Area Forecast Discussion
Issued by NWS Charleston, SC

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238
FXUS62 KCHS 232102
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
402 PM EST Tue Jan 23 2018

.SYNOPSIS...
High pressure will build in from the west tonight and prevail
through the end of the work week. Another cold front will
impact the area early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
This Evening and Tonight: A cold front will continue to shift east
over the western Atlantic this evening while dry high pressure
builds from the west over the region in its wake. The setup will
support a quiet night of weather. However, weak cold air advection
aloft along with sfc temps around 70 this evening should continue to
support low-lvl mixing and gusty winds up to 20 mph for the next few
hours. Thereafter, winds will decrease fairly quick as we approach
sunset. Dry high pressure will then prevail over the region tonight,
leading to some radiational cooling under clear skies. Temps should
dip into the mid/upper 30s, lowest inland.

Lake Winds: Gusty conditions continue to occur across the area
early this evening with sfc temps near 70 degrees. Water temps
on Lake Moultrie remain much cooler, in the mid 40s. Given the
setup, mixing over the lake will likely be kept to a minimum,
but we could see wind gusts around 20 kt along the lakeshore for
the next couple hours.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Quiet weather is expected to persist through the period. Surface
high pressure will build into the region from the west on Wednesday.
A shortwave will move across Wednesday night, helping send a
reinforcing shot of cooler, drier air through the area. The surface
high will then shift overhead Thursday and eventually offshore on
Friday. Subsidence and dry air will preclude any mentionable PoPs.
Temperatures will be fairly seasonable, although slightly warmer on
Friday as the flow turns onshore.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
High pressure will be moving offshore Friday night and a strong cold
front will approach from the west on Saturday. The 00Z models show
differences in the timing and the rainfall potential. The GFS is the
outlier and the ECMWF and Canadian are relatively similar. We opted
to go with the foreign duo of models, which seems more realistic and
keeps the overall forecast pretty similar to what we had. POPs
gradually increase on Saturday, followed by rain on Sunday. Periods
of heavy rain and thunderstorms are not out of the question, but
we`re still several days out. Following frontal passage, building
high pressure and dry conditions are expected on Monday.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
VFR conditions will prevail at both CHS and SAV terminals through
18Z Wednesday. West/southwest winds could gust around 20-25 kt
this evening at times.

Extended Aviation Outlook: There are no concerns.

&&

.MARINE...
This Evening and Tonight: An enhanced pressure gradient along/near
a departing front along with a fair amount of cold air advection
behind it will support southwest/west winds near 15-20 kt,
highest near the coast where mixing has been enhanced from sfc
heating over land. 25 kt gusts are possible over northern South
Carolina waters for the next few hours before winds and seas
begin to decrease/subside. A Small Craft Advisory will therefore
continue for AMZ350 until 6pm before the pressure gradient
relaxes with the arrival of dry high pressure from the west.
Seas will peak near 3-5 ft early this evening, then subside to
2-4 ft tonight.

Wednesday through Sunday: Surface high pressure is expected to
prevail through the end of the week. A brief surge expected
Wednesday night into Thursday, and wind speeds, especially in the
outer GA waters, could support a Small Craft Advisory. It looks
marginal at this time so will continue to monitor trends. Beyond
that, winds/seas will remain below advisory levels. A cold front
will approach from the west late in the weekend.

&&

.EQUIPMENT...
The KCLX radar remains out of service until further notice.
Repairs are ongoing. Adjacent radars include: KLTX, KCAE, KJGX,
KVAX and KJAX.

The Downtown Charleston observation site (CHLS1/KCXM) remains
out of service until further notice.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for AMZ350.

&&

$$
NEAR TERM...DPB
SHORT TERM...ECT
LONG TERM...
AVIATION...DPB/ECT
MARINE...DPB/ECT
EQUIPMENT...



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