588
FXUS62 KCHS 141931
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
331 PM EDT Tue May 14 2024

.SYNOPSIS...
A cold front will move through late Wednesday, 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 /UNTIL 6 AM WEDNESDAY MORNING/...
Late this afternoon through tonight: Visible satellite imagery
shows a good amount of clearing taking place across most of the
forecast area. This is allowing temperatures to rise quickly
into the low 80s, and we will even see some locations top out in
the mid 80s. While there is some convection initiating across
the Midlands, our forecast area is still in the recover process.
Current thinking is still that isolated to scattered
thunderstorms will develop later this afternoon and persist into
the evening hours. Wind profiles still reveal mid-level flow on
the order of 50 knots, yielding effective shear of around 40
knots. Profiles still have a little bit of low-level veering,
but are much more unidirectional than they were this morning.
Also, mid-levels are drying out and DCAPE values are forecast to
rise into the 800-1,000 J/kg range in a few hours. Therefore,
any storms that develop will be capable of producing an isolated
damaging wind gust and small hail can`t be ruled out either.
Coverage should remain isolated to scattered through the
evening, and then gradually wane into the early morning hours.
Late tonight, the focus for convection is expected to steadily
shift further south and offshore and the forecast shows rain
chances decreasing from west to east. Overnight lows could dip
into the mid 60s across the far inland tier, but will mostly be
in the upper 60s.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Low and mid level flow will become westerly on Wednesday as a
broad shortwave trough moves into the Carolinas. Downslope flow
and subsidence will result in a warm day with highs in the mid
to upper 80s. Fairly deep mixing should bring drier air aloft
down to the surface, with surface dewpoints mixing down into the
low 60s inland. For much of the day, there doesn`t look like
there will be enough forcing or moisture to support precip.
However, late in the afternoon into the evening, the main
shortwave will pass to the north, pushing a weak cold front
through the area from the northwest. Models show a slight uptick
in PWATs and SBCAPE across our northern zones ahead of the
front, so scattered showers and thunderstorms could develop as
the front drops through late Wednesday. Given the 35 kt bulk
shear values and decent instability, it`s not out of the realm
of possibility that we could see isolated severe thunderstorms
across southern SC, particularly north of Beaufort. Damaging
winds appear to be the main concern, though large hail would
also be possible.

Dry high pressure will build in for Thursday with highs
reaching the mid to upper 80s. Friday also looks warm, though
moisture should start to increase during the day as a southerly
flow develops. A shortwave moving in from the west late in the
day could spur scattered showers and thunderstorms.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Several potent upper shortwaves will move through Saturday
through Monday, likely bringing several rounds of showers and
thunderstorms. Drier high pressure may rebuild on Tuesday.
Temperatures will remain a couple degrees above normal.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
For the 18z TAF period, there are two main issues. The first
revolves around the potential for isolated to scattered
thunderstorms later this afternoon and into the evening. Current
thinking is that the chances of direct impacts at the terminals
are low enough to preclude any mention in the TAF`s. Instead we
will monitor radar and amend as needed.

The second forecast issue concerns the potential for MVFR or
IFR stratus development early Wednesday morning. Model guidance
and statistical guidance both are rather aggressive in showing
several hours of IFR ceilings at KCHS, KJZI, and KSAV generally
in the 08-14z time period. For now we have kept the forecast VFR
but have hinted at some lower clouds with a scattered condition
at or below 1,000 ft.

Extended Aviation Outlook: Occasional flight restrictions
possible Saturday through Sunday in scattered showers and tstms.

&&

.MARINE...
Tonight: Winds are expected to become more southwesterly with
time and speeds should hold in the 15-20 knot range. Seas around
6ft are expected to linger around the 20 nm line in the
Charleston County waters into the evening, and the Small Craft
Advisory remains in effect there through 8 pm. Elsewhere, seas
should fall into the 3-5 ft range.

SW winds on Wednesday should turn to the W Wednesday night
through Thursday after a cold front moves through. Southerly
flow briefly returns late in the week as high pressure builds
over the western Atlantic. Conditions expected to remain below
advisory thresholds.

Rip Currents: Strong onshore winds along with 2-3 ft swell
every 6-7 seconds will continue to favor a Moderate Risk of rip
currents along all beaches through this evening.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for AMZ350.

&&

$$

NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...BSH/JRL
MARINE...BSH/JRL