995
FXUS62 KCHS 181032
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
632 AM EDT Thu Jul 18 2024

.SYNOPSIS...
High pressure will persist offshore, while a weak trough
resides inland. A cold front will approach the region Friday
and likely stall nearby, before high pressure returns next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
No major changes made with the sunrise update, forecast is on
track.

Today: The forecast area will remain between a mid-level ridge
centered over FL and a longwave trough sweeping across the Mid West.
At the sfc, a cold front is expected to be drifting east across the
central Carolinas this morning, reaching the inland counties of the
CWA late tonight. This pattern should yield southwest winds across
the region today, with gusts between 20-25 mph across the SC
Lowcountry this afternoon. Using a blend of MOS, high temperatures
are forecast to range between 90-95 degrees. As a temperatures warm,
high resolution guidance indicates that a weak sea breeze will
develop and slide inland during the mid to late afternoon. Forecast
soundings indicate that the hot temperatures combined with dewpoints
in the mid to upper 70s may result in CAPE between 2500-3000 J/kg.
At least scattered showers and thunderstorms will develop near the
sea breeze and outflow boundaries this afternoon and evening. It is
possible that one or two storms could produce damaging wind gusts,
primarily over the SC Lowcountry.

Tonight: The combination of lingering instability, approaching cold
front, and the passage of mid-level disturbance should trigger
rounds of showers and thunderstorms through much of the night. With
time, storm coverage should gradually shift east tonight. Low
temperatures are forecast to range from the low 70s inland to the
upper 70s across the coastal counties.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Aloft, broad troughing will prevail over the eastern half of the
CONUS on Friday. Then high pressure will build into the region from
the east over the weekend. At the surface, a cold front will
approach the region on Friday. The front will likely stall in the
vicinity of the Carolinas through the weekend. Deep moisture will be
present over the forecast area through the weekend, with PWATs over
2 inches. High temperatures on Friday will likely reach into the low
to mid 90s, which combined with humid conditions will yield
plentiful instability for afternoon convection. Numerous to
widespread showers and thunderstorms are forecast on Friday
afternoon. A strong to marginally severe thunderstorm is possible,
with the main hazard of damaging wind gusts. Additionally, heavy
rainfall is possible, however some steering flow aloft may help push
storms along and prevent significant training. Similar conditions
are expected through the weekend, though PoPs are slightly lower
across the region. Heat Index values will continue to reach triple
digits each day, peaking around 101-105F. However, afternoon
convection may prevent temperatures from reaching their full
potential. Overnight lows will be in the 70s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
High pressure aloft and at the surface will build into the forecast
area from the east through the middle of the week. PWATs are
forecast to remain elevated along with plentiful instability.
Scattered to numerous showers and thunderstorms will be possible
each afternoon, generally focused along boundary interactions and
the afternoon sea breeze. The current forecast maintains chance to
likely PoPs. With precipitation and increased cloud cover through
the period, temperatures are forecast to return to near normal or
even slightly below normal through the period.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
VFR conditions with SW winds around 10 kts during the morning
hours. SW winds at KCHS and KJZI are forecast to strengthen,
with gusts near 20kts during the afternoon hours. Thunderstorm
activity late this afternoon will be highlighted in each TAF
with a TEMPO from 22-2Z. High resolution guidance indicates that
a band of showers and thunderstorms may pass near KCHS and KJZI
later this evening, highlighted with a mention of VCSH.

Extended Aviation Outlook: Scattered afternoon showers/tstorms could
produce brief flight restrictions at all terminals through the
weekend and into early next week.

&&

.MARINE...
Early this morning, sfc wind observations and KCLX indicated that a
land breeze was developing 10-15 nm from shore. Winds along the land
breeze remained too strong to favor the development of waterspouts.
We will continue to monitor conditions for the waterspout potential
this morning.

Today and tonight, the sfc pattern will support SSW winds generally
between 10-15 kts with gusts in the low 20s during the afternoon.
Conditions will approach Small Craft Advisory criteria across the
Charleston County nearshore waters late this afternoon. Seas are
forecast to generally range between 3-4 ft, with some 5 ft across
beyond 15 nm from the mouth of the Santee River. A band of
thunderstorms may sweep across the SC nearshore waters this evening
into late tonight. Some of these storms may bring strong wind gusts,
Special Marine Warnings may be needed.

Friday through Monday: High pressure will prevail across the marine
zones while a cold front approaches the inland zones on Friday and
lingers in the vicinity of the Carolinas through the weekend.
Conditions are expected to remain below Small Craft Advisory
criteria through period, with southerly winds 10-15 knots
forecast. Slightly stronger wind speeds are possible along the
direct coastline in association with the afternoon sea breeze.
Seas should average 3 to 4 ft.

Rip Currents: Today: The combination of a 2 ft swell every 8-9
seconds and gusty onshore winds will support a Moderate Risk for rip
currents at all of our beaches.

&&

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

&&

$$

NEAR TERM...CPM/NED
SHORT TERM...CPM
LONG TERM...CPM
AVIATION...CPM/NED
MARINE...CPM/NED