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000
FXUS62 KCHS 181603
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1103 AM EST Sat Jan 18 2020

.SYNOPSIS...
A warm front will lift through the region later today and this
evening. A cold front is expected to move through late tonight
into Sunday, followed by cold and dry high pressure into the
middle of next week. A low pressure system could impact the
region next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
A weak high pressure wedge will persist across the Charleston
Tri-County area through mid-afternoon. Elsewhere, winds will
more quickly veer to southerly with increasing warm air
advection. A fairly wide temperature range is anticipated from
north to south today. The combination of stratus and cold
advection over northern areas is expected to keep temps from
rising much higher than the low 60s, while farther south where
sunshine and warm advection develop, temps may approach 70.
Can`t rule out a few showers over the waters and immediate
coastal areas though the forcing associated with the weakening
coastal trough is quite limited.

Tonight: An ill-defined warm front will lift north of the area
early this evening and surface flow is forecast to veer to SW
ahead of an approaching cold front. Warming temps along coastal
zones should set the stage for increasing SW winds in the 10-15
mph range this evening. If warm temps become realized, there
could be some gusts over 20 mph tonight. Ahead of the front,
deeper moisture profiles appear to shift through S GA with upper
forcing rather unfocused through the overnight. We generally
maintained good chance POPs, rainfall amounts should be less
than a tenth of an inch. Temps will rise ahead of the front with
readings in the lower 60s overnight at many areas.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Sunday: A cold front will progress through the area during morning
hours, favoring scattered showers across much of the area (highest
coverage along the Southeast Georgia coast). Cool and dry high
pressure will then build in wake of the front, quickly ending precip
from northwest to southeast during early afternoon hours and
resulting in a downward trend of temps during mid-afternoon hours
through the evening. In general, highs should range in the low/mid
60s ahead of fropa early. Conditions will remain dry through the
overnight period while colder air arrives from the west-northwest.
In general, temps should cool into the low 30s inland to mid/upper
30s closer to the coast.

Monday and Tuesday: Dry and cold high pressure will prevail at the
sfc below a broad trough of low pressure expanding across the East
Conus. The pattern will result in noticeably colder conditions on
Monday with temps some 10-15 degrees lower than the previous day. In
general, high temps will struggle to reach the upper 40s across
northern areas and lower 50s across Southeast Georgia. Temps will be
chilly Monday night, dipping into the upper 20s away from the coast
to low/mid 30s along the beaches. Tuesday afternoon temps should be
even colder as the center of a mid-lvl low shifts across the
Southeast while northeast sfc winds prevail at the sfc. Highs should
only reach the mid 40s across Southeast South Carolina and upper 40s
across Southeast Georgia.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A large area of sfc high pressure will dominate much of the East
Conus with its center shifting across the Midwest midweek, then into
the Northeast by Friday. Aloft, a large trough of low pressure will
begin to shift offshore midweek, setting up a period of mid-lvl
ridging through late week. The pattern will favor cold temps Tuesday
night with lows in the mid/upper 20s away from the coast, before
conditions gradually warm as winds become more directly onshore
through late week. Temps will likely warm into the low/mid 50s
Wednesday, then mid 50s well inland to upper 50s/lower 60s on
Thursday. On Friday, onshore winds should prevail as high pressure
shifts off the East Coast. A developing coastal trough could also
bring some showers onshore. In general, temps should approach the
mid/upper 60s. Chances of precip should increase during the weekend
as low pressure over the Gulf of Mexico merges with a cold front
approaching from the west on Saturday. Scattered to potentially
numerous showers are possible during peak forcing/moisture across
the area Saturday afternoon.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
MVFR cigs are possible around the SC corridor from mid morning
through mid afternoon as a coastal trough nudges near shore. At
KSAV, the chances for lower cigs should be a bit lower, but
still possible. This evening, VFR conditions at both terminals
likely per latest forecast soundings and time/height cross
sections. Later tonight, scattered showers are expected ahead of
a cold front. The timing looks late enough to allow the next
TAF cycles to include shower potential as well as cig flight
restrictions.

Extended Aviation Outlook: Flight restrictions are possible at both
CHS and SAV Sunday morning during showers associated with a passing
cold front. VFR conditions are then expected at both terminals
Sunday afternoon through the middle of next week.

&&

.MARINE...
Marine conditions should gradually improve today as the
gradient becomes weaker. Winds may be slow to veer initially,
directions will become S to SW by this evening. We may need to
issue another SCA for Charleston nearshore later tonight as
seas build offshore with stronger flow expected out near the
Gulf Stream. Since it will be marginal, will allow for 12Z model
run data before any SCA re-issue considerations. A cold front
will approach from the west late but suspect winds will be
gustier right along the land/sea interface than over the coldest
shelf waters.

Sunday through Thursday: A cold front will shift across coastal
waters Sunday, turning southwest winds to west-northwest in its
wake. A Small Craft Advisory will be ongoing across offshore Georgia
waters through much of the day and could be needed across northern
South Carolina waters off the Charleston County Coast due to
lingering 6 ft seas. Conditions should be somewhat elevated heading
into Monday as the pressure gradient remains enhanced and northerly
winds rush in colder air across the waters. Strongest cold air
advection should occur Monday night through Wednesday when a mid-lvl
low shifts across the region. Small Craft Advisories are likely for
at least a portion of the coastal waters during this period and
could linger into Thursday, especially across offshore Georgia
waters where northeast winds support the continuation of higher
seas. In general, north-northeast wind speeds should range between
25-30 kts at times Tuesday and Wednesday while seas build to 4-6 ft
across nearshore waters and 6-9 ft across offshore waters.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 6 PM EST Sunday for AMZ374.

&&

$$
NEAR TERM...JRL
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...
MARINE...