223
FXUS62 KCHS 162025
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
425 PM EDT Mon Sep 16 2024

.SYNOPSIS...
Low pressure will shift inland across the Carolinas and weaken
tonight into mid week. High pressure should develop inland late
week into the weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
This evening and tonight: The circulation associated with PTC8
continues to move very slowly NNW, away from our region.
Conditions continue to gradually improve, with no significant
impacts expected from this point forward. The latest radar loop
continues to show little/no precipitation, other than some
spotty light showers. Not expecting any significant rainfall
through tonight. The satellite imagery still showing broken to
overcast low clouds across our entire forecast area, around the
back side of the PTC8 circulation. Expect the low clouds to
erode/decrease after sunset and the loss of heating. After
midnight, expect skies to become partly cloudy. Low temperatures
in the mid to upper 60s most areas, which is near seasonal
normals.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
The remnant low of PTC8 should be somewhere over the Carolinas at
the start of the period. The surface low will continue to weaken
with time. An associated trough axis/weak boundary should transition
back towards the coast and possibly offshore on Thursday. Tuesday
should actually be rain-free over the local area, then isolated to
perhaps scattered showers will return for Wednesday and Thursday
with deeper moisture and upper trough moving back overhead. High
temperatures a touch below normal on Tuesday will warm to the mid to
even upper 80s for mid week. Lows will range from the upper 60s
inland to low/mid 70s at the immediate coast.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Mid level trough axis initially stretched down the east coast should
push a bit east over the weekend as a ridge centered over southern
Texas nudges into the region. Still some spread between models
during the latter half of the weekend with regards to if a mid level
low forms off the coast and how far offshore that would be. At the
surface, high pressure is expected to build south into the Carolinas
and Georgia. This pattern generally favors lower rain chances, so
PoPs are no higher than 20% and only located closer to the coast.
Temperatures will lean on the cooler side of normal through the
period.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Through this evening: KCHS and KJZI: guidance indicating
the potential for MVFR CIGS to hang on through the evening,
possibly rising to VFR after midnight. Have kept MVFR through
about 06/07Z, then trended into VFR. Gusty NW winds through
about 23z this evening. KSAV: Periodic MVFR CIGS through about
sunset, then expect VFR to prevail.

Later tonight/After midnight: Feel VFR conditions will prevail
all three sites.

Extended Aviation Outlook: Low chance for brief flight restrictions
in showers and thunderstorms Wednesday and Thursday.

&&

.MARINE...

Tonight: Conditions continue to gradually improve as the
circulation associated with PTC8 moves slowly northward, away
from the marine area. SCA conditions over the entire marine area
will improve most areas by midnight. Expect highlights to drop
first in Charleston Harbor before sunset this evening, then rest
of the nearshore waters by around midnight tonight. Have kept
SCA conditions for seas for the offshore GA waters through early
afternoon Tuesday. Northwest winds of 10 to 15 knots with gusts
to around 25 knots will decrease to 5 to 15 knots after
midnight, except by sunset for Charleston Harbor. Nearshore
seas of 4 to 6 feet are expected to decrease to 3 to 5 feet
after midnight. For the offshore GA waters, SCA level seas of 5
to 7 feet, then 4 to 6 feet after midnight.

Tuesday through Saturday: Fairly benign marine conditions are
expected through at least Friday with wind speeds generally less
than 15 knots. Seas will subside on Tuesday, settling in 2-4 foot
range thereafter. High pressure should build south into the
Carolinas and Georgia late week into the weekend. Winds will turn
out of the northeast and could see some increase in speeds with the
pressure gradient tightening.


Rip Currents: Lingering swell of around 3 ft every 10 seconds and
astronomical influences from the full moon and perigee will maintain
a High Risk of rip currents for all beaches on Tuesday. It is worth
noting that local calculations for Georgia beaches were
borderline moderate-high but opted to maintain the High for
now.

&&

.TIDES/COASTAL FLOODING...
Charleston and Coastal Colleton Counties: The latest departures
are in the 0.3-0.5 range at the Charleston tide gauge. If those
hold for the evening high tide, the tide would reach around 7 ft
MLLW, or right at Coastal Flood Advisory criteria. Will hold
off for a bit to make sure the trend continues before deciding
if a Coastal Flood Advisory will be needed. Tides are expected
to remain below Coastal Flood Advisory Levels for the remainder
of our coastline from Beaufort County, SC southward to McIntosh
County, GA.

Charleston and Coastal Colleton Counties: As we continue into
mid to late week, the risk for at least minor flooding will
continue due to high astronomical tides with the full moon on
September 17th.

Beaufort County, SC, south to McIntosh County, GA: Waters levels
could be close to minor flood levels later this week as onshore
winds return.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents through Tuesday evening for GAZ117-119-
     139-141.
SC...High Risk for Rip Currents through Tuesday evening for SCZ048>051.
     Lake Wind Advisory until 6 PM EDT this evening for SCZ045.
MARINE...Small Craft Advisory until 6 PM EDT this evening for AMZ330.
     Small Craft Advisory until midnight EDT tonight for AMZ350-352-
     354.
     Small Craft Advisory until 1 PM EDT Tuesday for AMZ374.

&&

$$

NEAR TERM...RFM
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...RFM
MARINE...ETM/RFM