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000
FXUS62 KCHS 081925
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
325 PM EDT Sat Aug 8 2020

.SYNOPSIS...
A stationary front will linger to the west through the weekend
before dissipating. The region will then be positioned between
Atlantic high pressure centered offshore and an inland area of
broad low pressure.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Through Sunset: Afternoon temperatures in the 90s are combining
with plenty of moisture (PWATs ~2") to fire off convection.
CAMs seem to focus it in two different areas. One area is along
the sea breeze as it moves inland. The other area is over
central GA, with the convection shifting towards our GA counties
and coast during the evening. We have this all accounted for in
the POP grids, but should note that some of the models have
trended a bit drier. Though, we kept the POPs in the chance
category. SPC Mesoscale Analysis shows MLCAPEs peaking in the
2,500-3,000 J/kg range in the next few hours. Additionally,
DCAPEs will be 1,000-1,200 J/kg. Marginally severe pulse
thunderstorms with damaging winds gusts remain a concern into
the evening. Additionally, weak steering flow aloft will equate
to very little storm movement, so locally heavy rainfall is
expected. Outflow boundaries and the sea breeze will drive the
convection into this evening.

Tonight: Very little change is anticipated in the mid-level
pattern. Meanwhile, a stationary front will linger to the west
of our area. Any remnant convection over land during the
evening hours should dissipate. The focus for convection then
shifts over the coastal waters. Though, the models differ on the
coverage. We leaned more towards the CAMs, which show minimal
coverage. This equates to slight chance POPs. Low temperatures
should range from the low to mid 70s inland and the upper 70s
at the immediate coast.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Sunday: Short term guidance indicates that the axis of a H5 trough
will ripple over the forecast area during the afternoon and evening.
At the sfc, the CWA will remain between high pressure centered over
the western Atlantic and a trough just east of the Fall Line. A sea
breeze should develop during the late morning, sliding inland during
the afternoon and evening hours. HREF indicates that showers and
thunderstorms will develop along and west of the sea breeze and
ahead of the H5 trough. Thunderstorms coverage appears the greatest
during the late afternoon into the early evening, PoPs generally
ranging between 50-70 percent. Given the broad area of llvl
convergence and PW around 2 inches, high resolution guidance
indicates that some areas could see rainfall amounts exceed 2
inches. High temperatures are forecast to range from around 90 along
the coast to the mid 90s across inland GA. Peak Heat index may favor
values around 105 degrees over the coastal counties. Convection
should generally dissipate during the late evening hours. Low
temperatures are forecast to range from the upper 70s along the
coast to the mid 70s inland.

Monday and Tuesday: The mid level trough will remain over the region
and ridging builds to the west. The sfc pattern should support the
formation of a sea breeze both days. Given a broad field of
instability and deep moisture, the environment should yield
scattered to numerous thunderstorms each afternoon. High
temperatures are forecast to range from 90 near the coast to mid 90s
inland.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Little change in the large scale pattern, with a deep layer Atlantic
ridge situated to the east and deep layer trough of low pressure
well to the west. Global models show that an upper trough may try to
sharpen well to the west during this period, as well as an increase
in deep layer moisture. With this combination, guidance continues to
show likely afternoon/early evening PoPs each day. A little
uncomfortable going with such high PoPs this far out, but blended
PoPs have been consistently high, and those PoPs collaborate well
with surrounding offices. Highs will continue near normal, around 90
to the lower 90s. Lows in the lower to mid 70s.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
18Z TAFs: Both TAF sites start out with VFR. Hi-res models
indicate thunderstorms could bring brief flight restrictions to
either TAF site later this afternoon into this evening, possibly
as late as 01-02Z. Given this large time window, we opted to
maintain the VCTS until then. If radar trends indicate a direct
impact, then an amendment will be made to add a TEMPO group.
Otherwise, the thunderstorms are forecasted to dissipate this
evening, followed by a dry night. Another round of convection is
possible Sunday afternoon.

Extended Aviation Outlook: Scattered to numerous thunderstorms will
develop over the Coastal Plain each afternoon and evening. It is
possible that brief flight restrictions could occur with the
passage of any thunderstorm. Areas of heavy rain could see fog or
stratus develop during the pre-dawn hours.

&&

.MARINE...
Tonight: S winds 10-15 kt in the evening will veer to the SW
and ease to around 10 kt after midnight. Seas will be around 2
ft.

Sunday through Wednesday: The sfc pattern will feature high pressure
centered over the western Atlantic and broad low pressure inland.
This pattern should generally support south winds between 10 to 15
kt and seas between 1-2 ft.

&&

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

&&

$$
NEAR TERM...
SHORT TERM...NED
LONG TERM...RFM
AVIATION...NED
MARINE...NED