Summerville, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

037
FXUS62 KCHS 221120
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
620 AM EST Sun Dec 22 2024

.SYNOPSIS...
Arctic high pressure will build across the region today. A
coastal trough or weak low will develop nearby on Monday,
before lifting north away from the area Tuesday. High pressure
is expected to return mid week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: West-northwest flow will prevail aloft while high
pressure centered near the eastern Great Lakes ridges down the
Eastern Seaboard. Plentiful dry air and clear skies will
prevail, producing a sunny but chilly day. Low-level thickness
progs support highs reaching the upper 40s to low 50s for
southeast SC and low to mid 50s for southeast GA. The day will
start off quite chilly this morning, with wind chill values as
low as the low to mid 20s at sunrise.

Tonight: The center of the surface high will settle more over
New England while a coastal trough starts to take shape just off
the coast. The overall trend will be for increasing cloud cover
as offshore stratocumulus attempts to push onshore late. The
main question is how much cloud cover makes it onshore and what
impact does this have on low temperatures. Current thinking is
that cloud cover will have the greatest impact late, and along
the coastal counties. The forecast advertises mid to upper 20s
inland, ranging to the mid to upper 30s at the beaches. These
lows, combined with persistent northeast flow will yield wind
chill values dipping into the low to mid 20s for many areas,
with the potential for values at or just below 20 degrees right
an hour or two either side of sunrise Monday morning. A
reasonable case can be made for needing a Cold Weather Advisory
for the inland tier of counties, but will hold off for now and
see how guidance trends through the day.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
High pressure remains anchored inland Monday, while a coastal
trough sharpens offshore. There are some indications that a weak
low could form within the trough aided by weak shortwave energy
just off the GA/SC coast, before it lifts northward away from
the area later Tuesday. This feature is expected to bring
scattered showers to the area, mainly Monday night into early
Tuesday. Drier air and lower rain chances are expected to return
for the latter half of Tuesday. Monday will be unseasonably
chilly, with highs topping out in the upper 40s to lower 50s.
Tuesday will be more mild, ranging from the mid 50s near the
Santee River to low 60s closer to the Altamaha in Georgia. Lows
will be within a few degrees of normal.

High pressure will expand back into the area for
Wednesday/Christmas Day. Aloft, mid level ridge overhead will
give way to another shortwave approaching later in the day. Most
signals point to a rain- free day, with the possible exception
being right along the coast where a 20% PoP resides. Highs will
average around 60/lower 60s, except mid 60s over far southeast
Georgia.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
Fairly persistent pattern late week with high pressure inland,
and yet another coastal trough developing offshore. Ridge
largely prevails aloft, with perhaps some weak shortwave energy
moving through. No significant weather concerns at this time
with PoPs no higher than 20-30%. Temperatures will trend on the
warmer side of normal.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
VFR conditions will prevail at KCHS, KJZI, and KSAV through 12z
Monday.

Extended Aviation Outlook: Flight restrictions are possible in
showers and low clouds associated with a coastal trough Monday
night into midweek.

&&

.MARINE...
Today through tonight: High pressure across the Northeast will
continue to drive elevated northeast flow across the local
waters. Sustained wind speeds will be in the 15-20 knot range
through the period, with frequent gusts around 25 knots. Small
Craft Advisories are in effect for all waters outside of
Charleston Harbor through the period. Seas are forecast to
gradually increase, becoming up to 6 feet in the nearshore
Georgia waters and 5-8 feet in the outer Georgia waters by
sunrise Monday.

Monday through Friday: High pressure will persist inland
Monday, while a coastal trough sharpens offshore. A weak low
could form within the trough before it lifts north away from the
area on Tuesday. A tight pressure gradient between the inland
high and coastal trough will lead to gusty northeast winds
Monday into Monday night. Small Craft Advisories will remain in
place for all coastal waters outside of the Charleston Harbor.
Conditions should improve as we head into midweek. Northeast
winds will remain gusty through the latter half of the week, but
current forecast keeps winds/seas below advisory levels. The
exception possibly being over the outer Georgia waters where 6
foot seas could return.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 10 PM EST Tuesday for AMZ350-374.
     Small Craft Advisory until 1 PM EST Tuesday for AMZ352-354.

&&

$$

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