399
FXUS62 KCHS 040524
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
124 AM EDT Tue Jun 4 2024

.SYNOPSIS...
High pressure will extend across the area through Wednesday. A
cold front will approach from the northwest on Thursday, then
slowly move through on Friday. High pressure returns for the
weekend.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Early this morning: No change to the forecast through sunrise.
Late evening convection that was impacting Jenkins County has
since dissipated and retreated inland, leaving the forecast area
dry. We should remain dry through the overnight as well. There
are no significant fog concerns and lows are forecast to mostly
fall into the upper 60s away from the coast. There could be a
few mid 60s in the typical cool spots, also the immediate coast
will only see temperatures in the low 70s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
Tuesday will bring an abrupt changed from upper subsidence to
broad lift as a potent shortwave is forecast to move in from the
west later in the afternoon. Surface ridge axis oriented along
the Savannah River area will discourage convection locally
through early afternoon, but a few showers and storms developing
over the Midlands could work toward the SC I-95 corridor by mid
afternoon, with the progression of the sea breeze and
additional boundary collisions prompting continued convective
initiation inland through the later afternoon and into the early
evening.

PWATs above 1.8" and moderate instability should be in place
during the afternoon, and some localized downpours and gusty
winds are possible under the strongest storms inland, but the
overall severe and heavy rainfall threat is very low.

Wednesday has trended a bit more active as mid-level height
falls increase later in the day with weaker surface
ridging/greater deep moisture content relative to Tuesday.
Southerly prevailing flow should allow for a more progressive
sea breeze in the afternoon. Widespread convection now looking
likely in the afternoon inland, with activity more
uncertain/scattered near the coast, depending on the progression
of the sea breeze. Model DCAPE values exceed 1000 J/kg over
inland areas so we could see some gusty winds in some storms,
with PWAT values near 1.8 in bringing the potential for some
localized downpours, though storm motions on the order of 10-15
kt should limit any flooding threat.

Thursday could be the most active day of the week, with the
upper pattern transitioning to troughing, and a shortwave
crossing the area during the day as ample low level moisture
remains in place ahead of an approaching cold front. While the
overall severe and heavy rainfall threat will be largely
dependent on the timing of the upper shortwave (too early in the
day will result in convective suppression during peak heating),
Thursday justifies continued monitoring with at least a
conditional heavy rainfall and severe thunderstorm threat.
Additionally, highs in the lower to mid 90s and dew point values
in the upper 60s to lower 70s will bring heat index values to
near 100F, one of the warmest days of the season so far.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A cold front drops through the area on Friday, however
convective coverage is uncertain since mid-level subsidence
seems likely given the quasi-zonal flow. Compressional heating
looks to push highs into the low to mid 90s.

A noticeable airmass change is expected this weekend as high
pressure builds from the northwest. Downslope flow should still
keep highs above 90 in most spots, but dewpoints should mix down
into the upper 50s to lower 60s.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
VFR conditions are expected to prevail at KCHS, KJZI, and KSAV
through 06z Wednesday. The best chance for afternoon and evening
showers and thunderstorms looks like it will be near KSAV.
However, we still expect that most activity will remain well
inland of the terminal and for now have opted to not include any
mention of convection.

Extended Aviation Outlook: Outside of any convection,
conditions will be VFR through the period.

&&

.MARINE...
Tonight: The coastal waters will be situated under the western
side of the Bermuda-Azores High, leading to a S or SSE flow,
that turns more SW over the Charleston County waters late. Sea
breeze influences will allow for some gusts near 20 kt at times
in Charleston Harbor early on, otherwise winds will be 15 or
less throughout. Seas will be just 2 or 3 feet.

Tuesday through Saturday: High pressure will remain over the
western Atlantic Tuesday through Thursday night, maintaining
southerly flow at or below 15 kt, seas at or below 4 ft, and a
daily sea breeze circulation along the coast. A cold front will
move through on Friday, briefly shifting winds to the NW before
they turn back E by Saturday.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides are on the rise this week. Although wind
direction is not particularly favorable for surge, we continue
to see a positive tidal anomaly of 0.5 to 0.7 ft. The evening
high tides Tuesday through Thursday could reach at least 7.0 ft
MLLW in Charleston, necessitating Coastal Flood Advisories.

&&

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

&&

$$

NEAR TERM...BSH
SHORT TERM...
LONG TERM...
AVIATION...BSH
MARINE...