571
FXUS62 KCHS 290839
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
439 AM 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/...
Today: Aloft, a ridge will extend across the Southeast United States
along with dry air noted on water vapor imagery. At the sfc, high
pressure will extend across the region from the Atlantic, resulting
in a light southerly/onshore wind. There will be very little in the
way of mid-upper level features to promote afternoon convection, but
ample low-lvl moisture driven onshore and a sea breeze circulation
will likely contribute to afternoon showers and thunderstorms away
from the coast during peak diurnal heating. Expect convection to be
typical of summertime, being pulse type in nature within an
environment displaying PWATs near 2.0 inches, SBCAPE between 2000-
2500 J/kg and weak 0-6 km bulk shear. Gusty winds and brief
downpours will be the main result, although a stronger thunderstorm
or two can not be ruled out during peak heating. High temps should
peak in the low-mid 90s, warmest well inland. The combination of
warm temps and sfc dewpts in the low-mid 70s should support heat
indices in the 100-105 range for most areas away from the beaches.
There could be a brief window where heat indices reach 105-108 where
highest dewpts and warmest temps overlap near an inland moving sea
breeze (around the I-95 corridor), but the duration of the event
should fall just short for the issuance of a Heat Advisory.

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 well
inland, 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 /09Z SATURDAY THROUGH WEDNESDAY/...
KCHS/KJZI/KSAV: VFR conditions will prevail through much of valid
06Z TAF cycle. However, tempo MVFR cigs/vsbys are possible at
JZI/CHS terminals between 06-09Z Saturday due to showers and/or
potentially thunderstorms that shift onshore during the next few
hours. Additionally, there could be some light fog/stratus a
few hours on either side of daybreak at any terminal resulting
in sub-VFR weather.

There is then the potential for some SHRA/TSRA activity along the
sea breeze Saturday as it moves inland. At this time, VCSH
remains in the JZI TAF late morning and early afternoon while
VCTS is in place at CHS/SAV terminals Saturday afternoon. Any
direct impacts from showers or thunderstorms will likely result
in brief flight restrictions and gusty winds.

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

&&

.MARINE...
Today and Tonight: A weak pressure gradient will remain in place
across local waters along the western periphery of high pressure
extending across the Atlantic and south of a stationary front
positioned across the Mid-Atlantic states. In general, winds/seas
will remain well below Small Craft Advisory levels, remaining 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 after daybreak. For now it is just
something to be aware of.

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