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000
FXUS62 KCHS 171736
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
136 PM EDT Wed Apr 17 2024

.SYNOPSIS...
High pressure will persist through the end of the work week. A
cold front is forecast to bring unsettled weather to our area
this weekend. High pressure returns early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Rest of this Afternoon: Surface analysis from this morning
shows high pressure extending into the local forecast area from
the east, while to the west a long wave trough aloft is
positioned over the Great Lakes. A short wave trough could be
analyzed in the vicinity of far western NC. Quiet and cloudy
conditions will likely prevail across the forecast area through
the rest of the afternoon. Due to the thicker cloud cover, high
temperatures were decreased across most locations away from the
direct beaches. A weak sea breeze has begun to form, with 1 PM
observations showing winds tipping to the SSW across the
coastline.

Tonight: The aforementioned short wave trough will swing across
the southeastern states, with guidance suggesting a few showers
could form across the SC Midlands. 15% PoPs have been introduced
across portions of inland southeastern GA for a few hours
overnight to account for these showers. However, forecast
soundings indicate the showers would have a lot of dry air to
overcome, so any rainfall may not actually make it to the
surface. The cloud cover is forecast to remain in place through
the overnight hours, yielding overnight low temperatures in the
low to mid 60s. This cloud cover will also limit the potential
for fog formation across the region.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
Thursday: The mid-levels will consist of zonal flow over our region
in the morning. Ridging will develop over the Southeast U.S. in the
afternoon, then stretch and strengthen along the entire East Coast
into the evening and overnight. This will yield rising heights over
our area. At the surface, a weak cold front will be located to our
northwest early in the morning. It`ll pass to our north during the
morning hours, then shift offshore in the afternoon. Weak High
pressure to our southeast will then stretch into our region during
the afternoon and evening. Another front will approach from the
distant west overnight. Though, it won`t make it to our area during
this time period. POPs 5-10% in the morning will lower into the
afternoon, which is when the synoptic models keep our area dry. POPs
start to creep up in the evening and overnight, mainly inland. But
they only max out around 10%, so once again no rainfall is expected.
SW surface winds during the day will be followed by an afternoon sea
breeze quickly moving inland. Mostly cloudy skies in the morning
will become mostly sunny by the late afternoon, then become partly
cloudy overnight. The combination of warm 850 mb temperatures and
low-level thickness values support well above normal highs in the
upper 80s to around 90 degrees, except cooler at the beaches. Lows
will be very mild, in the lower to mid 60s.

Friday: Mid-level ridging over the East Coast in the morning will
shift offshore into the afternoon, leading to lowering heights over
our area. Zonal flow then develops in the evening and persists
overnight. Surface High pressure located to our Southeast in the
morning will move away into the afternoon. Meanwhile, a cold front
will approach from the northwest, reaching our inland counties
around daybreak Saturday. Moisture creeps higher ahead of the front,
with PWATs rising to ~1.5". Synoptic models indicate isolated to
scattered showers developing in the afternoon. Some will be well
ahead of the front and others will be associated with the afternoon
sea breeze moving inland. There should be enough instability in the
afternoon that a few thunderstorms cannot be ruled out. The showers
will gradually dissipate in the evening, with it becoming dry after
midnight. Again the combination of warm 850 mb temperatures and low-
level thickness values support well above normal highs in the upper
80s to lower 90s, except cooler at the beaches. These temperatures
will quickly drop when the showers develop. Lows will remain very
mild, generally in the mid 60s.

Saturday: The mid-levels will consist of zonal flow over our region.
At the surface, a cold front located across our inland zones at
daybreak will slowly move southeast across our area during the day.
Decent moisture will remain in place ahead of the front, with PWATs
ranging from 1.25-1.5". Lift from the front and the afternoon sea
breeze moving inland should generate isolated to maybe scattered
convection late in the afternoon. Depending on the amount of
instability, some of the storms could produce gusty winds and
locally heavy rainfall. These details will need to be ironed out
with future forecasts. Highs will still be above normal, generally
in the mid to upper 80s, except cooler at the beaches.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
Mid-level troughing will start to develop over the eastern half of
the U.S. on Sunday, gradually strengthening into Tuesday. This
will cause heights to lower over our area. A front will be
spread across our area Saturday night, shifting offshore by
Sunday night or Monday morning. The models have come into
somewhat better agreement, indicating unsettled weather into
early next week. High pressure and drier conditions build in
late Monday into Tuesday. Temperatures will also cool down
directly behind the front, before rebounding on Tuesday.

Temperatures remain above normal through Saturday, cooling down
Sunday through Tuesday.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Prevailing VFR through 18Z Thursday at KCHS/KJZI/KSAV.

Extended Aviation Outlook: VFR through Thursday night. A slow moving
front may bring occasional flight restrictions Friday through
Sunday, with restrictions most likely on Sunday.

&&

.MARINE...
Today and Tonight: High pressure will remain the dominant weather
feature locally, extending from the western Atlantic and across the
Southeast United States. Expect south-southwest winds with speeds up
to 10-15 kt across most waters, turning more south this afternoon. A
local seabreeze should contribute to a few gusts up to 20 kt along
the coast late morning and afternoon, especially along the
Charleston County coast and across the Charleston Harbor. Winds
should tip back to south-southwest overnight as sfc high pressure
slowly nudges further offshore, but wind speeds should remain in the
10-15 kt range. Seas will range between 2-3 ft across most waters,
but occasional 4 ft waves are possible across far offshore Georgia
waters overnight.

Thursday: A weak cold front will be located to our northwest early
in the morning. It`ll pass to our north during the morning hours,
then shift offshore during the afternoon. Weak High pressure to our
southeast will then stretch into our region during the afternoon and
evening. Another front will approach from the distant west
overnight. In the morning, expect backing winds, followed by gusty
winds along the land/sea interface in the afternoon due to the
formation of the sea breeze. Gusts should be around 20 kt in the
Charleston Harbor with its passage. In the evening, winds will veer
and increase as some coastal jetting develops overnight.

Friday: Surface High pressure located to our Southeast in the
morning will move away into the afternoon. Meanwhile, a cold front
will approach from the northwest, reaching our land areas around
daybreak Saturday. In the morning, expect backing winds, followed by
gusty winds along the land/sea interface in the afternoon due to the
formation of the sea breeze. Gusts should be around 20 kt in the
Charleston Harbor with its passage. In the evening, winds will veer
and increase as some coastal jetting develops overnight.

Weekend: A cold front located across our inland zones Saturday
daybreak will slowly move southeast across our area Saturday.
It`ll be spread across our area Saturday night, then shift offshore
by Sunday night or Monday morning. Winds and seas don`t appear to be
high enough to prompt Small Craft Advisories. Expect
southerly/southwesterly flow ahead of the front and
northerly/northeasterly flow behind it.

&&

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

&&

$$

NEAR TERM...CPM
SHORT TERM...
LONG TERM...
AVIATION...CPM
MARINE...DPB