689
FXUS62 KCHS 031827
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
227 PM EDT Wed Jul 3 2024

.SYNOPSIS...
A weak front will linger near the area tonight. Through the
rest of the week, a hot and humid air mass will build over the
region. A weak cold front could approach the region by early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The satellite GOES Water Vapor product showed a mid-level ridge
centered over the Deep South with a plume of moisture across
SE SC/GA. The sea breeze is expected continue to drift inland
through the rest of this afternoon and evening. The 12z observed
KCHS sounding indicated poor low and mid-level lapse rates with
meager instability. However, recent runs of HRRR and RAP
indicate that a field of weak instability will remain across the
stationary front across SE GA this afternoon. The combination
of weak moisture convergence within the trough/stationary front
and development of the sea breeze should trigger isolated
showers and thunderstorms across SE GA this afternoon. Early
this afternoon KCLX detected some initial showers over extreme
SE GA. These showers and possible thunderstorms should gradually
drift to the South by this afternoon. Given the timing of the
sea breeze, high temperatures are forecast to range from the low
90s inland to the mid to upper 80s along the coast.

Tonight: Overall, a quiet night is expected as see little to no
overnight convection. The boundary we have been dealing with
for the last few days will no longer be present and we carry a
dry forecast for the forecast area. Look for lows in the low to
mid 70s.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
A mid level ridge will extend across the region late week into
the weekend. A closed low over the Atlantic will drift westward
towards the Southeast coast late. The surface pattern will
largely feature high pressure offshore and trough of low
pressure inland. A weak front will approach the region on
Saturday but will stay well west of the local area.

The weather should be fairly quiet for Independence Day and
Friday with influence of the ridge helping to limit convection.
Just isolated showers and thunderstorms are forecast. Saturday
should be a bit more convectively active, especially inland,
with better instability and possibly some weak upper support.
There could be development with the sea breeze, but it appears
most will trigger off the inland trough and then move into the
local area from the west. Rain chances peaking 40-50% in these
locations seems reasonable.

Temperatures will rise with time. Highs in the low to mid 90s
Thursday will warm to the mid to upper 90s away from the
immediate coast for Friday and Saturday. It will feel even
hotter with heat indices approaching the local Heat Advisory
criteria of 108 in spots. Friday looks more marginal, with
Saturday having the better chance for excessive heat headlines.
Lows average in the mid to upper 70s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
Ridging generally prevails aloft early next week in between a
mid level trough to the west and closed low over the Atlantic
which should eventually weaken. Surface pattern maintains high
pressure offshore and troughing inland. Guidance indicates PWats
exceeding 2 inches through much of the period. At least
scattered showers and thunderstorms will be possible each day,
with highest coverage in the afternoon and evenings.
Temperatures are forecast to stay slightly above normal.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Prior to the 18z TAFs, KCLX detected isolated and scattered
showers with one, or two thunderstorms in the vicinity of KSAV.
With the passage of the seabreeze later this afternoon, a
thunderstorm could pass over KSAV between 18-20z. The potential
for this thunderstorm has been highlighted in the KSAV TAF with
TEMPO. For KCHS and KJZI, the potential for an afternoon shower
is too low to mention in the TAFs. KCHS and KJZI is expected VFR
with a steady SE wind around 10 kts till sunset. The concern
for late tonight is the potential for fog and possible low
ceiling. Forecast soundings indicate some potential for IFR
stratus between 09z and daybreak, however MOS guidance does not
indicate low ceilings. Given narrow dewpoint depressions and
light calm winds, each TAF will feature a mention of either
ground fog, or light patchy fog during the pre-dawn hours. After
sunrise, conditions will remain VFR with a light E wind. There
appears to be little to no chance of deep convection at the
terminals on Independence Day.

Extended Aviation Outlook: Brief flight restrictions are
possible in showers and thunderstorms, mainly in the afternoon
and evenings through the period.

&&

.MARINE...
Today and tonight: North-northeast flow should prevail across
the local waters through the period. Wind should be strongest
today, focused along the coast with the development of the
afternoon sea breeze. Speeds should mostly be 10-15 knots, with
gusts up to 20 knots along the coast. Overnight, speeds should
drop off to 5-10 knots late. Seas are expected to average 2-4
feet.

Thursday through Monday: Northeast/east winds initially will
turn southerly by late week. Marine conditions should stay
solidly below small craft advisory criteria with speeds 15 knots
or less and seas averaging 2-3 feet.

Rip currents: Longer period swell and the approaching new moon
will lead to an elevated risk for rip currents on Thursday.
Local calculations give borderline low-moderate risk, but given
the Independence Day holiday, opted for moderate.

&&

.TIDES/COASTAL FLOODING...
Onshore winds and the approach of the new moon will lead to
elevated tides over the next couple of days along the Charleston
and Colleton county coasts. Tides levels could approach minor
coastal flooding criteria of 7 ft MLLW in the Charleston Harbor
with the evening high tides today and Thursday. Further south,
no tide issues are expected.

&&

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

&&

$$

NEAR TERM...ACD/NED
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...NED/ACD
MARINE...BSH/ETM