309
FXUS62 KCHS 140845
AFDCHS

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

.SYNOPSIS...
A cold front will move slowly south of the area this morning.
High pressure will then build from the north into late week.
Another cold front may approach the area early next week, then
remain nearby through late week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Overnight analysis reveals upper level troughing from New
England down into the Carolinas, downstream from ridging that
stretches from the Upper Midwest to the Texas Gulf coast.
Large expanse of surface high pressure is across the Great
Lakes/Ohio Valley region, expanding into the southeast CONUS.
Surface boundary extends off the southeast Georgia coast near
Altamaha, northeastward into the Atlantic with a fair amount of
post-frontal stratus expanding out of southeast SC into
southeast GA within the shallow cooler air mass that`s spreading
into the region. Quiet weather persists for the most part,
although there is a thin line of convection off the SE SC coast,
perhaps along an old outflow boundary that migrated into the
coastal waters.

Surface high pressure will continue to expand into New England
and the Mid Atlantic through tonight with some semblance of a
wedge pattern setting up through the Carolinas into Georgia.
This will drive a relatively cooler and drier air mass into the
region and bring a needed break from the hot/humid conditions
of late.

Precip-wise: Despite the lowering boundary layer moisture/dewpoints,
with suppressed upper level heights and slightly cooler temperatures
aloft, daytime heating will generate a few to several hundred
J/Kg MLCAPE this afternoon across southeast SC and bit higher
values through southeast GA. There may be enough low level
convergence along the coastal marine layer/sea breeze this
afternoon to kick off some convection...primarily along the
southeast GA coastal corridor where higher dewpoints/instability
will reside. But overall precip coverage will be diminished
today as compared to the last few days.

Highs today will run from the mid to upper 80s across South
Carolina to the upper 80s to lower 90s in Georgia.

Tonight: Any showers/storms that do develop will fizzle this
evening with quiet weather through the night. Cooler nighttime
temperatures with lows in the upper 60s to lower 70s inland, to
the middle 70s along the coast.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
Thursday and Friday: Aloft, a broad trough will shift offshore,
becoming more distant across the Atlantic while deep layer ridging
extends across the Deep South and Southeast. This will help drive
drier air across the region, with PWATs decreasing to around 1.5
inches and a light northeast wind maintaining mostly rain-free
conditions across the entire area Thursday, and likely through
Friday despite a more direct onshore wind returning locally. Temps
will also be slightly cooler despite mid-lvl ridging and full days
of sun, while overnight temps will become noticeably cooler as
stronger radiational cooling takes place under clear/mostly clear
skies and light/calm winds. In general, highs should range in the
mid-upper 80s, warming a degree or two higher on Friday. Lows should
dip into the mid-upper 60s inland and low-mid 70s closer to the
coast.

Saturday: Aloft, the mid-upper ridge will start to shift offshore as
a deep low tracks across the Great Lakes region and toward the
Northeast during the weekend. Troughing will take place south of the
feature, with h5 vort energy rounding its southern edge toward the
Southeast. This should bring a few showers and/or thunderstorms well
inland as a light southerly wind advects deeper moisture back to the
region, but mainly late day as upstream convection drifts into
western most zones before nightfall. Afternoon highs should be
slightly warmer than the previous day, generally peaking in the
upper 80s near the coast to low-mid 90s inland, warmest across
Southeast Georgia.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
A cold front extending south from a parent low passing across the
Northeast/Mid-Atlantic states is anticipated to approach the
Southeast United States early next week, potentially stalling nearby
into mid-week before another mid-lvl trough forces it further
offshore heading into the second half of the week. The pattern
should favor more unsettled weather conditions Sunday through
Wednesday while the front and h5 shortwave energy provide sufficient
forcing across ample moisture. Temps should be within a few degrees
of normal for this time of year with highs generally in the upper
80s to lower 90s and lows in the low-mid 70s.

&&

.AVIATION /08Z 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: VFR conditions will likely prevail at
CHS/JZI/SAV terminals through Saturday. Brief flight restrictions
come early next week to all terminals as a front brings
showers/thunderstorms to the region Sunday.

&&

.MARINE...
Northeasterly winds will dominate across the coastal waters
through tonight with a touch of gustiness (around 20 knots)
developing later this morning and through the afternoon/early
evening. Seas 3 feet or less this morning will build to 3 to 4
feet through the day, possibly touching 5 feet in the outer
Georgia waters.

Wednesday: 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 through Sunday: High pressure will build across the
Southeast United States Thursday into Friday while Tropical Cyclone
Ernesto tracks northward far offshore across the Atlantic.
Conditions are expected to remain below Small Craft Advisory levels
into Friday morning, with east-northeast winds averaging around 10-
15 kt along with a few gusts up to 20 kt on Thursday becoming more
easterly on Friday. However, seas are expected to build through late
week due to increasing swells associated with Ernesto, which could
lead to Small Craft Advisories across offshore Georgia waters Friday
and Saturday for 6-7 ft seas, and potentially across nearshore
waters Friday night into early Saturday with 6 ft seas making it as
close as 10 nm from the shore. 6 ft seas could linger across
offshore Georgia waters into Sunday, but conditions should improve
sufficiently to where Small Craft Advisories are less likely with
south-southwest winds between 10-15 kt and seas generally between 3-
5 ft.

Rip Currents: Risk for rip currents will likely increase late
this week, as swells from distant Tropical Cyclone Ernesto
impact the beaches.

&&

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

&&

$$

NEAR TERM...TBA
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...TBA/DPB
MARINE...TBA/DPB