800
FXUS62 KCHS 310917
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
417 AM EST Fri Jan 31 2025

.SYNOPSIS...
A cold front is expected to move through tonight, followed by
high pressure Saturday through much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Overnight composite analysis reveals a well defined southern
stream closed upper low over the central/southern U.S. and
downstream ridging through the southeast region. Occluding
surface low is over the mid Mississippi River Valley with an
boundary extending to the Gulf and a warm front that arcs into
the Carolinas. Baroclinic leaf cloud structure has emerged
across the lower/mid Mississippi River valley into the Ohio
Valley ahead of the upper low/surface boundary, along with a
narrow corridor of precipitation that extends from Louisiana
into the Ohio Valley. Quiet weather across the local forecast
area with some thicker high cloud cover streaming through the
region and some hint of marine stratocu along the Charleston
coast.

Upper low will progress eastward and phase with the northern
stream across the mid Atlantic region through tonight. Occluding
surface boundary will press into the southeast later this
afternoon and advance off the southeast coast later tonight.

Today: Ahead of the occluding surface system, axis of warmer/more
humid air will be spreading into the southeast region fairly
quickly today pushing temperatures well into the 70s for
afternoon highs and possibly some lower 80s for the far Georgia
counties; more akin to April conditions. But there will also be
a fair amount of high cloud cover around throughout the day
leading to mostly to partly sunny conditions.

Meanwhile, with 50s dewpoints advecting across the chilly
coastal waters (upper 40s to lower 50s SST`s) marine fog and/or
stratus remains a possibility today into tonight. There has been
some lower cloud cover reported at KJZI/KLRO during the
overnight, which could be the start...although it does not show
on GOES multispectral IR product. Patchy marine fog was
maintained along the coast through the day and into tonight.

Tonight: As mentioned above, occluding surface boundary will
press through the region later this evening and early overnight
ahead of the phasing upper low/trough. Blended guidance/precip
probabilities continue to suggest a broken line of showers will
pass through the region through the course of the night with a
period of likely to categorical pops warranted. Axis of instability
(a few hundred J/Kg of MUCAPE) will also nose up through
Georgia and into southeast South Carolina. Some TSTM activity
is certainly possible, particularly across Georgia. But given
the lower thunder probs (largely <20 percent), keeping thunder
out of the forecast for now.

Finally, BufKit soundings show generally 30 to 35 knot winds
developing within the mixed layer today, suggesting 20 to 25
knot gusts developing later this morning and continuing through
the afternoon. Not enough for any land based wind headlines, but
the ongoing Lake Wind Advisory has been maintained. Gustiness
should tend to subside heading into the evening, although
another period of enhanced gustiness is possible after FROPA
later this evening/overnight.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
Dry high pressure will build over the area behind the cold front
on Saturday, with skies quickly clearing during the morning.
Despite weak cold air advection, downslope flow will result in
an unseasonably warm day with highs in the upper 60s to lower
70s.

Sunday into Monday, a zonal flow will persist aloft while at the
surface high pressure moves off the Southeast coast.
Unseasonably warm temperatures are expected, with Sunday highs
in the low to mid 70s and Monday in the mid to upper 70s.
Increasing surface dewpoints late Sunday afternoon into Sunday
night over the cool Atlantic waters could result in sea fog
formation. If this develops, it could spread over land areas
Sunday night.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
An unseasonably strong, deep layered ridge will prevail for much
of next week, with highs reaching the upper 70s to lower 80s
most days. A weak cold front could drop into the area on Friday.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
VFR conditions are expected at CHS/JZI/SAV through early Friday
evening, although there remains some risk for brief MVFR cigs
late tonight and Friday as moisture shifts onshore. Expect gusty
winds at the terminals late morning Friday into early Friday
evening, peaking between 22-27 kt, before subsiding after
sunset. LLWS is also forecast late tonight and post daybreak
Friday as low-lvl wind fields increase considerably before gusty
winds develop at the sfc.

Friday evening: MVFR cigs are looking to develop late evening
toward the end of the current TAF cycle, with showers pushing
into the region late evening and overnight.

Extended Aviation Outlook: Fog and/or low stratus possible
Sunday night and again Monday night.

&&

.MARINE...
A cold front will approach the region today bringing enhanced
south/southwest winds and gusts to around 25 knots across the
coastal waters today and through much of tonight. Seas will
also build through tonight, peaking between 4-6 ft across
southern nearshore SC and nearshore GA waters and 5-7 ft across
northern nearshore SC and outer GA waters. Small Craft
Advisories have been issued for all marine zones including the
Charleston Harbor this afternoon.

Additionally, the formation of sea fog remains a possibility
with 55-60 degree dew point air atop the cooler shelf waters.
Forecast will continue to mention patchy across all coastal
waters into this evening. Some of the fog could become dense at
times.

Saturday through Tuesday: High pressure will prevail over the
waters with conditions remaining below advisory criteria. Sea
fog could be a concern Sunday night and again Monday night.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Lake Wind Advisory from 10 AM this morning to 1 AM EST
     Saturday for SCZ045.
MARINE...Small Craft Advisory from 1 PM this afternoon to 11 PM EST
     this evening for AMZ330-354.
     Small Craft Advisory from 1 PM this afternoon to 6 AM EST
     Saturday for AMZ350-352.
     Small Craft Advisory from 10 AM this morning to 6 AM EST
     Saturday for AMZ374.

&&

$$

NEAR TERM...Adam
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...Adam/JRL
MARINE...Adam/JRL