528
FXUS62 KCHS 172339
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
739 PM EDT Tue Sep 17 2024

.SYNOPSIS...
Low pressure across the Carolinas will weaken through mid week.
High pressure will then develop inland late this week, and
persist into the weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Early this evening: Radar imagery remains quiet and satellite
data shows the diurnal cumulus field has quickly dissipated with
the loss of heating. Through the overnight, conditions should
be quiet. The area will remain within the broader circulation
around the remnant low of PTC8, situated to the northwest. Model
soundings do show moistening in the low and mid levels, thanks
to southwest flow around the aforementioned circulation. A
subtle boundary will begin to approach from the southwest late,
and that could be the trigger for isolated to scattered showers
across portions of southeast Georgia right around sunrise. There
could be some shallow ground fog late tonight thanks to the
increased low-level moisture, but we aren`t anticipating any
significant visibility reductions. Lows are forecast to reach
the mid 60s far inland, ranging to around 70 at the coast.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Wednesday: The mid-levels will consist of a trough over the
East Coast. Embedded within it will be a Low, roughly 579 dam at
500 mb. It`ll be located just to our northwest in the morning.
But it`ll shift to the north and elongate, becoming located over
the Mid- Atlantic States overnight. At the surface, a
stationary front will be spread over our far inland zones, or
just to our west during the day. It`ll start to transition to a
cold front and move towards the coast by daybreak Thursday.
There will be a decent amount of moisture in place with PWATs
peaking around 2", which is around the 90th percentile for this
time of year. Both the synoptic models and the long-range CAMs
have isolated, light showers developing over by the late
morning. By the afternoon, scattered showers are expected across
most of our area. A few rumbles of thunder are also possible.
The showers should gradually decrease as the atmosphere
stabilizes in the evening, then things dry our over land
overnight. High temperatures will be in the mid to maybe upper
80s, except cooler at the beaches. Low temperatures will be in
the upper 60s, except lower 70s at the beaches.

Thursday: A mid-level trough will be over the East Coast in the
morning. Embedded within it will be a Low located over the Mid-
Atlantic State. While the trough will stay in place, the Low
will shift towards New England. The surface stationary front
will be spread over our coast at daybreak. It`ll quickly shift
offshore as time progresses. High pressure will then form
further inland. PWATs will initially be as high as 2" in the
morning. Though, they`ll gradually trend lower as time
progresses. The combination of this moisture and lift from the
front and maybe sea breeze will lead to isolated showers along
our coast in the afternoon, and scattered shower across the
Charleston Tri-County. A few rumbles of thunder are also
possible. These showers will quickly dissipate during the
evening, with it being dry overnight. High temperatures will
again be in the mid to maybe upper 80s, except cooler at the
beaches. Low temperatures will be in the mid/upper 60s, except
lower 70s at the beaches.

Friday: The mid-levels will consist of a trough over the East
Coast, with an embedded Low over or near New England. At the
surface, broad High pressure will be over roughly the mid-
Appalachians. This will usher much drier air into our region,
with lower PWATs and dew points. Expect a mostly sunny day with
a bit of an increase in clouds during the afternoon. Northeast
winds will keep highs in the low to mid 80s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
WPC has High pressure over portions of the Southeast U.S. for
much of the long term. The NBM reflects this thinking well.
Simply put, we`ll have dry conditions with temperatures at or
slightly below normal.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are expected to prevail at KCHS, KJZI, and KSAV
through 00z Thursday. There could be some shallow ground fog
around sunrise, but no restrictions are expected. Isolated to
scattered showers will also be possible around KSAV around or
just after sunrise, continuing through the morning. The
potential for showers, and possibly a thunderstorm, will then
shift to around KCHS and KJZI for the afternoon. However,
confidence in direct impacts is too low to include anything
other than VCSH at this time.

Extended Aviation Outlook: Very brief flight restrictions are
possible due to showers again Thursday afternoon/evening.
Otherwise, VFR.

&&

.MARINE...
Tonight: Southerly flow this evening will gradually turn more
southwesterly with time overnight. Wind speeds should generally
be 10 knots or less. Seas should average 2-4 feet.

Low pressure and a stationary front across the Carolinas will
weaken on Wednesday. The front should transition into a cold
front and quickly move through the waters on Thursday. High
pressure will then prevail inland Friday and persist into the
weekend. Additionally, Low pressure should be located well to
our northeast this weekend. Sustained winds will generally be 10
kt or less Wednesday with seas 2-4 ft. Wind direction will
change as the front moves through on Thursday, while seas are
2-3 ft. Northeast winds become more dominant starting on Friday.
They may be at their strongest each night. Regardless, both
winds and seas appear to remain just below Small Craft Advisory
criteria throughout the long term time period.

Rip Currents: The combination of a lingering swell around 2 ft
at 9 seconds and high astronomical tides from the full moon will
lead to a Moderate Risk of rip currents for all of our beaches
on Wednesday.

&&

.TIDES/COASTAL FLOODING...
Latest trends and guidance indicate that tide levels for
Charleston and Colleton County coast will reach minor Coastal
Flood levels this evening. Thus, have issued a Coastal Flood
Advisory for the Charleston and Colleton coasts. Tide levels are
currently expected to peak just shy of Coastal Flood Advisory
levels for the remainder of the coast, but will continue to
monitor trends in the event an Advisory is needed for that area
too this evening.

Positive tidal anomalies along with high astronomical tides
from the full moon will lead to elevated tides for the rest of
this week. Coastal Flood Advisories will probably be needed,
especially for Charleston and coastal Colleton Counties.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Coastal Flood Advisory until 10 PM EDT this evening for SCZ049-
     050.
MARINE...None.

&&

$$

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