558
FXUS62 KGSP 050014
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
814 PM EDT Sat Apr 4 2026

.WHAT HAS CHANGED...
Updated for the 00z aviation discussion.

&&

.KEY MESSAGES...
1. Well above normal and humid with isolated to scattered diurnal
showers and thunderstorms possible this afternoon and evening.
2. The passage of a cold front Sunday will bring the best rain
chances over the next week. The risk of flooding rain or severe
weather appears to be low.
3. Frost and/or freeze concerns are still in place for the
mountains starting Sunday night, and will continue to be an
issue each night through Wednesday. The coldest night regionwide
is Tuesday when frost chances spread into the North Carolina
piedmont. Protection of sensitive vegetation may be required.

&&

.DISCUSSION...
Key message 1: Well above normal and humid with isolated to scattered
diurnal showers and thunderstorms possible this afternoon and
evening.

Bermuda High will continue to filter in deep low-level WAA with
the deep layer southwesterly flow helping to aid in a warm and
humid airmass with afternoon highs 8-12 degrees above normal and
dewpoints in the low to mid 60s. Subtle height falls in response to
a closed upper low over the Northern Great Plains and the Southeast
ridge propagating further offshore will set the stage for diurnal
convection this afternoon and evening. Earlier showers hampered the
environment slightly, but latest mesoscale analysis places 1000-1500
J/kg of SBCAPE across the area. Mid-level lapse rates have steepened
slightly, which will erode any cap that was in place. Could see
a few strong to possibly severe storms, but confidence is low
as to whether or not storms get that strong. Likely trigger for
convection will be in the form of a differential heating boundary
and orographic enhancement in the southwestern mountains. Bulk
shear will be <=20 kts and will limit organized convection,
which will lower the threat of severe storms. DCAPE values are
higher than originally forecasted with modest inverted-v profiles,
so a wet microburst can`t be ruled out. This activity may linger
into the later evening hours if outflow boundaries develop and
potentially collide with each other. Highest PoPs will be in the
mountains and lower the further east.


Key message 2: The passage of a cold front Sunday will bring the
best rain chances over the next week. The risk of flooding rain
or severe weather appears to be low.

The aforementioned stacked low over the Northern Great Plains
today will quickly shift into the Upper Great Lakes into Ontario
and Quebec tonight and Sunday as an attendant cold front moves
in from the west late tonight. Timing for rainfall will likely be
late overnight through Sunday afternoon before the front completes a
full fropa by Sunday evening. Guidance show a QLCS setup as the
front encroaches the region, but loses its organization and weakens
as it moves across the NC/TN border. Expect a broad band of
organized showers likely with embedded thunder overnight across the
mountains and shifting into the Piedmont around or shortly after
daybreak. There is a very limited severe threat Sunday afternoon as
increasing instability develops ahead of the front and the main line
crosses into locations along and east of I-77, but will have to see
how that shapes out closer in time with the main threat being
isolated damaging wind gusts, if any.

With the antecedent dry conditions, especially ongoing severe
to extreme drought conditions, any rainfall we receive will be
beneficial as a hydro threat would basically be zero. Some favorable
southwesterly slopes could receive 1-2", but the rest of the area
likely receives 0.50"-1" and some locations receiving less that
miss out on convection from Saturday and gets the short end of
the stick with the rainfall associated with the incoming cold front.

Much drier air filters in behind the front Sunday night as CAA
helps to quickly drop dewpoints and temperatures, while skies
clear. Expected overnight lows to drop into the 30s across the
mountains and 40s elsewhere. Winds will pick up ahead, along, and
behind the front as the direction turns the dial from southwesterly
ahead of the front to northwesterly and eventually northerly behind
the front by daybreak Monday. Any gust will be low-end with the
exception of the higher elevations where gusts could get up to 45
mph behind the front and remains less than 30-35 mph elsewhere.


Key message 3: Frost and/or freeze concerns are still in place for the
mountains starting Sunday night, and will continue to be an issue
each night through Wednesday.  The coldest night regionwide is
Tuesday when frost chances spread into the North Carolina piedmont.
Protection of sensitive vegetation may be required.

In the wake of Sunday`s cold frontal passage, the leading edge of a
colder airmass will make inroads into the Southern Appalachians
giving rise to light advective freeze possibilities for the high
elevations of the NC mountains.  Llvl ridging builds in starting on
Monday with maximum temperatures returning to the early April climo.

After the initial continental sfc high builds in, a reinforcing shot
of colder air arrives Tuesday night thanks to stronger hipres, the
center of which translates eastward within the quicker flow off to
our north. Frosty temperatures are still forecast to develop in the
NC piedmont during the pre-dawn hours on Wednesday but with the
tightening sfc pressure gradient and easterly flow it is doubtful
much in the way of frost will develop thanks for the wind remaining
up all night.

The GSP frost/freeze program for the concern area in NC, (roughly
along and south of I-40), commences tomorrow, 5 April. With the
initial shot of chilly air Sunday night, light freeze conditions
should be limited to just the highest elevations and much in the way
of any frost development will be hampered by lingering wind.
Tuesday night still looks like the best chance to have frost/freeze
issues but again, wind should limit frost development save for
select sheltered mountain valleys. So looking ahead, a frost
advisory for the NC mountains may be in the cards for pre-dawn hours
Wednesday.

Fire weather concerns for next week will concentrate on the
likelihood that minimum RH values will dip below 25-30 percent each
afternoon from Monday through Wednesday, though accompanied by
generally light winds. After what we hope will be a wetting rainfall
on Sunday, fuel moisture will dry back out by Tuesday and fire
danger will likely increase by then.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Clusters of showers and thunderstorms con-
tinue to make their way NE over the fcst area this evening. I have
a TEMPO for -TSRA at KCLT until 03z for the activity near the ter-
minal and VCTS for KAVL for the next few hrs. I don`t expect the
other taf sites to be impacted by this activity this evening, but
can`t totally rule it out. A cold front will move in from the west
overnight and bring widespread showers to the area, with the onset
of rain just before daybreak for the Upstate terminals and KAVL,
and a few hrs later for KHKY and KCLT. I still can`t rule out some
embedded thunder, but my confidence is only high enough at KAVL for
a PROB30 mention of -TSRA. IFR cigs and MVFR/IFR visby is likely to
accompany the line of showers and embedded thunder tomorrow morning
thru the early afternoon. In addition, I included either a TEMPO for
-TSRA or VCTS at all taf sites (except KAVL) for convection tomorrow
afternoon as the front moves thru. Any lingering showers and/or storms
should be east of our area by 00z Monday. Winds will remain S/SW at
5 to 10 kts with low-end gusts thru the morning. They will toggle
around to W and then NW behind the front Sunday afternoon/evening
with low-end gusts subsiding outside the mtns, but lingering at KAVL.

Outlook: High pressure spreads over the region behind the front
Sunday night and lingers thru the middle of next week with dry/VFR
conditions expected.

&&

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

&&

$$

CAC/CSH/JPT