Greer, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

019
FXUS62 KGSP 261117
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
717 AM EDT Tue May 26 2026

.WHAT HAS CHANGED...
Updated the aviation forecast for the impending 12Z TAFs.

&&

.KEY MESSAGES...
1. Mostly quiet conditions continue through Tuesday morning,
although several flood products remain in place for the next few
hours due to previous rainfall. Widespread showers and storms
are expected to redevelop on Tuesday afternoon, presenting both
a low-end severe threat and a low-end hydro threat.
2. Daily chances for showers and thunderstorms continue into the
weekend. Drier conditions may briefly return on Friday, but there
is not a signal for more robust drying until at least Sunday.

&&

.DISCUSSION...
Key message 1: Mostly quiet conditions continue through Tuesday
morning, although several flood products remain in place for the
next few hours due to previous rainfall.  Widespread showers and
storms are expected to redevelop on Tuesday afternoon, presenting
both a low-end severe threat and a low-end hydro threat.

Following a rogue band of showers that developed over our
southern zones a few hours ago and quickly made tracks now, most
of the forecast is now dry apart from occasional patchy drizzle.
Multiple flood products remain in effect across Henderson County,
where intense evening rainfall yesterday spurred significant
rises along area streams.  Will continue to monitor these products
through the morning as conditions (hopefully) improve.

Otherwise...we can expect a brief period of quiet conditions
early today.  Whatever weak, shallow in situ wedge is in place
now will gradually mix out through late morning.  The lull won`t
last long, however.  Hi-res guidance rapidly destabilizes most of
the Deep South, depicting widespread convective initiation there
as early as 11AM...and all that convection will gradually arrive
in the Upstate through early afternoon, with most of the 00Z
HREF members featuring widespread showers and embedded thunder
across the region throughout the afternoon and early evening.
It`s increasingly looking like the severe threat will be nonzero;
the HRRR as well as most of the CAMs feature a plume of some
1500-2000 J/kg sbCAPE across the area in an environment of
20-25kts of deep layer shear.  It`s by no means a slam dunk,
but a couple of strong to severe storms are well within reason.
About the only thing they have going against them is the lack of
any strong forcing mechanism and thus fairly weak mid-level lapse
rates that will result in updrafts which are taller, but weaker.

Meanwhile, the environment continues to feature 1.75-2.0" PWs and
very warm, very moist profiles.  Any deeper showers and storms that
develop could produce locally heavy rainfall, and given antecedent
conditions, some locations may not take long to realize an isolated
nuisance flood risk, perhaps even a low-end flash flood.  Indeed,
while the 00Z HREF depicts generally less-impressive QPF response
across the area than it did for Monday, it continues to key on a
corridor across the western two-thirds of the Upstate receiving
another localized 1.5+ inches through the afternoon.


Key message 2: Daily chances for showers and thunderstorms continue
into the weekend.  Drier conditions may briefly return on Friday,
but there is not a signal for more robust drying until at least
Sunday.

By Wednesday, long-range guidance begins to depict a subtle pattern
shift, with slight height rises early in the day and a more
WSW direction to low-level flow.  The result is more of a Deep
South moisture fetch from that point forward, with trajectories
crossing the lower Tennessee Valley rather than advecting moisture
to us directly from the Gulf.  With no more shortwaves featured in
synoptic guidance, low-level upglide tends to falter in most of the
ensemble output...and so the CAMs that go out that far (as well
as the operational guidance) feature considerably lower coverage
of afternoon showers on Wednesday afternoon...with anything more
than isolated activity confined to the Appalachians.  That said,
there does appear to be potential for another low-end severe
risk on Wednesday afternoon: height falls over the Ohio Valley
and Mid-Atlantic will result in an area of confluent flow aloft
that`ll actually strengthen the 500mb wind, so whatever convection
does develop will do so in an environment of moderately-better deep
layer shear than we`ve had the last several few days (and Tuesday).

The remainder of the week remains somewhat of a question mark.
LREF members are tending strongly toward a scenario where a weak
backdoor cold front arrives sometime Thursday...likely too late in
the day to prevent a band of frontally-focused showers and storms
from crossing the area that afternoon...and briefly ushering in some
drier air.  However, that front is variously depicted stalling in
or just south of the Upstate, then acting as a focus for renewed
isentropic ascent, possibly even another hybrid CAD event, as
the parent high moves off the New England coast and another upper
trough reactivates the boundary.  That means - you guessed it -
more rain for Friday night and Saturday.

There remains very high uncertainty for the rest of the weekend
and early next week.  There are really two camps among long-range
ensembles: one in which we get a strong cold backdoor cold
front Sunday night, ushering in a dry cP air mass that persists
through the end of D7, and another in which we get a much weaker
backdoor cold front and only modest, short-lived drying at best.
Unfortunately, the stronger/drier scenario is currently the
less-favored among ensembles...but at this time range and with how
unsettled the atmosphere has been, there`s really no confidence
to be had.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: A band of rogue showers has crossed
the terminal forecast area through the last several hours, but
at this point most of the area has returned to typical patchy
drizzle conditions.  As a result, more widespread LIFR ceilings
were disrupted, and sites are generally looking better than
guidance expected.  So, in the 12Z TAFs, went more optimistic with
the morning forecast, but included TEMPOs for lower restrictions.
Conditions should improve to VFR in most locations by late Tuesday
morning.  Afternoon convection will again develop across the entire
area, with SHRA and embedded TSRA possible at all six TAF sites.
Confidence is limited on Tuesday night`s forecast, as restrictions
will be heavily dependent on the evolution of afternoon convection.

Outlook: The pattern remains unsettled through the workweek with
at least scattered diurnal convection expected each day (possibly
persisting into the overnight hours) and lowered visibility and
ceilings forecast each night.

&&

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

&&

$$

MPR