452
FXUS62 KCHS 222025
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
325 PM EST Wed Jan 22 2025

.SYNOPSIS...
Cold and dry conditions will prevail through the rest of the
week and into the weekend. A weak system would move through the
area early next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Quiet, albeit frigid, conditions will prevail through the
overnight period across the forecast area. A broad upper level
trough will slowly shift off the east coast through the
overnight as high pressure builds in at the surface. An Arctic
airmass will continue it`s hold over the region as the high
pressure builds in. Temperatures this afternoon have struggled
to reach more than a few degrees above freezing. Tonight skies
are forecast to remain clear through the first portion of the
overnight period, and in conjunction with light to calm winds
and the current snowpack near record breaking temperatures are
forecast (see Climate section for more details). After midnight
some cloud cover will move into the region associated with a low
pressure system passing well to the south. Temperatures will
likely remain steady heading into daybreak. A Cold Weather
Advisory is in effect for the entire forecast area for apparent
temperatures of 10 to 15 degrees. There are a few locations that
could reach apparent temperatures just below 10 degrees,
however as of this juncture the coverage was not enough to
warrant an Excessive Cold Warning. Any precipitation associated
with the low pressure system to the south is forecast to remain
well offshore, with rain-free conditions expected through the
period.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
Thursday through Saturday: Aloft, a positively tilted longwave
trough will gradually work eastward Thursday and Friday with zonal
flow settling in for Saturday. At the surface, a reinforcing cold
front will pass through and expansive high pressure will spread
across the region through Saturday. The only real thing of note
during this period is the area of showers we have been monitoring
over the last few days that model consensus continues to keep
offshore on Thursday. Fortunately, the dry forecast precludes any
small chance of precipitation problems Thursday morning as we get
off to a very cold start with temperature slowly climbing out of the
low to mid teens in most areas. Thursday will be yet another very
chilly day with highs likely topping out in the lower end of the
upper 30s. Thursday night will be cold, but not as cold, with lows
dipping into the low 20s. Friday highs will finally climb above 40,
but only into the low 40s with overnight lows dipping back into the
upper teens. Saturday will continue the run of well below normal
temperatures, as highs try to rise into the upper 40s. Overall,
these temperatures will prevent rapid improvement of road
conditions, especially for secondary roads. Also, additional Cold
Weather Advisories could be needed for late Thursday night and
Friday morning, as well as late Friday night and Saturday
morning.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
High pressure will persist across the area Saturday night and Sunday
ahead of a weak system that will move into the area Monday. This
system could bring isolated to scattered showers to the area, but
overall does not appear to be a threat for widespread significant
rainfall. Dry weather should then prevail into the middle of next
week. Temperatures will continue to be below normal, perhaps rising
to near normal values by the middle of next week.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
All terminals will initialize VFR to start the 18Z TAF period
under mostly sunny skies. Northerly winds may gust to around 18
knots at times this afternoon at all terminals. Clouds will
begin to increase in coverage in the latter half of the night,
remaining VFR. Some guidance indicates that some brief MVFR cigs
are possible around daybreak Thursday, however confidence is not
high enough to include mention of any restrictions in the 18Z
TAFs.

Extended Aviation Outlook: VFR.

&&

.MARINE...
Tonight: Conditions across the marine zones will continue to
improve through the overnight period as high pressure builds
into the region from the west. Winds will decrease to 10 to 15
knots with gusts to around 20 knots. Wave heights across the
nearshore waters will generally be 3 to 4 ft with 5 to 6 ft
across the 20 to 60 nm offshore GA waters. All nearshore Small
Craft Advisories will likely come down at various times this
evening and into the overnight, with the offshore GA waters
holding on a little longer due to 6 ft seas.

Thursday through Monday: Elevated winds will prevail Thursday into
Friday, with wind speeds mostly topping out in the 15-20 knot range.
Seas up to 6 ft will linger across the outer GA waters at least into
the afternoon, and the Small Craft Advisory remains in effect there.
Otherwise, winds and seas will then diminish significantly this
weekend and into early next week.

&&

.CLIMATE...
Record Low Maximum Temperatures:

Wednesday, January 22:
KCHS: 31/1970
KCXM: 31/1970
KSAV: 34/1970

Thursday, January 23:
KCHS: 34/1970
KCXM: 38/2016
KSAV: 40/2016

Record Low Temperatures:

Thursday, January 23:
KCHS: 19/1985
KCXM: 24/2003
KSAV: 19/1960

Record Snowfall:

Tuesday, January 21:
KCHS: T/1984*
KSAV: 0.2/1910

Wednesday, January 22:
KCHS: T/2022*
KSAV: T/2011*

Greatest One Day Snowfall:
KCHS: 6.0 inches/Dec 23, 1989
KSAV: 3.6 inches/Feb 8, 1968
(Snowfall observations ended in downtown Charleston in 1980)

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Cold Weather Advisory until 10 AM EST Thursday for GAZ087-088-
     099>101-114>119-137>141.
SC...Cold Weather Advisory until 10 AM EST Thursday for SCZ040-
     042>045-047>052.
MARINE...Small Craft Advisory until 7 PM EST this evening for AMZ350-
     352.
     Small Craft Advisory until 1 AM EST Thursday for AMZ354.
     Small Craft Advisory until 7 PM EST Thursday for AMZ374.

&&

$$

NEAR TERM...CPM
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...BSH/CPM
MARINE...BSH/CPM