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116
FXUS62 KCHS 221701
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
101 PM EDT Wed May 22 2024

.SYNOPSIS...
High pressure will persist into late week. Diurnal convection
is expected during the weekend. A cold front might bring
impacts to our area next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
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No significant changes to the ongoing forecast, with
cumulus/stratocumulus continuing to form , and the early
afternoon sea breeze close to the US-17 corridor and moving
slowly inland. The feature will reach about halfway through the
forecast counties by late afternoon. There has been a decrease
in showers over parts of southeast georgia from this morning.
But there can still be a few brief, light showers that form
along the sea breeze through the afternoon. This is mainly over
inland Mcintosh, Liberty, and Long, eventually reaching Evans
and tattnall late. The vast majority of the forecast area will
not receive and rainfall. early afternoon temperatures are still
on track to reach the mid and upper 80s, with upper 70s and
lower 80s near the coast.

Today: Surface high pressure extends across the area from
northeast to southwest, while aloft ridging that is directly
overhead slides a little east through the day. This allows for a
short wave approaching the Appalachians to brush nearby late.

The 12Z KCHS sounding indicates that PWat is actually less
today than yesterday. That along with a decent subsidence
inversion around 850 mb will prevent any showers from
developing. However, in our far southern counties there is less
of a cap and PWat is higher. That will allow for isolated
showers to develop on the sea breeze as it moves slowly inland
through the day. We added mention of slight chance PoPs mainly
between I-16 and the Altamaha River as a result.

Temperatures are a bit of a challenge, with 850 mb temperatures
not much different from yesterday, but the thickness is a little
greater. Given that we`re already several degrees warmer than
the same time yesterday, we went a tad warmer than the previous
forecast. We show mid and upper 80s away from the coast.

Tonight: Quiet weather continues. Diurnal cloud cover will fade
quickly this evening although there will be some high cloud
cover rolling through the region and there may be some patchy
fog development once again. A touch milder tonight with lows
spanning the 60s inland to around 70 along the coast.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
Thursday: A mid-level ridge over the Southeast U.S. in the morning
will weaken as time progresses. This will lead to west southwest
flow overhead by the evening and overnight. Surface High pressure
just off the Southeast coast in the morning will move further
offshore as time progresses. Meanwhile, a front will continue to
approach from the north and northwest, getting nearby overnight.
However, it`s not expected to reach our area. The western periphery
of the High will be the main driver of our weather, bringing mainly
dry conditions. Though, subsidence will be weaker, so expect a
decent amount of cumulus clouds in the afternoon along with a strong
sea breeze quickly moving inland. We can`t rule out a few sprinkles
in a spot or two. But the POPs remain too low to include any mention
of showers in the forecast. Low- level thickness values and 850 mb
temperatures support highs around 90 degrees before the passage of
the sea breeze, except cooler at the beaches. Lows will be mild, in
the mid 60s far inland to the lower 70s along the immediate coast.

Friday: The mid-levels will consist of zonal flow overhead, with a
weak disturbance just passing to our north during the evening and
overnight. At the surface, High pressure will be centered in the
western Atlantic, with it`s periphery trying to reach into the
Southeast. A front to our north and northwest during the morning
will dissipate into the afternoon, partly due to the High trying to
build back into our area. But weak surface troughing should develop
near our area during the evening and overnight. Moisture increases
ahead of the front and around the periphery of the High, with PWATs
rising to almost 1.85" during the afternoon. Temperatures peaking in
the lower 90s will cause instability to increase. Therefore, the
models have come into better agreement indicating a few
thunderstorms forming around the vicinity of the weakening front and
along the sea breeze in the afternoon, especially across our SC
counties. Locally heavy rainfall is possible, especially in the
stronger storms. Convection should gradually decrease into the
evening, then form just offshore overnight. Lows will be mild,
mainly in the 70s.

Saturday: Weak troughing will form off the Southeast coast in
response to weak ridging forming over the Southeast. Surface High
pressure should remain in the western Atlantic while weak troughing
is over a portion of the Southeast. Low level winds will continue to
usher a decent amount of moisture into our area. High temperatures
again peaking in the lower to maybe middle 90s will generate a
decent amount of instability. Therefore, convection is expected to
form along the sea breeze in the afternoon and try to shift inland.
Rising DCAPEs point to some marginally severe storms with damaging
wind gusts being the main concern. But there will also be locally
heavy rainfall.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
Weak ridging over the Southeast Saturday night into Sunday will
transition to west southwest flow Sunday night. A longwave trough
will develop over the eastern half of the U.S. Monday and prevail
into Tuesday. Surface High pressure will remain in the western
Atlantic. A cold front could approach our area on Tuesday. Expect
convection along/near the sea breeze each afternoon/evening,
decreasing during the overnight hours. Temperatures will remain
above normal each day and night.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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VFR through at least most of the time through 18Z Thursday. Patchy
fog is possible between 09Z and 13Z Thursday morning, possibly
leading to a brief period of sub-VFR conditions.

Extended Aviation Outlook: Mainly VFR through Thursday night. Brief
flight restrictions are possible due to showers/thunderstorms each
afternoon/evening beginning on Friday.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Under the influence of high pressure, the sea breeze
circulations will continue to dominate, leading to
east/southeasterly winds this afternoon...veering south tonight.
Winds largely 10 knots or less and seas 3 feet or less.

Extended Marine: High pressure will remain the main synoptic feature
in the western Atlantic. A cold front should approach from the north
and northwest on Friday, but it`s not expected to reach our area.
Otherwise, expect a typical summer wind pattern. Each day, winds
will back and be stronger along the land/sea interface with the
formation of the afternoon sea breeze. Gusts could approach 20 kt
across the Charleston Harbor with the passage of the sea breeze.
Each night, winds should veer as the low level jet sets up along the
coast. Additionally, convection is expected to return this weekend
and persist into next week.

Rip Currents: There were reports of rip currents at Tybee
yesterday and also earlier today. But given the lack of wind
and only limited swell energy, we maintain a low risk in the
forecast.

Thursday: The combination of astronomical influences
from the Full Moon and a small swell will lead to an enhanced risk
of rip currents at all of our beaches. The in-house Rip Current
Calculator continues to indicate a Moderate Risk, while the Rip
Current MOS points to a Low Risk. For consistency, we maintained the
Moderate Risk. Rip currents are most likely at Tybee Island.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
Minor flooding is briefly possible with the evening high tides
through Thursday along coastal Charleston and coastal Colleton
Counties. There are no concerns along the remainder of our
coast.

&&

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

&&

$$

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