FXUS62 KCHS 160755

Area Forecast Discussion
National Weather Service Charleston SC
355 AM EDT Sun Jun 16 2024

A weak cold front will linger over the area today before slowly
lifting back northward early this week. High pressure will then
ridge in from offshore mid to late week.


Today: A strong 5910-5920 meter anticyclone will prevail at 500
mb atop the local counties, while surface high pressure over New
England builds south along the eastern seaboard. This allows for
a weak cold front to drift south across the region, and that
along with the sea breeze will be the main features for any

PWat is as much as 1.5 to 1.8 inches, and MLCAPE is around
1500-2000 J/kg. This will be enough to generate at least
isolated to scattered convection this afternoon, mainly inland.
With the warm mid levels and some weak capping, there isn't any
risk for severe weather. In fact the HREF has little to no
chance of any t-storms at all, due to poor convective growth
with plenty of dry air above 700 mb. Maybe some gusty winds can
occur where boundary interactions occur, since DCAPE is forecast
to reach 800-900 J/kg.

Despite the strong ridging aloft, an easterly synoptic flow will
prevent temperatures from getting as hot as yesterday. A blend
of the various MOS, Hi-Res, and NBM guidances supports highs in
the upper 80s and lower 90s across the coastal counties and the
Charleston Tri-County district, and up to 92-94 near and west of
I-95. The immediate coastal sections will be a tad lower with
onshore winds peaking around 20 mph.

Tonight: Ridging persists aloft, maybe even strengthening a tad,
while at the surface the cold front washes out, and strong high
pressure east of Long Island extends across the Southeast and
into the Gulf of Mexico. Stabilizing influences with the
nocturnal environment will allow for isolated to scattered
convection to end by around sunset. High level clouds will
expand out of the Gulf of Mexico, which could have some
influence on low temperatures if they remain thin enough. Given
winds slackening through the night inland), we do anticipate it
getting a bit lower than it was the previous night. We have
minimums down to the upper 60s and lower 70s most places, except
middle 70s in the Charleston-North Charleston metro, downtown
Savannah, and along the barrier islands 9where breezy onshore
winds persist)


High pressure aloft will be centered over the southeastern states on
Monday. This anticyclone will progress towards New England on
Tuesday and Wednesday, with high pressure still holding strong over
the local area. At the surface, high pressure initially extending
into the forecast area from the NE will shift further into the
Atlantic by mid week, taking up residence with a more typical
Bermuda High location. A weak, stalled front will likely linger in
the vicinity of southeastern GA through Tuesday, yielding slight
chance PoPs Monday and Tuesday afternoons, primarily focused along
southeastern GA and coastal southeast SC. However, with subsidence
from the high pressure both aloft and at the surface, model
soundings are indicating a decent amount of dry air aloft. This dry
air will likely limit the overall coverage of showers/thunderstorms.
As the high pressure both aloft and at the surface start to shift
away from the local forecast area heading into mid-week
precipitation chances begin to increase as the subsidence begins to
break down. Temperatures are expected to remain around average, with
highs in the mid to upper 80s and overnight lows in the upper 60s to
low 70s.


Subsidence will continue to diminish aloft with the retreating high
pressure at the surface and aloft. The forecast will trend back
towards a more typical summertime pattern, with isolated to
scattered showers and thunderstorms in the afternoon hours. Moisture
is forecast to begin streaming into the region late week as a
possible low pressure disturbance lingers off the east coast of
Florida. This additional moisture will help to enhance afternoon
showers and thunderstorms, especially across southeast GA later in
the week. Temperatures are expected to remain near normal.


KCHS/KJZI/KSAV: VFR will prevail with the 06Z forecast, although
there is a chance for a period of MVFR ceilings for a few hours
this morning at any or all of the terminals with the flow off
the ocean.

Isolated to perhaps scattered afternoon convection will likely
not impact any of the sites.

All sites do become a little gusty during the peak heating of
the afternoon.

Extended Aviation Outlook: Prevailing VFR. Brief flight
restrictions are possible in afternoon showers/tstorms,
especially at KSAV.


Today: High pressure extends across the local waters as a weak
cold front meanders inland. There is a most gradient in place
which allows for E winds to reach 10 or 15 kt, with even some
gusts near 20 kt in Charleston Harbor this afternoon. Given the
favorable onshore fetch, seas will be at least 2-3 feet

Tonight: There's about a 2 mb spread in the gradient from north
to south across the area, as a 1026-1027 mb high east of Long
Island builds southeast. This will allow for E winds at least 10
or 15 kt, with seas of 2-4 feet.

Monday through Thursday: Generally, high pressure will prevail over
the local waters through the period. With high pressure extending
into the region from the northeast and a developing low pressure off
the east coast of FL the pressure gradient is expected to pinch
Tuesday into late week. This pinched gradient will likely result in
E winds 15 to 20 knots with gusts to 25 knots and seas building to
as high as 5 to 6 ft across the nearshore waters and 8 to 9  ft
across the 20-60 nm offshore GA waters. Small Craft Advisories will
likely be needed for most, if not all, marine waters.

Rip Currents: The Rip Current MOS shows a Low Risk of rip
currents at the beaches today, while the in-house calculator
came up with borderline Moderate Risk. Since both WFO JAX and
WFO ILM have a Moderate Risk, there have been numerous rip
currents during recent days, and there is a modest onshore wind,
we went with Moderate Risk as well.