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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KCHS 212000
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
400 PM EDT Sat May 21 2022

.SYNOPSIS...
-- Changed Discussion --
Warm and somewhat humid conditions will persist through the
next several days. Along with a few weak weather systems moving
through the region, will lead to periodic showers and
thunderstorms through late next week.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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This Evening and Tonight: High pressure will prevail across the
western Atlantic with a mid-upper lvl ridge axis nudging further
offshore as pockets of mid-lvl energy traverse across the Southeast
United States. Deep moisture advecting across the region within a
south-southwest sfc flow will continue to favor scattered to
potentially numerous showers and thunderstorms into early evening
hours, a few of which could be strong and/or marginally severe
within an environment displaying MLCAPE up to 2500-3000 J/kg and
DCAPE around 800-900 J/kg, especially if thunderstorms are able to
interact with outflow boundaries and/or the inland moving sea breeze
circulation. Greatest chances of thunderstorms should occur along
and west of the I-95 corridor with isolated instances of damaging
winds and hail being the primary concerns, but some areas could see
brief heavy rainfall due to slower moving thunderstorms. The SPC
currently marks the entire area in a Marginal Risk of severe
weather.

Shower and thunderstorm activity could linger for a few hours after
sunset this evening with ample moisture, mid-lvl energy aloft, and
remnant boundaries in place. However, diurnal heat loss will
eventually take over, resulting in convection weakening/diminishing
by midnight. The rest of the night should remain dry with light/calm
winds in place. Temps will remain mild, only dipping into the upper
60s inland to lower 70s near the coast.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
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Pattern Synopsis/Forecast: Larger scale troughing will remain in
place across the northern/central Plains into the Great Lakes
through this period, while larger scale ridging, and a warm and
fairly moist/unstable airmass holds across the SE states into the
Atlantic. A weakening surface cold front will slowly press into the
inland Carolinas and Georgia heading into Monday before stalling
across the region. Larger scale forcing for ascent will be notably
absent through the balance of the weekend. Thus daily convective
trends will continue to be modulated by mesoscale features,
convective outflows or small scale mcv`s interacting with the sea
breeze, with the usual tendency for higher pops during the day,
waning at night.

Slightly better larger scale forcing for ascent might arrive on
Monday with some hint of a wave riding along the stalled boundary,
potentially bringing some increased rain chances and needed higher
QPF totals. But the upshot, periodic chances for showers and some
thunderstorms will persist, largely tied to the diurnal heating
cycle. Overall severe weather potential will remain on the lower
side owing to weaker wind profiles. That said, a few brief pulse
storms could produce an isolated wind/hail threat, and slow moving
convection could lead to localized heavy rainfall.

Otherwise, temperatures will continue to run at or a little above
normal through Monday, perhaps cooling down slightly Tuesday with
the boundary, for at least parts of the forecast area.
-- End Changed Discussion --

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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Upper level ridging, warm and somewhat humid conditions remain in
place across the SE states through the midweek timeframe, along with
periodic chances for showers storms. Meanwhile, a bit deeper and
progressive upper level trough is expected to swing through the
Mississippi River Valley and across the eastern CONUS, driving a
stronger cold front through the region for the end of the work week.
This may bring a bit higher rainfall chances and a bit more
widespread rainfall amounts to the region during that time. Still a
ways out yet with the usual timing uncertainties, and thus plan to
maintain our higher chance forecasts for now. High pressure and
modestly drier air is looking to build into the region for the start
of next weekend.
-- End Changed Discussion --

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
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Showers and thunderstorms are expected to develop across the area,
likely impacting all terminals for a few hours this evening. At this
time, latest trends suggest a few showers to impact CHS and JZI
terminals late evening while thunderstorms occur at the SAV terminal
late afternoon into early evening. Tempo MVFR conditions are
possible during showers/thunderstorms, before activity shifts inland
and/or weakens this evening. VFR conditions should then prevail at
all terminals tonight and through Sunday morning.

Extended Aviation Outlook: Periodic restrictions remain possible at
the terminals through the upcoming week, as a weak cold front stalls
over the area bringing a higher than normal chance for showers and
some thunderstorms, especially each afternoon and evening. Could
also see a bit better chance for at least MVFR ceilings Monday night
into Wednesday, especially at KCHS and KJZI which are more likely to
be on the north side of the front. Another stronger cold front will
swing into the region Thursday into Friday, maintaining the risk for
periodic flight restrictions.
-- End Changed Discussion --

&&

.MARINE...
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This Evening and Tonight: Showers and thunderstorms will impact
portions of the coastal waters this evening, mainly off the Georgia
coast, a few of which could be strong with winds in excess of 34 kt.
Outside thunderstorms, south/southwest winds will prevail across
local waters through tonight. Wind speeds will remain highest along
the land/sea interface this evening, generally up to 15-20 kt. A few
isolated gusts to 25 kt winds are possible, mainly near the
Charleston Harbor. However, the duration of higher gusts should fall
short of the need for a Small Craft Advisory. Expect winds to weaken
and slowly veer to south-southwest later tonight, generally remaining
at or below 15 kt. Seas are expected to remain in the 2-4 ft range.

Sunday through Thursday: Atlantic high pressure will prevail across
the southern SC/northern GA Atlantic nearshore waters into early
next week before a cold front likely pushes into the area Monday
night and lingers into Wednesday. This will lead to varying wind
directions depending on the timing and location of the front,
although overall winds and seas will remain below Small Craft
Advisory.

A bit stronger southeasterly winds may develop through the coastal
waters for the mid to late week period as a strong cold front
approaches from the west. However, at this juncture, winds and seas
will remain below headline criteria.
-- End Changed Discussion --

&&

.CLIMATE...
May 21 Record High Min Temperatures:
KCHS: 74/last set in 2001
KCXM: 78/1998
KSAV: 74/last set in 2017

&&

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

&&

$$

NEAR TERM...DPB
SHORT TERM...TBA
LONG TERM...TBA
AVIATION...DPB/TBA
MARINE...DPB/TBA
CLIMATE...