Area Forecast Discussion
Issued by NWS Charleston, SC

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181
FXUS62 KCHS 262254
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
654 PM EDT THU MAY 26 2016

...Dense Smoke Advisory Issued for Portions of Berkeley and
Charleston Counties...

.SYNOPSIS...
Atlantic high pressure will prevail through Friday. A wave of low
pressure is then expected to develop over the western Atlantic and
approach the Southeast coast Saturday and Sunday. The low could
affect the area into early next week before eventually lifting
northeast.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A Dense Smoke Advisory has been issued for Berkeley and Charleston
Counties from 10pm-9am per a request from the US Forest Service. A
200-acre wildfire burning along the Berkeley and Charleston
County border is ccontained, but extensive smoke is expected to
occur overnight as dispersion profiles become very poor.

A quiet night is on tap. Skies will clear with the loss of
diurnal heating, resulting in temperatures cooling to near normal
values. Lows will be in the lower-mid 60s inland and near 70 at
the coast.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Friday: A deep layered ridge will prevail across the area,
maintaining similar conditions to Thursday with mostly sunny skies
and high temperatures in the mid/upper 80s.

Friday night: Low pressure begins to approach the Southeast after
gradually developing north of the Bahamas. Dry surface high
pressure will remain over western areas which should minimize the
potential for any rain Friday night over land areas. However there
should be increasing moisture and lift to allow scattered showers
and thunderstorms over outer portions of the coastal waters
especially late Friday night.

Saturday through Sunday: Increasing confidence that some form of
low pressure system, be it extratropical or tropical, will impact
the forecast area. The National Hurricane Center continues to
indicate a high likelihood of this system becoming tropical or
subtropical and may investigate the developing low pressure system
with a reconnaissance aircraft midday Friday if needed. Regardless
of whether the system gets named as a tropical system, the
expected impacts on local weather would likely be similar. Given
the relatively cool water temperatures over the western Atlantic,
at best the system could become a weak tropical storm before
moving inland late in the weekend.

Saturday morning could remain dry for many areas, then by Saturday
afternoon we expect significant increase in PWs as onshore flow
strengthens and deepens. Scattered showers/tstms expected to
spread onshore during the afternoon, gradually becoming more
numerous by Sunday as the system moves into or very close to the
SC coast. There continues to be high uncertainty regarding the
rainfall potential with this system since the models are showing a
large spread in the expanse of the precipitation fields. However
the heavy rainfall potential is at this point the greatest concern
for local impacts, especially if strengthening northeast winds
result in above normal tides during the same period.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As would be expected, the long term forecast period continues to be
very low confidence thanks to possible impacts from an area of low
pressure near the South Carolina coast. The details of the forecast
continue to be heavily dependent on the exact track and strength of
the system, so the details in the current forecast should carry
little weight.

Two of the possible scenarios include a more progressive, eastward
track that keeps the greatest impacts to our east, and a slower
more meandering solution that keeps the system over us for several
days. The forecast is essentially unchanged for now, featuring
days of chance pops, until a discernible model trend develops.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR. There could be some very shallow ground fog, but no impacts
are expected.

Extended Aviation Outlook: Chances for at least periodic flight
restrictions then increase this weekend and beyond as a low
pressure system approaches from the southeast.

&&

.MARINE...
Tonight: Atlantic high pressure will prevail tonight. Southerly
to southeasterly surface winds will begin to back to the
east/east- northeast near daybreak Friday with windspeeds
remaining generally 10 knots or less. Seas will be 1 to 3 feet,
highest offshore.

Saturday through Tuesday Night: Forecast confidence gradually
decreases by Saturday as an area of low pressure near the Bahamas
is expected to draw closer to the waters and potentially develop
into a tropical system. Northeast winds strengthen on Saturday due
to the gradient between residual inland high pressure and the
approaching low. We could be low on wind speeds but for now have
things capped at 20 kt. Depending on the eventual track of the
low, winds will probably come around to north or northwest by
Sunday which would somewhat decrease wind speeds due to the
offshore fetch. The bottom line is that the marine forecast is
highly uncertain and mariners should closely monitor the latest
forecasts before venturing offshore.

Rip Currents: An increased risk of rip currents for the upcoming
holiday weekend appears likely as onshore flow and swell energy
increases in advance of an approaching low pressure system.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Dense Smoke Advisory from 10 PM this evening to 9 AM EDT
     Friday for SCZ045-050-052.
MARINE...None.

&&

$$

ST



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