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420
FXUS62 KCHS 131544
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1144 AM EDT Thu Jun 13 2024

.SYNOPSIS...
A stationary front will meander near or just off the coast
through the end of the week. A weak cold front will drop into
the forecast area early this weekend before high pressure
spreads in from the north.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Lingering outflow boundary draped along the coast late this
morning continues to spawn showers where it intersects the
greatest low level moisture content mainly along the SC Low
Country coast. Ample cloud coverage in this area has limited
instability so far this morning, but some convective elements
could begin to develop over the next several hours, and a few
storms are possible in this area by early afternoon. Outflow
from these showers and ample sunshine/heating inland will work
to generate a hybrid outflow boundary/sea breeze front that will
race inland through the afternoon.

As the sea breeze advances inland this afternoon, sfc conditions
should feature temperatures in the mid to upper 80s with dewpoints
peaking in the mid 70s in some locations. SBCAPE values are forecast
to exceed 1500 J/kg, primarily along and east of the I-95 corridor.
Recent runs of the HRRR and HREF indicate that isolated to scattered
thunderstorms will develop in this environment. Shear should remain
weak, convective activity should be limited to pulse-like
thunderstorms.

Tonight, the sfc low over the western Atlantic is expected to
accelerate to the NE. As the low departs, dry high pressure will be
drawn east across the forecast area. PoPs will end over land this
evening, then decreasing across the marine zones through tonight.
Low temperatures are forecast to range from the upper 60s across the
inland counties and low 70s along the coast.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Friday: An upper trough, largely limited to the Mid-Atlantic,
will push a cold front toward the area from the northwest
Friday/Friday night. Drier high pressure inland will keep showers
and thunderstorms largely limited to the coastal waters in
proximity to a weak surface low. Mostly sunny skies are
forecast with dew points mixing out into the low to mid 60s away
from the coast. Highs will reach the low/mid 90s with lows in
the lower/middle 70s.

Saturday: As the weakening cold front pushes across the area
Saturday, the coastal low will quickly push out into the
Atlantic. Weak flow aloft will become replaced by a building
ridge from the southwest. As a result, Saturday features rain-
free conditions with mostly clear skies as subsidence over the
area strengthens. A rogue shower or storm could occur with the
FROPA, but for now we have POPs 15% or less across the area. An
increase in temperatures will occur due to compressional
heating. Highs will likely reach the upper 90s most places,
while some places could top out at 100 degrees. The beaches will
remain a bit "cooler", peaking near 90 degrees. Strong
subsidence will allow surface dew points to mix out into the
low/mid 60s for areas away from the coast heading into peak
diurnal heating. Therefore, heat indices should stay shy of Heat
Advisory criteria; ranging between 100-104 degrees.

Sunday: A deep layered ridge will center nearly overhead as surface
high pressure sets up across the Northeast. Return flow helping to
wrap the deeper Gulf moisture around the backside of the high could
provide enough moisture/instability to support isolated to scattered
showers and thunderstorms, mainly during the afternoon and evening
hours when the sea breeze is active. However, a strong subsidence
cap around H6 should limit deep convection/thunderstorm
chances. Highs are expected to reach the low to mid 90s away
from the immediate coast.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Anticyclonic flow aloft, mainly across the Southeastern U.S.,
will prevail through early next week. Surface high pressure
located along the New England coast will advect modestly dry air
into the area despite the onshore flow, although some Atlantic
moisture could move in far south into Southeast Georgia. The
forecast features isolated showers in the afternoon/evening each
day through early next week. Thunderstorms chances look slim at
this juncture with little instability to work with and little
to no forcing with a fairly strong capping inversion in place.
Convection chances could increase if additional moisture
advection occurs, which for this time of year, is pretty easy to
have happen. Temperatures should sit around normal or slightly
above normal due to increased insolation.

&&

.AVIATION /16Z THURSDAY THROUGH MONDAY/...
12Z TAFs: An area of low pressure will develop well off the GA
and SC coast through the TAF period. Circulation around the low
will provide the terminals with steady NE winds through this
morning. Prior to the 12Z TAF, KCLX detected a boundary just
offshore, drifting to the west. This feature should push
onshore and could transition to a sea breeze feature. This
feature should advance quickly inland across KCHS/KJZI/KSAV by
late this morning, yielding ENE winds gusting near 20 kts.
Instability will increase across the coastal counties in the
wake of the sea breeze. Isolated to scattered showers and
thunderstorms may develop near the terminals this afternoon.
KCHS and KJZI TAFs will feature a TEMPO for TSRA from 17-21Z.
KSAV will feature a mention of VCSH this afternoon. Winds will
settle to 5 to 10 kts by 0Z.

Extended Aviation Outlook: Mostly VFR conditions expected through
Saturday. Flight restriction chances return Sunday with greater
coverage of showers/thunderstorms, followed by brief flight
restriction possibilities early next week within afternoon
showers/thunderstorms.

&&

.MARINE...
Today, the coastal waters of SE GA/SC will be positioned between a
developing area of low pressure over the Gulf Stream and weak ridge
across the Carolinas. This pattern should result in a tightening
pressure gradient today, especially after the sea breeze develops
early this afternoon. ENE winds are forecast to range from 10-15 kts
with gusts exceeding 20 kts. Some locations across the coastal
waters may approach Small Craft Advisory criteria winds this
afternoon. Seas should build through the day, reaching 3-5 ft this
afternoon.

Tonight, the low should accelerate to the northeast, gradually
relaxing the pressure gradient across the nearshore waters. By late
tonight, winds are expected to favor a northeast direction, speeds
decreasing to 10 to 15 kts. Seas should decrease to 2-4 ft late
tonight.

Rip Currents: Gusty east-northeast winds will remain along the
beaches today. The winds should result in a moderate to strong
longshore current. In addition, breaker heights may exceed 2 ft,
especially along the SC coast, at 7 second periods. There is some
potential that wind gusts could approach 25 mph, especially if the
area of low pressure over the Gulf Stream deepens faster than
anticipated. Given the combination of stronger longshore current,
gusty winds, and larger breakers, and recent rip current activity;
the rip risk will be moderate today.

Friday through Tuesday: A weak area of low pressure will reside off
the Carolina coast Friday. Broad high pressure inland will result in
winds initially out of the north/northeast. But with the low quickly
departing into the Atlantic Friday night, winds will briefly veer
out of the southwest Saturday with speeds dropping to 5-10 kt.
Easterly winds will return Sunday as high pressure builds in from
the north. Wind speeds will average 10-15 kt with seas 2 to 4 feet
through early next week.

&&

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

&&

$$

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