437
FXUS62 KCHS 151059
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
659 AM EDT Sat Jun 15 2024

.SYNOPSIS...
A weak cold front will linger over the area this weekend before
the front slowly lifts back northward early next week. High
pressure will then ridge in from offshore mid to late next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
No changes made with the sunrise update, forecast is on track.

Today: The upper levels of the atmosphere will be dominated by
ridging over the southeastern states, building in from the SW. At
the surface a weak cold front is forecast to be just inland of the
local forecast area. This cold front will slowly sink southward
through the daytime hours, however it is not expected to bring many
impacts to the local area. The main forecast story for today is the
heat. 850 hPa temperatures are forecast to be around 18/19C, which
given decent daytime mixing today yields surface temperatures
in the upper 90Fs, close to 100F. The current forecast features
highs representative of this, away from the beaches where
conditions will remain slightly cooler in the upper 80s. Dew
points are forecast to mix out, which will limit heat index
values to 100-101F, below Heat Advisory criteria. The
temperature at the KCHS may challenge the record high
temperature, see the Climate section for more details. As the
cold front sinks southward CAMs depict isolated convection,
mainly across southeast SC in the later afternoon hours. It is
worth noting that model soundings indicate a significant amount
of dry air in the upper levels, a result of subsidence aloft.
Showers and thunderstorms may struggle to overcome the dry air.
Any showers/thunderstorms that are able to form will likely
dissipate with nightfall.

Tonight: The cold front will likely be stalled across southeast GA
around nightfall, with high pressure building in from the north
behind it. A quiet night is forecast, with any showers/
thunderstorms likely dissipating by nightfall. Overnight lows will
generally be in the low 70s away from the coastline, where
temperatures should remain in the mid 70s.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Sunday: Strong upper ridging persists aloft. At the surface, strong
high pressure over New England will build down the eastern seaboard,
forcing a weak cold front southward across the area. Rainfall
coverage Sunday will ultimately be dependent on the progression of
the front, which will most likely be bisecting the area by midday,
and potentially be pushing down into Georgia by the evening. While
very dry air aloft will inhibit convective growth, there should be
enough moisture pooling on the southern side of the front (PWATs
1.5+ in) and instability (1500+ J/kg) to get a few isolated to
widely scattered showers and storms following a mainly diurnal
pattern, with any storm activity diminishing in the evening and dry
conditions prevailing overnight.

Despite the very strong upper ridging, E to NE/onshore flow will
moderate low level thickness values, and temps Sunday will be only a
few degrees above normal, upper 80s to lower 90s near the coast, and
mid 90s inland.

Monday and Tuesday: Upper pattern remains similar Monday and Tuesday
with ridging directly overhead leading to strong subsidence/very dry
air aloft. The aforementioned front will deteriorate near/over the
area Monday as it begins to lift back north, with surface ridging
building in from offshore by Tuesday. Rainfall chances confined
roughly along and south of I-16 both days, where there could be just
enough moisture to develop some short-live showers/storms around
peak heating/maximum instability each afternoon. Onshore component
of BL flow keeps temps near to a few degrees above normal both days
despite the strong upper ridging.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Upper ridging shifts north mid-to-late week, with height falls aloft
leading to diminishing upper subsidence. At the surface, high
pressure migrates off the Northeast coast and toward a more
seasonable Bermuda High location. Expect the forecast to trend back
toward a more summer-like precip pattern, with scattered afternoon
thunderstorms along and inland of the sea breeze and lesser storm
activity overnight. Temps remain within a few degrees of normal.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
KCHS/KJZI/KSAV: VFR through the 12 Z TAF period. Isolated
showers/tstms associated with an approaching cold front could
approach KCHS and KJZI mid-late afternoon, but confidence on
impacts is too low to include a mention of VCTS or TSRA for now.

Extended Aviation Outlook: Mainly VFR. There will be low
probabilities of brief flight restrictions due to convection each
afternoon/evening.

&&

.MARINE...
Today and Tonight: Generally tranquil marine conditions are forecast
through tonight. A weak cold front is forecast to progress southward
through the forecast area through the daylight hours, stalling
across southeast GA this evening. Winds will generally be S around
10 knots, with seas averaging 2 to 3 ft. With the cold front to the
south of the area, overnight winds are forecast to shift to the E,
still remaining around 10 knots.

Sunday through Wednesday: The gradient will remain fairly weak
through Monday as a front moves over the area and slowly
deteriorates. High pressure builds in from the north early next
week, then shifts offshore mid-to-late week, with mainly moderate
winds prevailing, but breezy/gusty conditions near the coast with
the sea breeze formation each afternoon. Modest medium period
southeast swell will keep 2-4 ft seas in place through Monday, with
seas increasing to 3-5 ft Tuesday through mid-week as increasing
fetch over the Sargasso sea causes the the southeast swell builds
further. 6 ft seas/SCA conditions could emerge by late week.

&&

.CLIMATE...
Record High Temperatures:

June 15
KCHS: 98/2015

&&

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

&&

$$

NEAR TERM...CPM
SHORT TERM...CEB
LONG TERM...CEB
AVIATION...CEB/CPM
MARINE...CEB/CPM