Scientific Forecaster Discussion
fxus62 kchs 090934
Area forecast discussion
National Weather Service Charleston SC
434 am EST Fri Dec 9 2016
cold high pressure will extend over the area through the first
half of the weekend. A weak trough of low pressure is expected
to develop off the southeast U.S. Coast Saturday night and
Sunday before shifting north of the area. A cold front will then
likely stall out over or near the area Monday night into mid
week before pushing through Thursday with colder high pressure
to follow for late week.
Near term /through tonight/...
today: temps will start off chilly this morning with high pressure
over the area and high clouds shifting offshore. Expect dry and
considerably colder conditions than previous days this afternoon as
polar high pressure continues to expand across the region from the
west/northwest along the base of a broad mid/upper level trough of
low pressure shifting off the northeast coast. Even with a full day
of sun, strong cold air advection and a northerly sfc wind will limit
afternoon highs to the lower 50s for most areas. A few locations north
of Charleston could have a tough time reaching 50 degrees.
Tonight: cold and dry high pressure will contribute to some of the
coldest temps the area has seen so far this season. A fair amount of
cold air advection should continue into at least early overnight
hours, favoring a light northerly wind through much of the night.
Even if sfc winds do not go calm, temps are still expected to dip
into the mid and upper 20s away from the immediate coast. Freezing
temps will also be possible within a few miles of the coast in both
southeast South Carolina and southeast Georgia.
Short term /Saturday through Monday/...
high pressure will build from the northwest into Sunday while a weak
trough of low pressure develops off the southeast U.S. Coast
Saturday night before shifting northward near the coast and/or just
offshore Sunday into Sunday night. This feature could bring a few
showers, mainly near the coast. A cold front will then approach the
area from the northwest Monday with breezy conditions likely and
more showers possible. A few weak thunderstorms can't even be ruled
out as low-mid level instability increases. Temperatures will be
well below normal through Saturday night before getting much above
Sunday night and especially Monday.
Long term /Monday night through Thursday/...
a cold front will stall out over or near the area mid week while the
flow aloft becomes fairly zonal. Low pressure could develop along
the front and shift through the area but confidence in details is
low at this point. Either way unsettled conditions are likely with
increased rain chances. The front should then shift offshore
Thursday with colder high pressure to build in for late week with
temperatures dropping to near/below normal levels.
Aviation /10z Friday through Tuesday/...
VFR conditions will prevail at the chs and sav terminals through 06z
Extended aviation outlook: possible MVFR cigs thereafter through Wed
as a coastal trough and then stalling front affect the area. Breezy
conditions likely Mon.
today and tonight: cold high pressure will expand across the coastal
waters, allowing small craft advisories to persist over northern
South Carolina waters and offshore Georgia waters. However, a
relaxing of the pressure gradient and loss of the strongest cold
air advection will allow conditions to gradually improve throughout
the day. Expect winds/seas to drop below Small Craft Advisory
level conditions late morning in northern South Carolina waters
and early afternoon in offshore Georgia waters. In general, a
northerly wind will prevail during the afternoon and evening
with winds no higher than 15-20 kt. Seas will also range between
2-3 ft nearshore and 4-5 ft in offshore waters by the evening.
There could be a brief surge of winds tonight while high
pressure continues to extend across the waters and a northerly
wind occurs, but conditions should remain below Small Craft
Advisory levels for all waters. Winds will then gradually weaken
after midnight and tip to the north/northeast as the center of
high pressure slowly tracks over the mid-Atlantic states.
Saturday through wednesday: high pressure will build in from the
north Saturday while a weak coastal trough develops nearby Saturday
night/Sunday which will then shift north through the area Sunday
night. A cold front will then move into the area Monday night,
possibly stalling nearby through mid week. An area of low pressure
could develop and move along the front with conditions possibly
getting close to advisory levels Mon-Wed, mainly beyond 20 nm.
coastal flooding...the upcoming lunar perigee and full moon along
with periods of northeast winds could push tides to advisory levels
near times of the early morning high tides Saturday through the
middle of next week, especially along the SC coast.
Marine...Small Craft Advisory until 2 PM EST this afternoon for amz374.
Small Craft Advisory until 11 am EST this morning for amz350.