458
FXUS62 KCHS 291705
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
105 PM EDT Fri Aug 29 2025

.SYNOPSIS...
High pressure will extend across the area as a stationary front
lingers well to the south and offshore into the middle of next
week. A cold front is then anticipated to arrive late next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A band of channeled vorticity will continue to interact with a
stalled front to the south to produce some shower activity over
Southeast Georgia through the remainder of the afternoon hours,
especially near the Altamaha River. A few rumbles can not be
completely ruled out near the Altamaha River, but the better
mixed-layer instability should remain displaced well to the
south. 29/13z NBM highs in the mid-upper 80s look okay,
although they may end up being a tad high closer to the Altamaha
River where considerable cloud cover and ongoing light shower
activity may limit temperature rises somewhat. Pops for the
remainder of the afternoon range from 0-5% over the South
Carolina Lowcountry with 10-50% over Southeast Georgia, highest
near the Altamaha River.

Surface high pressure will maintain its influence on the region
tonight as it steadily propagates off the Southeast U.S. coast.
A deepening return flow atop the lingering shallow wedge will
promote weak to moderate isentropic ascent overnight. Lift looks
greatest along the 300-305K surfaces coincident with lowering
condensation pressure deficits. This should lead to a gradual
uptick in isolated to scattered shower development overnight
with the greatest coverage occurring over Southeast Georgia and
closer to daybreak. Pops range from 10-20% over the Lowcountry
with 20-40% over Southeast Georgia. A little bit of elevated
instability looks to work in along parts of the Georgia coast
and nearby Atlantic waters after midnight, which may support a
tstm or two, especially if corridors of locally stronger
isentropic forcing can be realized. Lows will range from the
mid-upper 60s well inland to the lower-mid 70s at the coast and
for areas near the Altamaha River.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
Mid-lvl troughing will dominate this weekend as shortwaves
ripple across the region along the southern periphery edge of
this trough. At the surface, a nearly stationary front will
position itself across the Florida Peninsula. Model guidance
continues to suggest that a low will develop along this boundary
and then eventually move offshore by the end of the weekend.
Although quite a bit of uncertainty remains in the evolution and
strength of this low, the majority of guidance supports
scattered to numerous showers and thunderstorms throughout the
weekend as ample moisture and mid-lvl support will be in place.
As of right now, the greatest coverage will likely occur along
and south of I-16. Given the recent large amount of rainfall in
the past week, it`s understandable that WPC has highlighted
portions of the region under a Marginal Risk (level 1 of 4) for
excessive rainfall on Saturday and Sunday.

On Monday, a mid-lvl low will attempt to cutoff across the Mid-
Atlantic and allow for subtle waves of h5 vort. energy to be
advected across the Southeast. This sort of setup will produce
additional showers and thunderstorms across the region, however
coverage will be less due to the downward trend of PWATs.

Temperatures will remain below normal this weekend into early
next week as east-northeasterly winds persist and high pressure
builds into the region. Expect highs in the upper 70s to low 80s
on Saturday, and then low to mid 80s on Sunday and Monday.
Overnight lows will range in the mid to upper 60s inland and low
70s near the coastline.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
With an amplified upper-lvl trough aloft, another weak low
pressure tries to form offshore early next week. However, recent
model guidance suggests a surface high sets up north of the
region and this could possibly place us in a wedge situation. As
deep moisture and isentropic ascent become more favorable
across the region, this setup should aid in higher afternoon
shower and thunderstorm coverage by the middle of the week.
Thereafter, a cold front approaches the region from the
northwest and unsettled conditions could continue through the
end of the week. Temperatures will remain below normal through
the middle of the week, and then near normal by the end of the
week depending on the strength of the high pressure ahead of the
front.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
29/18z Aviation Discussion:
KCHS/KJZI/KSAV: VFR will prevail through 30/18z. Isolated to
scattered shower activity could approach KSAV by 09z, but more
likely after daybreak as isentropic ascent persists. The rain
looks to remain fairly light so no major vsby restrictions are
expected at this time.

Extended Aviation Forecast: VFR conditions should generally
prevail at KCHS/KJZI/KSAV terminals through early next week,
although brief periods of flight restrictions are possible each
afternoon due to showers and thunderstorms. The greatest chance
for flight restrictions appear to be on Saturday, especially
KSAV as a low pressure tracks nearby.

&&

.MARINE...
Tonight: Onshore winds will prevail as high pressure shifts
offshore. Winds will remain less than 10 kt with seas 1-3 ft.

Saturday through Wednesday: A weak area of low pressure will
attempt to track across the Florida Peninsula along a frontal
boundary this weekend while surface high pressure holds across
the Carolinas into Central Georgia. Expect east-northeasterly
winds to persist across the Atlantic until early next week.
There is potential for winds to become quite gusty (w/ 20 to 25
kts possible) on Sunday as the pressure gradient tightens up.
Therefore, Small Craft Advisories could needed for portions of
the local waters on Sunday and potentially lasting through
Tuesday morning. Seas will range from 2 to 3 ft over the
weekend, and then build 4 to 6 ft early next week.

Rip Currents: A moderate risk for rip currents is in place for
all beaches on Sunday due to the increasing strength of the
pressure gradient.

&&

.TIDES/COASTAL FLOODING...
Tidal departures could begin to build over the weekend into
early next week as low pressure develops offshore and a wedge of
high pressure lingers inland. Tides could get close to minor
flood thresholds in the Charleston Harbor by Monday yielding a
risk for coastal flooding across coastal areas of Charleston and
Colleton Counties during mainly the afternoon high tide cycle.
This risk may extend into the middle of next week depending on
how strong the pinched gradient gets.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$