012
FXUS62 KCHS 260421
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1221 AM EDT Sat Apr 26 2025

.SYNOPSIS...
A cold front approaches on Saturday with a chance of showers
and thunderstorms. High pressure will build into the region
after the passage of the front on Sunday and into next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A quiet and seasonably warm night is in progress across
Southeast South Carolina and Southeast Georgia. Dry conditions
will prevail for most areas through the night, although a few
hours may approach the far western areas around daybreak. Lows
from the lower 60s inland to around 70 at the beaches look on
track. No major changes were made for the midnight update.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
Saturday: Large-scale ridging across the United States will persist,
as a shortwave situates itself overhead and slowly moves east and
eventually off the eastern seaboard overnight. Heights will increase
throughout the day as the aforementioned ridging nudges closer. With
the shortwave departure overhead, there is some signaling of
instability firing up in the afternoon. Latest HREF suggests CAPE
values ~1500 J/kg in the afternoon with 0-3 SRH values ~100-150
m^2/m^2 (some pockets of 200m^2/s^2). This combined with a potential
afternoon seabreeze could stir up some convection (especially over
interior southeastern South Carolina). PoPs were increased to 40-60%
in the afternoon for the Charleston Tri-County due to it being a
more favorable environment than the rest of the region. However,
rainfall amounts remain low, most areas will only see 0.05 to 0.10
inches with regions more inland seeing 0.15 inches at best. Highs
will be in the mid to upper 80s in southeastern South Carolina and
upper 80s to low 90s in southeastern Georgia with cooler
temperatures closer to the coastline. Overnight lows will drop into
the low to mid 60s and upper 60/low 70s closer to the coastline.

Sunday: As the aforementioned shortwave shifts off the Northeast
coast in the morning, an associated cold front passes through to the
south of the region. Some models are indicating that the front will
stall across southern Georgia to near the Florida state line in the
evening as a cyclonic flow persists aloft. It is possible to see
some showers and thunderstorms with this frontal passage as the
afternoon seabreeze could force some convection develop. Behind the
front, high pressure situated over the Midwest begins to build into
the region. Left PoPs in the 20-30% for southeastern Georgia, might
need to increase later on but will wait how things change in the
next day or so. Highs will warm into the low to mid 80s across
southeastern South Carolina and upper 80s to low 90s across
southeastern Georgia with cooler temperatures closer to the
coastline. A bit cooler on Sunday night partially due to the high
pressure building in behind the front and clearing out the skies
allowing good radiational cooling to occur. Lows will dip into the
upper 50s to low 60s with it being a tad warmer along the beaches.

Monday: A tropical ridge centered over Mexico will begin to shift
eastward over the Gulf and Southeast CONUS. It doesn`t look like a
very favorable environment for any showers and/or thunderstorms to
pop up, thus PoPs were lowered. Highs will climb into upper 70s to
low 80s with cooler temperatures along the coastline.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As an Atlantic high pressure nudges closer, subtropical ridging will
dominate aloft. Most of the extended period will remain quite until
Friday afternoon when the next chance for showers is expected.
Temperatures will hold at or slightly above normal levels for late
April. Resultant sea breeze influences are likely each
afternoon/evening.

&&

.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
26/06z TAF Discussion:
KCHS/KJZI/KSAV: Some shallow ground fog could impact all
terminals through daybreak, but most likely at KJZI. A TEMPO
group for 4SM MIFG was included 09-12z at KJZI to account for
this. Quiet conditions will prevail this morning with VFR
conditions. Scattered showers/tstms are expected to develop near
KCHS and KJZI later this afternoon during peak instability.
VCTS was included 19-22z at KCHS and 20-23z at KJZI for now as
timing is a bit uncertain. The need for anything more will be
reevaluated at 12z. For KSAV, activity will be much more
isolated and probabilities are too low to include a mention of
tstms just yet.

Extended Aviation: There is a possibility of fog and/or low
stratus Sunday morning Gusty winds are possible each afternoon
with the passage of the resultant sea breeze.

&&

.MARINE...
Tonight:The local waters will remain situated on the western
side of a huge Atlantic high. The gradient will stay fairly lax,
as SE and S winds around 10 kt early on, veer around to the S
and SW at similar speeds due to land breeze influences overnight.
The wave spectrum will be mainly due to swells, and will average
2-4 feet, highest on the outer Georgia waters.

Saturday through Wednesday: Expect southerly winds to
persist Saturday before turning northerly with the passage of the
cold front on Sunday. On Monday, northeasterly winds will gradually
veer easterly, and then southerly Tuesday and Wednesday. Marine
conditions look to remain calm, however gust to 15 to 20 kt with the
afternoon/evening sea breeze each day. Seas will generally be from 2
to 3 ft, except build 3 to 5 ft on Monday and Tuesday due to post
FROPA (especially for the outer Georgia waters).

Rip Currents: A 2 ft, 9 sec easterly swell will persist into
Saturday. These conditions combined with enhanced winds along the
land/sea interface with the sea breeze and the approaching new moon
will support a high risk for rip currents along the Charleston
County and Beaufort County beaches with a moderate risk for
southeast Georgia beaches on Saturday.

The risk deescalates some on Sunday, expect low risk for rip
currents along Charleston County and Beaufort County beaches with a
moderate risk for southeast Georgia beaches.

&&

.TIDES/COASTAL FLOODING...
Minor to moderate coastal flooding is possible with the evening
high tides due to the elevated tides from the approaching new
moon and perigee. For the Charleston Harbor gage, the
astronomical tides rise above 6.5 ft MLLW with the evening tides
Saturday through Wednesday. With the approaching surface high
pressure Sunday and Monday, northeasterly to easterly surface
flow may cause the waters to rise into minor flood stage (7.0 ft
MLLW) with the evening high tides with a possibility for
moderate flooding (7.5 ft MLLW) for the Sunday evening high
tide. For the Fort Pulaski gage, minor flooding (9.5 ft MLLW)
is possible with the Sunday evening high tide. Coastal Flood
Advisories will be needed for portions of the coast.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...High Risk for Rip Currents from 8 AM EDT this morning through this
     evening for SCZ048>051.
MARINE...None.

&&

$$