684
FXUS62 KCHS 170216
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1016 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/...
Tonight: Low pressure centered north of the local area will move
slowly northwest and inland across the Carolinas, gaining latitude
and shifting further away from the region overnight. South of this
feature, sfc winds should gradually back to the north-northwest
locally late evening, then west-northwest after midnight, slowly
diminishing during the remainder of the night as the low tracks
further away from the region. An isolated shower could drift into
extreme northwest locations of Berkeley County late evening, before
drier air (depicted on latest water vapor imagery) overtakes
lingering low-lvl moisture. Expect dry conditions to prevail across
all areas by midnight, then persist for the remainder of the night.
Latest sat imagery and sfc obs indicate broken to overcast low
clouds late this evening, but expect some of these clouds to erode
with drier air shifting into the area through the night. Given
breaks in clouds and sfc winds weakening overnight, temps should dip
into the low-mid 60s inland to upper 60s near the coast.

&&

.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 /02Z TUESDAY THROUGH SATURDAY/...
MVFR cigs will prevail at CHS/JZI through about 06Z Tuesday, before
trending to VFR by around 08Z Tuesday as drier air filters into the
local area. VFR conditions will then prevail at both terminals
through 00Z Wednesday. At SAV, tempo MVFR cigs have been introduced
through 04Z Tuesday, before VFR conditions prevail for much of the
night. Expect VFR conditions to then persist through 00Z
Wednesday.

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

&&

.MARINE...
Tonight: Conditions will gradually improve as low pressure centered
north of the area moves slowly northwest and further away from the
region overnight. The pressure gradient is expected to relax
substantially as the low weakens inland and guidance indicates
1000 mb geostrophic winds decreasing to 20 kt. Given recent
marine obs and expected trends, Small Craft Advisories have been
ended for nearshore waters south of Edisto, SC to the Altamaha
Sound in Georgia. Small Craft Advisories will continue across
offshore Georgia waters where 5-7 ft seas persist during the
night and across nearshore waters off the Charleston County coast
where west-northwest winds gust up to 20-25 kt at times and
seas range between 4-6 ft. However, conditions will continue to
improve during the night, likely ending the Small Craft Advisory
across nearshore waters within a few hours 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 through 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...
As we continue into mid to late week, the risk for at least
minor flooding will continue for Charleston and Coastal Colleton
Counties 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.
MARINE...Small Craft Advisory until 2 AM EDT Tuesday for AMZ350.
     Small Craft Advisory until 1 PM EDT Tuesday for AMZ374.

&&

$$

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