117
FXUS62 KGSP 241737
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
137 PM EDT Sat May 24 2025

.SYNOPSIS...
High pressure will linger over the area today keeping conditions
mostly dry. A warm front lifts north on Sunday and into early next
week, increasing the chances for widespread showers and scattered
thunderstorms. The pattern remains active thru the middle of next
week with showers and thunderstorms likely each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1042 AM EDT Saturday: No major changes to the forecast at this
time.  Surface high pressure now analyzed over central Appalachia
still maintaining dry low-levels while a subtle shortwave drifts
across the Tennessee Valley.  The increase in forcing and moisture
associated with this feature will drive a steady increase in cloud
cover through today...with thickening cirrus and mid-level clouds
already evident over the NC mountains and western Upstate.

Otherwise...mostly cloudy skies still expected across much of
the forecast area by around noon. This will shave a few degrees
off the heating potential today...and max temps are generally
expected to be 2-3 degrees cooler than on Friday...except across
the mountains where elevated warm advection should result in a
slight warm-up. With warm frontal zone activating in association
with a deepening cyclone in the lee of the Rockies...can`t rule
out a sprinkle or light shower across the far west today. However,
measurable precip chances are 20% at most during the daylight hours.

As aforementioned short wave moves closer to the CWA and weakens,
guidance broadly agrees that a remnant convective blob will approach
the CWA from the west at some point tonight through early Sunday,
with our southwest zones being the most likely area to be impacted.
There is not a great deal of agreement regarding timing, but
there`s enough of a signal to include 30-50 PoPs across roughly the
western 2/3 of the forecast area tonight. What little instability
is forecast is expected to be elevated in nature...thus lightning
may be tough to come by with this activity. Min temps are expected
to be near normal.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 3:15 AM EDT Saturday...

Key Messages:

1) Shower and thunderstorm chances increase on Sunday. A few
strong to severe storms will be possible along and south of
the I-85 corridor on Sunday afternoon/evening.

2) Temperatures will remain below normal thru the period.

The short-term fcst picks up at 12z on Sunday with flat upper
ridging slowly building over the Southeast as a large upper low
spins NE of New England. This upper low will linger well to our
NE for most of the period as heights continue to gradually in-
crease over our region. This will maintain relatively zonal upper
flow over our area as multiple embedded upper shortwaves translate
overhead thru the period. At the sfc, on Sunday the low-lvl flow
will take on an increasingly SLY to SELY component as a weak warm
front lifts north across our CWA. This will allow a broad area of
deeper moisture to spread northward from the Gulf and increase
precip chances thru the day on Sunday. On Monday, broad sfc high
pressure to our north will spread further SE and begin to set up
a weak wedge/CAD pattern by late Monday/early Tuesday. This will
keep precip chances elevated thru the end of the period early
Tuesday. Some sct thunderstorms appear likely on Sunday aftn/
evening. In addition, it appears that the severe potential has
expanded a bit further north and into our southern zones for
Sunday. It appears that the main threat from any stronger storms
that do develop will be damaging wind gusts. Temperatures will
start out a few degrees below normal on Sunday and cool thru the
period as the CAD develops.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 2:55 AM EDT Saturday...

Key Messages:

1) Unsettled weather is expected to linger for much of the
extended period.

2) Sct to numerous showers and thunderstorms are expected each
afternoon/evening thru the period.

3) Temperatures start out below normal on Tuesday but warm to
near-normal by mid-week.

The extended fcst picks up at 12z on Tuesday with relatively
flat upper ridging in place over the Southeast while a large
upper low becomes more organized west of the Great Lakes. Over
the next couple of days, multiple upper shortwaves are expected
to translate over our area from the west as we remain under flat
upper ridging. Towards the end of the period next Thursday and
Friday, most of the long-range guidance has the upper low opening
back up and amplifying southward towards our area. At the sfc, a
weak CAD pattern is expected to be in place over the western Caro-
linas as the period begins early Tues. This will allow for increas-
ing isentropic upglide from the west and sct to widespread showers
on Tuesday. The CAD is expected to be short-lived however, as the
parent sfc high gets pushed further offshore on Wednesday and sfc
cyclogenesis tries to initiate somewhere over our region. It re-
mains unclear where and how quickly any low will develop, but most
of the long-range guidance has the low lifting NE of our area on
Thursday with high pressure eventually beginning to spread back
over the area by the end of the period on Friday. We can expect
thunder chances to increase beginning Wednesday afternoon as the
CAD dissipates and we start getting some amount of return flow.
The severe wx potential still appears minimal thru the period,
but could increase for Thursday and Friday depending on how the
above-mentioned sfc low evolves. Otherwise, high temperatures are
expected to start out well-below climatology on Tuesday under the
CAD, and warm to near climo by Wednesday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Still expect VFR conditions to prevail
through most if not all of tonight at all the TAF sites.
Widespread cirrus and scattered to broken mid-level clouds are
already streaming across the forecast area, and by this evening,
expect moisture to begin increasing more steadily.  Hi-res guidance
continues to depict a deteriorating cluster of showers arriving in
the western Upstate, and perhaps parts of the southern NC mountains,
before midnight, and gradually expanding across the Upstate sites
through daybreak.  Fairly consistent signal at this point that
convection will remain south of KCLT and the other NC sites until
after daybreak tomorrow...so PROB30s advertised for SHRA at the
Upstate sites overnight, but held off on any mention at KCLT and
KHKY until after 15z.  A rumble of thunder still cannot be ruled
out, but any thunder will be elevated in nature and its coverage
far too sparse for any inclusion in the TAFs.  Generally expect
a south wind at all the TAF sites, though a period of light ENE
winds at KCLT appears likely overnight.

Outlook: Shower and thunderstorms chances increase into early next
week. The highest coverage is expected Tuesday, with diminishing
coverage expected Wed into Thu. Mainly mountain valley fog and low
stratus are possible each morning early next week, with chances
increasing for all areas toward the middle of the week.

&&

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

&&

$$

SYNOPSIS...JPT
NEAR TERM...JDL/MPR
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...MPR