411
FXUS62 KCHS 221958
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
358 PM EDT Sun Sep 22 2024

.SYNOPSIS...
High pressure will linger across the region through early week
this week. Later this week, a tropical cyclone is forecast to
move generally northward across the Gulf of Mexico, then
possibly tracking inland across portions of the Deep South or
Southeast U.S. late this week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Through This Evening: The HRRR continues to develop a few
showers inland. Though, it hints at them starting and ending
later than what some of the synoptic models and CAMs were
showing earlier. Radar imagery has been unimpressive so far, and
satellite imagery shows limited cumulus inland. However, west of
our area a few showers have developed. These could move into
our area in the next few hours and/or there could be new
development far inland. Therefore, we`re maintaining slight
chance POPs in these locations for the next few hours.

Overnight: The mid-levels will consist of ridging stretching
from southern TX to the east across the Deep South and
Southeast U.S. At the surface, weak High pressure will prevail
inland. Any showers inland will quickly diminish early, followed
by dry conditions. Winds away from the immediate coast are
expected to go calm with a mix of clear skies and clouds. This
should yield low temperatures in the upper 60s for most areas,
and the lower 70s near the beaches.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
A large ridge will remain centered over the northern Gulf of
Mexico through early this week. On Monday, a sfc trough is
forecast to slide over the forecast area by the afternoon.
Forecast soundings indicate that CAPE values will increase to
1000-1500 J/kg. Latest HREF indicates that a corridor of
isolated showers and thunderstorms may develop NW of the
forecast area, drifting over the inland counties Monday
afternoon and evening. High temperatures should range around 90
degrees.

On Tuesday, H5 ridge axis is expected to pivot across the
forecast area during the day. Forecast soundings indicate
shallow lapse rates under the ridge, limiting the convective
potential. The forecast will generally remain dry, with SCHC
PoPs across portions of the CHS Tri-county. High temperatures
should remain around 90 degrees.

Wednesday, the forecast area will remain under the influence of
the H5 ridge centered over the western Atlantic. At the sfc,
high pressure centered over the Mid-Atlantic States is expected
to ridge south across the region. It is possible that a sea
breeze could trigger isolated showers during the afternoon, SCHC
PoPs inland. High temperatures should remain in the upper 80s
to around 90.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Thursday through the rest of the week, details of the forecast
will largely depend on the intensity, placement, and timing of a
potential tropical system sourced from the Gulf of Mexico. See
latest NHC Tropical Weather Outlook for latest information.
Based on the collaborated low position, the system is expected
to remain centered west of the forecast area.

The H5 pattern will feature a ridge centered over the western
Atlantic and a closed low over the Southern Plains, this should
favor the expected tropical cyclone to track northward across
the Gulf of Mexico. The proximity of the low, and expected track
to the west, should result in increasing rainfall potential
Thursday through Friday. Concern is increasing for impactful
weather Thursday night into Friday, with the potential of a
rainband lifting northward across the region. This band could
bring rounds of heavy rainfall, gusty winds, and potentially the
risk for tornadoes.

The forecast is even more uncertain for the weekend, it is
possible that dry air could wrap around the central CONUS closed
low and bring drier conditions to the region. Or, some guidance
indicates that a strong CAD may develop over the region, with
rain, thick cloud cover and cool NE winds. The forecast will
keep scattered convection with day to day highs in the 80s.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
18Z TAFs: VFR.

Extended Aviation Outlook: VFR conditions expected to prevail
through Wednesday.

&&

.MARINE...
Tonight: Weak High pressure inland will lead to tranquil marine
conditions. Expect generally S winds 5-10 kt this evening,
backing a bit overnight. Seas will be 2-3 ft within 20 nm and
3-4 ft across the GA waters beyond 20 nm. Seas are expected to
subside about a foot after midnight.

Monday through Thursday: Broad high pressure offshore will
result in southeast winds around 10 kt or less. Seas will
average 1-3 ft for the nearshore waters out 20 NM and 3-4 ft for
the outer GA waters from 20-60 NM. Wednesday through Thursday,
there could be an increase in winds due to a potentially
developing tropical system in the Gulf of Mexico. Thursday,
guidance indicates that gusts may range between 25-30 kts with
seas build to 5-6 ft within 20 NM and 8- 9 ft across the outer
GA waters.

&&

.TIDES/COASTAL FLOODING...
Positive tidal anomalies and high astronomical tides from the
recent full moon will lead to elevated tides through early week.
Although the astronomical high tides are lowering, minor
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...
SHORT TERM...NED
LONG TERM...NED
AVIATION...NED
MARINE...NED