835
FXUS62 KCHS 151146
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
746 AM EDT Wed May 15 2024

.SYNOPSIS...
A cold front will move through late today, followed by high
pressure into Friday. A storm system will affect the area this
weekend, followed by high pressure from the north next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: Southwest flow this morning will gradually turn more
westerly along the base of a mid-upper lvl trough slowly
advancing toward the Mid-Atlantic States this afternoon. The
setup will tend to favor subsidence within a downslope wind by
late morning, keeping most if not all areas dry into mid
afternoon while stronger sfc heating promotes low-lvl mixing
into drier air aloft. Afternoon highs will become warmer than
the previous day, peaking in the mid-upper 80s across most
areas away from the beaches. For much of the day, forcing will
be lacking and moisture limited well ahead of a weak front
approaching from the northwest. However, there should be an
uptick in shower/thunderstorm chances heading into late
afternoon as weak h5 shortwave energy along the leading edge of
the mid-upper trough advances across the local area and
encounters an environment characterized by SBCAPE around
2000-3000 J/kg, mid-lvl-lapse rates around 7 C/km and
potentially a fair amount of DCAPE at a time when wind fields
support 0-6km bulk shear around 35-40 kt. A few thunderstorms
could become strong and/or severe in this setup, with the best
chances of occurrence across the Tri-County Area late afternoon
into early evening when larger scale forcing interacts with a
somewhat pinned seabreeze circulation near the South Carolina
coast.

Tonight: Showers and/or thunderstorms will likely weaken considerably
and/or shift offshore with a weak sfc front shortly after sunset,
ending precip across the entire area for the rest of the night.
Dry high pressure will then settle in for the night with temps
dipping into the low-mid 60s inland to upper 60s/around 70 near
the coast.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
The local forecast area will be positioned along the southern
periphery of a mid level trough situated off the Mid-Atlantic coast.
A nice day is expected on Thursday, owing to the NW flow aloft and
high pressure briefly building in at the surface. High temperatures
will reach into the mid to upper 80s, with mostly clear skies and
dry conditions forecast. Overnight lows Thursday will be in the mid
60s inland with 70 along the beaches.

The flow aloft will briefly transition to a zonal flow on Friday,
with surface high pressure retreating out into the Atlantic waters.
To the west a mid level trough and associated surface cold front
will begin trekking towards the Deep South. Ahead of the approaching
cold front isolated showers and thunderstorms are possible across
the far inland zones late Friday. Otherwise, another rain-free
forecast with high temperatures again reaching into the mid to upper
80s. Overnight lows will be rather mild, given the increasing cloud
cover ahead of the approaching cold front. Low temperatures are
forecast to only dip into the mid 60s inland with low 70s along the
coastline.

Saturday is expected to be another active weather day as a low
pressure system impacts the forecast area. A warm front is forecast
to lift northward early, with a cold front pushing through later.
PWATs are forecast to reach 1.5+ inches Saturday afternoon.
Additionally, both the GFS/ECMWF show a decent amount of instability
across the region (around 1000 J/kg of CAPE). Given the favorable
environment, numerous showers and thunderstorms will be possible.
Showers and thunderstorms as well as thick cloud cover will likely
hinder high temperatures on Saturday, only reaching into the low to
mid 80s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
The aforementioned mid level trough will slip offshore Saturday
night/Sunday morning, with broad ridging building in behind it. High
pressure will also build in at the surface and dominate through the
remainder of the weekend and into early next week. Apart from Sunday
afternoon which could see a greater coverage of showers and
thunderstorms due to lingering dynamics from the departing trough,
rain chances through early next week remain minimal as subsidence
builds into the region. Under plentiful sun, ridging aloft, and
surface high pressure temperatures each day will reach into the
upper 80s with some locations across southeastern GA possibly
touching 90.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
MVFR cigs will likely persist at the SAV terminal for the next
1-2 hours (12-14Z) until sfc winds increase and dry air filters
into the region from the west. Low clouds could also briefly
impact CHS/JZI terminals early this morning, where tempo MVFR
cigs are in place between 12-13Z. Expect VFR conditions to
prevail at all terminals thereafter, but gusty west-southwest
winds around 20 kt are anticipated much of the afternoon. There
is a small risk for showers and/or thunderstorms near the
CHS/JZI terminal late this afternoon, but confidence remains too
low to include in the latest TAF issuance.

Extended Aviation Outlook: Showers and thunderstorms could bring
flight restrictions to all terminals on Saturday as a low pressure
system impacts the region.

&&

.MARINE...
Today and Tonight: A somewhat enhanced pressure gradient will
persist across local waters today ahead of a weak cold front
advancing toward the coast late day and early night. The pattern
supports southwest winds generally up to 15-20 kt by late
morning and through afternoon hours, before stronger wind fields
shift to the north-northeast and the pressure gradient weakens
post fropa. Cold air advection behind the front will be somewhat
marginal, keeping marine conditions below advisory levels
through the night. However, winds will shift to west and
continue to gust in the 15-20 kt range. Seas should generally
range between 3-5 ft today, highest across offshore Georgia
waters and Charleston County waters. Overnight seas will subside
to 2-4 ft.

Thursday through Monday: Conditions through the period are expected
to remain below Small Craft Advisory criteria. High pressure will
briefly build in at the surface on Thursday, with winds generally
around 10 knots and seas averaging 2 to 3 ft. A cold front will push
through the region on Saturday, shifting winds more to the W and
surging slightly to around 15 knots with gusts to 20 knots. Seas are
expected to build on Saturday as well, increasing to 3 to 4 ft. By
Monday winds will shift to the NW, generally around 10 knots with
seas diminishing to around 1 to 2 ft.

&&

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

&&

$$

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