Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 280754
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
354 AM EDT Thu Mar 28 2024

.SYNOPSIS...
A cold front will move through today, then high pressure will
build in through Tuesday. A cold front could affect the area
next Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: A cold front is slowly easing off the coast early this
morning, with a wave of weak low pressure along the front near
the Georgia coast. That low will reach off the coast of
Charleston closer to daybreak, then steadily deepens as it lifts
northeast over the Gulf Stream waters, reaching off the North
Carolina Outer Banks late. Low level frontogenesis, plenty of
deep moisture where PWat is as much as 1.5 to 1.6 inches will
prevail across the local area early on. Aided by an nearby
upper jet and its associated divergence, along with a strong
upstream short wave trough, numerous to widespread showers will
occur. There might even be a stray t-storm or two near the
coast as we start the day. We`re showing 90-100% PoPs, except
less chances from Allendale to Tattnall County. There is no
risk for Flash Flooding, but with some elevated instability, and
the convection aligned parallel to the flow aloft, some
training will occur. So it remains possible for some minor
flooding of low-lying and poor drainage areas, and in the
Charleston, Beaufort, and Savannah metro regions. Fortunately
we`re in the low tide cycle.

In wake of the low and cold front, drier air will filter in
through the morning, as considerable drier air moves in aloft.
This will put an abrupt end to the rainy conditions from west-
southwest to the east-northeast as we go through the morning,
and the majority of the afternoon looks to be rainfree. However,
a swath of higher low level moisture and the short wave trough
will move on through with colder air aloft, leading to steep mid
level lapse rates. This might generate a few showers as
suggested by some of the guidance. For now we`ll not mention
anything in the forecast, but do show 10% chances for the
afternoon once the morning rains exit the area.

The low level inversion holds into the afternoon, and this has
implications regarding temperatures, especially since there is
some cold advection. Unless we get more afternoon insolation
than we`re anticipating, highs today will only reach the lower
and middle 60s. And with gusty northerly winds, it`ll definitely
be a cool day.

Lake Winds: Although it does appear marginal, there is enough
of a gradient and cold advection for a Lake Wind Advisory on
Lake Moultrie through late afternoon.

Tonight: Clear skies will encompass the area as high pressure
builds in from the west. Although winds never fully decouple in
most places, there is enough cold advection and some radiational
cooling to allow for temperatures to drop to the 40s just about
everywhere. If winds do go calm, a few upper 30s are possible in
normally colder rural interior sections.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Deep layered ridging expected Friday through Sunday, with dry
conditions and warming temperatures. Sunny skies should prevail
Friday and Saturday, then high cirrus should overspread the area
on Sunday. High temps will go from lower 70s Friday to mid 70s
Saturday and lower 80s Sunday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Above normal temperatures will continue Monday into Tuesday as
ridging persists. Monday will be dry, as well as most of
Tuesday, though an approaching upper shortwave could bring a few
showers into far western areas late Tuesday. A potent upper
trough will push a cold front through the area on Wednesday,
potentially accompanied by scattered showers and isolated
thunderstorms. Temps will cool down a bit by Thursday with
drying conditions.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
KCHS/KJZI/KSAV: Widespread SHRA and maybe a few TSRA will
impact the area through the predawn hours, with IFR or even
occasional LIFR conditions, as a cold front and associated weak
low pressure moves through. Convection diminishes during the
upcoming morning, but IFR ceilings will continue. MVFR returns
during the afternoon as mixing heights climb, then VFR finally
moves back in late as high pressure builds from the west.

In wake of the cold front, winds will shift to the N by daybreak,
and become gusty through the day, peaking around 25 kt, before
diminishing considerably toward sunset.

Extended Aviation Outlook: VFR conditions will prevail.

&&

.MARINE...
Today: A cold front and wave of low pressure will pass through
the waters early this morning, lifting off to the northeast as
it deepens thereafter. There`s a tightening of the gradient
that occurs between these features and high pressure from Texas
to Ohio, plus some cold advection, which will produce NW and N
winds as high as 20 or 25 kt, with even some stronger gusts. As
a result, Small Craft Advisories are in effect for all waters,
including Charleston Harbor. Sea height is cut down some by the
offshore fetch, but given the strength of the winds, they`ll
still be as high as 4-6 feet.

Tonight: High pressure continues to build in from the west. The
combination of weak cold advection, steady isallobaric pressure
climbs, and a modest gradient will keep winds elevated. Small
Craft Advisories will continue for at least the Charleston
County Atlantic waters, and the outermost Georgia waters.

Winds will turn to the SW on Friday as high pressure redevelops
off the FL coast. Wind speeds will increase over the weekend as
the gradient tightens between the surface high over the
southwest Atlantic and a developing surface trough inland. A
further tightening of the gradient is expected Tuesday into
Wednesday as a cold front approaches from the west. A brief
period of Small Craft Advisory gusts is possible Saturday
afternoon over the Charleston nearshore waters. We could be
close to advisory again Tuesday into Wednesday, mainly due to
gusts near 25 kt.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Lake Wind Advisory until 4 PM EDT this afternoon for SCZ045.
MARINE...Small Craft Advisory from 8 AM this morning to 6 PM EDT this
     evening for AMZ330-352.
     Small Craft Advisory from 8 AM this morning to 10 PM EDT this
     evening for AMZ350.
     Small Craft Advisory from 8 AM this morning to 4 PM EDT this
     afternoon for AMZ354.
     Small Craft Advisory until 11 AM EDT Friday for AMZ374.

&&

$$

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


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