780
FXUS62 KCHS 080032
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
732 PM EST Fri Feb 7 2025

.SYNOPSIS...
A cold front will reach near our northern area by early
Saturday, then lift north as a warm front. Another cold front
will drop into the area late Sunday or Sunday night, with high
pressure to build in from the north Monday into Tuesday. A
storm system could impact the region mid to late week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Lowered the PoPs due to the recent 00Z CHS sounding and radar
observations. Latest runs of HREF and NBM seem to be overdoing
the precipitation chances. Looking at current radar, rain
showers have begun to develop over the northern portion of
Berkeley County.

Tonight: A weak cold front over the Midlands and Pee Dee is forecast
to meander to the south tonight, reaching northern portions of the
Charleston Tri-County area by daybreak Saturday. With little
forcing aloft, other than weak isentropic ascent, near term
guidance continues to support an area of isolated to scattered
showers passing through as the front sags south. 20-40% pops
were highlighted for areas along the northeastern tier of the
forecast area. QPF looks to remain very light with around one-
tenth of an inch or less. Otherwise, partly cloudy skies are
forecast outside of showers.

Another area of low stratus and fog is progged to expand northeast
out of the Gulf again tonight and could approach southeast Georgia
around sunrise before quickly dissipating. Additionally, fog over
the waters could seep across the beaches. Probabilities are not
impressively high for dense fog, and therefore we maintained "patchy
fog" wording in the forecast. We expect to finish the day with
warmer than forecast temperatures across southeast South
Carolina, so we increased mins tonight by around a degree or so.
The current forecast reflects low temperatures reaching the mid
to upper 50s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Saturday and Saturday night: A weak cold front will be meandering
over parts of the Charleston Tri-County region early on, then lifts
back to the north as a warm front thereafter. This is in response to
low pressure in Oklahoma as Saturday begins, traveling to the Ohio
Valley by late in the day. Since there is little forcing with the
front with a zonal flow aloft, any showers near the front will come
to an end early on. With high pressure to the south, and west-
southwest synoptic flow, it`ll again be an very warm day for
February. With 850 mb temperatures of 12-13C, record highs could be
challenged. We went with highs in the upper 70s and lower 80s, but
there will be a sea breeze which limits coastal locations at least 5-
10F cooler. Some of the beaches of South Carolina will struggle to
reach the lower 60s due to the fetch off the ocean. Winds never
fully decouple in most areas with a 25-35 kt low level jet to move
through. So we don`t expect it get any cooler than the mid and upper
50s. There is likely enough of an offshore flow to keep any sea fog
offshore.

Sunday and Sunday night: Compressional heating within a deep
westerly flow in advance of a cold front on Sunday, will yield yet
another day with record challenging highs. While 850 mb temperatures
are similar to Saturday, the low level thickness is actually
greater. So we look for similar to slightly warmer afternoon highs
inland with the sea breeze pinned closer to the coast. The cold
front struggles to move in as it is parallel to the zonal flow
aloft. But since it does get a boost from high pressure building
from the north band northwest, it could be as far south as through
much of the Charleston Quad-County by Monday morning. Provided the
front indeed does get that far south, there could be some upper 40s
in the Francis Marion, with lower and middle 50s most common
elsewhere.

Monday: A high pressure wedge looks to develop inland, with front
forced through most of the local communities by late in the day.
There is little to no forcing aside from weak isentropic ascent. But
if the 150+ kt upper jet currently shown to stay to the Ohio Valley
and Mid-Atlantic is able to get further south, maybe it can help
generate a few showers. Otherwise, as is usual in a Cold Air
Damming (DAM) situation, expect a huge range in temperatures.
Presently we have near 60F far north to near 80F far south.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Zonal flow will persist aloft early in the week, followed by mid
level impulses passing over or nearby during the mid week period.
Finally by late in the week a stronger short wave trough could shift
on through. The surface patterns rather unsettled. First the inland
wedge Tuesday eventually breaks down, then a cold front sags into
the vicinity Wednesday, followed by a stronger cold front Thursday
into Friday. There looks to be higher rain chances starting Tuesday
as a result. The late week front shows some promise for t-storms if
the instability is suffice enough. Temperatures remain above climo
through most, if not all of the long term period.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
00Z TAFs: CHS/JZI/SAV will be VFR over the next couple of
hours. A weak front will sag into the Lowcountry late tonight.
Isolated to scattered light showers could be near KCHS and
possibly KJZI this evening therefore VCSH was included starting
03z. Greater coverage in showers should focus more inland/west
of the TAF sites, thus no mention of -RA was included at this
time due to low confidence for any direct impacts. Fog could
develop offshore tonight into early morning, which could spread
onshore and impact KCHS/KJZI/KSAV. Thus, fog was included
starting 06Z and becoming more impactful at 09Z to 013Z; the
vsbys to 4-5 miles with a scattered ceiling. At the moment, fog
ending at 14Z for CHS/SAV and ending at 15Z for JZI.

Extended Aviation Outlook: Flight restrictions in fog and/or low
stratus is possible during the overnight and/or early morning
periods at the terminals. Some chance for showers early to mid
week.

&&

.MARINE...
Tonight: Southwest winds will prevail as a weak cold front
approaches from the north, just barely entering the Charleston
County nearshore waters by daybreak Saturday. Speeds will
generally remain around 10 kt or less with seas 1-3 ft. Another
round of fog could develop and/or move into the Georgia waters
again tonight/early Saturday morning. For now, probabilities
look to be low for dense fog, so we maintained patchy fog in the
forecast.

Saturday and Saturday night: A weak cold front will be situated over
the Charleston County waters early Saturday, then shifts back to the
north of the Santee River by afternoon. High pressure from the
Atlantic will then be aligned east-west, and south of the immediate
waters thereafter. Winds and seas during this time remain beneath
any Small Craft Advisory limits. There is definitely a concern for
sea fog, with a favorable fetch of warmer and more humid air atop
the cooler shelf waters. Dense Fog Advisories are possible.

Sunday through Wednesday:  High pressure on Sunday gives way to a
backdoor cold front Sunday night into Monday, as a high pressure
wedge develops inland, and lingers into Tuesday. Another cold front
will approach Wednesday. Right now winds and seas look to stay below
Small Craft Advisory levels, although dependent on the pinching of
the gradient associated with the inland wedge Monday into early
Tuesday, conditions could be close. Sea fog is still a possibility
at times.

&&

.CLIMATE...
Record High Temperatures:

February 7:
KCHS: 80/2019
KSAV: 82/2019

February 8:
KCHS: 80/2019
KSAV: 82/1921

February 9:
KCHS: 80/1949
KCXM: 76/1921
KSAV: 83/1957

February 13:
KCHS: 78/1976


Record High Minimum Temperatures:

February 7:
KSAV: 62/1884

February 8:
KCHS: 59/2017

February 9:
KCHS: 60/1949
KCXM: 60/1949

February 13:
KCXM: 62/2020
KSAV: 64/1880

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$

NEAR TERM...Dennis
SHORT TERM...
LONG TERM...
AVIATION...Dennis
MARINE...