427
FXUS62 KCHS 140639
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
239 AM EDT Wed Aug 14 2024

.SYNOPSIS...
A cold front will move slowly south across the area tonight,
then pass through on Wednesday. High pressure will build from
the north into late week. Another cold front may approach the
area later this weekend or early next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Surface boundary extends off the Atlantic into southeast Georgia
with some lower cloud cover expanding down through the region
behind the boundary. Quiet weather for the most part, although
there is a thin line of convection that has developed off the SE
SC coast in the last few hours, perhaps along an old outflow
boundary that may be pressing southward through the region per
radar imagery. A few showers remain possible along the SC coast
as the boundary continues its southward advance. But overall,
rain-free conditions should prevail overnight.

There could be some shallow ground fog around, especially in
areas that received rain earlier this afternoon into the
evening, but coverage isn`t expected to be sufficient to warrant
carrying fog in the forecast. Lows are expected to be a bit
lower than previous nights, generally in the low-mid 70s inland
to upper 70s near the beaches.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
Wednesday: This will be the wettest day to an otherwise rather
unusually dry period. A weak backdoor surface front will be
pushing just south of the area by later in the morning, with
surface ridging building over the mid Atlantic and northeast
states, resulting in northeast low level northeast winds. The
area will still be under the backside of an upper level trough,
departing off of the mid Atlantic Coast. This feature, combined
with modest deep layer moisture of PWs of 2+ inches, will result
in scattered showers/thunderstorms, especially south of the
Charleston Tri-County area. Highs noticeably cooler over the SC
zones, in the mid to upper 80s, and around 90 to the lower 90s
southern GA zones and near the Altamaha. Expect any isolated to
scattered convection to diminish by the evening. Lows cooler
than they have been in quite some time, in the upper 60s to
around 70 inland, and lower to mid 70s near the coast.

Thursday and Friday: Deep layer ridging shown by all models to
build from the west and north, helping to drive drier air
southward through the area. PWs falling below 1.5 inches and
mean RH values generally below 50%, which is below normal for
this time of year. Have no mentionable precipitation chances for
both of these days, which will allow for some needed drying out
of the many flooded/saturated regions across our area. Highs a
tad below normal, in the mid 80s to near 90. Lows in the upper
60s inland/west of I-95 and lower 70s closer to the coast.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The deep layer ridging over the southeast U.S. is shown by
global models to weaken and push southward as a large/broad
upper trough forms over the Great Lakes Saturday, pushing into
southeast Canada and northern New England Sunday and Monday.
This will translate to a gradual increase in precip./convection
chances through the period. Have slight chance PoPs Saturday and
into Sunday, then chance by Monday, which is around normal for
this time of the year. Given the presence of a relatively strong
upper level trough axis for mid August, will continue to
monitor any potential threat for strong to severe storms,
especially by later in the weekend. Temperatures warming
slightly through the period, but guidance keeps highs around
normal in the lower 90s and lows in the lower to mid 70s, except
mid to upper 70s near the coast.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Some low stratus is expanding across parts of southeast SC and
heading toward southeast GA which could bring a period of IFR
ceilings at the SAV terminal toward morning. Some afternoon
showers/thunder are possible Wednesday afternoon, although
confidence for impacts at any one terminal is not high. 06Z
forecasts have VCSH during the afternoon hours to account for
this.

Extended Aviation Outlook:

Wednesday: Brief flight restrictions possible with scattered
mainly afternoon and early evening showers and thunderstorms,
especially KSAV.

Thursday and Friday: VFR to prevail with much drier conditions
expected, with less than 15% chance for afternoon
showers/thunderstorms.

Saturday and Sunday: Some moisture starts to return with
isolated afternoon showers/thunderstorms Saturday, and scattered
by Sunday with a higher chance for brief flight restrictions.

&&

.MARINE...
Tonight: A few thunderstorms will continue to shift further offshore
and south along a boundary, likely departing all local waters
within the next couple hours. An isolated strong thunderstorm is
possible, with gusty winds and perhaps even a waterspout. Otherwise,
a weak boundary will linger near or just south of the local
waters through the night. Winds north of the boundary will turn
northeasterly while winds to the south will continue to be
southerly. Speeds should top out in the 10-15 knot range, mainly
within the northeast flow in the Charleston County waters. Seas
are expected to average 2-3 feet.

Wednesday through Thursday: No highlights expected as a
backdoor cold front pushes south of the waters through this
period. Expect east-northeast winds of 10-15 knots with some
gusts to near 20 knots possible. Seas generally 3 to 4 feet.

Thursday night through Saturday: Seas expected to increase,
especially beyond 20nm offshore as swells from Ernesto, which
will remain well east of the area, arrive into the marine area.
Guidance indicating seas building to 4 to 6 feet, possibly up to
7 feet by later Friday and into Saturday. Decreasing northeast
winds through Friday, becoming south and southwest Saturday and
Sunday. Winds during this period generally 10 to 15 knots or
less and seas 3 to 5 feet.

&&

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

&&

$$