Thunderbolt, Georgia Weather Forecast Discussion

697
FXUS62 KCHS 221758
AFDCHS
Area Forecast Discussion
National Weather Service Charleston SC
158 PM EDT Mon Sep 22 2025
.SYNOPSIS...
High pressure north of the region will weaken through Tuesday.
A storm system could affect the area late in the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
High pressure to the north will steadily weaken through tonight.
Meanwhile a weak surface trough will take shape along the SC/GA
coast. A few weak showers or even an isolated tstm could persist
through late afternoon across the eastern half of the area
during peak diurnal heating and weak sea breeze convergence.
Overnight, the best chance for convection will be over the ocean
waters. Areas of fog are expected to develop across inland areas
later tonight.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Aloft, weak mid-upper lvl troughing will slide eastward across the
Mid-Atlantic states Tuesday, placing greatest lifting over the
nearby Atlantic by the afternoon, then will be followed by a period
ridging Wednesday into Thursday in advance of a large-scale trough
making way across the Central United States and toward the
Appalachians. At the sfc, high pressure extending across the local
area from the north is expected to weaken considerably on Tuesday
while coastal troughing dissipates offshore. This will place a
relatively dry pattern across the region between the large-scale
trough well west of the area and high pressure centered near Bermuda
through mid week. However, a stray shower cannot be ruled out along
afternoon sea breeze circulations. On Thursday, deeper moisture
returns within a southerly flow in advance to the approaching mid-
upper trough and associated sfc cold front. Precip chances should
increase Thursday afternoon with peak diurnal heating and more
favorable lifting. Few to scattered showers and thunderstorms are
possible, especially across inland areas prior to sunset.
In regards to temperatures, the pattern changes suggest a warming
trend mid-week as mid-upper ridging and southerly winds develop. In
general, afternoon highs should peak in the upper 80s to lower 90s
away from coastal areas Tuesday (lower 80s along the beaches), then
mid-upper 80s across the coastal corridor to low-mid 90s inland
Wednesday and Thursday. Overnight lows will trend warmer as well,
generally in the upper 60s inland to lower 70s near the coast
Tuesday night, then low-mid 70s Wednesday night.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Aloft, an expansive mid-upper lvl trough will approach the Southeast
United States with a cold front anticipated to shift across the
local area Thursday night into Friday. Deep moisture (PWATs
approaching 1.75-2.00 inches) along with favorable forcing support
numerous showers and thunderstorms, especially on Friday during the
time of greatest forcing. Timing will also play a factor in regards
to overall strength of thunderstorm activity later this week, which
appears to be limited given the arrival of the front prior to peak
diurnal heating Friday afternoon. However, a few stronger
thunderstorms can not be ruled out with the passing front. The
system could slow once reaching the local area, with some suggestion
that the mid-upper lvl trough becoming cutoff across the Southeast
and even retrograding southwest toward the northern Gulf during the
weekend while the sfc front remains offshore. This could place
unsettled weather conditions across the local area during the
weekend, with highest shower/thunderstorm coverage (20-40%)
occurring each afternoon Saturday and Sunday. Temps should become
noticeably cooler this weekend, generally in the mid-upper 80s for
highs and mid-upper 60s inland to lower 70s near the coast.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Brief MVFR ceilings possible at any terminal this afternoon due
to thickening stratocumulus in the increasingly onshore flow. A
coastal trough will strengthen a bit later tonight and spread
low-level moisture into the area. Guidance is in good agreement
that MVFR ceilings will develop at all terminals late tonight
and eventually lift to VFR mid to late Tuesday morning. We could
also see visibility reductions in fog, though the best chance
for dense fog appears to be inland of all of our terminals.
Extended Aviation Forecast: VFR conditions should prevail at
CHS/JZI/SAV terminals through Thursday morning. TEMPO flight
restrictions are possible Thursday afternoon into Friday with low
clouds and reduced vsbys associated with showers/thunderstorms ahead
and near a passing cold front late week.
&&
.MARINE...
A coastal trough will strengthen overnight, though no
appreciable marine impacts expected. Winds/seas should remain
just below SCA criteria.
Tuesday through Friday: Coastal troughing along the Southeast Coast
is anticipated to weaken Tuesday afternoon, setting up a period for
a weak pressure gradient through mid week as high pressure extends
across local waters from the east. In general, northeast winds
around 10 kt or less will veer, becoming southeast and gusting no
higher than 10-15 kt through Wednesday night. Seas will also slowly
subside from 3-4 ft to 2-3 ft during this time frame. Heading into
Thursday, the pressure gradient will slowly tighten with the
approach of a mid-upper low and sfc cold front from the west-
northwest late day, resulting in an uptick in wind speeds and seas.
Southerly winds should peak late Thursday into Friday, generally in
the 15-20 kt range, as the front approaches and shifts across local
waters. Seas should also respond, building up to 3-4 ft. Scattered
to numerous thunderstorms could accompany the front on Friday as
well.
Rip Currents: A Moderate Risk of rip currents will prevail at all
area beaches through Wednesday due to swell periods (up to 12 sec)
and height (3 ft).
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...JRL
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...DPB/JRL
MARINE...DPB/JRL

NWS CHS Office Area Forecast Discussion