Port Royal, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

429
FXUS62 KCHS 221320
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
920 AM EDT Sun Jun 22 2025

.SYNOPSIS...
Strong high pressure will remain across the Southeast U.S. this
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
This Afternoon: The center of a large 598DM anticyclone aloft
will settle just north of the area today with Atlantic high
pressure nosing in from the east. This pattern will promote a
fairly progressive sea breeze as high temperatures warm into
the lower-mid 90s away from the beaches. Today`s sea breeze may
favor more a pure vs resultant geometry, which typically produces
a much weaker low-level convergence field overall. This coupled
with warming temperatures aloft and the mixing out of dewpoints
into the 60s should yield very little in the way of convection
again this afternoon. There may be just enough convergence and
low-level moisture pooling to support a brief shower or tstm
along and just behind the sea breeze from late this morning into
the mid afternoon hours across the coastal counties, especially
coastal Colleton and far lower Charleston County south to
roughly Bryan County, but the chances look too small to justify
a mention at this time. Heat indices look peak once again into
the upper 90s to around 100 which is well below Heat Advisory
criteria of 108.

Tonight: No significant changes are expected to the overall pattern
with high pressure dominating the Southeast in the mid-lvls and near
the sfc. Sfc winds will likely decouple under clear skies for areas
away from the beaches mid evening, leading to light/calm conditions
overnight. Much like the previous night, hires models indicate the
potential for patchy fog developing away from coastal areas late
night, which has been introduced in the latest forecast for most
inland areas given low condensation pressure deficits. Temps will
remain mild, but should cool a degree or two more than the previous
night, with lows generally ranging in the lower 70s inland to mid-
upper 70s closer to the coast.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
A strong upper-lvl ridge will build over the Southeastern CONUS
throughout the week. According to the GFS, the 500MB heights will be
near the climatological maximum by Monday afternoon. This indicates
a very strong warming pattern throughout the week under this ridge.
Expect temperatures to climb into the mid to upper 90s, with heat
indices creeping to ~105-107 in the afternoons. As of right now,
heat indices remain just below Heat Advisory criteria (108F), but
this will continue to be monitored over the next couple days. This
sort of heat is not uncommon for this time year, however it is
important to remember to stay hydrated and limit outdoor activity
(esp. in the afternoon). Unfortunately, overnight lows will remain
mild and only dip into the low to mid 70s. With little moisture
available and model guidance continuing to show subsidence filtering
into the mid-lvls, the atmosphere will have a really hard time
developing showers and thunderstorms while this strong ridging
persists. PoPs were kept below 20% for each day, however if any
convection should develop, it will be along the seabreeze and it
will be extremely limited in coverage.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
This strong upper-lvl ridging pattern will continue to stay situated
over the region and limit shower and thunderstorm activity.
Simultaneously, heat will build over the region and temperatures
will remain above average for this time of the year with highs
ranging from the mid to upper 90s. Dewpoints were lowered a couple
degrees in accordance to model consensus. However, this will still
push heat indices near and/or above 100 in the afternoons. As of
right now, these heat indices remain under Heat Advisory criteria
(108F), but this will continue to be monitored over the couple days.
As this ridge finally begins to weaken by the end of the week, some
moisture is able to return to the region and ensembles indicate a
better chance for rain over the weekend. Again, overnight lows look
to remain mild.

&&

.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
VFR conditions should prevail at CHS/JZI/SAV terminals through
12Z Monday. However, shallow ground fog could produce vsbys
restrictions at all terminals tonight, mainly between 08Z-12Z
Monday. For now, 6SM MIFG has been included at the terminals
for this time frame, but MVFR vsbys could eventually be needed
in future TAF issuances.

Extended Aviation Outlook: With the strong upper-lvl ridge in place
over the Southeast, VFR should prevail throughout the period.
Chances of afternoon convection remains too low to mention in the
forecast at this time.

&&

.MARINE...
Today and Tonight: Atlantic high pressure will dominate the pattern
across local waters, favoring conditions that remain well below
Small Craft Advisory levels during the day and night. In general,
south-southeast winds will peak around 10-15 kt this afternoon,
highest across the Charleston Harbor and perhaps along beaches as a
sea breeze develops, then shifts inland. Winds should then become
more directly south and remain around 10 kt or less during the
night. Seas will generally range between 1-2 ft.

Monday through Thursday: As a weak south-easterly swell continues to
filter in, seas will be kept to 1 to 3 ft. Expect winds at 5 to 10
kt to prevail throughout the period as this upper-lvl ridge builds
over the region and then eventually shifts offshore by the end of
the week. It could become a bit gusty each afternoon with gusts up
to 15 to 20 kt as the seabreeze pushes inland (gusts strongest
across the Charleston Harbor).

Rip Currents: A 2 ft, 8 sec swell will impact the beaches through
this evening with a 10 kt onshore wind in place. These conditions
along with recent rip currents reported along Tybee Island, GA
yesterday, supports a Moderate Risk for rip currents along Georgia
beaches through this evening. Should these conditions persist and
new reports occur today, the rip current risk could need to be
upgraded to Moderate Risk along Georgia beaches on Monday as
well.

&&

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

&&

$$