the same field from the HREF have trended
lower overall on the latest run. Thus it will be worth monitoring
for a localized flash flood threat overnight into early Saturday
morning, but not looking worthy of a Flash Flood Watch.

There looks to be a lull in the convection over the stationary front
after daybreak Saturday as midlevel winds wane diurnally. A mature
area of low pressure off the Northeast coast still is expected
to pull a backdoor cold front into NC early in the day, at the
leading edge of a cool/dry high building south from Hudson Bay
across the Great Lakes. The front then progresses south across the
rest of the CWA through evening. PWATs will remain similarly high
preceding it. Diurnal destabilization is put somewhat in question by
the potential for low stratus and early morning convective debris
taking time to scatter, but despite abundant high altitude cloud
cover lingering into afternoon on the HREF, its SBCAPE probs still
suggests 500+ J/kg are likely to develop near peak heating, with
1000+ J/kg more likely over GA/SC. CAMs mostly produce isolated
to scattered cells along the front as it sinks southward in the
afternoon. Potential for locally excessive rainfall will persist
with this diurnal convection; storm motion would probably be
a little faster but with more potential instability, and the
storms could occur over areas with soils wet from heavy rain
overnight. 0-6km shear is stronger to our east where the gradient
aloft is stronger around the offshore low. The severe threat would
appear to be limited in our area assuming the shear and instability
remain in check as most guidance suggests. So a situation where
we destabilize more due to earlier scattering of clouds, or if
any storms are still ongoing along the front in the far southern
CWA during the evening when shear begins to increase, a threat of
damaging wind and possibly marginally severe hail could materialize.

Saturday`s front will have settled to a position on our southwest
fringe once again by Sunday morning, and moist SE to S flow again
develops over the front, probably producing some cloud cover that
will keep temps on the order of 10 below normal, in conjunction
with the cooler/drier airmass. Lapse rates are poor under the high,
and convection should be suppressed over most of the area. Small
PoPs linger over the far western mountains and in parts of the
Savannah River Valley nearest the front.

The Friday-Saturday pattern evolution almost repeats Sunday
night into Monday as the front once again reverses, warranting
increasing PoPs overnight, and then another reinforcing backdoor
cold front coming in from the north during the day. Hence PoPs
increase. PWATs will start out generally lower Sunday evening,
but by Monday will have rebounded enough for another potentially
localized flash flood threat with convection as the cold front
moves through. Temperatures return to near normal Monday.


Key message 2: Dry and cooler than normal weather is expected Tuesday
through at least Thursday. Slightly warmer with low chance of
diurnal convection Friday.

An upper low off the Mid-Atlantic coast will keep northerly flow and
anomalously low heights over the area Tuesday and Wednesday. The low
begins to pull east Thursday and Friday with an upper ridge axis
moving east toward the area. Cool and dry high pressure builds in
from the north Tuesday and Wednesday then slides east Thursday and
Friday with weak southerly flow developing. The result will be dry
conditions with below normal temps Tuesday and Wednesday. A slow
warming trend, but still below normal, Thursday and Friday. Weak
moisture return begins Friday, leading to a low end chance of
diurnal convection, mainly across the mountains.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Mostly dry conditions expected through late
this evening before rain chances return late tonight into daybreak
Saturday as a front remains stalled south of the area. Could not
entirely rule out some TSRA embedded at times tonight into Saturday
morning but confidence is low. A brief lull should develop mid to
late Saturday morning into early Saturday afternoon before another
round of TSRA develops ahead of a another cold front dropping in
from the north. Went with PROB30s for SHRA overnight into Saturday
morning and PROB30s for TSRA Saturday afternoon/early evening.
Should see VFR prevail outside of SHRA/TSRA. Confidence on the
timing and coverage of both SHRA and TSRA remain low which is why
PROB30s were maintained for the 00Z TAF cycle. Winds will start out
S/SW before going light and VRB to calm this evening into most of
Saturday. A N`ly wind shift may occur behind the cold front Saturday
afternoon but confidence is low with light and VRB winds expected.

Outlook: Drier conditions return Sunday before another cold front
brings rain chances back Monday. A drier pattern should return for
the rest of the workweek.

&&

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

&&

$$

AR/JCW/RWH