182
FXUS62 KCHS 222032
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
332 PM EST Fri Nov 22 2024

.SYNOPSIS...
Canadian high pressure will remain the primary feature through
early next week. A cold front could approach the area towards
the middle of next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Late Afternoon: Aloft, a large mid-lvl low centered across the
Northeast United States will meander near the Northeast Coast with a
trough axis extending south across along the Southeast Coast.
At the sfc, dry high pressure will prevail with a west-northwest
downslope wind in place. Cold air advection along the southern base
of the trough will help promote low-lvl mixing during the next few
hours prior to sunset, favoring westerly winds between 10-15 mph
with gusts to 20-25 mph at times. Few to no clouds will allow for
ample sunshine, but temps will struggle to remain in the mid-upper
50s before trending down heading into sunset.

Tonight: Cold air advection along the southern periphery of a mid-
lvl trough will be slow to weaken during the night while dry sfc
high pressure remains in place. This trend along with clear skies
should lead to a fair amount of radiational cooling and light west
winds across inland areas during the second half of the night. In
general, low temps will dip into the mid-upper 30s away from the
coast. Conditions should also support some patchy frost away from
coastal areas late, and perhaps a few areas of frost across far
interior locations should winds go calm a few hours prior to
daybreak. However, a Frost Advisory is not anticipated overnight
given a calm wind is less likely to occur for an extended period of
time prior to daybreak.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
An amplified trough/ridge/trough pattern will be in place across the
CONUS to start the period with anomalously deep stacked low pressure
migrating off the mid Atlantic/New England coast and short-wave
ridging building through the central and into the eastern CONUS
later Sunday into Monday. Meanwhile, surface high pressure will
continue to build across the central and southeastern states through
the weekend and eventually off the coast by Monday. This will
prolong our recent stretch of rain-free conditions into early next
week.

Saturday through Monday: After a cool start to Saturday, quick
temperature moderation takes shape with high temperatures rebounding
back into the lower 60s Saturday, middle to upper 60s Sunday (near
normal), and back into the 70s for Monday. Another chilly
night/early morning is anticipated Saturday night/Sunday morning
with inland lows in the middle to upper 30s, warmer along the coast
of course. But with a weaker pressure gradient and lighter/calm
winds, the greatest frost potential still appears to be Saturday
night. Forecast will advertise patchy to areas of frost away from
the coast and a Frost Advisory will need to be considered. Sunday
night/Monday morning low temps should run a bit warmer and frost
potential looks low.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Large scale pattern transitions to a more zonal arrangement
through the middle part of next week, fully erasing the cold
temperature anomalies across the eastern/southeastern U.S. There
may be a weak surface boundary pressing through the region
later Tuesday/Tuesday night with little fanfare other than a
wind shift and temperatures dipping back down into the 60s for
Wednesday. By later in the week, longer term guidance does hint
at the re-development of deeper troughiness across the eastern
CONUS late week along with an attending stronger storm system
that traverses the region during the Thursday into Friday
timeframe. That will be our next chance of appreciable rainfall.
Temps warm ahead of the boundary into the 70s for highs
Thursday but back into the 60s on Friday after FROPA...subject
to later revisions.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions will prevail at KCHS/KJZI/KSAV terminals through 18Z
Saturday. Gusty northwest/west winds to 20-25 kt are likely at all
terminals through about 22Z this afternoon.

Extended Aviation Outlook: VFR.

&&

.MARINE...
Late Afternoon and Tonight: Cold air advection occurring along the
southern base of a mid lvl trough will help promote low-lvl mixing
into 1000 mb lvl geostrophic winds around 30 kt through a bulk of
the night, but will start to weaken as warm air advection starts to
take place a few hours prior to daybreak. In general, northwest/west
winds will gust up to 25-30 kt at times early, strongest across
northern South Carolina waters off the Charleston County coast. Seas
will generally range between 3-4 ft nearshore to 4-7 ft across outer
Georgia waters. The pressure gradient will be slow to weaken
overnight, but should result in winds that gradually decrease late.
Given the setup/trends, Small Craft Advisories will continue across
all local waters through the night, with the exception of the CHS
Harbor ending at 6 PM this evening.

Saturday through Wednesday: High pressure will build across the
coastal waters this weekend into early next week, with winds
diminishing to 10 to 15 knots for the Saturday through Monday
timeframe ans seas diminishing to 3 feet or less. Winds will
increase slightly for the Tuesday/Wednesday timeframe as a weak
boundary slips through the region. But winds/seas remain below
headline criteria.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for AMZ330.
     Small Craft Advisory until 7 AM EST Saturday for AMZ350-352-
     354.
     Small Craft Advisory until 10 AM EST Saturday for AMZ374.

&&

$$

NEAR TERM...DPB
SHORT TERM...Adam/NED
LONG TERM...Adam/NED
AVIATION...Adam/DPB/NED
MARINE...Adam/DPB/NED