531
FXUS62 KCHS 221930
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
330 PM EDT Wed May 22 2024

.SYNOPSIS...
High pressure will persist into late week. Diurnal convection
and hot temperatures expected during the holiday weekend. A
cold front might bring impacts to our area on Tuesday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Although there were isolated showers early in parts of southeast
Georgia earlier, they have since dissipated, and we have
removed mention from the forecast. Maybe a stray shower forms
along the sea breeze across interior Georgia prior to sunset,
but that`s it.

Diurnally induced cumulus will fade with sunset, leaving us with
mainly clear skies through the night. However, late at night
there are indications of some stratus and potentially some fog
developing. We maintained mention of patchy fog after 4 am, but
most guidance implies that it won`t be as bad as it was in some
places during this morning. That`s likely due to us having a
difficult time achieving our cross-over temperatures.

Radiational cooling will again prevail as winds become light or
calm in most places with the sunset, offset somewhat by the
synoptic flow that turns southerly. Lows will be down in the
lower and middle 60s far inland, upper 60s and lower 70s closer
to the coast, in downtown Charleston and downtown Savannah.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
Thursday: The day will begin with the H5 ridge along the coast,
shifting east through the afternoon. A shallow H5 trough will slide
over the southern Appalachians during the afternoon. At the sfc, a
wavy front should remain across the Ohio River Valley, with moisture
pooling to the east. Short term guidance indicates that a weak sea
breeze may develop Thursday afternoon. However, with poor lapse
rates lingering llvl CIN should keep the forecast area dry. High
temperatures are forecast to range around 90 degrees.

Friday, the H5 heights will remain generally zonal with a weak
trough across the Coastal Plain in the afternoon. Isolated to
scattered showers and thunderstorms are forecast to develop along a
sea breeze Friday afternoon. Given sfc conditions in the low 90s and
dewpoints in the upper 60s to low 70s, a wide field of instability
should develop during the heat of the afternoon.

Saturday, models indicate that broad H5 trough will develop across
the Southeast U.S. At the sfc, a weak trough is expected to form
along the coast, reinforced with an afternoon sea breeze. High
temperatures will once again favor values in the low 90s. However,
dewpoints should increase, generally ranging in the upper 60s to
around 70. Deep moisture convergence and instability along and west
of the sea breeze should support isolated to scattered thunderstorms.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Mid-level ridging should build across the region on Sunday. The
forecast area will remain between deep low pressure over the Ohio
River Valley and high pressure over the eastern Gulf of Mexico. This
pattern should provide the region with deep south winds. Given the
ridge overhead, showers and thunderstorms should hold off until the
afternoon and evening, forming along the sea breeze. Sunday is
expected to be the hottest day, with mid 90s possible across the
forecast area.

The H5 ridge will remain across the forecast area on Monday. Sfc
high pressure over FL is expected to ridge northward across the CWA.
The forecast will continue to feature isolated to scattered showers
and thunderstorms with highs in the low 90s.

A cold front is forecast to impact the region on Tuesday. At this
time, the forecast will feature PoPs in the high chance range. With
the late arrival of the front and convection, temperatures may reach
the low 90s.

Wednesday, temperatures may range a bit cooler, with values in the
upper 80s. Slight dryer conditions should result in lesser coverage
of afternoon and evening showers and thunderstorms.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
VFR through at least most of the time through 18Z Thursday. Patchy
fog is possible between 09Z and 13Z Thursday morning, possibly
leading to a brief period of sub-VFR conditions.

Extended Aviation Outlook: Mainly VFR through Thursday night. Brief
flight restrictions are possible due to showers/thunderstorms each
afternoon/evening beginning on Friday.

&&

.MARINE...
This evening and tonight: High pressure extends atop the local
waters, leading to a fairly relaxed gradient. Once sea breeze
circulations fade this evening, winds that start out SE`erly
willveer around to the S or SW. Speeds on average won`t be
anything more than 10 or 12 kt, and seas are 3 feet or less. At
this time it does not appear that a repeat of the fog/stratus
from this morning will happen again as we get close to daybreak
Thursday.

Extended Marine: High pressure should yield typical summer-time
weather across the forecast area. In fact, a sea breeze is expected
to develop each afternoon through the holiday weekend. A cold front
may arrive on Tuesday, bringing an increase in thunderstorm
activity. Otherwise, conditions should remain below Small Craft
Advisory conditions.

Rip Currents: On Thursday, the combination of astronomical
influences from the Full Moon and a small swell will lead to an
enhanced risk of rip currents at all of our beaches. The in-house
Rip Current Calculator continues to indicate a Moderate Risk, while
the Rip Current MOS points to a Low Risk. For consistency, we
maintained the Moderate Risk. Rip currents are most likely at Tybee
Island.

&&

.TIDES/COASTAL FLOODING...
Tidal departures have come down near 0.8 ft MLLW in Charleston
Harbor. These departures might rise a bit due to southeast
winds around 10-12 mph with the sea breeze. But comparing the
past several high tides with the departures at the preceding
low tide (they were almost the same), this would suggest that we
don`t reach levels where minor coastal flooding begins. So no
Coastal Flood Advisory is planned.

Minor flooding is briefly possible with the evening high tides
through Thursday along coastal Charleston and coastal Colleton
Counties. There are no concerns along the remainder of our
coast.

&&

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

&&

$$

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