069
FXUS62 KCHS 041639
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1239 PM EDT Sat May 4 2024

.SYNOPSIS...
Atlantic high pressure will remain across the Southeast U.S.
through much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Midday update: Inland band of convection has weakened as
anticipated with "heating of the day" convection becoming more
prevalent across much of the CWA...particularly through the
South Carolina counties. That trend will continue through the
afternoon with convection tending to become more concentrated
across the inland areas of the forecast area. Just some cosmetic
tweaks were made to precip chances based on trends.

Previous discussion...
Convoluted pattern across the region this morning with a short-
wave circulation moving northeastward into north-central
Georgia and weak low-mid level troughing aligned through eastern
Georgia into upstate South Carolina. Forcing with the wave
aligned with lower level convergence has/is producing a solid
narrow corridor of slow moving showers and thunderstorms in
eastern Georgia into the Midlands...just edging into the far
western part of the CWA. Convection does appear to be weakening
as we transition into the daytime heating cycle.

Meanwhile, showers (no lightning thus far) are expanding off
the Atlantic into the South Carolina counties readily this
morning, particularly the tri-county area. No surprise given
the morning CHS sounding showing a moist low level air mass and
nearly 500 J/Kg MLCAPE already in place, with minimal CINH.

Short-wave trough will slowly pass through the region through
the afternoon. Aforementioned corridor of showers/thunder just
upstream will probably thin out to some degree over the next few
hours. However, heating will generate 750-1000 J/Kg MLCAPE this
afternoon and possibly a bit better along the inland advancing
sea breeze...and minimal CINH. Additional showers and some
thunderstorms are likely as we go through the afternoon with
higher pops trending inland with the sea breeze push. Severe
storms are unlikely. But given weak wind profiles and resultant
slow moving convection, we will need to keep an eye on rainfall
rates and amounts.

Thunderstorm activity should gradually decrease this evening as the
sea breeze pushes inland and temperatures begin to cool around
sunset. The sfc pattern is expected to support light SSE winds
through tonight. The light SSE winds combined with mostly cloudy sky
conditions should keep temperatures in the upper 60s along the coast
with mid 60s inland. The mid-level trough is forecast to swing east
over the CWA late tonight. Guidance indicates that a band of moisture
convergence will develop from the Gulf Stream northwest across the
South Santee basin late tonight. Scattered showers and isolated
thunderstorms will be featured in the forecast for late tonight over
the SC waters and portions of Charleston and Berkeley Counties late
tonight.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
A mid-level ridge will sit off the Southeast coast as passing waves
of shortwave energy ripple across the region through the short term
forecast period. High pressure will remain the primary feature at
the surface. Convection will be a bit active Sunday and Monday with
the presence of a weak shortwave aloft and deeper moisture - noted
by PWATs around 1.5-1.7 inches. Coverage of showers/thunderstorms
will be highest in the daytime when instability is maximized, but
activity could linger into the late evening with some upper forcing
present. The greatest POPs are focused in southeast South Carolina
and away from the immediate coast each day owing to the
juxtaposition of upper forcing and the inland moving sea breeze.
Chances for showers/thunderstorms will be slightly less Tuesday as
the deeper moisture and remnant shortwave energy moves off the Mid
Atlantic coast.

High temperatures will generally peak in the low to mid 80s Sunday,
warming into the mid 80s Monday, then into the upper 80s Tuesday.
Min temperatures both Sunday and Monday are only expected to drop to
the mid/upper 60s, with locations along the beaches and Downtown
Charleston in the lower 70s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Atlantic high pressure will persist through the majority of next
week before a cold front approaches late next week. Rainfall chances
are little to none as a ridge rebuilds overhead. This will cause
temperatures to rise into the low/mid 90s through the remainder of
next week, approaching record levels Wednesday and again
Thursday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Showers will be moving through the terminals over the next few
hours. A few thunderstorms are possible, although most of the
thunderstorm activity should remain a bit more inland.
Otherwise, VFR conditions will be the rule this afternoon and
tonight. A touch of fog is possible later tonight through
sunrise Sunday, although fog probabilities are too low to
include in the forecasts at this juncture.

Extended Aviation Outlook: Brief flight restrictions are possible
within isolated to scattered showers/thunderstorms through
Tuesday.

&&

.MARINE...
The surface pattern will yield south-southeast winds between 5-10
kts today and tonight. Wave heights are forecast to favor values
around 2 ft, with 3 ft seas possible beyond 40 nm late tonight.

Sunday through Thursday: Atlantic high pressure will maintain
relatively benign conditions over the local marine waters. Southerly
winds in the morning will back slightly during the afternoon and
evening hours nearly each day as the sea breeze develops. Winds will
average 10-15 kt with seas 2-4 ft.

&&

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

&&

$$

NEAR TERM...Adam/NED
SHORT TERM...BRM
LONG TERM...BRM
AVIATION...Adam/BRM/NED
MARINE...BRM/NED