040
FXUS62 KCHS 200522
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
122 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 by next Thursday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
No major changes were made for the early overnight update. Dry
conditions will prevail overnight. The boundary layer has
decoupled at most locations with calm winds being reported. The
best fog parameters still look to setup across parts of
Southeast Georgia again tonight, although 1000 hPa condensation
pressure deficits look marginal. "Patchy fog" was maintained
over much of interior Southeast South Carolina with "areas of
fog" over parts of interior Southeast Georgia where the axis of
best fog parameters look to align. Lows from the upper 60s
inland to the lower 70s at the beaches and Downtown Charleston
look on track.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/...
Friday: The axis of the mid-level trough is expected to push
east over the western Atlantic as strong ridge centered over TX
ridges NE over the Ohio River Valley. GFS indicates that a short
wave is expected to track from north to south across the
forecast area during the afternoon, followed by rising heights.
As temperatures reach the mid to upper 80s over dewpoints in the
70s, weak instability should develop across extreme SE GA.
Latest run of the HREF indicates that a weak sea breeze may
develop along the GA coast Friday afternoon. The combination of
the shortwave passage, weak sea breeze, and limited instability
may support isolated showers along the coast of SE GA during the
afternoon.

Saturday and Sunday, the forecast area will become dominated by
weak sfc high pressure as a large H5 ridge builds across the
Deep South and Southeast U.S. GFS forecast soundings indicate
that the environment will remain less than 1.6 inches of PW with
a significant inversion at H8. High temperatures should favor
values in the upper 80s, with low 90s possible across inland GA
on Sunday. PoPs will remain less than SCHC through this weekend.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Monday through Tuesday: Long term guidance indicates that the
H5 590 DM ridge will shift east across the northern Gulf coast
and FL. This ridge combined with a low over the western
Caribbean could set up a Rex Block through early next week. H5
heights should increase across the forecast area, peaking Monday
and Monday night, limiting any instability across the forecast
area on Monday and Tuesday. The forecast will feature dry
weather through early next week. High temperatures are forecast
to remain in the mid to upper 80s.

Wednesday: H5 heights will begin to break down, possibly with
the approach of amplifying wave. GFS shows a cold front
accelerating east, possibly pushing across the forecast area by
Wednesday evening. The forecast will feature SCHC to CHC PoPs
for showers and thunderstorms. High temperatures will generally
range in the mid 80s.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
20/06z TAF Discussion:
KCHS/KJZI/KSAV: VFR conditions anticipated over the next few
hours. However, some stratus and/or fog-mist development is
anticipated toward sunrise this morning particularly at JZI and
SAV, with a period of MVFR conditions possible. There is a risk
for a brief period of IFR conditions although the 06Z forecasts
will not explicitly have conditions that low. Amendments are
possible as we near sunrise.

Any fog/stratus will mix out quickly after sunrise.

Extended Aviation Outlook: No significant weather expected.

&&

.MARINE...
Tonight: Winds will back to the north overnight with speeds
less than 10 kt and seas 1-3 ft.

Friday through Monday: Building high pressure should result in winds
between 10-15 kts with gusts around 20 kts. Wave heights should
generally remain between 2-5 ft. Conditions should remain below
Small Craft Advisory criteria.

&&

.TIDES/COASTAL FLOODING...
Given high astronomical tides and latest tidal departures, minor
coastal flooding is expected along the Charleston and Colleton
county coasts with the evening high tide cycle. A Coastal Flood
Advisory has been issued with tide levels expected to peak between
7.3-7.5 ft MLLW. Further south and along the Georgia coast, current
forecast keeps tides from reaching minor flooding criteria of 9.5
ft MLLW in Fort Pulaski, but will continue to monitor trends.

Positive tidal anomalies along with high astronomical tides from the
full moon will lead to elevated tides for the rest of this week and
through the weekend. Coastal Flood Advisories will probably be
needed for both the morning and evening high tides through Friday
for both Charleston Harbor and Fort Pulaski.

The astronomical high tides start to lower Saturday and Sunday, but
the morning high tides will likely be elevated enough to still
require Coastal Flood Advisories (especially for Charleston and
coastal Colleton Counties). More uncertainty exists for Fort
Pulaski.

&&

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

&&

$$