771
FXUS62 KCHS 240535
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
135 AM EDT Fri May 24 2024

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

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Tonight: Sfc high pressure will persist across the local area
while a mid-upper ridge axis remains nearby over the western
Atlantic. The pattern will generally result in quiet/dry
conditions for much of the area during the night while a light
south/southwest wind maintains mild lows in the upper 60s inland
to low-mid 70s near the beaches. However, a light shower can
not be ruled out along/near a seabreeze pushing west across far
interior locations for the next few hours. Late tonight,
upstream convection associated with h5 shortwave energy rippling
east from the lower and middle Mississippi River Valley could
make a run towards extreme northern areas of Berkeley County a
few hours prior to daybreak. A slight chance of showers and
thunderstorms have been included to northern Berkeley to account
for latest trends upstream.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/...
Friday: Interesting setup across the forecast area by Friday
afternoon. Using a blend of MOS, high temperatures are forecast to
favor values in the low 90s across SE GA/SC. Forecast soundings
indicate by Friday afternoon, SBCAPE values along and ahead of sea
breeze will pool between 2500-3000 J/kg with little to no CIN.
Guidance indicates that a MCV, sourced from the Deep South, is
expected to pass over the forecast area Friday afternoon. The
combination of the mid-level disturbance and sea breeze should
concentrate thunderstorm coverage over the CHS Tri-county. PW values
around 1.7 inches with SRH 0-3 km around 100 m2/s2. These
thunderstorms should develop into loosely organized clusters. In
addition, DCAPE values are forecast to range between 900-1000 J/kg,
likely supporting long lasting cool pools of outflow air, serving as
areas for thunderstorm development. These thunderstorms should
produce swaths of torrential downpours, yielding pockets of 1.5 to 2
inches with a general area of .5-1 inch of rainfall. In addition,
one or two storms may produce damaging wind gusts. These hazards
will be added to the Hazardous Weather Outlook.

Saturday: The broad mid-level trough will ripple over the Atlantic
during the morning, with heights beginning to rise during the
afternoon. Surface conditions should once again feature high
temperatures in the low 90s with dewpoints in the low 70s. Model
guidance indicates that a field of CAPE of 1500-2000 J/kg with
shallow CIN should develop by the heat of the afternoon. Isolated to
scattered thunderstorms should develop along a sea breeze, but less
coverage that expected on Friday.

Sunday: GFS indicates that a broad H5 ridge will build across the
region. Conditions should become hot and humid during the
afternoon. High temperatures are expected to range in the mid 90s
with dewpoints in the low 70s along the coast. Heat index values may
exceed 100 degrees across the coastal counties, especially across SE
GA. Given poor mid-level lapse rates, convection will be limited to
a SCHC.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The H5 ridge axis will shift east on Memorial Day, with heights
slowly falling from west to east during the afternoon. Temperatures
should peak within a degree or two from values reached on Sunday.
Tuesday appears to be an active day, with the approach and passage
of a cold front. The forecast will feature solid CHC PoPs at this
time. However, if upstream MCS activity arrives over the CWA from
upstream, PoPs will need to be increased. High temperatures are
forecast to range around 90 degrees. Drier air should spread across
the forecast area on Wednesday and Thursday. High temperatures
should favor values in the upper 80s.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
VFR conditions are expected at the CHS/JZI/SAV terminals
through at at least 18Z Friday. However, showers and/or
thunderstorms could eventually impact the terminals mid-late
afternoon for a few hours and produce flight restrictions. With
increased confidence for showers/storms to impact the KCHS/KJZI
terminals, we have introduced VCTS to the forecasts from 20Z
through 01Z. Still a bit more chancy for KSAV, with VCSH in the
forecast there for now.

Extended Aviation Outlook: Brief flight restrictions are
possible due to showers/thunderstorms each afternoon/evening.

&&

.MARINE...
Tonight: The local waters will remain positioned along the western
edge of sfc high pressure centered further offshore and under a mid-
lvl ridge axis. This will lead to a fairly relaxed pressure gradient
across the area through the night with south winds up to 10-15 kt
generally veering overnight to south-southwest, then remaining
around 10 kt or less. Seas will range between 1-2 ft.

Extended Marine: The forecast area will remain between high pressure
across the western Atlantic and Gulf of Mexico and a series of low
pressure tracking over the Mid West. This pattern should result in a
sea breeze to develop each afternoon. A cold front should sweep
across the coastal waters on Tuesday. Wind and sea conditions should
remain below Small Craft Advisory conditions.

&&

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

&&

$$

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