Port Royal, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

095
FXUS62 KCHS 250744
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
344 AM EDT Fri Apr 25 2025

.SYNOPSIS...
A cold front will move south through the area Sunday. High
pressure will then prevail into next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Overnight composite analysis reveals subtle short-wave ridging
across the Florida Peninsula into the southeast, downstream
from a short-wave progressing through Louisiana into
Mississippi. Surface high pressure remains tucked along the
southeast CONUS into the Atlantic. Difficult to discern, but
there may be some semblance of a boundary/trough extending from
the Carolina coastal waters westward into central Georgia, and
there are some wannabe showers in the SC coastal waters
migrating toward the coast. Otherwise, cloud cover varies across
the forecast area with some stratus and fog trying to develop.

Subtle short-wave ridging and surface high pressure holds across the
local forecast area through today, before the aforementioned short-
wave ripples through the southeast region later tonight into
Saturday.

Early this morning: Main forecast concern revolves around dense fog
possibilities. There are certainly reductions to vsby out there
along with some stratus build down, particularly across the SC
counties. However, given the persistent higher level cloud cover
drifting through the region, which appears to be expanding,
persistent widespread dense fog is looking less likely at this
point. Will continue to monitor.

Meanwhile, as mentioned, there are some wannabe showers in the SC
Atlantic waters that might make a run toward the coast this
morning...similar to yesterday morning. Keeping the forecast dry
this morning for now but again...will continue to monitor.

Today: Barring any morning showers off the Atlantic, attention turns
to the potential for convection later this morning and through the
afternoon. Per forecast soundings/high-resolution plan view
data, instability this afternoon does not appear quite as
conducive to convection compared to the last few days, with a
few to several hundred J/Kg MLCAPE values...greatest across the
SC counties. Less instability and a bit more capped heading
south through Georgia. Thus, plan to trend pops downward for
today, maintaining some low end chances just across the
Charleston tri-county area. High temperatures will reach the
lower to middle 80s.

Tonight: Mid level short-wave will be rippling through the
southeast region during the course of the night and may be
driving a batch of showers and some thunderstorms through
Georgia and into the Carolinas. Looking like bulk of the
activity will be impacting the western Carolinas and the
Midlands, just grazing the western/northern parts of the
forecast area later this evening and overnight. Otherwise, mild
temperatures anticipated with lows in the lower to middle 60s.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
Saturday: Shortwave energy will exit off the Southeast U.S. Saturday
morning. Heights will rise through the day as subtropical ridging
centered over northern Mexico nudges east. While some recovery of
instability could occur Saturday afternoon, the degree of recovery
is unknown with some DAVA/subsidence noted behind the departing
shortwave possibly lingering into the afternoon hours. There is a
potential the afternoon resultant sea breeze to meet up with
boundaries generated by convection of the Midlands late in the
afternoon which could help concentrate convection across the
interior, especially over interior Southeast South Carolina. This
assumes some instability recovery occurs and any lingering
subsidence can be overcome. Pops were lowered slightly to 20-40%
with both the 25/03z NBM and 25/00z operational GFS with support
from the 25/00z HREF trending drier. Highs will warm into the mid-
upper 80s with cooler conditions at the beaches. Overnight lows will
range from the lower 60s well inland to the the upper 60s/near 70 at
the beaches.

Sunday: A cold front will move south through the area Sunday as
shortwave energy pivots across New England into the Mid-Atlantic and
high pressure over the Ohio Valley begins to bridge the Central
Appalachians and wedge into the Southeast States. The front looks to
stall somewhere across southern Georgia to near the Florida state
line by Sunday evening with a cyclonic flow persisting aloft. The
front and the afternoon sea breeze could be foci for convection, but
much will depend on how quickly the front pushes south and how much
shortwave energy will propagate through via the northwest flow
aloft. Pops were limited to slight chance for now consistent with
the 25/03z NBM. The operational GFS is considerably wetter, but may
be suffering from convective feedback issues. The corresponding GEFS
plumes are showing a drier solution overall, but do highlight better
chances for measurable rainfall over Southeast Georgia. See no
reason to deviate from the NBM at this time, but additional changes
may be needed once confidence on how the convective pattern will
unfold builds. Highs will warm into the lower 80s across Southeast
South Carolina with mid-upper 80s across Southeast Georgia; cooler
at the beaches. Lows Sunday night will range from the mid-upper 50s
inland with mid-upper 60s at the beaches. Breezy conditions could
also develop along the beaches where an enhanced pressure gradient
could occur.

Monday: Subsidence will build Monday as the subtropical ridge
centered over northern Mexico shifts east into the Gulf, Deep South
and Southeast States. Onshore winds/speed convergence over Southeast
Georgia could generate a few low-topped showers, especially near the
Altamaha River. 20-30% pops were highlighted consistent with the
latest NBM, but confidence in measurable rainfall is low. Highs will
warm into the lower 80s away from the beaches.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Much of the extended period will remain fairly quiet with Atlantic
high pressure nudging in from the east and subtropical ridging
dominating aloft. Subsidence with the ridge aloft will keep rain
below climatological levels although rain chances will increase
Thursday into Friday as the ridge aloft dampens. Temperatures will
hold at or slightly above normal levels for late April. Resultant
sea breeze influences are likely each afternoon/evening.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
KCHS/KJZI: VFR conditions are holding at the moment, although
with signs of some shallow fog out there. Guidance continues to
suggest fog and/or low stratus will develop late tonight,
generally in the 08Z-13Z Friday time frame. Prevailing MVFR
groups have been set for 08Z-13Z, while tempo IFR cigs/vsbys are
a possibility. Conditions will improve after daybreak Friday,
likely becoming VFR by around 14Z, then continuing through the
day.

KSAV: VFR conditions continue. MVFR cigs/vsbys are possible
late tonight, and a TEMPO MVFR group between 09Z-12Z is in
place to account for these conditions. Expect VFR conditions to
return shortly after daybreak Friday, then prevail through the
day.

Extended Aviation Outlook: Thunderstorm impacts are possible
Saturday. Patchy low clouds and fog are possible Saturday
night/Sunday morning. Gusty winds are possible each afternoon with
the passage of the resultant sea breeze.
&&

.MARINE...
Today and tonight: East to southeasterly flow will persist
across the coastal waters through tonight with speeds 5 to 15
knots and seas largely running 2 to 3 feet.

Saturday through Wednesday: Southerly winds will persist Saturday
before winds turn northerly with the passage of a cold front through
the area Sunday. Northeast winds will gradually veer more easterly
Monday, then more southerly Tuesday and Wednesday. Speeds will
remain 15 kt or less through the period, although it could be
locally higher (15 kt with gusts to 20 kt) with the resultant sea
breeze in the Charleston Harbor and along the land/sea interface
each afternoon. Seas could build as high as 4-7 ft Monday and
Tuesday with the post frontal northeast winds. A Small Craft
Advisory may be needed during this time, especially over the Georgia
offshore waters out 20-60 NM.

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 beaches with a moderate risk for all remaining beaches for
Saturday. Depending on how strong the sea breeze becomes, stronger
winds could tip the Georgia and far southern South Carolina beaches
into the high category.

The risk will remain elevated Sunday, possibly lingering into the
early part of next week.

&&

.TIDES/COASTAL FLOODING...
Minor 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. Coastal Flood
Advisories may be needed. For the Fort Pulaski gage, tides look to
remain just below minor flood thresholds (9.5 ft MLLW).

&&

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

&&

$$

NEAR TERM...Adam
SHORT TERM...ST
LONG TERM...ST
AVIATION...Adam/ST
MARINE...Adam/ST