608
FXUS62 KCHS 132159
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
559 PM EDT Thu Jun 13 2024

.SYNOPSIS...
A stationary front will meander near or just off the coast
through the end of the week. A weak cold front will drop into
the forecast area early this weekend before high pressure
spreads in from the north.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Two waves of low pressure will pass offshore overnight along a
stalled frontal boundary. Drier, low mean theta-e air will
slowly work south through the night as these lows pass by. KCLX
shows isolated showers slowly diminishing with time with the
better focus shifting south. As drier air works in from the
north, the risk for isolated showers will remain mostly confined
to the Georgia coast overnight as northeast winds slowly back.
Breezy conditions along the beaches will persist into mid-
evening before the pressure gradient begins to relax some. Pops
were adjusted slightly to reflect current trends and to hang
onto mentionable pops along parts of the Georgia coast well into
the overnight period. Lows from the upper 60s inland to the mid
70s at the beaches look on track, although lows for Waterfront
Park in Downtown Charleston were nudged up by about 2-3 degrees
given the expected wind directions should keep air parcels
advecting across the warmer waters of Charleston Harbor.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Friday: The mid-levels will initially consist of a weak trough
stretching from off the Southeast Coast into the eastern Gulf of
Mexico. As time progresses, this trough will shift further
offshore, then lift to the northeast. At the surface, a
stationary front will be just off our coast in the morning,
gradually shifting further away into the evening and overnight.
Additionally, a dry cold front will approach from the northwest
late at night. Though, it`s not expected to reach our area. The
highest PWATs should remain offshore during the day, with drier
air likely over a large portion of our area. The synoptic
models have trended drier, pointing to isolated to maybe
scattered convection across GA. This is also in line with the
CAMs. So we kept slight chance POPs along our GA coastline
during the afternoon, and low POPs across our SC coastline.
Soundings indicate limited instability, so probabilities are
higher for showers as opposed to thunderstorms. Anything that
does develop will dissipate in the evening, with the overnight
being dry. Highs will peak in the lower to mid 90s for most
areas, except cooler at the beaches. Lows will be in the lower
to mid 70s.

Saturday: A mid-level trough offshore will continue to move
away while ridging gradually builds over the Southeast. A weak
cold front will be located just to our north at daybreak. It`s
expected to slowly shift south during the day and weaken, likely
stalling around the Savannah River during the evening and
overnight. Moisture increases around the front, with PWATs
possibly rising to 1.75 by late afternoon. The combination of
the increasing moisture, lift from the front, and a somewhat
robust afternoon sea breeze could generate isolated to maybe
scattered convection in the afternoon. This will be highly
dependent on how much mid-level dry air is in place. We have
slight chance POPs, but these may need to be raised. Any
remaining convection should shift towards the coast during the
evening, then remain along the immediate coast overnight. Highs
will be in the mid to upper 90s for most areas, except cooler at
the beaches. Lows will be in the lower to mid 70s.

Sunday: The mid-levels will consist of High pressure mainly over
the Southeast. At the surface, a stationary front should be
located over our GA counties in the morning. It`s expected to
shift south and dissipate in the afternoon as High pressure to
our north and northeast tries to build into our area. There
should be enough moisture and lift near the front to generate
scattered convection, so we have chance POPs across most our our
area, with lower POPs generally across the Charleston Tri-
County. Though, the dry air moving in from the north will
determine how much convection is able to develop or not develop.
Highs will again reach into the low to mid 90s away from the
immediate coast.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Anticyclonic flow aloft, mainly across the Southeastern U.S.,
will prevail through early next week. Surface high pressure
located along the New England coast will advect modestly dry air
into the area despite the onshore flow, although some Atlantic
moisture could move in far south into Southeast Georgia. The
forecast features isolated showers in the afternoon/evening each
day through early next week. Thunderstorms chances look slim at
this juncture with little instability to work with and little
to no forcing with a fairly strong capping inversion in place.
Convection chances could increase if additional moisture
advection occurs, which for this time of year, is pretty easy to
have happen. Temperatures should sit around normal or slightly
above normal due to increased insolation.

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
14/00z TAF Discussion:
KCHS/KJZI/KSAV: VFR. Marine-based stratocumulus could once again
impact all three terminals overnight at least until winds back
more northerly prior to daybreak Friday. Cumulus will develop
shortly after daybreak and push inland through the afternoon
with the passage of the sea breeze.

Extended Aviation Outlook: Mainly VFR. There will be low
probabilities of brief flight restrictions due to
afternoon/evening showers/tstms.

&&

.MARINE...
Tonight: A quick update has been issued to hoist a Small Craft
Advisory for all nearshore legs between South Santee River and
Altamaha Sound, including Charleston Harbor, through 8 PM. Buoy
and wind observations from the WeatherFlow network show winds
20-25 kt with gusts as high as 30 kt. The latest RAP shows a
nice wind surge working slowly south down the coast over the
next few hours. The highest winds should be confined to
Charleston Harbor and the South Santee-Edisto Beach leg, but
gusts to 25-30 kt will be common as far south as Saint
Catherines Sound.

Low pressure offshore will gradually deepen as it rides up the
Gulf Stream tonight. Moderate NE winds persist. Showers and a
few storms remain possible over the waters into the evening, but
coverage and storms will be limited. Seas remain 3-5 ft through
the evening, diminishing to 2-4 ft late in a mix of southeast
and northeast wind swells.

Friday through Tuesday: A stationary front will be just off our
coast Friday morning, gradually shifting further away into the
evening and Friday night. Additionally, a dry cold front will
approach from the northwest late Friday night. The cold front is
expected to slowly shift south Saturday and weaken, likely
stalling around the Savannah River during the evening and
Saturday night. The front is expected to shift south and
dissipate Sunday afternoon as High pressure to our north and
northeast tries to build into our area. Wind speeds will average
10-15 kt with seas 2-4 ft.

Rip Currents: Gusty NE winds in the morning will become onshore
in the afternoon Friday. Additionally, a SE swell around 2 ft
near 7 seconds should impact the beaches along with a
potentially moderate to strong longshore current. This could
lead to rip currents. Hence, there is a Moderate Risk for the
GA beaches, especially Tybee Island.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for AMZ330-
     350-352-354.

&&

$$