181
FXUS62 KCHS 140229
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1029 PM EDT Sat Jul 13 2024

.SYNOPSIS...
Atlantic high pressure will rebuild across the area while a
surface trough exists inland Sunday through the middle of next
week.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Dry conditions continue late this evening with gradual cooling
as debris clouds linger over much of the area. Weak gradient
will result in fair radiational cooling once debris clouds
dissipate late, but dew points in the 70s will bring another
muggy night. In general, lows will range in the mid 70s well
inland to upper 70s closer to the coast and lower 80s at the
beaches. Temps unlikely to cool enough to bring significant fog
threat, but some very shallow patchy fog is possible mainly away
from the coast.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
The region will remain on the west side of a deep layer ridge,
centered well to the east-southeast over the Atlantic. This will
keep southerly low level flow, which will become onshore each
afternoon near the coast. Given the lack of any significant upper
level features, expect any afternoon/evening convection to be
initiated by the seabreeze, differential heating and/or convective
outflow boundaries. Model guidance has been trending a bit too high
with PoPs, especially in this pattern. So, have kept chance/high end
chance PoPs for afternoon into early evening. Light steering flow
and PWs around 2 inches will once again lead to the potential for
locally heavy rainfall, especially where multiple boundaries
collide.

Guidance temperatures also seem a bit high, but very difficult to go
too low given the deep ridge centered just to the southeast. Have
kept low to mid 90s. Amount of convective coverage will dictate high
temperature values. Lows will also continue to be very warm, in the
mid 70s to around 80, warmest near the coast. Max heat indices
through this period showing 105 to 109, which if they verify, would
be marginal Heat Advisory levels, especially along and east of I-95.
For the past several days, afternoon convection has made it
difficult to predict whether max Heat Indices will reach criterion
levels. Thus, stay tuned for the potential for Heat Advisories to be
issued during this period.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Models indicate that a broad upper level trough will develop over
the Great Lakes and TN River Valley, and sag southward through this
period. Further east, the deep layer Atlantic ridge should retreat
east-southeastward. With decreasing upper heights gradually working
into the region from the northwest, helping to pool deep layer
moisture/PWs of 2-2.5 inches, expect an increase in PoPs through the
period. However, still concerned that guidance/blended PoPs continue
to be a bit high, especially for this far out in the forecast
period. Have generally gone high end chance to very low end likely
PoPs, which is above climo for this time of year. Low level flow
should veer to south-southwest, which will likely help to keep the
afternoon seabreeze from moving as far inland as earlier in the
week. High temperatures slightly above normal, and could fall back
toward normal or even slightly below by late in the week, deepening
on amount of clouds/convection that develop. Given the very humid
low levels, still not much relief with the low temperatures, which
are expected to remain in the mid to upper 70s most areas.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Bermuda high pressure ridges over the area, keeping warm and
humid conditions in place, with VFR prevailing through the TAF
period. Limited cooling will limit the fog threat tonight, with
any fog expected to remain inland of the terminals. Scattered
showers and storms Sunday afternoon bring the next threat for at
least brief flight restrictions to the terminals.

Extended Aviation Outlook:
Sunday night through Tuesday: More typical scattered afternoon
and early evening showers and thunderstorms could produce brief
flight restrictions, especially given storms will likely be slow
moving with the potential for locally heavy rainfall.

Wednesday and Thursday: Increasing chances precipitation, with
scattered to numerous afternoon showers/thunderstorms as an upper
trough of low pressure starts to advance toward the region from the
northwest.

&&

.MARINE...
Tonight: Light to moderate SW flow prevails with Bermuda High
ridging in from the west. Seas remain mostly 3-4 ft as medium
period SE swell very slowly fades.

Sunday through Tuesday Night: A deep layer Atlantic ridge will
remain centered well east-southeast of the waters. This will
maintain southerly flow at 15 knots or less and seas generally 2 to
4 feet. Winds could be locally stronger in the afternoon near the
coast with the seabreeze. Mostly late night through morning
scattered showers and thunderstorms.

Wednesday and Thursday: An upper level trough of low pressure starts
to advance toward the area from the northwest. As the Atlantic ridge
slowly retreats eastward, the pressure gradient could increase
during this period, with southwest winds 10-20 knots and seas 3 to 5
feet, highest beyond 20 nm. However, still not expecting conditions
to reach SCA levels. Mostly late night through early afternoon
scattered to numerous showers and thunderstorms.

Rip Currents: A Moderate Risk for rip currents is in place for the
Charleston County beaches until 8 PM this evening where winds will
remain slightly stronger compared to the rest of the coast from
Edisto Beach south. 2-3 ft swells with periods of 7-8 seconds will
persist.

&&

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

&&

$$

NEAR TERM...CEB/DPB
SHORT TERM...RFM
LONG TERM...
AVIATION...CEB/RFM
MARINE...CEB/DPB/RFM