723
FXUS62 KCHS 210541
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
141 AM EDT Sat Sep 21 2024

.SYNOPSIS...
High pressure will 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 /UNTIL 6 AM THIS MORNING/...
Tonight: Aloft, mid-lvl vort energy will continue to shift south and
across the Atlantic along the base of a trough positioned just
offshore. At the sfc, high pressure will extend south across the Mid-
Atlantic and Southeast states. The pattern will favor dry conditions
across the local area. A fair amount of radiational cooling can be
expected with a light/calm wind in place under clear skies for much
of the area. There could even be pockets of patchy fog across inland
areas within a few hours of daybreak, but coverage should remain
limited. Low temps will range in the upper 60s inland to low-mid 70s
near the beaches where a light onshore wind prevails.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
The mid-levels will consist of a trough just off the East Coast
Saturday morning and ridging over the central U.S., with
embedded high pressure over TX. By Monday, the trough will have
shifted further offshore, pushed by the ridge that will have
moved over the East Coast. Additionally, the embedded High
should be over the FL Panhandle. At the surface, High pressure
will remain over the Southeast U.S. Subsidence associated with
the High is expected to bring mainly dry weather during the
short term. We will note that most of the synoptic models are
completely dry on Saturday. Though, the long-range CAMs are
split between it being completely dry and some members showing
light showers along the GA coast. PWATs are around 1.5", but
many model soundings show decent dry air in place. So we opted
to go with 10% POPs in these locations Saturday afternoon. If
anything does manage to form, it will be isolated, brief,
light, and may just be sprinkles. Saturday evening through
Monday are completely dry. Temperatures will trend higher due to
approaching ridge. Highs will be in the mid to upper 80s
Saturday, and the upper 80s to around 90 degrees on Sunday and
Monday. Though, it will be cooler at the beaches. Lows Saturday
will be in the mid to upper 60s for most locations. Sunday
night they`ll be in the upper 60s inland to the lower 70s along
the immediate coast.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Surface high pressure will initially be over our region, then
shift offshore mid to late next week. A cold front should
approach from the northwest on Friday. This synoptic pattern
will yield dry conditions through Wednesday, with increased POPs
Thursday and Friday. High temperatures should be at or slightly
above normal Tuesday and Wednesday, trending lower Thursday and
Friday.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions are expected at CHS/JZI/SAV terminals through 06Z
Sunday.

Extended Aviation Outlook: There are no concerns.

&&

.MARINE...
Tonight: High pressure will increase across the marine zones
through the night. Winds across the nearshore and outer waters
will remain from the ENE around 10 kt, increasing to 10-15 kt
and slowly backing to NE late tonight. Seas should range between
2-4 ft.

Saturday: The interaction between High pressure inland and a
weak trough south of FL will yield sustained NE winds 10-15 kt
during the day. Winds will ease during the evening and
overnight. Seas will average 2-4 ft during the day with some 5
footers in the GA waters from 20-60 nm. Seas should drop about 1
foot during the evening and overnight.

Sunday through midweek: High pressure will prevail inland, then
begin to move offshore midweek. Expect sustained winds to be
mainly 10 kt or less. Seas will average 2-3 ft within 20 nm and
3-4 ft for the GA waters from 20-60 nm.

&&

.TIDES/COASTAL FLOODING...
Coastal flooding is likely again up and down the entire coast
with high tide late Saturday morning. For Charleston Harbor, the
current 7.9 ft MLLW forecast look solid. There is some concern
that levels could reach major flood levels (8.0 ft MLLW), but
this scenario only has about 10% probability of occurrence. A
Coastal Flood Watch for Charleston and Colleton Counties will
not be issued with this forecast update for this reason. Fort
Pulaski looks to say solidly in the minor flood category.
Coastal Flood Advisories will be needed for all coastal zones
from late morning into the early afternoon hours.

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 are lowering,
coastal flooding is expected with each daytime high tide cycle
along the Charleston and Colleton county coasts.

&&

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

&&

$$

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