336
FXUS62 KCHS 201543
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1143 AM EDT Fri Sep 20 2024

.SYNOPSIS...
An area of high pressure is expected to gradually strengthen
across the region through early next week. A weak cold front
may approach from the west around the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Blue sky coastal flooding ongoing across portions of the City of
Charleston. At 10:30 AM, the Charleston Harbor tide gauge
observed 7.86 FT MLLW, on the upper side of moderate flood
stage. Long Point Road in Mount Pleasant is expected to be
covered in flood waters by 11 AM. The Coastal Flood Advisory for
Charleston and coastal Colleton Counties has been extended until
1 PM.

Latest visible satellite indicated shallow cumulus cloud
streets developing over portions of the SC Lowcountry and along
the GA coast. The 12Z KCHS observed sounding indicated a
convective temperature around 85 degrees with an inversion
around 590 mb. However, a mid-level vort max was indicated on
satellite water vapor, tracking south across the forecast area.
By this afternoon, the combination of a weak sea breeze, passage
of vort max, and CAPE around 1000 J/kg should support isolated
showers along the GA coast this afternoon. High temperatures are
on track to peak in the mid to upper 80s.

Tonight: Mid level trough axis will advance off the coast with
upstream ridging expanding into the southeast states, and inland
high pressure wedging become better defined. Any convection
that develops this afternoon will fade quickly this evening
with clear to partly cloudy skies dominating overnight. Lows dip
back into the middle to upper 60s, warmer along the coast.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
The synoptic pattern will remain largely unchanged through the
period with a large upper ridge across the Deep South. Surface high
pressure will remain over the Southeast U.S., providing subsidence
and generally quiet weather conditions through the period. Mostly
sunny skies are expected each day through Monday. Any potential for
convection will be largely suppressed due to relatively dry air
aloft and the lack of significant forcing mechanisms. No mentionable
rainfall chances have been included in the short term forecast.

Temperatures will trend warmer due to the ridge aloft with highs in
the mid to upper 80s Saturday, increasing to the upper 80s/low 90s
Sunday and Monday. Lows will start somewhat cool Saturday night,
dipping into the mid to upper 60s for most locations. Sunday night
will feature lows in the upper 60s inland and low 70s near the coast.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
The long-term forecast features continuing dry conditions initially,
with increasing chances of afternoon showers and thunderstorms
around the middle of next week. The region will see a slight uptick
in moisture with surface high pressure shifting offshore Tuesday,
followed by the upper ridge axis. Slight chance POPs return
Wednesday with peak rain chances anticipated to occur mid to late
week as an upper trough and cold front approach. Temperatures will
remain seasonable with highs generally in the mid 80s and lows in
the mid to upper 60s, with an ever so slight cooling trend through
the week.

&&

.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
20/06z TAF Discussion:
KCHS/KJZI/KSAV: Brief IFR conditions in fog and/or stratus will
impact the terminal sites until 13Z. But fog/stratus will erode
quickly with VFR conditions developing and persisting
thereafter.

Some fog is again possible overnight into Saturday morning,
although fog probabilities look much lower as compared to this
morning and will be left out of the 12Z terminal forecasts for
now.

Extended Aviation Outlook: VFR conditions expected to prevail.

&&

.MARINE...
Light offshore winds will be in place to start the day but will
veer north/northeasterly later this morning and this afternoon.
Speeds 10 knots or less anticipated and seas 3 feet or less.

Saturday: Inland high pressure with a coastal trough off the
southern Florida Peninsula will result in northeast winds between 10-
15 kt with gusts around 20 kt Saturday. Seas will average between 2-
4 ft with some 5 foot seas in the outer Georgia waters from 20-60
nm. Conditions are expected to be below Small Craft Advisory
criteria.

Sunday through Wednesday: As the coastal trough to the south
subsides and high pressure begins to migrate offshore, the pressure
gradient will relax bringing northeasterly to southeasterly winds
around 10 kt or less. Seas will decrease to around 1-3 ft with 4
foot seas beyond 40 nm.

&&

.TIDES/COASTAL FLOODING...
Blue sky coastal flooding ongoing across portions of the City of
Charleston. At 10:30 AM, the Charleston Harbor tide gauge
observed 7.86 FT MLLW, on the upper side of moderate flood
stage. Long Point Road in Mount Pleasant is expected to be
covered in flood waters by 11 AM. The Coastal Flood Advisory for
the entire coast of SE GA/SC will remain in effect until noon.
Additional minor coastal flooding is possible with the evening
high tide.

Further south and along the Georgia coast, minor coastal
flooding is expected with the morning high tide. Coastal Flood
Advisory will also be issued with tide levels expected to peak
between 9.7-9.9 ft MLLW at the Fort Pulaski tide gauge.

Positive tidal anomalies and high astronomical tides from the
recent full moon will lead to elevated tides through the
weekend. Although the astronomical high tides start to lower
Saturday and Sunday, minor to moderate coastal flooding is
likely with each high tide cycle along the Charleston and
Colleton county coasts. Further south and along the Georgia
coast, minor coastal flooding is likely with the morning high
tide cycle.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Coastal Flood Advisory until noon EDT today for SCZ049-050.
MARINE...None.

&&

$$

NEAR TERM...NED
SHORT TERM...BRM
LONG TERM...BRM
AVIATION...Adam/BRM
MARINE...Adam/BRM