391
FXUS62 KGSP 290218
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1018 PM EDT Fri Jun 28 2024

.SYNOPSIS...
Seasonable temperatures are expected today and tomorrow as shower
and thunderstorm activity increases ahead of an approaching cold
front. Hot and humid conditions Sunday before the front, which will
usher in drier and cooler conditions Monday and Tuesday.
The summer heat returns Wednesday and beyond.

&&

.NEAR TERM /THROUGH SATURDAY/...
Evening Update...Showers are becoming a little more prevalent across
the FA this evening. A few are moderately strong and are lowering
visibility to around a mile along with generating 25 kt gusts.
Expect this activity to continue thru most of the overnight as the
focus shifts to the NC mtns and foothills. The current mesoanalysis
shows dCAPE on the order of 800 J/kg to the north of the current
activity so moderate gusts are likely to continue with some of these
cells.

As of 215 PM...Some weak mid-level height rises today are helping
keep warm mid-level temps in place atop the fcst area. Sfc
high pres lingers along the Northeast Coast, with a weak front
draped across central SC west thru northern GA/AL. A light SELY
upslope flow across the region should force scattered showers,
with perhaps a few isolated general thunderstorms. But such weak
mid-level lapse rates and lack of deeper forcing should limit storm
strength. The latest CAMs indeed do not look very impressive on
simulated reflectivity, suggesting mainly showers the rest of today
and thru tonight. Showers may linger near the Escarpment well into
the overnight, as the SELY flow works with some MUCAPE. Plenty of
stratocumulus is expected to also develop in the flow by daybreak
Saturday, which will help keep min temps slightly above normal
(mainly upper 60s mountains and low to mid 70s Piedmont).

A broad, flat upper trough will shift east across the Upper
Midwest and Great Lakes, with subtropical high holding on across the
Southeast. The day will start out with plenty of low clouds, but the
clouds should scatter out somewhat by early aftn, allowing for more
insolation and 1500-2000 J/kg of sbCAPE at peak heating. Guidance
generally agrees on an uptick in coverage of diurnal convection, but
with the threat of strong to severe storms remaining low. Highs are
expected to be similar, if not a couple degrees warmer than today.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 150 PM Friday: By Saturday night, a typical summertime pattern
emerges synoptically. Broad, weak upper flow and high pressure
dominates the southern CONUS. Sfc high pressure amplifies in the
central part of the country and pushes toward the area. By Sunday,
troughing over the Great Lakes and a shortwave traverse the Ohio
Valley, triggering a cold front to move toward the CWA. Ahead of the
FROPA, guidance from the GFS and NAM suggest an increase in temps,
with a decrease in dewpoints. Guidance has been trending the
dewpoints down from previous runs and hinting at values closer to
climatology for the area. Given the westerly winds ahead of the
front and well mixed boundary layer depicted in model upper air
profiles, heat indices are likely to be in the low 100-105 range,
especially in areas south of I-85. But, this is still a few days out
and will be further monitored at this time. As for any precip or
convective chances on Sunday, guidance holds off until the boundary
approaches the area. Despite the guidance ranging 1000-2000 J/kg
sbCAPE, the BL will have a stout T/Td depression spread. There is
also weak forcing aloft and at the sfc with light winds, limiting
support for convective development prior to the FROPA. When the
front moves through, it could provide a little more forcing and
trigger showers and thunderstorms, but not anticipating a widespread
threat of severe weather. Again, Sunday is expected to be the
hottest day so far with a break following the cold front into
Monday. Given the Holiday Weekend, it`s important to note that aside
from the heat, fire conditions will be higher. Though winds will be
relatively light, RH values are expected to dip into the 40% range
on Monday. Combine this with drier vegetation and it elevates fire
concerns.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 140 PM Friday: By Monday night, an area of upper high pressure
continues to amplify over the central U.S. and spread eastward into
the southeast. This ridge axis grows on Tuesday and Wednesday,
quickly rebounding the heat across the CWA. Guidance from the GFS
and EURO show strong subsidence aloft, building through at least mid
week, shunting most chances for decent precipitation. The BL remains
well mixed and a well defined inverted-V on upper air guidance. The
dewpoints should remain in the low 60s through early Wednesday, but
as sfc winds veer more S/SE, moisture advection prompts an increase
in Td throughout Wednesday and into Thursday. Dewpoints look to
creep back up, raising chances for higher heat indices by the end of
the week. Will continue to monitor. Long range guidance on the GFS
and EURO depict a possible weak front reaching the mountains toward
the end of the week, but confidence is very low as the area will
remain in a dominating high regime. Not much in the way of rain
chances for the extended. Temperatures in the extended period start
off near climo and likely increases into the high 90s.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR conds with vicinity showers will continue
this evening across all TAF sites. There is a signal for longer
lasting precip near KHKY and KAVL into the later morning hrs as a
moist se/ly flow continues to interact with the higher terrain. Not
a great chance of thunder tonight as a mlvl inversion helps stunt
vertical growth. Not enuf confidence to include thunder at any
specific TAF site, yet a few brief storms may develop periodically.
CIGS lower before daybreak to mainly MVFR and possibly IFR with MVFR
CIGS lingering thru mid morning generally east of the mtns. Saturday
afternoon and evening will see the best chance of tstms with a
stalled frontal zone becoming active. Thus, all sites have a Prob30
TS for this potential scenario. Southeasterly to s/ly winds remain
generally low-end with occasional gusts possible Sat afternoon.

Outlook: A cold front approaches the area on Sunday, resulting in
higher aftn/eve convective coverage. The front pushes trough and
stalls out just south of the area, resulting in quieter weather for
Monday and Tuesday.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...ARK/SBK
SHORT TERM...CP
LONG TERM...CP
AVIATION...SBK