810
FXUS62 KCHS 302348
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
748 PM EDT Tue Apr 30 2024

.SYNOPSIS...
A weak disturbance will move through the region tonight into
Wednesday. High pressure will then prevail through late week,
before a weak cold front stalls in the vicinity this weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Early this evening: Overall, ongoing convection has mostly
played out as anticipated with most of it being confined along
and west of I-95 through the afternoon and into the early
evening. Water vapor satellite imagery shows a beautifully
defined shortwave that runs the spine of the Appalachians into
central Georgia. The shortwave is providing sufficient lift in
the presence of precipitable water values into the 1.2-1.4"
range to produce the ongoing scattered convection. SPC
mesoanalysis has shown MLCAPE values peaking around 1,000 J/kg
along and west of I-95, coincident with the convection and that
has been sufficient to yield a few storms to produce some 60+
dBZ up to around 20 kft for short periods of time. The current
placement of convection is also where the sea breeze and
convective outflow are meeting and that convergence is adding
some extra lift. KCLX and MRMS rainfall estimates suggest that
some localized rainfall amounts of 1-1.5" have occurred so far,
though most areas are less than that.

As we go through the evening and overnight, the shortwave will
continue progressing eastward and the forecast area will remain
within the forcing associated with it and the deeper moisture
noted above. Instability will certainly be quite low in the
absence of surface heating, but we should continue to see
isolated to scattered showers and thunderstorms across the area
for much of the overnight. The trough axis should shift offshore
just before sunrise and the convective coverage is expected to
diminish. There is no severe threat, but we could still see some
localized heavy rainfall totals. On the backside of the
shortwave and the departing convection, light winds and plenty
of residual low-level moisture should be sufficient to produce
at least some patch fog across the inland tier of the forecast
area. That has been added to the forecast. Lows are expected to
be a few degrees warmer than last night, with low to mid 60s
across the area.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Mid level shortwave will shift off the Carolina coast Wednesday
morning. Convection should be limited in wake of this feature,
but a few isolated showers/thunderstorms will still be possible
through the day with lingering moisture and instability,
especially along the coast.

Ridge builds overhead on Thursday before transitioning offshore
on Friday in advance of a weak shortwave moving in. This
pattern will largely act to suppress convection but will need to
monitor potential for a few storms to impact far inland areas
later Friday.

High temperatures peak in the mid to upper 80s inland of the
immediate coast. Lows will span the 60s, coolest inland.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Surface high pressure remains the primary feature, although a
weak front will approach the region and stall before largely
dissipating. Aloft, a series of weak shortwaves will pass
through. Expect at least isolated to scattered showers and
thunderstorms each day. Highs remain in the mid/upper 80s, while
lows stay in the 60s.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Afternoon convection has mostly remained west of the terminals,
but that should change through the evening and into the early
morning hours. Current thinking is that the best chances for
direct impacts will be at KCHS and KJZI. Therefore we have gone
with prevailing VCSH beginning at 02, with a TEMPO group from
04-08 to cover periods of possible MVFR conditions as showers
move through the terminals. The potential at KSAV certainly
isn`t zero, but based on the current upstream interaction of the
sea breeze and outflow boundaries, it will likely remain just to
the north. There could be some fog and stratus development
around sunrise, but it is expected to remain inland of the
terminals. Winds will be northwesterly Wednesday morning and
into the early afternoon before the sea breeze moves through and
brings winds around to be southerly. We will also have to watch
for isolated shower and thunderstorm development along the sea
breeze beginning in the early afternoon, but confidence in
direct impacts at the terminals is too low to include anything
in the 00z TAF`s.

Extended Aviation Outlook: Flight restrictions possible in
overnight/early morning fog and stratus.

&&

.MARINE...
Tonight: High pressure centered across the western Atlantic
will extend toward the Southeast Coast while a trough remains
inland. The pattern will favor a southerly sfc wind around 15 kt
or less across local waters with the exception of the
Charleston Harbor into early evening, where 20 kt gusts are
possible. Seas will range between 2-4 ft, largest across
offshore Georgia waters. Mariners should remain alert for
thunderstorms tonight, producing gusty winds and frequent
lightning strikes.

Wednesday through Sunday: No marine concerns expected. Atlantic
high pressure will remain the dominant feature with a
relatively weak gradient in the area. Wind speeds will generally
stay below 10 kt except right along the coast with the
afternoon sea breeze, and seas will mostly run 2-3 ft.

&&

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

&&

$$

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