864
FXUS62 KCHS 250502
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
102 AM EDT Tue Jun 25 2024

.SYNOPSIS...
High pressure will remain over the western Atlantic while a
weak cold front approaches the area. This front will likely
linger near the area through mid-week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Tonight: Convection to the west of the local area has diminished
this evening with the loss of daytime heating and the low-lvl
inversion in place. To the north, a cluster of showers/thunderstorms
are ongoing, aided by stronger low-lvl convergence, shear and deeper
moisture supply along the northeast periphery of sfc low pressure
that resides by a trough axis/front. These showers and thunderstorms
will make a run to the coast during the next few hours as the front
nudges into the local area, and should brush northern locations of
Berkeley and Charleston Counties through midnight/1 AM, before
shifting offshore across coastal waters. Although instability
continues to weaken through the night, high levels of DCAPE (1000-
1200 J/kg) and 0-3 km lapse rates around 7 C/km could support a
stronger thunderstorm with gusty winds, especially at locations near
the Santee River during the next 2-4 hours. Once convection moves
offshore, a warm/humid night will remain in place with lows ranging
in the low-mid 70s well inland to lower 80s at the beaches and
Downtown Charleston.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
Broad troughing will persist across the East Coast on Tuesday,
gradually shifting to zonal flow on Wednesday and a return to
broad troughing Thursday. At the surface a weak cold front will
likely linger in the vicinity of the forecast area through
midweek. 850 hPa temperature anomalies will remain rather warm
through the period, which combined with little mixing each day,
will yield hot and humid conditions. Heat index values are
forecast to reach 102-107F inland. A few spots may make a run at
108F along the coastal counties, however coverage of these
values is not enough to warrant Heat Advisories at this
juncture. Each afternoon isolated to scattered showers and
thunderstorms will be possible, as PWATs remain elevated with
the front in the vicinity. PWAT values are forecast to remain
near 1.6-1.8", which is slightly above normal for this time of
year. CAPE values are forecast to reach around 1500 J/kg, with
model soundings indicating >1000 J/kg of DCAPE. A strong to
marginally severe thunderstorm cannot be ruled out any
afternoon, with strong wind gusts as the main hazard.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
An anticyclone aloft will be positioned over the southern U.S.
and will slowly shift eastward over the southeastern states
through the weekend. At the surface high pressure will extend
into the forecast area from the east with the center of high
pressure centered over Bermuda. Hot and humid conditions will
likely persist into the weekend. Heat index values are forecast
to reach from around 103-105F inland with values approaching
108F along the coastline. Head Advisories may be required. A
summertime pattern is expected through the period, with the
highest precipitation chances in the afternoon hours.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
KCHS/KJZI: A few clusters of showers and thunderstorms will move
through the terminals through around 06Z or so and heavy rainfall
could drop visibilities into the MVFR range. Thereafter, cannot
rule out a touch of fog develop across the tri-county region
overnight including the terminals. On Tuesday, VFR conditions
prevail through the day into Tuesday night. Hit and miss shower
and thunderstorms are possible during the afternoon hours
although confidence in coverage/timing and duration is too low
to include in the forecasts at this juncture.

KSAV: VFR conditions prevail through the TAF period. Hit and
miss showers and thunderstorms are possible across southeast
Georgia during the afternoon hours. But again, confidence in
coverage/timing and duration is too low to include in the
forecasts at this juncture.

Extended Aviation Outlook: Brief flight restrictions will be
possible at all terminals with afternoon showers and
thunderstorms.

&&

.MARINE...
Tonight: The pressure gradient will remain enhanced this evening
between high pressure centered well offshore and a trough/front
advancing toward the coast late. As a result, south to southwest
winds between 15-20 kt will be common across most local waters. The
gradient remains even more pinched across nearshore SC waters along
the Charleston County coast late this evening, supporting gusts
around 25 kt ahead of a cluster of showers/thunderstorms approaching
the area after midnight. A Small Craft Advisory has been issued
until 4 AM for the Charleston Harbor and nearby coastal waters along
Charleston County given the gradient is expected to remain quite
strong until showers/thunderstorms arrive and dampen wind fields.
However, a few stronger thunderstorms with gusty winds are possible
across northern most waters along the Charleston County Coast until
the trough/front arrives and/or stalls nearby. Heading closer to
daybreak, southwest winds should trend below Small Craft Advisory
levels for all waters, with gusts returning to around 15 kt across
nearshore waters and perhaps upwards to 20 kt across offshore
Georgia waters. Seas will average between 3-5 ft, largest beyond 10
nm from the coastline.

Tuesday through Friday: Generally tranquil marine conditions
are expected through the period. Winds will gradually back each
day and veer overnight, strongest along the coastline as the
afternoon sea breeze/overnight land breeze develops. Seas should
average 2 to 3 ft.

&&

.CLIMATE...
The low temperature at KCHS so far today is 80. If this holds,
this will break the previous record high minimum of 79 set back
2016.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 4 AM EDT early this morning for
     AMZ330-350.

&&

$$

NEAR TERM...DPB
AVIATION...Adam
MARINE...DPB