539
FXUS62 KCHS 291747
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
147 PM EDT Sat Jun 29 2024

.SYNOPSIS...
Atlantic high pressure will prevail this weekend, while a
trough of low pressure resides inland. A cold front is expected
to impact the area Monday into Tuesday. High pressure will
return for the latter half of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
This afternoon: No significant changes for the early afternoon
update. Convection a bit slower to form than CAMs have been
indicating. The temperatures were also a bit slower to rise, but
in the last 30-60 minutes, most of them have popped into the
lower 90s away from the immediate coast.

The issue continues to be little in the way of large scale
forcing for showers/thunderstorms. Scattered convection well
inland has been slowly advancing eastward, with only very
isolated showers trying to develop within the seabreeze,
especially around Charleston. Expect convection to become more
active within the next hour or two, with at least scattered
showers and thunderstorms to be near the coast within the
seabreeze and additional scattered convection inland. Higher
coverage possible in the interior as the convection over the
interior interacts with any convection within the slowly
westward advancing seabreeze. Outflow boundaries from any
convection will also play a role in developing additional
convection.

Highs still on track to be in the lower to mid 90s across areas
away from the immediate coast. With surface Tds in the lower to
mid 70s, it will feel very uncomfortable, but not reaching Heat
Advisory criteria.

Tonight: Similar to the previous night, mild and humid conditions
will be in place for the night. A few showers and/or thunderstorm
can not be ruled out with boundary interactions early evening,
but activity will likely be waning with diurnal heat loss. Late
night, a continued onshore wind could drive a few showers onshore.
Patchy fog is also possible late, mainly for locations that see
rain during the day. In general, low temps will range between
the mid 70s inland to upper 70s/around 80 near the beaches.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
High pressure will be situated offshore on Sunday, while a trough of
low pressure resides inland ahead of an approaching cold front. Main
drivers of convection will be daytime heating and the sea breeze and
then along the inland trough which could eventually move into the
local area later in the day and into Sunday night. Ample instability
near or over 2000 J/kg will be present but shear doesn`t look
particularly impressive. Widespread organized severe weather is not
expected, but a few strong to severe thunderstorms with gusty winds
are possible, in addition to locally heavy rainfall with PWats well
over 2 inches. Also of note is the heat. High temps largely in the
mid 90s will combine with elevated dew points to make it feel even
hotter. Heat indices are forecast to top out in the 105-109F range.
Heat Advisories will be possible for some areas, but worth noting
that convection could disrupt temperature trends and heat indices
may not reach the 2 hour duration requirement. Lows only fall to the
mid/upper 70s.

The aforementioned front will sink into the area late Sunday night
into Monday. It looks to be a fairly active day with numerous to
widespread showers and thunderstorms expected. Activity generally
looks to shift south and east through the day as drier air tries to
work in behind the front. A couple strong to severe storms will be
possible along and ahead of the front in the afternoon/evening with
slightly better wind fields and sufficient instability. Damaging
wind gusts would be the primary hazard. It will not be quite as hot,
with highs ranging from the upper 80s near the Santee River to low
90s south near the Altamaha.

The front will stall nearby into Tuesday before eventually
dissipating. Additional showers and thunderstorms will be possible,
with best coverage in the south in proximity to better moisture, but
the trend overall has been drier. It will be notably cooler than
previous days, with highs mainly in the mid to upper 80s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Mid level ridge builds over the Southeast for mid to late week.
Atlantic high pressure will largely prevail at the surface, with a
trough of low pressure eventually developing inland. Large scale
subsidence under the ridge will help limit convection, but isolated
to scattered diurnally-driven showers and thunderstorms will still
be possible. Main concern looks to be the return of the heat. Still
several days out, but the set-up does appear to bring the potential
for excessive heat headlines.

&&

.AVIATION /18Z SATURDAY THROUGH WEDNESDAY/...

KCHS/KJZI/KSAV: Have not made any significant changes to the
previous forecast for the remainder of this afternoon and
evening.

In general, VFR conditions still expected to prevail through
much of valid 18Z TAF cycle. However, tempo MVFR cigs/vsbys are
possible at CHS/SAV terminals later this afternoon within any
showers/thunderstorms along an inland moving sea breeze. Left
VCSH for KJZI for next few hours today, but think convection
will generally stay just inland of the site. Any convection is
expected to dissipate after sunset with VFR conditions
prevailing.

Extended Aviation Outlook: Prevailing VFR. Brief flight restrictions
are possible in showers and thunderstorms, mainly in the afternoon
and evenings.

&&

.MARINE...
This afternoon: No significant changes were made to the
previous forecast, with no highlights expected.

A weak pressure gradient will remain in place across the waters
along the western periphery of high pressure extending across
the Atlantic and south of a stationary front positioned across
the Mid-Atlantic states. Winds/seas generally south-southwest
around 10-15 kt or less with seas no higher than 2-3 ft. Peak
winds should occur near the coast, when a sea breeze circulation
develops and shifts inland early afternoon.

Sunday through Thursday: Southerly flow will persist Sunday into
Monday with speeds 15 knots or less. Winds turn to the
northeast/east Monday night into Tuesday as a cold front sinks
through the waters and high pressure ridges in from the north. The
high will eventually shift offshore and remain the primary feature
through late week. No marine headlines are expected. Seas average 2-
3 feet.

Waterspouts: We`re well into the local "Waterspout Season", and an
in-house Waterspout Index provides us with a Moderate Risk this
morning with light winds, weak shear, and ample low-lvl moisture in
place. Much will depend if a land breeze lingers and/or a line of
cumulus develops along a boundary this morning.

Rip Currents: Latest guidance indicates a Moderate Risk for rip
currents along all beaches today. Given the weekend is here, have
opted to maintain the Moderate Risk for today. A Low Risk is in
place for all beaches Sunday.

&&

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

&&

$$

NEAR TERM...DPB/RFM
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...DPB/ETM/RFM
MARINE...DPB/ETM/RFM