North Charleston, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

937
FXUS62 KCHS 172350
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
650 PM EST Sat Jan 17 2026

.WHAT HAS CHANGED...
The aviation section has been updated for the 00Z TAF issuance.

&&

.KEY MESSAGES...
- 1) Increased risk for a rain/snow mix with minor accumulations
  possible across far inland areas Sunday morning as a coastal
  low develops over the Atlantic.

- 2) Cold temperatures in the low to mid 20s (upper 20s to
  lower 30s along the coast) possible Monday, Tuesday, and
  Wednesday morning.

&&

.DISCUSSION...
KEY MESSAGE 1: Increased risk for a rain/snow mix with minor
accumulations possible across far inland areas Sunday morning
as a coastal low develops over the Atlantic.

Showers will slowly increase in coverage overnight and
especially Sunday morning as a cold front pushes offshore with
the approach of a large upper trough that is forecast is dig
across the eastern CONUS on Sunday. The core of the strongest
deep-layered forcing owing to increased DPVA ahead of a secondary
shortwave that will round the base of the longer wave trough
and ageostrophic contributions from the right entrance region of
a 170 kt jet streak embedded in the polar jet is forecast to
traverse the area from mid-morning through mid-afternoon
helping to induce cyclogenesis offshore of the Southeast U.S.
coast (Miller-A pattern). Expect widespread rains to impact
Southeast South Carolina and Southeast Georgia during the
morning into the early afternoon hours with precipitation
tapering off from west-east as colder and much drier air filters
into the region. Some much needed rainfall will occur with most
areas averaging near 0.50". While these amounts are not overly
heavy, any rainfall will help with the ongoing drought
situation.

The remains a concern for p-type issues across far interior
areas Sunday morning as the column cools with strengthening
post-frontal cold air advection behind the cold front that will
push offshore prior to daybreak. As is typically the case in
winter Miller-A cyclogenesis patterns, the p-type forecast is
highly complex and sensitive to timing as the cold air will be
chasing the exiting rain shield. 18/12-18z model soundings still
suggest interior Southeast Georgia favors the best juxtaposition
of lingering precipitation with thermal profiles supportive of
snow with soundings at KAQX, K2J5, KMHP and KRVJ all showing
cloud temperatures of at least -20C (sufficient for 100% ice
nucleation) with sub-freezing profiles all the way down to just
above the boundary layer. Farther to the east, guidance suggest
conditions will become increasingly less favorable for cloud
ice nucleation as the column begins to dry from the top-down.
While a brief rain/snow mix may occur as far east as the I-95
corridor, the primary p-type east of the Reidsville-Allendale
corridor should be all rain.

Scenarios: Similar to yesterday, the most likely scenario is
for rain expanding across the area overnight, then transitioning
to a rain/snow mix in the Reidsville-Allendale corridor by mid-
morning, possibly changing to all snow before ending during the
early afternoon hours. There is about a 2-4 hour period where
some minor accumulations could occur and snow could become the
dominant p-type. Warm ground temperatures and light-moderate
precip rates should limit any brief accumulations to grassy
areas, elevated surfaces and possibly some bridges, but
significant impacts are unlikely at this time. There are still
signals in the morning`s guidance that suggest some convective
enhancement could occur where bands of strong 850-500 hPa
frontogenesis align with pockets of negative EPV, thus locally
augmenting both thermal and UVV profiles. This could yield
corridors of localized, heavier snowfall rates even with surface
temperatures above freezing. There are signals of this
enhancement occurring in both the H3R and RAP simulated
reflectivity products which highlight the formation of several
convective bands as the sharp tail end of the negatively-tilted
shortwave rounding the base of the mean upper trough pivots through.
Should this enhancement be realized, the resulting heavier snowfall
rates could support some localized amounts as high as 0.5-1" before
rapid melting occurs. This should be treated as a reasonable worse
case scenario for planning purposes.

Snow Amounts/Impacts/Winter Headlines: There is low confidence
for snow amounts given the uncertainties noted above. Snow
amounts of 0.1-0.4" where introduced for parts of interior
Southeast Georgia up into Allendale County, SC, given the latest
deterministic, ensemble and statistical guidance trends. These
accumulations should be largely limited to grassy areas and
possibly some elevated bridges/overpasses if freezing surface
temperatures can be realized. While these amounts are just below
Winter Weather Advisory criteria, a few slick spots can not be
ruled out so people are encouraged to use extra caution while
traveling Sunday morning. It should be noted that the early
morning run of the Probabilistic Winter Storm Severity Index
(WSSI-P) showed a 30-40% chance for minor impacts and a 5-10%
for moderate impacts, mostly for driving conditions. These
probabilities may increase later this afternoon with the arrival
of the afternoon WFO forecast. The need for a Winter Weather
Advisory will be reassessed this evening and again overnight
when shorter term thermal profile trends can be more readily
identified.


KEY MESSAGE 2: Cold temperatures in the low to mid 20s (upper
20s to lower 30s along the coast) possible Monday, Tuesday, and
Wednesday morning.

On the backside of the departing surface low and exiting
shortwave aloft, cooler temperatures filter down into the region
Sunday night into Monday. Weak cold air advection (CAA) from a
surface high pressure moving into the Gulf of America will aid
in temperatures falling down into the lower to mid 20s, and into
the upper 20s to lower 30s along the coast. Wind speeds are a
bit uncertain given the weaker CAA, but there appears to be two
ways we may end up needing a cold weather advisory. The first
being winds remain fairly steady (though still on the weaker
side) with temperatures in the lower to mid 20s, resulting in
wind chills in the mid teens to lower 20s, which is currently
the favored scenario. The second scenario would be winds further
weakening, which would then allow for increased radiational
cooling potential bringing temperatures down into the upper
teens to lower 20s.

For both scenario`s, inland southeast Georgia and inland
southeast South Carolina have the highest potential of either
temperatures or wind chills at or below 20 degrees F, in the
40-60% range. While temperatures won`t be as cold as you head
towards the coast, temperatures in the mid/upper 20s combined
with increased wind speeds may also result in wind chills at or
below 20 degrees F, with probabilities 20-30%. A Cold Weather
Advisory may be needed.

Ahead of our next cold front, highs on Monday are only expected
to reach into the upper 40s to lower 50s. The front pushes
through during the late evening hours, with a surface high
pressure moving into the southeast region from the central
CONUS. This will bring another round of overnight lows in the
mid 20s inland to lower 30s along the coast, with wind chills in
the upper teens to upper 20s. Probabilities for wind chills at
or below 20 degrees F are highest for areas west of the I-95
corridor, ranging from 30 to 50%, which may prompt another Cold
Weather Advisory.

Highs on Tuesday are again expected to be in the mid 40s to
lower 50s. Our final cold overnight period from this event will
occur as the aforementioned surface high pressure slides by just
to the north of the local area. Similar to the Monday morning
set up, we could see Cold Weather Advisory criteria (20 degrees
F or lower) across inland areas from either temperatures alone
if there is no wind (40- 70% chance), or from wind chills if
winds are a touch stronger (30- 40% chance).

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
The 00Z TAF period will begin with VFR conditions at
KCHS/KJZI/KSAV. Conditions will begin to deteriorate early
Sunday morning as showers move into the terminals, bringing
lower cigs and reduced vsbys. IFR conditions are expected at all
terminals on Sunday, with conditions improving later in the
evening.

Extended Aviation Outlook: Rain/cig impacts will diminish Sunday
afternoon. There are no other concerns at this time.

&&

.MARINE...
Through Sunday: Southwest winds remain on the breezier side out
ahead of an approaching cold front today, though winds and
waves remain well below Small Craft criteria. Winds decrease
overnight, but will again rise Sunday morning behind the cold
frontal passage which swings the winds around to become out of
the northeast, with scattered to areas of showers continuing
throughout the day. Wind gusts into the lower to mid 20s will
overspread the waters throughout the morning hours, strongest
across our near and offshore Georgia waters from Savannah down
to the Altamaha Sound. 6 foot waves look to remain confined
close to the 60NM boundary, decreasing to 3 foot waves along the
coast. A Small Craft Advisory has been issued for the waters
from Savannah to Altamaha Sound out to 60NM. Rain exits the area
Sunday afternoon/evening, with winds subsiding into the
overnight hours.

Monday to Wednesday: No high confidence marine concerns in the
extended. Northwesterly winds become breezy on Tuesday, with
gusts up to 20 kts throughout the afternoon hours. Wave heights
begin to trend upwards on Wednesday as swell moves in from the
Atlantic.

&&

.CLIMATE...
Snowfall Records for January 18:
KCHS: 0.4/1977
KSAV: 1.0/1893

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from 7 AM to 4 PM EST Sunday for AMZ354.
     Small Craft Advisory from 7 AM Sunday to 1 AM EST Monday for
     AMZ374.

&&

$$

APT/CPM/ST