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883
FXUS62 KCHS 232317
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
717 PM EDT Sun Jun 23 2024

.SYNOPSIS...
High pressure will remain over the western Atlantic through
much of next week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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Tonight: Aloft, the local area will remain nestled between weak low
pressure meandering over the western Atlantic off the Southeast
Coast and a ridge extending west across the Deep South and into
parts of the Southeast United States. At the sfc, weak low pressure
positioned near Charleston County early this evening will shift
north/northeast, pulling deeper moisture out of the local area
within the next hour or two. Expect the bulk of ongoing convection
to wane near sunset with the loss of daytime heating and lack of
substantial forcing in the area. However, a few showers can not be
ruled out for the next few hours, mainly associated with outflow
boundaries that interact with an inland progressing sea breeze.

Overnight, conditions should be fairly quiet with light winds and
some lingering clouds in place. Sfc winds could even decouple for a
few hours, but light winds from the southwest should return and
gradually increase late night as a trough approaches from the west-
northwest heading through daybreak. Temps should remain mild tonight
ahead of this feature, generally only dipping into the mid 70s
inland to upper 70s/around 80 near the beaches.
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&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
A broad upper ridge will remain over the central United States
on Monday while a weak shortwave drops through southeast GA/SC
in the afternoon. A weak surface front is forecast to drop
into the area Monday afternoon, potentially providing a focus
for afternoon convection. Fairly unidirectional W flow will
result in a downslope trajectory, not only pushing temps into
the upper 90s but potentially producing subsidence that works
against convective initiation. The offshore winds will also keep
the sea breeze pinned near the coast much of the day, with only
a small amount of inland movement late in the afternoon. 0-6 km
bulk shear expected to be 25-30 kt with SBCAPE around 1,000
J/kg. Given the approaching cold front, there could be some
storm organization along and ahead of the front in the
afternoon, though the downslope flow could limit the overall
coverage. Heat indices are forecast to top out 105-108F in the
afternoon, just shy of Heat Advisory criteria.

The weak upper ridge pattern will transition to a weak trough
over the Southeast Tuesday into Wednesday. At the surface, a
weak surface wave will linger near the area Tuesday, then
dissipate Tuesday night. A relatively typical summertime pattern
is expected both days, with scattered mainly diurnal convection
and highs in the 90s. Forecast heat indices both days top out
just below 108F in a few spots.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A potent shortwave will move through Thursday and Thursday
night. On Friday, surface high pressure will be centered over
the Northeast, with a deep onshore flow over the local area.
Fairly good coverage of showers and thunderstorms expected
Thursday and Friday. A deep layered ridge will build over
the area for the weekend, decreasing diurnal convection
coverage.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
KSAV: The center of the surface low is now located over western
Charleston county this afternoon with most of the shower
formation being towards the Charleston terminals. Behind the
surface low, winds have veered around from the northwest with
not much in the way of precipitation expected. A sea breeze will
push inland later this afternoon with winds turning around from
the south/ southeast. Overnight, only some high and mid clouds
will remain with VFR conditions expected. No fog is forecast
tonight as the pressure gradient remains elevated which should
keep winds up. Late Monday morning, winds will again turn from
the west and be 10 to 15 kts. No precipitation is expected
through the morning hours of Monday.

KCHS/KJZI: The center of the surface low is now located over
western Charleston County this afternoon with most of the shower
activity occurring in close proximity to KCHS and KJZI. A sea
breeze will push inland later this afternoon with winds turning
around from the south/ southeast. Showers will likely come to an
end very soon with coverage decreasing through the afternoon
hours. Overnight, only some high and mid clouds will remain
with VFR conditions expected. No fog is forecast tonight as the
pressure gradient remains elevated which should keep winds up.
Late Monday morning, winds will again turn from the west and be
10 to 15 kts. No precipitation is expected through the morning
hours of Monday.

Extended Aviation Outlook: Mostly VFR. However, convection will
bring brief flight restrictions, mainly each afternoon and
evening.

&&

.MARINE...
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Tonight: Weak low pressure centered just off the Charleston County
Coast will shift north-northeast early this evening, departing local
waters. The pressure gradient will remain somewhat enhanced in wake
of this feature between sfc high pressure centered further offshore
across the western Atlantic and a sfc trough approaching the
Southeast United States late. As a result, southwest winds ranging
between 15-20 kt this evening could gust upwards to 25 kt after
midnight across nearshore SC waters off the Charleston County
Coast and across offshore GA waters. Seas should also build to
4-6 ft in these waters. Small Craft Advisories will therefore
start across these coastal zones starting around midnight and
remain in effect through the night. Elsewhere, seas should build
up to 3-5 ft, falling just short of Small Craft Advisory levels.

Extended Marine: A slight gradient enhancement will persist
Monday and Monday night due to the cold front approaching from
the west and high pressure offshore. Wind gusts and seas should
remain just below Small Craft Advisory criteria.

Monday night through Friday, a typical summertime maritime
pattern expected with S or SW winds less than 15 kt and seas no
greater than 4 ft.
-- End Changed Discussion --

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from 2 AM to 8 AM EDT Monday for AMZ350.
     Small Craft Advisory from midnight tonight to 8 AM EDT Monday
     for AMZ374.

&&

$$

NEAR TERM...DPB
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...Haines/JRL
MARINE...DPB/JRL