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558
FXUS62 KCHS 161944
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
344 PM EDT Thu May 16 2024

.SYNOPSIS...
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High pressure will persist into Friday. A storm system will
affect the area this weekend, followed by high pressure from
the north next week.
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&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Afternoon visible satellite detected a field of shallow cumulus
across the forecast area. Interestingly, there was a corridor of
cloud-free sky across Berkeley County, downstream of Lake Moultrie.
These clouds should dissipate around sunset, leaving thin cirrus-
level clouds this evening. Overnight, the axis of a H5 ridge will
ripple over the forecast area. To the west, a number of MCSs are
expected to advance east from the Southern Plains across the lower
Mississippi River Valley. Debris clouds sourced from the convection
should stream across the Deep South, generally remaining just west
of the forecast area before daybreak Friday. Given weak sfc high
pressure across the Southeast U.S., winds across the forecast should
become light to calm late tonight. The combination of increasing
cloud cover and little to no wind should allow temperatures to fall
into the mid to upper 60s tonight, coastal areas may remain in the
70s.
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&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
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A potent shortwave will spread extensive mid and high clouds
over the area on Friday. Nevertheless, warm thicknesses should
support high temps pushing into the mid/upper 80s. Some drier
air is expected to mix down across inland areas with surface
dewpoints dropping into the lower 60s Friday afternoon. Much of
the guidance including synoptic scale models and CAMs show a
decaying MCS moving into our far western zones late Friday
afternoon. The best instability is forecast to remain just south
of the forecast area Friday afternoon/evening.

A warm front will lift north through the area Friday night, with
scattered showers and isolated thunderstorms possible through
the night. Saturday an increasing SW flow will bring >1.7"
PWATs into the area ahead of a longwave upper trough. There are
some hints that after warm frontal precipitation lifts north of
the area by mid Saturday morning, much of the day could be
relatively rain-free. A series of shortwaves will then move
through late Saturday afternoon through Saturday night, bringing
numerous to widespread showers and thunderstorms. The greatest
chance for severe thunderstorms will be Saturday afternoon
during which the strongest instability will be present. Most
guidance shows at least 1500 J/kg SBCAPE across the area and 50
kt bulk shear. This would support some storm organization with a
damaging wind threat. Forecast LIs <-7C would also support
large hail.

Plenty of moisture is expected to remain over the area through
Sunday as a cold front drops in from the NW, then the upper
trough axis swings through. Showers and thunderstorms are
likely to persist through the day. Isolated severe thunderstorms
could be possible due to decent instability ahead of the front.
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&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
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Isolated showers and thunderstorms will be possible through
Monday due to moisture and forcing on the western periphery of
the developing surface low off the NC/SC coast. Temperatures
will be considerably cooler due to cold advection as high
pressure builds from the north. The cooler weather will be
short-lived as the surface high shifts southeast and a southerly
flow redevelops. A few showers will be possible Wednesday as a
shortwave moves through.
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&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
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VFR conditions are expected to prevail at CHS/JZI/SAV terminals
through 18Z Friday.

Extended Aviation Outlook: Showers and thunderstorms could bring
flight restrictions to all terminals Saturday through Sunday
as a low pressure system impacts the region.
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&&

.MARINE...
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No marine concerns tonight. South winds are forecast to range
between 5 to 10 kts across the forecast area tonight. Wave heights
should favor values between 1-2 ft.

Friday through Tuesday: Conditions through the period are
expected to remain below Small Craft Advisory criteria.
Southerly flow will persist through Sunday, then the winds turn
northerly behind a cold front early next week. Wind gusts could
approach 25 kt late Sunday night into Monday morning with an
initial burst of cold advection, mainly over the Charleston
County nearshore waters.
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&&

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

&&

$$

NEAR TERM...NED
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...JRL/NED
MARINE...JRL/NED