513
FXUS62 KGSP 172351
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
751 PM EDT Sun May 17 2026

.WHAT HAS CHANGED...
The aviation forecast was updated to reflect the recent 00Z TAF
issuance.

&&

.KEY MESSAGES...
1. A summer-like pattern will continue through mid-week, with
above normal temperatures and spotty diurnal convection expected,
mainly today and on Wednesday.
2. A cold front brings better rain chances mid to late week
but rainfall amounts are expected to remain light so any drought
relief will be limited. Above normal highs linger through Thursday
before cold air damming develops behind the front, allowing for
the return of near to below normal highs Friday and Saturday.

&&

.DISCUSSION...
Key message 1: A summer-like pattern will continue through mid-week,
with above normal temperatures and spotty diurnal convection
expected, mainly today and on Wednesday.

More or less as expected, showers and storms are underway well
south and west of the CWA, in the vicinity of Atlanta Metro...but
despite a modestly-unstable air mass and only very weak capping as
per recent NUCAPS/GOES profiler data, there`s little evidence of
impending initiation over our area.  Based on hi-res output from
the HRRR and RRFS, seeing increasingly little support for any of the
upstream convection over Central Georgia making it into our western
zones, either.  Still can`t rule it out, but with the sun going
down, the window is quickly closing for us to see any action at all.

In response to the building ridge, low level Bermuda high is
forecast to intensify/expand over the next couple of days...allowing
the surface ridge to build into the Southeast...turning trajectories
off the western Atlantic rather than the Gulf. This will begin to
circulate subsidence-induced drier air into the CWA tonight, with
afternoon dewpoints only expected in the 50s Monday and Tuesday.
Meanwhile, temps will be steadily warming aloft. These factors are
expected to result in much weaker PM instability...and little in
the way of diurnal convection is expected Mon and Tue.

By Wednesday, the upper ridge/Bermuda high is forecast to begin
weakening as a strong short wave trough sweeps across eastern
Canada/the northeast Conus. Moisture and instability profiles are
therefore expected to improve across our areas, especially as the
leading edge of a frontal zone approaches the southern Appalachians
from the west. PoPs for diurnal convection increase to likely across
the mountains by Wed evening. Shear parameters will improve somewhat
during this time, but signals for any organized severe storm threat
area weak at best. Otherwise, temperatures will remain 6-9 degrees
above normal through the first half of the week.


Key message 2: A cold front brings better rain chances mid to late
week but rainfall amounts are expected to remain light so any
drought relief will be limited. Above normal highs linger through
Thursday before cold air damming develops behind the front, allowing
for the return of near to below normal highs Friday and Saturday.

The main change of note is that the timing of the cold front has
sped up a bit compared to this time yesterday and is now expected to
track across the GSP forecast area Wednesday night into early
Thursday morning. As a result of this earlier FROPA timing, highs
have trended down ever so slightly on Thursday compared to the
previous forecast. However, highs are still expected to remain warm
and above normal on Thursday. The front stalls across the Carolinas
Friday into Saturday as weak cold air damming develops behind the
front (per 06Z the GFS), bringing near to below normal highs back to
the area. The front should then reactivate and lift back north as a
warm front over the Carolinas on Sunday. The 06Z GFS depicts the
wedge eroding by Sunday, allowing just above normal highs to return.
This front will bring better rain chances to the area starting
Wednesday evening, with rain chances sticking around through at
least the weekend. Although we are trending more towards a wetter
pattern with higher chances for rain mid to late week, rainfall
amounts appear to remain light at this time (especially considering
how long rain could stick around). Most locations could see rainfall
amounts ~1-1.5" Wednesday evening through Sunday, with some isolated
locations along the Blue Ridge Escarpment possibly seeing 2"+. Will
continue to monitor QPF trends closely in the coming days but for
now it still looks like there would be limited relief from the
drought with these rainfall totals. With the timing of the front
coming through prior to peak heating on Thursday, and with CAD
expected behind front Friday into Saturday, any potential for severe
weather should remain low for most of the period. However, with the
warm sector returning Sunday behind the warm front, better
instability may develop during peak heating, but confidence is low
with this being day 7.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Stagnant cu field still in place this
evening across the southern half of the terminal forecast area,
but it`s just about reached its zenith and should collapse over
the coming few hours.  We remain within a moderately unstable, but
mostly-capped, air mass across the area.  There remains a possiblity
that convection currently located well southwest of the terminal
forecast area could wander into the upper Savannah River Valley and
southwest NC mountains...but it`s looking increasingly unlikely
based on recent hi-res model output, and even more unlikely that
such convection would make it to any of the TAF sites.  Statistical
guidance continues to key on the potential for a plume of low-level
moisture to result in FEW/SCT MVFR-level clouds - mostly at the
Upstate sites - before dawn Monday.  Thereafter expect a return
to SKC/FEW cirrus, and a continuation of 5-10kt SSW winds all day
Monday and into the early evening.

Outlook: VFR to persist through mid-week, except perhaps in mountain
valleys, where patchy morning fog/low stratus may develop each
morning.  An active cold front may bring restrictions associated
with convective precip by late week.

&&

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

&&

$$

AR/JDL/MPR