North Charleston, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

696
FXUS62 KCHS 092015 AAA
AFDCHS

Area Forecast Discussion...UPDATED
National Weather Service Charleston SC
415 PM EDT Fri Oct 9 2026

.WHAT HAS CHANGED...
All sections have been updated.

&&

.KEY MESSAGES...
- 1) Moderate to Major coastal flooding expected with the
  Saturday morning high tide, with additional coastal flooding
  possible through the weekend.

- 2) Hurricane Isaias is expected to approach the northern Gulf
  Coast late today, before shifting across the Deep South on
  Saturday. Although the center of the storm will remain well
  west of the region, heavy rainfall is likely across Southeast
  Georgia and the South Carolina Lowcountry this weekend. Flash
  and urban flooding is possible. A flash flood watch is in
  effect from 8 PM tonight through 2 AM Sunday.

-3) A few tornadoes are possible across Southeast Georgia and
 Southeast South Carolina Saturday.

&&

.DISCUSSION...
KEY MESSAGE 1: Coastal flooding will gradually increase along the
Southeast Georgia and South Carolina coast through Saturday.
Moderate, to potentially major, coastal flooding is possible along
the coast of Charleston and coastal Colleton Counties on Saturday.

This evening, ENE winds will continue to strengthen across the
nearshore Atlantic waters through the rest of this afternoon into
the evening high tide around 7:50 PM. Heading into low tide this
afternoon, the Charleston harbor tidal departures were running
around 0.8 ft. Using the climatology tide guidance, the tide in the
Charleston Harbor appears on pace to crest within minor flood stage
this evening. The tide a Ft. Pulaski should crest within action
stage.

Saturday: A Coastal Flood Watch in effect for Saturday morning for
coastal Charleston and Colleton Counties. The combination of gusty
onshore winds, widespread rainfall, and broad coastal low pressure
should drive the tidal waters well above the astronomical tide
Saturday morning, with tidal departures increasing between 1.3-1.5 ft
within the CHS Harbor. Fort Pulaski on the Savannah River is
forecast to crest within minor flood stage Saturday morning. Ongoing
heavy rainfall and gusty onshore flow should keep departures elevated
through Saturday evening. Further south, high tide is most likely to
remain below minor flood stage for the Savannah/Beaufort area.

Minor coastal flooding is possible within the Charleston Harbor
Sunday morning. Eventually, winds should turn offshore following a
cold front Sunday into Sunday night, ending the coastal flood threat.

Rip Currents/High Surf/Beach Erosion: Increasingly gusty
northeasterly winds combined with building wave heights will create
a High Risk of rip currents along the southeast Georgia beaches
today, with a Moderate Risk of rip currents along beaches from
Edisto, SC to Savannah, GA.

On Saturday: High Risk of rip currents for all area beaches. High
surf is possible on Saturday, especially during the high tide
cycles, were breakers in excess of 6 ft are possible along the GA
and SC coasts. The large breakers and flooding high tides may lead
to areas of significant beach/dune erosion.

Sunday: Lingering large swell waves and gusty southwest winds will
yield a high risk of rip currents along Charleston County with a
moderate risk to the south.

KEY MESSAGE 2: Hurricane Isaias is expected to approach the northern
Gulf Coast late today, before shifting across the Deep South on
Saturday. Although the center of the storm will remain well
west of the region, heavy rainfall is likely across Southeast
Georgia and the South Carolina Lowcountry this weekend. Flash
and urban flooding is possible. A flash flood watch is in effect
from 8 PM tonight through 2 AM Sunday.

Hurricane Isaias is on its final approach to the northern Gulf coast
and the current NHC forecast is for the hurricane to make landfall
later tonight across the western Florida Panhandle. Several main
players will be in place to setup the potential for heavy rainfall
starting late tonight and persisting through late Saturday. As
Isaias marches inland a slug of deep rich tropical moisture will
come along with it as PWATS will climb above 2 inches and
potentially approach 2.1 to 2.2 inches by Saturday. The next moving
part is the cold air damming/Wedge that has built into the Carolinas
this afternoon with the surface backdoor front stalling somewhere
near the SC/GA border and then arching along a surface trough just
off the coast. This boundary will provide a low level convergence
focus as we move through the night and especially on Saturday.

Tonight: Rainfall has begun to steadily encroach on southeastern
Georgia this afternoon and into the evening. The backdoor front and
associated wedge will act as sort of a ramp allowing for moisture to
be lifted upward over the wedge producing widespread moderate rain
to start. By after midnight, some higher instability and elevated
instability should begin to work its way into Georgia as we should
see a uptick in heavier storms as we head into the early morning
hours. As these storms start to work inland, localized bands of
heavier rainfall could result in localized amounts of 3 to 5 inches
across Georgia with more widespread 1 to 2 inches of rainfall
falling overnight. Where exactly this band sets up is tough to
pinpoint right now, however if these bands were to develop, an
overnight flash flood risk could materialize. Further north, banding
could approach the South Carolina coastline after midnight and
especially as we approach daybreak on Saturday. However, the main
heavy rain threat likely materializes during the day on Saturday.
Any rainfall that occurs overnight across the Lowcountry will only
just help "prime" the soils for potential flooding later.

Saturday: As Isaias moves north into Alabama on Saturday, that surge
of moisture will begin to spread across the Carolinas. At the
surface, the aforementioned wedge front will begin to erode and lift
northward throughout the day as a warm front. At the same time the
coastal trough will move inland. Confidence is increasing on the
potential for heavy rainfall across a good chunk of the area on
Saturday, especially along the coastal areas of South Carolina
including the Charleston metro/Tri-county area. With the lifting
surface boundary and slowly advancing coastal trough, there will be
a period where low level convergence will be maximized mainly
Saturday morning into early afternoon. Widespread rain with heavier
embedded banding features are expected to develop and slowly push
inland from the Atlantic. Widespread rainfall totals of 2 to 4
inches look likely across most of the area with the potential for a
narrow corridor of 4 to 6 inches mainly along the South Carolina
coast. The biggest question will be if and where heavier banding
does setup. Given the PWATs across the area and increasing
instability throughout the afternoon, heavier bands will certainly
be able to produce rain rates approaching 2 inches per hour in the
heaviest of bands. If these bands sit over an area too long then
localized flash flooding concerns will quickly materialize as
rainfall totals could quickly pile up to near 8 to 10 inches in very
localized spots. Flash flooding concerns will also occur in and
around the two high tide peaks as the aforementioned coastal flooding
will restrict rain runoff and compounding coastal and rain flooding
would be likely to occur. This is especially true for Charleston
county where coastal flooding may reach Moderate flood stage with
just tide influences.

The biggest uncertainty for this event evolves around 1. where the
coastal trough/heaviest banding sets up on Saturday and 2. whether or
not a dry slot (pocket of dry air wrapping around Isaias) cuts into
totals across Georgia and interior South Carolina on Saturday. The
biggest question with the coastal trough is whether or not it stays
offshore. If the heaviest band stays offshore then totals will
likely run more on the 1 to 3 inch side and be a more widespread
soaking rain. However; if the band moves inland then much more
significant flash flooding concerns will develop. The dry slot on the
other hand will likely limit how much parts of Georgia sees on
Saturday. As Isaias lifts north it will wrap a big punch of dry air
over Georgia and into central South Carolina. This dry slot will
help limit storms Saturday afternoon and evening across interior
parts and depending on the timing of this feature and how much rain
is able to fall prior to its arrival will determine the flood risk
for areas not along the immediate coastline. Nonetheless,
Concern for some localized flash flooding will persist through
Saturday night for a good portion of the area, especially along
coastal South Carolina. Nonetheless the potential is there for
flash flooding and a Flood Watch for flash flooding has been
issued for our entire area beginning 8 PM tonight.

Key Message 3: A few tornadoes are possible across Southeast Georgia
and  Southeast South Carolina Saturday.

The overall tornado risk continues to remain the same as yesterdays
forecast. Two areas of concern seem to be shaping up as early as
late tonight into the day on Saturday.

The first of which will be the slowly advancing coastal trough along
the South Carolina coastline. Bands of storms will develop along the
warm side of the boundary over the Gulf stream in a deep moist
tropical environment. Given rather moist profiles and storm relative
inflows around 25 ish knots,  small transient supercells (AKA mini-
spinnies) will likely be the storm mode. These mini-spinnies will
approach the coastline beginning as early as tonight and persisting
throughout the day. Typically in these setups, surface instability
will be the biggest question as the surface front tends to hang up
just offshore. However, if we manage to push enough instability
onshore during the afternoon then the environment should be ripe
with curved low level hodographs with plenty of streamwise vorticity
for a couple of tornadoes along the immediate coastline from
Savannah earlier in the morning to Charleston later in the
afternoon. Given the deep tropical moisture any storms that would be
tornadic would likely need some level of storm merging to produce
and thus the storms to watch on Saturday will likely come in
clusters of supercells within close proximity of one another.

The second area of interest will be across interior parts of GA into
interior parts of South Carolina late Saturday afternoon and
possibly another round Sunday. Several low level convergence bands
will likely setup across central Georgia as Hurricane Isaias lifts
north throughout the afternoon. As mentioned earlier, a pocket of
drier air will begin to overspread Georgia which will help lead to
some clearing in the mid and upper level clouds during the
afternoon. Scattered storms could develop along these convergence
bands along the nose of the lifting instability and moisture
gradient throughout the afternoon. Given the environment will still
be suitable for mini-spinnies capable of producing a tornado or two.
The biggest caveat to this risk is 1. will we see enough instability
to get strong enough updrafts and 2. the dry air not be too dry to
prevent convection to develop. The big thing to watch would be any
clearing or sunshine during the morning across Georgia. If we can
get the instability to develop without being too dry then a decent
risk could materialize across Georgia as usually the limiting factor
in tropical cyclone tornadoes is instability. The same scenario
could develop again on Sunday across parts of South Carolina as the
same convergence bands lift northward with the dry slot. The only
difference on Sunday is that the overall wind profile is not quite
as conducive as the better low level shear lifts north of the area.

We will have to keep an eye on the mesoscale details over the next
24 to 48 hours to see how the tornado threat shapes up, but there is
certainly a threat to keep a close eye on.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
18Z TAFs: VFR conditions with light rainfall arriving late this
afternoon and evening. Tropical moisture will build across the
terminal through the TAF period. Rainfall rates will gradually
increase overnight through Saturday morning. Thunderstorms will
increase, highlighted with PROB30s from late tonight into Saturday
morning. Winds gusts into the low 20s will is expected through the
TAF period.

Extended Aviation Outlook: Flight restrictions are likely at all
terminals through Sunday with widespread showers and/or
thunderstorms, some capable of heavy downpours and gusty winds.

&&

.MARINE...
Tonight: See NHC forecast for the latest on Hurricane Isaias. For
our region, the pressure gradient will increase between a high
pressure to our north and the hurricane to our southwest as it
travels northwards. This is expected to strengthen the northeast
this evening, with wave heights building as well. Gale gusts may
remain over the nearshore and outer SC waters outside the CHS Harbor
tonight.

Saturday: Combination of inland ridging and developing coastal
troughing as a warm front moves up from the south will maintain Gale
conditions to the SC coastal waters through early afternoon.
Strongest winds will be on the west side of a coastal boundary
expected to linger offshore, with the GA waters remaining south of
this coastal boundary and unlikely gust above 30 kt. Moderate
southernly flow develops later Saturday as the warm front lift north
of the area.

Lake Moultrie: Wind gusts across Lake Moultrie expected to reach 30
kts  Saturday morning. A Lake Wind Advisory has been issued
accordingly.

Sunday into Monday: The surface high pressure gets pushed off into
the Atlantic as the remnant surface low pressure of Isaias is
expected to push off into the northeast states before moving
offshore. This will likely keep winds breezy on Sunday as southerly
winds move in, with breezy westerly winds on Monday. Currently,
expecting at least Small Craft Advisory conditions to persist into
Sunday, with a non-zero chance for them to continue to portions of
Monday.

&&

.CLIMATE...
Record Precipitation:

October 10:
KCHS: 1.82/1990
KCXM: 2.13/1990

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Flood Watch from 8 PM EDT this evening through late Saturday
     night for GAZ087-088-099>101-114-115-137-216>219-238>241.
     High Risk for Rip Currents through Saturday evening for GAZ217-219-
     239-241.
SC...Flood Watch from 8 PM EDT this evening through late Saturday
     night for SCZ040-042>045-147>152.
     High Risk for Rip Currents through Saturday evening for SCZ148>151.
     Lake Wind Advisory from 5 AM to 2 PM EDT Saturday for SCZ045.
     Coastal Flood Advisory until 9 PM EDT this evening for SCZ149-
     150.
     Coastal Flood Watch Saturday morning for SCZ149-150.
MARINE...Small Craft Advisory from 11 PM this evening to 1 AM EDT
     Sunday for AMZ340.
     Gale Warning from 10 PM this evening to 5 PM EDT Saturday for
     AMZ360-380.
     Gale Warning until 5 PM EDT Saturday for AMZ362-382.
     Small Craft Advisory until 1 AM EDT Sunday for AMZ364-384.

&&

$$

Black/NED