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155
FXUS62 KCHS 040158
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
958 PM EDT Mon Jun 3 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 TUESDAY MORNING/...
-- Changed Discussion --
Late this evening, KCLX has detected isolated showers and
thunderstorms across portions of Jenkins and Screven Counties.
The convection has been focused along an old outflow boundary.
Based on recent runs of the HRRR, the lingering convection may
dissipate before midnight. Otherwise, conditions across the CWA should
feature light winds with a partly cloudy sky. Minimum
temperatures tonight are forecast to range from the upper 60s
inland to the low 70s along the coast.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM TUESDAY 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 /02Z TUESDAY THROUGH SATURDAY/...
VFR conditions expected at KCHS, KJZI, and KSAV through mid-day
Tuesday. Sea breeze thunderstorms are possible near KCHS between
19-21Z Tuesday. The KCHS TAF will feature a PROB30 for -TSRA
along with gusty winds and MVFR visibility. Otherwise, showers
and thunderstorms should develop too far inland of KJZI and KSAV
to mention in the TAFs.

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

&&

.MARINE...
This evening and 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...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...