Islandton South Carolina Weather Forecast Discussion

345
FXUS62 KCHS 101133
AFDCHS
Area Forecast Discussion
National Weather Service Charleston SC
733 AM EDT Fri Oct 10 2025
.SYNOPSIS...
High pressure will prevail inland through early next week.
Meanwhile, at the surface, expect a coastal low to develop
offshore today and linger through Saturday before lifting
northward along the Atlantic coast.
&&
.NEAR TERM /THROUGH TONIGHT/...
Today: Aloft, a mid-lvl low will attempt to cut-off across the
Southeast, meandering nearby throughout the day. At the sfc,
high pressure will continue to build across the local area from
the north prior to low pressure developing off the Southeast
Coast late. Most locations will start off dry early morning,
particularly across inland and northern zones where drier air is
present with the building high. However, the general model
consensus is that few to scattered showers are to begin
developing by mid-late morning as weak isentropic lift develops
and the mid-lvl provides additional forcing while PWATs slowly
increase to 1.5 inches locally. By late morning, the primary
focus for additional showers and perhaps a few thunderstorms
should occur/arrive from the Atlantic, where troughing begins to
take place and a north-northeasterly wind eventually nudges
precip activity closer to the coast. There should be a fine line
in regards to rainfall late morning and afternoon, with the
bulk of shower/thunderstorm activity likely to occur near the
coast. However, there are some suggestions that activity is
mostly stratiform based once reaching land given more stable air
associated with high pressure inland. For this reason, highest
rainfall accumulations should remain across coastal zones
(particularly in Southeast SC) with amounts generally in the
0.25 to 0.75 inch range late morning through the afternoon.
Temps will remain noticeably cooler with the persistent north-
northeast wind and high pressure in place. In general, highs
should range in the lower 70s.
Tonight: The mid-upper lvl low will continue to meander across the
Southeast while the right-rear quadrant of an h25 jet becomes
favorably positioned for weak sfc troughing to become the primary
focus of sfc low pressure developing/deepening off the Southeast
Coast. Latest guidance continues to indicate a slight uptick in
shower/rain coverage across coastal areas overnight, but again
activity should remain mostly confined to coastal zones in regards
to accumulating precip. A strong gradient between the high inland
and low developing/deepening offshore late will continue to promote
breezy north-northeasterly winds across land, generally in the 15-20
mph range with slightly higher gusts around 25 mph near the beaches.
Additional rainfall accumulations in the 0.25 to 0.50 inch range are
possible along the beaches, with upwards to an inch possible across
northern Charleston County during the night. Low temps will remain
on the cooler side, generally dipping into the upper 50s inland to
low-mid 60s near the coast.
Lake Winds: Cold air advection associated with high pressure
building across the region will continue to support gusty north-
northeasterly winds around 25 kt across Lake Moultrie today and
tonight. A Lake Wind Advisory remains in effect through tonight.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
Coastal low will continue to linger offshore for much of Saturday
before lifting northward Sunday. While some deviations in the speed
of exit still exist, overall guidance agrees that conditions should
be on an upward trend. That being said, still expect to see isolated
to scattered showers during this time, with higher rainfall amounts
possible late Saturday night on the backside of the departing low.
This would mainly impact Colleton county northward, including the
Charleston Tri-County area. In terms of accumulations, have rainfall
amounts between 8 AM Saturday and 8 PM Sunday ranging between a few
tenths to just over an inch, with the highest totals occurring in
the areas mentioned previously. Outside of this, will also see
breezy winds continue, with direction shifting more northwesterly.
Otherwise, should see the largely dry conditions return Sunday
afternoon as the aforementioned low lifts north of the area. Sunny
skies then return Monday as highs warm back into the lower 80s, with
winds forecast to become notably lighter as the pressure gradient
relaxes.
Lake Winds: Winds on Lake Moultrie will remain elevated into the
weekend as a strong, pinched gradient dominates in response to
building high pressure across the region and cyclogenesis off the
coast. A Lake Advisory is in effect for Lake Moultrie through
Saturday afternoon for NE wind gusts 25 to 30 knots and waves 2
to 3 ft.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Upper level ridging develops across the central CONUS heading into
the new week as a coastal low continues its journey northward along
the Atlantic coast. As noted in the previous discussion, should see
conditions remain largely dry. Otherwise, look for a moisture
starved cold front to dive southeastward across the region Wednesday
into Thursday, causing highs in the low to mid 80s to dip back into
the upper 70s.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Gusty north-northeasterly winds are expected at CHS/JZI/SAV
terminals throughout the TAF period, generally gusting to the
20-25 kt by mid morning and continuing through at least evening
hours. Showers coming onshore are anticipated to impact all
terminals at various times today and tonight, starting between
12-13Z at CHS/JZI terminals and early morning, then early
afternoon at the SAV terminal. TEMPO MVFR groups have been
included at all terminals during morning and early afternoon
hours, but expect all sites to eventually transition to
prevailing MVFR conditions between the 17-20Z time frame, then
persist through 12Z Saturday. IFR vsbys have also been included
at JZI due it the proximity to potentially heavier showers
drifting onshore later this morning. There is also a low-end
chance for IFR conditions late tonight at all terminals, but
confidence is too low to include in the 12Z TAF issuance.
Extended Aviation Outlook: Gusty N to NE winds will impact
KCHS/KJZI/KSAV through Saturday. Flight restrictions may occur
with low clouds into the weekend as a low pressure lingers off
the Southeast coast.
&&
.MARINE...
Today and Tonight: Strong high pressure building inland along with
low pressure developing offshore will favor a strong pressure
gradient and fluctuations of cold air advection across local waters
throughout the day. The setup will continue to support dangerous
marine conditions across local waters with Gale Warnings in effect
across all nearshore and outer Georgia waters through tonight. A
Small Craft Advisory will continue in the Charleston Harbor through
tonight as well. Strong and persistent north-northeasterly winds
gusting to around 35 kt (outside the Charleston Harbor) will support
large seas, generally in the 6-11 ft range, largest off the
Charleston County Coast and outer Georgia waters, before subsiding
about a foot late night. Rounds of showers and thunderstorms are
anticipated to develop across coastal waters early today and will
continue during the afternoon prior to low pressure developing/deepening
off the Southeast Coast overnight. This activity could temporarily
reduce wind gusts to below gale force across some local waters
at times late day/tonight, but the pressure gradient remains
strong through the night suggesting the potential for gale force
gusts continuing late night.
Saturday Onward: Elevated winds and seas will continue through much
of Saturday as low pressure develops off the Southeast coast. The
low is expected to lift north of the area late Saturday into early
next week, leading to improving conditions. However, winds and seas
will take time to subside, so Gale Watches/Warnings are expected to
be replaced by Small Craft Advisories - which could persist into
Monday.
Rip Currents: Strong northeast winds and building seas will lead to
an enhanced risk of rip currents through the weekend. A High Risk of
rip currents is forecast at all area beaches today through Saturday.
High Surf: Large breaking waves of 5+ feet are expected at all area
beaches today through Saturday as strong high pressure builds inland
and low pressure develops offshore. A High Surf Advisory is in
effect for the entire coastline. This in addition to very high tide
cycles will likely lead to some erosion at area beaches.
&&
.TIDES/COASTAL FLOODING...
Strong NE winds resulting from high pressure inland and developing
low pressure offshore will allow tidal departures to increase
through the next several high tide cycles. Astronomical tide values
are already elevated owing to the recent full moon and perigee,
which combined with increasing departures will result in coastal
flooding with each high tide cycle into the weekend.
Charleston Harbor Tide Gage: The late morning high tide cycles
Friday and Saturday have the potential to hit major coastal flooding
thresholds (>8 ft MLLW). A Coastal Flood Warning is in effect for
Charleston and Coastal Colleton Counties for the late morning high
tide cycle when levels could peak in the 8.3-8.5 ft MLLW range. A
Coastal Flood Advisory is in effect for Tidal Berkeley County.
Flooding can occur several hours before and after the tide peaks.
It`s worth noting confidence is not quite as high in reaching major
on Saturday as pure astronomical values start to come down. While
the morning tides are dominant, minor coastal flooding will be
possible with the evening high tides. The threat for coastal
flooding should decrease early next week.
Fort Pulaski Tide Gage: The late morning high tide cycles for today
through Saturday have the potential to reach moderate coastal
flooding (10 to 10.5 ft MLLW). A Coastal Flood Advisory is now in
place for the late morning high tide cycle when levels could
peak in the 10.2 to 10.4 ft MLLW range. Additional Coastal
Flood Advisories are expected. Minor coastal flooding will be
possible with the Sunday early afternoon tide cycle, then the
threat for coastal flooding should decrease.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents through this evening for GAZ117-119-139-
     141.
     High Surf Advisory until 8 AM EDT Sunday for GAZ117-119-139-
     141.
     Coastal Flood Advisory until 3 PM EDT this afternoon for
     GAZ117-119-139-141.
SC...High Risk for Rip Currents through this evening for SCZ048>051.
     High Surf Advisory until 8 AM EDT Sunday for SCZ048>051.
     Coastal Flood Advisory until 3 PM EDT this afternoon for
     SCZ048-051-052.
     Lake Wind Advisory until 2 PM EDT Saturday for SCZ045.
     Coastal Flood Warning until 3 PM EDT this afternoon for SCZ049-
     050.
MARINE...Small Craft Advisory until 6 AM EDT Sunday for AMZ330.
     Gale Warning until 11 PM EDT Saturday for AMZ350-352.
     Gale Warning until 8 PM EDT Saturday for AMZ354.
     Gale Warning until 2 AM EDT Sunday for AMZ374.
&&
$$
NEAR TERM...DPB
SHORT TERM...SST
LONG TERM...SST
AVIATION...DPB/SST
MARINE...DPB/SST

NWS CHS Office Area Forecast Discussion