116
FXUS62 KCHS 060524
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
124 AM EDT Sat Jul 6 2024

.SYNOPSIS...
A weak cold front approaching from the west will stall inland
this weekend and linger through the middle of next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A mid-level ridge will remain across the forecast area tonight,
as a cold front draped over the Ohio and Tennessee Valley
gradually approaches the area. The rest of the night should
remain dry with few clouds and light southerly winds. Low
temperatures are forecast to favor values in the mid to upper
70s away from the immediate coast. Along the beaches and
Downtown Charleston, lows will struggle to get below 80 degrees.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
The upper ridge will be centered over northern Florida on
Saturday while a weak shortwave rotates around the northern
periphery during the afternoon. A weak cold front is forecast to
drop southeast into the area during the day, then stall nearby
through early next week. A corridor of extremely high PWATs
(2.25-2.5 in, near/above the 99% percentile) is expected to
roughly be oriented along and inland of I-95 in the afternoon,
between the surface front to the west and the 700 mb ridge axis
oriented roughly along the beaches to the east. Weak mid-level
subsidence inversion will help convective initiation to hold off
until midday to early afternoon, allowing temps to warm into the
mid-90s away from the immediate coast. This, in combination with
dew points in the mid 70s, will bring heat index values once
again to 105-110 degrees away from the beaches, and a Heat
Advisory will be needed for tomorrow afternoon.

By early afternoon, low level moisture convergence and inland
troughing will allow for the initiation of convection along and
inland of the sea breeze. Weak flow aloft will bring storm
motions only around 10 mph or less, which, combined with the
aforementioned elevated PWAT values and CAPE values near 2500
J/kg will bring the potential for a few strong storms inland
with locally heavy rainfall (amounts up to 3+ inches) and wet
microbursts producing gusty winds the primary concerns into the
evening. Convective activity diminishes and shifts inland
through the evening Saturday.

Sunday and Monday will continue to bring an unsettled pattern as
the weak front remains inland and weak disturbances aloft bring
periods of enhanced storm chances. POPs generally follow a
diurnal pattern, with widespread coverage inland both
afternoons, and relatively quieter conditions overnight.
Weakening of the upper ridge decreases the threat for dangerous
heat, but sufficient instability and moisture remain in place
for there to still be at least a limited threat for stronger
storms or locally heavy rainfall mainly along and west of I-95
each afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A fairly wet pattern likely to persist for much of next week due
to deep tropical moisture in place, continual shortwaves, and
inland/Piedmont troughing and weak moisture convergence
near/east of the weak cold front well inland. The greatest
coverage should be during the afternoon and evening hours.
Weaker ridging aloft and uncertainty surrounding precip timing
and coverage makes the dangerous heat threat more uncertain next
week. Additionally, there are no clear signals of any specific
day having an elevated severe weather threat, but at least a few
stronger storms and some localized heavy rainfall is possible
each day through at least mid-week as is normal this time of
year.

&&

.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...
KCHS/ KSAV: Terminals will remain VFR through most of the
issuance. Mid-level high pressure will begin to breakdown this
morning with upper level disturbances to the west and east. A
weak lee side trough (or convergence of surface winds) is again
forecast to take shape across the Midlands of South Carolina.
The best chance of showers and thunderstorms will likely be west
of KCHS/ KSAV, but these terminals appear far enough inland (at
least from current guidance) to maintain the mention of vicinity
thunder. Confidence is slightly lower at KCHS though, as
forecast soundings do show some dry air remaining in the profile
tomorrow afternoon (much less so at KSAV).

KJZI: VFR through the issuance expected. Mid-level high
pressure will begin to breakdown this morning with upper level
disturbances to the west and east. A weak lee side trough (or
convergence of surface winds) is again forecast to take shape
across the Midlands of South Carolina. Charleston Executive will
be to close to the coast Saturday with showers and
thunderstorms forming inland, or away from the terminal.
Therefore there is no mention of vicinity thunder.

Extended Aviation Outlook: Brief flight restrictions are possible in
showers and thunderstorms, mainly in the afternoon and evenings,
this weekend through the middle of next week.

&&

.MARINE...
Tonight: The sfc pattern will support south winds between 10 to 15
kt. Seas will favor values around 3 ft, with 2 ft seas common
within 5 km of shore.

Saturday through Wednesday, a typical summertime pattern will
persist, with prevailing moderate southerly flow, gusty winds
developing near the coast in the afternoon and persisting into
the evening/overnight hours, and only modest medium period SE
swell keeping seas mainly 2-3 ft. In summary, winds/seas
expected to remain below advisory thresholds.

Rip Currents: A swell of 2 feet every 9 to 10 seconds and proximity
to the new moon will maintain a Moderate Risk for rip currents for
Saturday.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for GAZ087-088-099>101-114>119-137>141.
SC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for SCZ040-042>045-047>052.
MARINE...None.

&&

$$

NEAR TERM...BRM/NED
SHORT TERM...CEB
LONG TERM...CEB
AVIATION...BRM/CEB/Haines
MARINE...CEB/NED