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819
FXUS62 KCHS 280736
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
336 AM EDT Tue May 28 2024

.SYNOPSIS...
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A cold front will stall near the coast today. High pressure will
return for the second half of the week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Through Daybreak: Warm/moist conditions remain in place early
this morning. Regional radars show isolated showers/tstms
developing over Southeast South Carolina and Southeast Georgia
within the pre-frontal warm sector. This activity is developing
within an enhanced 850 hPa theta-e ridge axis that stretches
from Dublin and Metter, GA east to the Charleston Metro Area.
Despite the onset of nocturnal cooling, RAP soundings show quite
a bit of elevated CAPE (1500-2000 J/kg) in place above the
shallow noctural inversion. If isolated convection can begin to
tap into this instability, then a greater uptick in showers/tstms
could occur over the next few hours. This is implied by both
the H3R and RAP which shows additional convection developing
through daybreak and gradually shifting east to the lower South
Carolina coast. With meaningful DCAPE still in place and
freezing levels below 14 kft, there is still a risk for an
isolated strong to severe tstm. This is certainly something
that will have to be watched over the next few hours.

Today: The cold front will push through area in two pieces this
morning. The first will comprise of a wind shift co-located
with a sharp 850 hPa theta-e and mixed-layer instability
gradient which will push offshore after daybreak. The second
will be delineated with a wind shift to the west/northwest and
the arrival of lower dewpoints. The second piece of the front
looks to hang up near the coast which will become intermingled
with what appears to be a weak sea breeze circulation pinned to
the coast later this afternoon. There may just enough convergence
and lingering moisture near/behind the sea breeze itself to
support isolated showers/tstms for a few hours this afternoon,
mainly in the upper parts of Charleston County and far eastern
Berkeley County where near term guidance shows a small pocket
of marginal 850 hPa theta-e, K-indices rising 30-35C and
dewpoints pooling back into the lower 70s. Slight chance were
highlighted in this area mid-late afternoon. Elsewhere
conditions will become increasingly unfavorable for deep
convection as considerably drier air advects in from the west
and northwest. Even though low-level thicknesses drop a bit
behind the front, a modest downslope flow developing downwind of
the Southern Appalachians will tend to counteract and cooling
influences. Highs look to peak in the lower 90s almost all the
way to the beaches, but lower dewpoints will make it feel a bit
less sticky and humid compared to the past few days.

Tonight: High pressure will build in from the west overnight as
a stalled front begins to push farther offshore. The gradient
between these two features will likely keep a bit of wind going
through the night, but clear skies and low dewpoints will
promote at least some degree of modest radiational cooling.
Lows will range from the lower 60s well inland to the lower 70s
at the beaches. A northwest wind across Lake Moultrie will
likely keep areas immediately downwind of the lake (i.e. Bonneau
and Moncks Corner) a bit warmer given water temperatures are in
the upper 70s/lower 80s.
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&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
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Surface trough develops over the region on Wednesday, before
high pressure builds Wednesday night and pushes a secondary
front offshore. High pressure remains the dominant surface
feature through late week. Aloft, broad troughing persists over
the eastern U.S., until a shortwave dives across the mid-
Atlantic and eventually shifts offshore. Not much in the way of
forcing or moisture for convection, so rain chances remain
pretty low through the period. Highs near 90 on Wednesday return
to the mid 80s for Thursday and Friday. Lows span the 60s.
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&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
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Surface high pressure initially centered over the mid-Atlantic
will transition offshore and persist into early next week.
Aloft, ridging will shift across the Southeast on Saturday
before a series of weak disturbances possibly pass through. No
stand-out day for precip at this point, with rain chances just
in the 20-30% range. Temperatures will be within a few degrees
of climo through the period.
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&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
28/06z TAF Discussion:
KCHS/KJZI/KSAV: VFR through 29/06z. There is a risk for some
isolated tstms forming near KCHS and KJZI as daybreak
approaches. May need to include VCTS overnight as confidence
increases in this activity passing by both terminals.

Extended Aviation Outlook: VFR.

&&

.MARINE...
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Through Tonight: Winds will back more southerly this afternoon
as a cold front stalls near the coast and a weak sea breeze
develops near the beaches. Winds will remain less than 15 kt
with seas 2-3 ft. Winds will finally turn west and eventually
northwest tonight as the front finally begins to push farther
offshore. Again, speeds will remain less than 15 kt with seas
2-3 ft.

Wednesday through Sunday: No marine concerns anticipated midweek
through the weekend. Secondary front passes through Wednesday
night with high pressure the main feature for Thursday and
beyond. Wind speeds average less than 15 knots. Seas 1-2 feet
initially build to 2-4 feet over the weekend.
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&&

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

&&

$$