Port Royal, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

359
FXUS62 KCHS 042207
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
607 PM EDT Mon Aug 4 2025

.SYNOPSIS...
A stationary front will linger near or just south of our area
this week, while high pressure remains centered well to the
north. Low pressure could develop off the Southeast U.S. coast
Thursday and persist into the weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
Rest of Today: The region sits between a well-defined upper trough
extending from the Midwest into the ArkLaTex and ridging centered
over the northern Caribbean. At the surface, a stationary front
remains draped across the FL/GA border, with a wedge of high
pressure inland. The front will act as the primary trigger for
deep convection, though additional lift will be provided by
embedded shortwave energy aloft and isentropic ascent across the
Midlands and interior portions of the forecast area. Numerous
showers and isolated thunderstorms will continue to develop
near the front this afternoon and evening, mainly south of the
forecast area, and drift northeastward into our southern most
counties. As they move into the area, deeper convection will
initially be sustained thanks to greater instability (MLCAPE
~1400 J/kg), but is expected to weaken or erode as it pushes
into southeast South Carolina where SBCAPE drops below 500 J/kg.
Models also show signs of deeper convection developing
near/along the coast due to enhanced convergence. Therefore,
the heaviest rainfall will be confined mainly to areas south of
I-16 and the immediate coast aligned with the axis of greatest
instability and low level convergence. Despite PWATs near 2.25
inches, limited instability will inhibit rainfall rates,
especially away from the coast, and storm motions of 10-15 kt
should help limit prolonged rainfall at any one location. HREF
highlights the coastal areas and locations along the Altamaha
River with a 20-30% chance of receiving 2" of rainfall or
greater between 5-11 PM, with the highest probabilities (4050%)
centered over Tattnall and Evans Counties. As with yesterday,
widespread rainfall amounts are not particularly impressive, but
we cannot rule out an isolated locally heavy rainfall and flash
flooding threat especially for areas across extreme southeast
Georgia and along the coast that have already received multiple
inches over the past two days. Flood Advisories and/or Flash
Flood Warnings could eventually be needed this evening or later
tonight.

Abundant cloud cover and persistent showers will keep afternoon
highs slightly cooler, especially in areas under the influence of
northeast surface flow and high pressure. Most locations will peak
in the low to mid 80s, with some far inland areas potentially
staying in the upper 70s. Conversely, portions near the Altamaha
River could reach the upper 80s.

Tonight: Showers will persist into the evening but coverage should
diminish slightly overnight with the loss of daytime heating.
However, given abundant moisture and forcing mechanisms aloft,
isolated to scattered showers could linger into the early
morning hours. Similar to previous nights, along the coast,
enhanced moisture convergence and modest instability from the
nearby Atlantic could support moderate showers and perhaps an
isolated thunderstorm, with a continued threat for localized
flooding. Overnight lows will range from the upper 60s to low
70s inland, and low to mid 70s along the coast.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A stationary front will remain to our south while High pressure is
to our north. There could be occasional waves of energy flowing over
our area during the short term. This coupled with typical diurnal
instability will support numerous showers/tstms each day with the
greatest coverage occurring across Southeast Georgia. There will be
plenty of moisture in place (PWATs 2.00-2.25"), so this supports the
convection. But it will be drive by the sea breeze, and mesoscale
boundary interactions. Convection will be slow to dissipate each
evening with isolated to scattered convection overnight. The
forecast becomes a bit more uncertain beginning Thursday with Low
pressure possibly developing off the Southeast U.S. coast. High
temperatures will be slightly below normal with low temperatures
near normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Low pressure off the Southeast U.S. will persist. The forecast will
hing on this feature with its strength, timing, and track still
highly uncertain. The National Hurricane Center currently shows a
low chance for tropical cyclone development. We maintained what the
NBM has, which is unsettled weather.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
05/00z TAF Discussion:
KCHS/KJZI: Conditions will mostly remain VFR through the period.
A period of MVFR cigs could develop late tonight and linger
through mid-morning, but the better probabilities are to the
west of both terminals. Scattered to numerous showers/tstms
could approach both sites late in the afternoon. VCTS was
highlighted 21-00z for now.

KSAV: Convection south of the Altamaha River could approach
KSAV later this evening, but current data suggest it will fall
apart before reaching the terminal. Otherwise, a brief period of
VFR cigs could occur before cigs drop back down to MVFR by mid-
evening. A TEMPO for VFR cigs was introduced 00-02z to account
for this. There is a low risk for some IFR cigs forming just
before daybreak, but chances are too low to mention at this
time. VFR should return by late morning. Scattered to numerous
showers/tstms could approach both sites late in the afternoon.
VCTS was highlighted 21-00z for now.

Extended Aviation Outlook: Periodic flight restrictions are expected
due to showers/thunderstorms.

&&

.MARINE...
Rest of today and tonight: The synoptic setup remains largely
unchanged from the previous day, with inland high pressure and a
nearly stationary front situated just south of the local
waters. This pattern continues to support a modestly enhanced
pressure gradient, resulting in sustained northeasterly winds
around 15 kt with occasional gusts near 20 kt through the
afternoon. As the gradient relaxes this evening, winds will ease
to 10 to 15 kt and veer more easterly overnight. Seas will
subside to 2 to 4 ft by late tonight.

Tuesday and Wednesday: Generally easterly winds will prevail as a
stationary front is to our south and High pressure is to our north.
While occasional pinching of the pressure gradient is likely, winds
will generally remain 15 kt or less. Seas will be 2-3 ft within 20
nm and 3-4 ft for the GA waters beyond 20 nm.

Thursday through Saturday: This portion of the forecast will
depend on Low pressure that forms off the Southeast U.S. coast,
generally how weak or strong it gets. East to northeast winds
will continue, but speeds as well as waves/swell may become
enhanced depending on the eventual track, strength, and speed
the Low takes.

&&

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

&&

$$