974 
FXUS62 KCHS 070742
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
342 AM EDT Fri Oct 7 2022

.SYNOPSIS...
High pressure will prevail until a cold front moves through the
area early Saturday. High pressure will then return for the 
weekend and early next week. 

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: Aloft, west-southwest flow will prevail as a trough 
progresses across the Great Lakes region. At the surface, weak 
high pressure will sit across the region as an upstream cold 
front shifts into the Appalachians. Overall, another quite day 
with a dry forecast and very little in the way of cloud cover. 
Low-level thickness values continue to trend higher from 
previous days and will be supportive of temperatures in the low 
80's at KCHS. This should result in highs in the low to mid 80s 
for southeast South Carolina and mid to upper 80s for southeast 
Georgia. We should see another solid sea breeze in the mid to 
late afternoon hours as well with only light west to southwest 
flow ahead of its development. 

Tonight: The advancement of the upstream cold front will slow 
as it moves into the lee of the Appalachians. The front should 
enter inland portions of the forecast area late, but won't clear
the entire region by sunrise Saturday. The forecast continues 
to be dry, with lows in the mid to upper 50s away from the 
immediate coastline.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
Saturday morning a cold front will be positioned just offshore 
of the southeastern coast, having moved through the region 
Friday night. High pressure will build in behind the cold front.
Zonal flow to broad troughing will prevail aloft. This cold 
front is not forecast to be particularly strong, therefore 
little will change between Friday and Saturday. Temperatures 
Saturday are forecast to be in the upper 70s across southeastern
SC and low 80s across southeastern GA. With clear skies and 
light and variable winds, Saturday night looks poised to be a 
good set up for radiational cooling. Overnight lows on Saturday 
are forecast around 50 far inland, with upper 50s to near 60 
along the coastline. 

Sunday and Monday look to follow a similar pattern of building 
high pressure at the surface and broad troughing to zonal flow 
aloft. High and low temperatures will be right around normal. 
Subsidence from the building high pressure will allow the sunny 
and rain-free pattern to persist.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
High pressure will continue to prevail at the surface through 
next week. A cold front is forecast to move through the region 
late week, bringing with it the first chance of precipitation in
the forecast period. Temperatures are forecast to be right 
around normal. 

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
The main forecast challenge through sunrise will be the 
potential for fog at the terminals. Model guidance supports at 
least some shallow fog, with the potential for MVFR 
visibilities. The KCHS, KJZI, and KSAV TAF's have been adjusted 
to feature a TEMPO group for MVFR conditions roughly from 
10-12z. Any fog that develops will dissipate quickly after 
sunrise and then VFR conditions will prevail through 06z 
Saturday. 

Extended Aviation Outlook: Prevailing VFR.

&&

.MARINE...
Today through tonight: Light flow will prevail this morning 
before turning onshore later this afternoon with the development
of the sea breeze. winds closer to the land/sea interface 
should top out in the 10-15 knot range. Overnight, southwest 
winds in the 5-10 knot range will prevail ahead of a cold front 
approaching from the northwest. Seas are expected to be in the 
1-2 ft range through the period.

A cold front will be positioned in the vicinity of the coastal 
waters Saturday, having passed through the land zones Friday. As
high pressure builds in at the surface behind the front a 
slight surge in the winds is forecast. Conditions are forecast 
to remain below Small Craft Advisory criteria, with 
northeasterly winds around 15 knots with gusts to 20 knots 
currently in the forecast. High pressure will then prevail 
across the marine zones into early next week, with generally 
tranquil marine conditions forecast.

&&

.TIDES/COASTAL FLOODING...
Upcoming evening high tide (~7 pm): At Charleston, the
astronomical high tide is 6.55 ft MLLW. Tidal departures are
still running positive around 0.6-0.8 ft despite coastal winds
not being particularly favorable. It appears near certain that
Charleston will reach minor flood stage this evening, and could
approach moderate flood stage. A Coastal Flood Advisory will
almost certainly be needed. At Fort Pulaski, the astronomical
high tide is 8.39 ft MLLW. While high could approach minor flood
stage, current thinking is that it will fall short in the
9.2-9.4 ft MLLW range. A Coastal Flood Advisory could be needed
there if minor flooding becomes more likely. 

Astronomical influences from the upcoming full moon will lead 
to elevated tide cycles this weekend and into next week. Over 
the weekend, both morning and evening high tides could have 
moderate to major coastal flooding along the Charleston and 
Colleton County coasts, then with the morning high tides through
mid-week. From Beaufort County to McIntosh County, minor to 
moderate coastal flooding will be possible with the morning and 
evening high tides this weekend, then with the morning high 
tides through mid-week.

&&

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

&&

$$

NEAR TERM...BSH
SHORT TERM...CPM
LONG TERM...CPM
AVIATION...BSH/CPM
MARINE...BSH/CPM
TIDES/COASTAL FLOODING...