861
FXUS62 KCHS 220201
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
901 PM EST Thu Nov 21 2024

.SYNOPSIS...
Canadian high pressure will build across the area tonight and
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 FRIDAY MORNING/...
A secondary cold front has pushed off the coast as shortwave
energy pivots through overnight. High pressure will prevail
overnight. Skies will remain clear, although ongoing cold air
advection will keep winds up through daybreak. It will be a
chilly night with lows from the mid-upper 30s inland to the mid
40s at the beaches. There looks to be enough wind to keep
significant frost from forming, except in the the most sheltered
of areas. The coverage is certainly not enough for a Frost
Advisory at this time, but a mention of patchy frost in the some
of the normally colder spots was introduced.

Lake Winds: Winds have temporarily diminished slightly on Lake
Moultrie this evening after a rather potent late
afternoon/sunset surge. Speeds should pick back up to 15-20 kt
with gusts to 25 kt overnight as the tail end of the shortwave
aloft swings through. A Lake Wind Advisory remains in effect.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Deep mid level low will meander over the Northeast on Friday,
before exiting on Saturday. The pattern will then flatten and be
replaced by weak ridging by the end of the weekend. At the
surface, low pressure will finally exit allowing high pressure
to continue to build over the local area. Gusty winds are
expected on Friday, then the pressure gradient eases through the
weekend. Gusts over Lake Moultrie could approach Lake Wind
Advisory criteria Friday into Friday night, but at this point
remains just shy.

Otherwise, expect full sunshine with moderating temperatures.
It will be coolest on Friday when highs top out in the mid to
upper 50s (~10 degrees below climo). By Sunday, temperatures
will recover to the upper 60s. Lows will be chilly, falling
solidly into the 30s inland of the coast. Attention then turns
to the potential for frost over far interior areas. For Friday
night/Saturday morning, while temps are supportive, winds could
stay too elevated for widespread frost development. Certainly
not out of the question to see patchy frost in more sheltered
locations. For Saturday night/Sunday morning, we did go on the
cooler side of guidance with ideal radiational cooling
conditions in place. As winds are expected to go calm, this
could lead to a higher threat for frost. Will continue to
monitor trends.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Surface high pressure will continue to extend into the area
early next week, although a cold front could approach during the
latter half of the period. Still some uncertainties in the
evolution of that feature, whether it actually passes through or
stalls, so changes to the forecast are likely. At this point,
no rain is in the forecast. Temperatures will be above climo for
Monday and Tuesday then possibly cooler for Wednesday if fropa
occurs.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
22/00z TAF Discussion:
KCHS/KJZI/KSAV: VFR. Gusty conditions will continue into the day
Friday.

Extended Aviation Outlook: VFR. Gusty west winds are expected
again Friday.

&&

.MARINE...
Tonight: Winds are starting to surge hard again as a secondary
cold front pushes through and shortwave energy pivots through
aloft. Have seen gusts to 34-36 kt gales at the Charleston
Pilot Buoy, Capers Nearshore and 41004, but suspect these gusts
far infrequent enough and short enough in duration that an
upgrade to a Gale Warning is not needed. A Marine Weather
Statement has been issued to address this through mid-evening,
after that, the gale gust potential should diminish. Otherwise,
west winds 20-25 kt with gusts to 30 kt will be common with
15-20 kt with gusts to 25 kt in the Charleston Harbor. Small
Craft Advisories remain in effect for all waters tonight.

Friday through Tuesday: Gusty west winds will persist over the
coastal waters Friday into Friday night, maintaining the ongoing
Small Craft Advisories. For the Charleston Harbor, gusts should
fall below 25 kt Friday evening so the Advisory is scheduled to
come down at 23z/6 PM. Conditions will improve on Saturday,
with winds and seas remaining below advisory levels through
Tuesday. Winds eventually turn southwest with speeds generally
15 knots or less and seas 1-3 ft.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Lake Wind Advisory until 9 AM EST Friday for SCZ045.
MARINE...Small Craft Advisory until 6 PM EST Friday for AMZ330.
     Small Craft Advisory until 7 AM EST Saturday for AMZ350-352-
     354.
     Small Craft Advisory until 10 AM EST Saturday for AMZ374.

&&

$$