National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS62 KCHS 111509
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1109 AM EDT Thu Apr 11 2024

.SYNOPSIS...
A storm system will impact the region today. High pressure
should build over the region on Friday and persist into early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Late this morning, KCLX indicated that the heavy rainfall has
shifted offshore. Over land, a cluster of moderate showers and
isolated thunderstorms will lift across the SC Lowcountry
through early this afternoon. Based on radar trends and recent
CAMs, isolated showers should develop over the forecast area
during the mid to late afternoon. Then another band of showers
is expected to develop along the cold front, sweeping west to
east across the forecast area this evening.

Strong Winds Outside of Thunderstorms: Background wind fields
are quite impressive and strong low-level jetting will spread
across the area today ahead of the approaching front. Southerly
winds will strengthen through mid-day, with wind gusts of 35-40
mph expected for the entire forecast area. Stronger gusts of
40-45 mph will be possible along the coast. A Wind Advisory
remains in effect.

By the late evening the front will shift offshore and any rain
chances will come to an end. The gradient will remain relatively
tight and winds will remain elevated and gusty through the
overnight. Frequent gusts into the 20-25 mph range are expected,
highest during the evening and early morning hours. Skies will
clear out completely late tonight and lows are forecast to fall
into the low to mid 50s away from the immediate coast.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Broad troughing will prevail aloft on Friday, slowly
transitioning to zonal flow over the weekend as the mid-level
trough to the north ejects off the east coast. At the surface
high pressure will be centered over the northern Gulf of Mexico
on Friday, building into the local forecast area from the
southwest. Surface high pressure will be the dominant synoptic
feature through the weekend. A rain- free weekend is in store
for the region, with plentiful sunshine. Temperatures will
gradually warm through the period, with highs in the low to mid
70s on Friday, mid to upper 70s on Saturday, and then low to mid
80s by Sunday. Overnight lows will generally be in the 50s,
warmest along the beaches.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Quiet weather is expected through the period with broad ridging
prevailing aloft through the middle of the week. At the surface
high pressure will dominate, centered over the northern Gulf of
Mexico and building into the region from the south.
Temperatures are forecast to be several degrees above normal,
with highs in the mid to upper 80s (cooler directly along the
beaches). Overnight lows will also be rather mild, only dipping
into the upper 50s to low 60s.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Overall, the 06z TAF period is expected to be active with
widespread rainfall, the low end potential for thunderstorms,
and increasingly gusty gradient winds.

KCHS and KJZI: Radar imagery shows that the edge of the area of
stratiform rain will arrive around 06-07z, and light to
occasionally moderate rain will persist through sunrise and
likely into mid morning. Ceilings should lower into the MVFR
range by around 09z, with IFR conditions expected later in the
morning. By around midday, the nature of the precipitation
should transition from stratiform to become more convective
showers and possibly a thunderstorm. We currently think the
potential for direct impacts from thunderstorms is too low to
include in the TAF, but it will need to monitored. Showers and
any thunderstorm potential should end by around 20z. Southerly
winds will strengthen and become quite gusty, especially after
sunrise. Peak winds are expected from around mid morning through
the afternoon, with gusts up around 35 knots. VFR conditions
should return by the afternoon once the rainfall potential ends.

KSAV: Light to moderate rain has settled into the terminal, and
based on nearby observations, MVFR ceilings should arrive in the
next couple of hours. Light stratiform rain should prevail
through about 14z, when the nature of the precipitation will
change to become more convective with showers and possibly a
thunderstorm. Shower and thunderstorm potential should mostly
end by around 18z. MVFR ceilings are expected to lower to IFR by
mid morning. VFR conditions should return by the afternoon once
the rainfall potential ends. Southerly winds will strengthen and
become quite gusty, especially after sunrise. Peak winds are
expected from around mid morning through the afternoon, with
peak gusts in the 30-35 knot range.

Extended Aviation Outlook: Prevailing VFR. Gusty W winds 15 to
20 mph may linger into Friday across the terminals.

&&

.MARINE...
Today: Winds and seas will steadily ramp up this morning as
dangerous marine conditions are expected across the local waters
throughout the day. Frequent gale force gusts are expected for
all waters as well as Charleston Harbor, so Gale Warnings are in
effect everywhere. Winds will peak from the late morning
through the early afternoon and gusts will begin to drop off
below gale force late this afternoon first across the nearshore
Georgia waters. Also, thunderstorms are expected to move across
the waters and will be capable of producing strong convective
wind gusts as well possibly a waterspout.

Tonight: Winds will diminish this evening such that the Gale
Warnings will come to an end and will need to be replaced by
Small Craft Advisories for all waters for the rest of the
overnight.

Friday through Tuesday: Conditions across the marine zones will
rapidly improve on Friday, decreasing to 3 to 4 ft by Friday
evening, but W winds will likely remain elevated through the
daytime hours, gusting to around 25 knots. Small Craft
Advisories will likely be required for most, if not all, of the
marine zones. Conditions will continue to improve through the
weekend as high pressure builds into the local region, with
winds generally 10 to 15 knots and seas 2-3 ft.

High Surf: Large breaking waves are expected to develop at the
beaches today, highest along the Charleston county coast. A High
Surf Advisory has been hoisted there.

Rip Currents: Breaking wave heights exceeding 5 ft with very
gusty winds will yield a High Risk for rip currents at all
beaches today. A Moderate Risk is forecast for tomorrow
(Friday).

&&

.HYDROLOGY...
As mentioned before, model guidance is depicting a dramatic
increase in expected rainfall totals for the forecast area.
Widespread 2-3 inch amounts are expected, with a clear signal
for 3+ inches along the coast, especially the southeast South
Carolina coast. A plume of deep moisture with precipitable
waters values of around 2 inches is aligned nicely with
impressive deep layer southwesterly flow, a solid heavy rainfall
signal. Current radar trends and observed rainfall totals
indicate that hourly rainfall rates are peaking in the
0.25-0.50" range early this morning. Such rates would not cause
significant flooding issues, but the flooding concern comes late
in the morning through the early to mid afternoon with model
guidance indicates the presence of developing convection and
intense rainfall rates. This is where the corridor of heavier
rainfall amounts is coming from along the southeast South
Carolina coast. We considered the need for a Flood Watch, but
decided that the risk for any flash flooding will be very
isolated and highly dependent on where the more intense rainfall
develops and evolves. So, in general, the greatest risk for
flooding will be across the Charleston Tri-County region,
Colleton, Jasper, and Beaufort counties. We will have to watch
the faster responding basins carefully, including Ireland Creek
in Walterboro, Church Creek in West Ashley, and Sawmill Branch
in the Summerville area. There is also risk for flooding in and
around the Charleston peninsula and at least minor flooding is a
near certainty there.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Wind Advisory until 8 PM EDT this evening for GAZ087-088-
     099>101-114>119-137>141.
     High Risk for Rip Currents until 8 PM EDT this evening for GAZ117-
     119-139-141.
SC...Wind Advisory until 8 PM EDT this evening for SCZ040-042>045-
     047>052.
     High Risk for Rip Currents until 8 PM EDT this evening for
     SCZ048>051.
     High Surf Advisory until 8 AM EDT Friday for SCZ050.
MARINE...Gale Warning until 7 PM EDT this evening for AMZ330-352.
     Gale Warning until 11 PM EDT this evening for AMZ350-374.
     Gale Warning until 5 PM EDT this afternoon for AMZ354.

&&

$$

NEAR TERM...NED
SHORT TERM...CPM
LONG TERM...CPM
AVIATION...BSH/CPM
MARINE...BSH/CPM