304
FXUS62 KCHS 291718
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
118 PM EDT Mon Sep 29 2025

.SYNOPSIS...
Tropical Storm Imelda will move through the northern Bahamas
tonight, then northeast away from the Southeast U.S. coast
Tuesday and Wednesday. Cooler high pressure will then build in
from the northwest.

&&

.NEAR TERM /THROUGH TONIGHT/...
The Predecessor Rain Event (PRE) signature noted just offshore
in the vicinity of the coastal front has not made any
meaningful westward progress so far today. This should continue
this afternoon into the overnight hours as Tropical Storm Imelda
begins to slow down a bit and turn more to the northeast as it
exits the northern Bahamas. Steadier light to locally moderate
rainfall will persist across central and upper Charleston
County, but should diminish later this evening once Imelda
beings to trek more northeast. The risk for isolated to
scattered showers will persist along/west of I-95 for the
remainder of the afternoon before evening this evening. The
best chances of rain overnight will generally be confined for
areas east of I-95 as the inland high pressure wedge holds.
Additional rainfall will generally average <0.10", except up to
0.25" over upper Charleston County. Lows tonight will range from
upper 60s well inland to the lower 70s at the beaches. A
tightening pressure gradient between the inland wedge and Imelda
will yield breezy to locally windy conditions at the beaches
where gusts as high as 30-35 mph could occur.


&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
The forecast area will be positioned between Imelda tracking
northeastward well off the Southeast coast and high pressure
inland on Tuesday. The primary impacts associated with Imelda
will be marine/coastal-related (see sections below). While a few
showers will still be possible, the trend has been drier with
the deepest moisture remaining offshore. PoPs are generally
20-30%. Otherwise expect winds to be a bit gusty and
temperatures in the upper 70s to perhaps lower 80s.

High pressure will expand and build across the area Wednesday
into Thursday. This period should be mostly dry, although could
not rule out a shower or two impacting the far southeast Georgia
coast on Thursday with increased low level convergence within
northeast flow regime. Near normal temperatures Wednesday will
trend cooler on Thursday as highs top out in the mid to upper
70s. Low temperatures Wednesday night should dip into the upper
50s across most interior locations.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A ridge of high pressure will continue to extend into the area
late week into the weekend, while a coastal trough
develops/sharpens offshore. As this occurs, rain chances will
return, especially along coastal areas. Still some uncertainty
with the evolution of this feature with some hints that the
trough could shift inland late in the period or early next week.
Temperatures are expected to be near or slightly below early
October normals.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
29/18z TAF Discussion:
KCHS/KJZI/KSAV: Widespread IFR/MVFR cigs should lift to MVFR all
terminals later this afternoon. Once the sun sets, cigs should
lower back to IFR which will persist through the night. Gusty
northeast winds will persist. Cigs may lift to MVFR at KSAV
after daybreak.

Extended Aviation Forecast: Sub-VFR ceilings could continue
into Tuesday night, along with occasional vsby reductions due to
showers and thunderstorms. Gusty NE winds also expected through
Wednesday.

&&

.MARINE...
Tonight: Northeast winds will increase to 20-25 kt with gusts to
30 kt overnight as Imelda turns northeast and inland high
pressure holds. Winds in the Charleston Harbor will be a bit
less, averaging 15-20 kt with gusts to 25 kt. Seas will build to
5-9 ft nearshore waters, 9-12 ft over Georgia offshore waters
with waves 1-2 ft in the Charleston Harbor. The combination of
winds and seas necessitate keeping the Small Craft Advisory in
place for all legs through tonight. There is a low-end risk for
frequent gusts to gale force over the eastern portion so the
Georgia offshore waters (mainly 40-60 NM out). HREF probs for
gusts >34 kt hold 10-20% through the night, which is too low to
justify an upgrade to a Gale Warning at this time.

Tuesday through Saturday: A tight pressure gradient between
Imelda passing well off the Southeast coast and high pressure
inland will lead to breezy north to northeast winds. Speeds
should peak in the 20-30 kt range. A few gusts to gale force are
possible, mainly in the far outer reaches of the outer Georgia
waters, but probabilities seem too low to hoist a Gale Watch at
this time. In addition, seas will build across the marine zones
with wave heights expected to reach 7-13 feet. Small Craft
Advisories remain in effect for all waters. Elevated winds and
seas are expected to persist late week into the weekend as
strong high pressure builds into the area, resulting in
continued SCAs. There is another threat for a period of gale
force wind gusts later Thursday into Thursday night.

Rip Currents/High Surf: A High Risk of rip currents is expected
through at least Wednesday at all beaches due to large, long-
period swells and strong winds. In addition, large breaking
waves of 5+ feet are expected through much of the week. A High
Surf Advisory remains in effect.

&&

.TIDES/COASTAL FLOODING...
Strengthening and persistent north-northeasterly winds this
week will result in increasing tidal departures along the
southeast South Carolina and southeast Georgia coast. Minor
coastal flooding is possible during the late afternoon/early
evening high tide cycle, mainly for the Charleston and Colleton
county coast, starting as early as Tuesday. The risk will
continue into late week.

Heading into this weekend and next week, astronomical tides
will increase due to the upcoming Full Moon (Oct 7) and Perigee
(Oct 8). This in combination with the anticipation of continued
northeasterly flow will cause the possibility of coastal
flooding to become more likely along the entire coast, including
both Downtown Charleston and Fort Pulaski. Saltwater inundation
could then occur during both the morning and evening high tide
cycles during this time. Although there is considerable
uncertainty this far out, persistent favorable winds have the
potential to produce up to major coastal flooding.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents through Tuesday evening for GAZ117-119-
     139-141.
     High Surf Advisory from 8 PM this evening to 8 AM EDT Saturday
     for GAZ117-119-139-141.
SC...High Risk for Rip Currents through Tuesday evening for SCZ048>051.
     High Surf Advisory from 8 PM this evening to 8 AM EDT Saturday
     for SCZ048>051.
MARINE...Small Craft Advisory from 5 PM this afternoon to 2 AM EDT
     Wednesday for AMZ330.
     Small Craft Advisory until 6 AM EDT Sunday for AMZ350-352-354-
     374.

&&

$$