280
FXUS62 KCHS 142253
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
653 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/...
The atmosphere is slowly starting to recover from the morning
convection, and there has been a few showers developing here and
there. Nothing significant though given MLCAPE mainly less than
1000 J/kg and Normalized CAPE no greater than 0.1. However, with
a very moist southwest flow in advance of strong mid and upper
level trough moving through the Tennessee Valley, we maintain
isolated to scattered activity through the night. There is at
least 50-60 kt of winds at 500 mb and 90 kt or greater at 250
mb that occur in tandem with each other. That along with DCAPE
on the order of 800-1000 J/kg suggests that there still could be
an isolated strong or severe storm. As such, SPC still has the
region in a Marginal Risk of Severe Weather.

Later tonight there are indications that convection will form
along a baroclinic zone across Florida, and also in advance of
a short wave approaching form the northwest in the trough
aloft. This could require some fine-tuning to the forecast, but
for now we still have as much as scattered PoPs.

The low temperature at KCHS today has been 71F so far, which for
the time being has tied the record high minimum temperature for
the date. Lows tonight will only be down in the mid 60s to lower
70s given mostly cloudy skies, a southwest flow, and elevated
dewpoints.

&&

.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 /23Z 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, although Charleston Harbor might get close
to advisory levels Wednesday afternoon, depending upon how warm
it gets.

Rip Currents: Strong onshore winds along with 2-3 ft swell
every 7-8 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...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...