219
FXUS62 KCHS 221805
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
105 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 /THROUGH TONIGHT/...
This Afternoon: Aloft, a large mid-upper lvl low centered across the
Northeast United States will slowly meander near the Northeast Coast
with a trough axis extending south across the Southeast United
States and offshore. At the sfc, dry high pressure will prevail
throughout the day 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 peak heating, favoring breezy westerly
winds between 10-15 mph with gusts to 20-25 mph into late day. Clear
skies will allow for ample sunshine, but cold air advection will
offset afternoon sfc heating. In general, high temps will range in
the mid-upper 50s.

Tonight: By the evening, winds should decouple after sunset and
allow for decent radiational cooling overnight bringing lows
down to the mid to upper 30s. Conditions should be more
supportive of patchy frost tonight compared to the night before,
however a Frost Advisory does not look likely at this time.

Lake Winds: Although northwest/west winds could briefly gust to
25 kt near the lakeshore this afternoon, low-lvl wind fields
will gradually decrease, limiting sfc gusts primarily in the
15-20 kt range through late day.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
Long wave trough axis will ripple east over the Atlantic on
Saturday. Mid-level flow across the forecast area will become
generally zonal flow on Sunday, tilting slightly from SW to NE
on Monday. On Saturday, the center of surface high pressure
should remain centered over Deep South, resulting in light WNW
winds across the forecast area. Using a blend of MOS, high
temperatures with sunny conditions should favor values in the
low 60s, 5 to 7 degrees below normal.

Saturday night, the center of sfc high pressure is forecast to
slide over the FL/GA line. After sunset, winds should become
light to calm across the forecast area. The combination of clear
sky with little to no wind should provide several hours of
excellent radiational cooling conditions. Dewpoints should
gradually narrow through the night, with most areas reaching the
upper 90s RH during the pre-dawn hours. Low temperatures should
range in the mid 30s, with a few spots reaching freezing across
portions of the inland counties. It appears that areas of frost
will develop inland late Saturday night into early Sunday
morning. Elsewhere, scattered frost is possible, especially just
inland of the coastal counties. The frost potential will remain
highlighted in the Hazardous Weather Outlook.

Sunday through Monday, the forecast area is expected to remain
between high pressure over the western Atlantic as a cold front
across the middle CONUS. This pattern will provide the region
with steady return flow and rising LLVL thicknesses.
Temperatures should return to normal on Sunday, with highs in
the upper 60s. On Monday, temperatures will continue to
moderate, with highs on Monday reaching the low to mid 70s.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Medium range guidance indicates that a cold front is timed to
approach the CWA from west Monday night, then pushing across on
Tuesday. The front is expected to bring a band of SCT to BKN
cloud cover across the region. Temperatures ahead of the front
should remain well above normal, high Tuesday ranging in the mid
to upper 70s.

Wednesday, high pressure should slide across the region in the
wake of the cold front. Conditions should remain dry with
temperatures near normal.

GFS and ECMWF indicate that broad longwave trough will amplify
over the Southern Plains Wednesday night into Thanksgiving. This
disturbance will ripple across the region during the daylight
hours Thanksgiving into Friday. During this period, the forecast
will feature SCHC PoPs for light showers. Temperatures should
remain mild, with the warmest values expected Thanksgiving
afternoon in the mid to upper 70s.

&&

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

Extended Aviation Outlook: VFR.

&&

.MARINE...
This 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 near 30 kt. In general, northwest/west
winds will gust up to 25-30 kt at times, strongest across northern
South Carolina waters off the Charleston County coast. Seas will
generally range between 3-5 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 overnight. 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 remain across
the coastal waters this weekend into earl next week, then a weak
cold front is timed to push across the region on Tuesday. Winds
through the period should favor values of 10 kts or less. Seas
are forecast to range between 1-2 ft.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 6 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...NED
LONG TERM...NED
AVIATION...DPB/NED
MARINE...DPB/NED