492
FXUS62 KGSP 290559
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
159 AM EDT Sat Jun 29 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 TODAY/...
As of 145 AM Saturday...the KGSP radar shows shower activity in
a broad arc from the NC Foothills down to the Charlotte metro
area. No lightning activity recently, but a rogue strike or two
will not be ruled out as this stuff drifts northward in the light
southerly flow that continues across the region. Also can`t rule
out a shower developing at any time elsewhere, even though it won`t
be indicated in the forecast grids. Temps will remain warm with
high RH through daybreak. Plenty of stratocumulus is expected to
also develop in the flow by daybreak Saturday.

Otherwise...a broad, flat upper trough will shift east across the
Upper Midwest and Great Lakes, with subtropical high holding on
across the Southeast. Saturday 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 /TONIGHT 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 /06Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: A light moist southerly flow continues
across the region early this morning, which should continue to push
a broad and loosely organized band of shower activity northward
across the NC foothills and western Piedmont. This stuff should
either drift northward out of the forecast area or weaken before
daybreak. Other showers could pop up at any time, but the chances
are too low to include. Otherwise, the guidance still suggests
that low clouds will develop steadily across the region through
the pre-dawn hours, with an MVFR-level cloud ceiling developing
shortly and then dropping down possibly into the IFR category,
especially near the Blue Ridge Escarpment. The TAFs will continue
to feature this restriction through mid/late morning. Wind will
stay SSE to SSW and light. On Saturday, the ceiling will eventually
lift to VFR and scatter out by afternoon, thereafter we will look
for better coverage of showers and thunderstorms in the mid/late
afternoon. This will be handled with a PROB30 until confidence in
timing improves. Expect a similar evolution late Saturday night.

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/PM/SBK
SHORT TERM...CP
LONG TERM...CP
AVIATION...PM