548
FXUS62 KCHS 282300
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
700 PM EDT Fri Jun 28 2024

.SYNOPSIS...
A weak front will linger near the area today. Atlantic high
pressure will return over the weekend, while a trough of low
pressure resides inland. A cold front will likely to impact the
area early late Sunday into early next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Aloft a weak, elongated, positively tilted shortwave trough
will be positioned over the southeast coastline. At the surface
a stationary front will linger in the vicinity of the forecast
area.

Poor lapse rates and much less DCAPE than yesterday has kept
storms in check, and with the lack of forcing and the onset of
the nocturnal environment, the trend will be for a decreasing
coverage to convection. Expect the region to be completely
rainfree before midnight. There are indications that a few
showers could make it onshore of coastal areas closer to
daybreak. But the probabilities are much too low to include at
this stage.

Patchy fog and stratus may impact some areas in the early
morning hours, especially places which received precipitation.
Overnight temperatures are forecast to dip into the lower 70s
well inland to the mid and upper 70s along the coastal
coutnies.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Saturday and Saturday night: The area will be dominated by a deep
layer ridge, centered to the south and east. Very little in the way
of upper level features to help force afternoon convection. However,
with light southerly flow, ample deep layer moisture with PWs around
2 inches, and mean CAPE values of 1500-2000 J/Kg, expect scattered
afternoon showers and thunderstorms. The main trigger will be the
seabreeze, then the combo of the seabreeze and convective outflow
boundaries. Have continued likely PoPs west of I-95 and chance
elsewhere. With light steering flow, locally heavy rainfall will be
possible. Convection should be diurnally driven, decreasing into the
evening. Temperatures above normal, with highs in the lower to mid
90s and lows in the mid to upper 70s.

Sunday and Sunday night: The pattern becomes a little more active
during this period as a broad upper trough takes shape over the
northeast U.S. and OH River Valley area. The associated surface cold
front approaches from the northwest by late day/Sunday night, but
should remain well northwest of the area through the day. However,
the increased low level convergence upstream/northwest of the area
will likely help to spark a line of shower/thunderstorms, which
could propagate southeast into our northern area via outflow
boundaries. The presence of some cyclonic flow at upper levels,
better low level convergence, and CAPE values near 2000 J/Kg will
lead to the potential for isolated strong to severe storms,
especially over our SC region, which is where the SPC has a Marginal
Risk. Main impact from stronger storms will be strong/gusty winds.
Also, depending on cloud/convective coverage, temperatures could
spike into the lower to mid 90s due due to some compressional
warming ahead of the front. These temps combined with surface Tds in
the lower to mid 70s, would result in max heat indices of 105 to
109, which would be marginal Heat Advisory conditions. Will continue
to monitor this potential. Again, convection likely to decrease by
evening with loss of heating. However, given the presence of the
upper trough along with the cold front sagging into the area, would
not be surprised to see isolated to scattered convection last
through the night, especially north of the Savannah River.

Monday:  The cold front that was advancing into the area Sunday
night is shown by models to stall over the region. Deep layer
ridging builds north and west of the area, with low level easterly
flow. Given the lingering front and sufficient moisture /PWs around
2-2.25 inches/, expect scattered to numerous showers/thunderstorms.
Highs a tad lower than the previous day given the front and cloud
cover.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A slightly quieter weather pattern is expected for much of this
period as a deep layer ridge continues west and north of the area
with light south-southeast winds. With little to no upper level
features to trigger convection, any convection during this period
will mainly be triggered by afternoon heating and the presence of a
seabreeze. Expect a weak front to linger over the area Tuesday, but
then dissipate Wednesday and beyond. Given the lingering front on
Tuesday, have continued likely PoPs, especially over the southern
half of the area where the best moisture will reside. Wednesday and
beyond, kept more climo level/chance PoPs. Given PWs remain 2+
inches much of this period, along with light steering flow, any
stronger showers/thunderstorms could produce locally heavy rainfall.
Temperatures generally near normal Tuesday, then possibly climbing
back to above normal Wednesday and Thursday.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
KCHS/KJZI/KSAV: Keeping watch on the nearby showers around KSAV
early this evening. Otherwise convection is done with at the
terminals for tonight.

There will be some SHRA/TSRA activity along the sea breeze
Saturday as it moves inland. No more than VCSH during the late
morning and early afternoon at KJZI as it passes through, with
VCTS at KCHS and KSAV during the afternoon hours. Any direct
impacts would result in brief flight restrictions.

Extended Aviation Outlook: Prevailing VFR. Brief flight
restrictions are possible in showers and thunderstorms, mainly
in the afternoon and evenings.

&&

.MARINE...
South to southwest winds at less than 10 or 15 kt will remain
dominant across the coastal waters through tonight. Seas will
run 3 feet or less.

Extended Marine: No highlights are expected through the period.
Generally southerly winds are expected to persist through
Monday as a surface ridge remains east and south of the waters.
Winds of 15 knots or less and seas 2 to 4 feet. Slightly
stronger winds possible Sunday and Sunday night as the pressure
gradient increases ahead of a cold front. Monday and Tuesday, a
cold front is expected to stall over the waters, creating
lighter winds, generally 10-15 knots from the south- southeast
and seas 2 to 3 feet.

Rip Currents: Latest guidance indicating very marginal Moderate Risk
for rip currents on Saturday. Given surrounding offices going with
Moderate, and we are going into a weekend, have opted to maintain
Moderate Risk for Saturday. Low risk for Sunday.

&&

.FIRE WEATHER...
The South Carolina forestry commission reported low fuel moistures
across portions of the area on Thursday. However, rainfall on
Thursday and the potential for rainfall over the next few days
will help to alleviate some of the low fuel moisture values.

&&

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

&&

$$

NEAR TERM...
SHORT TERM...CPM/RFM
LONG TERM...RFM
AVIATION...
MARINE...Adam