464
FXUS62 KCHS 111953
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
353 PM EDT Thu Jul 11 2024

.SYNOPSIS...
A weak front will meander across the area through Saturday.
Atlantic high pressure will then rebuild across the area while
a surface trough exists inland Sunday through the middle of
next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A weak front will be draped across the region tonight. Focus
for isolated to scattered showers and thunderstorms the rest of
the afternoon and evening will be across the Charleston tri-
county, especially closer to the Santee River where deeper
moisture and better instability resides. Rain chances will
persist over these general areas through the night, with
coverage expected to really pick up during the latter half of
the night towards daybreak as weak vort energy shifts onshore
the South Carolina coast. Main concern with this activity is
locally heavy rainfall. Areas further south across Georgia
should largely remain precip-free. Low temperatures will average
in the low to mid 70s, with upper 70s/near 80 along the coast
and in Downtown Charleston.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Friday: A weak surface low will be over southeast GA by late Friday
morning, drifting slowly west while dissipating during the day. A
subtle boundary associated with the low may remain draped across
southern SC for much of the day. A decent moisture gradient will
persist across the area, with somewhat drier air remaining over
southeast GA while 2.25-2.5 inch PWATs spread into southern SC.
Moisture convergence and greater theta-e advection across the Low
Country will likely result in persistent at least scattered showers
and storms through the morning. Weak winds aloft and moderate
southerly low level winds bring the potential bring the potential
for persistent development on the southern flank of cold pool and
other boundaries, with slow storm motions and potential back
building storms possibly mainly across the Charleston Tri-County
area, where some localized daily rainfall amounts could reach into
the 3-4+ inch by the afternoon. Further south, convective initiation
will be mainly driven by a solid afternoon resultant sea breeze
pushing inland. Convection may persist well into the evening,
but coverage and intensity are expected to wane after sunset.

Saturday: Upper ridging begins to strengthen Saturday, though a
plume of greater low level moisture persists across the coastal
Carolinas with a weak front remaining inland. A weak wave could
bring some modest rainfall potential enhancement early Saturday
morning along the SC coast, with POPs otherwise trending toward a
more summerlike pattern, with scattered to widespread showers/storms
focused in the afternoon. Marginally lower dewpoint and clearer
skies will bring temps climbing into the mid to upper 90s along and
west of I-95 Saturday afternoon, while more moderate temps by
greater dew point values east of I-95 bring a relatively uniform
expectation of heat index values reaching 100-105 across the area
Saturday afternoon.

Sunday: Latest guidance indicates a weak sfc trough/front drifting
further inland and likely in a dissipating state while subtle h5
vort energy passes across the Mid-Atlantic and Southeast states
along the base of a low amplitude trough. These features should
provide sufficient forcing and/or a focusing mechanism for afternoon
convection in a moist environment (PWATs around 2 inches) just
inland to the area, before a westerly flow between the mid-upper
trough to the north and a ridge to the southwest nudges activity
across the local area. Some enhancement along a sea breeze shifting
inland is possible, at least in regards to carrying chances of
showers and thunderstorms across the entire area. A stronger
thunderstorm can not be ruled out, but overall organized severe
weather potential remains low. Outside of precip, conditions will
become quite warm, with afternoon highs in the mid-upper 90s away
from the coast. The combination of these temps and mid-upper 70s sfc
dewpts could lead to heat indices that approach Heat Advisory levels
along and east of the I-95 corridor. A Heat Advisory could
eventually be needed across part of the local area.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Broad upper ridging will gradually strengthen across the Southeast
United States early next week, though subtle h5 vort energy could
drift across the area at times along the base of a low amplitude
trough to the north. At the sfc, Atlantic high pressure will prevail
to the east while a sfc trough lingers just inland. The summer like
pattern will support at least scattered showers and thunderstorms
each afternoon. Outside of precip activity the pattern supports very
warm and humid conditions through the first half of the week. High
temps in the mid-upper 90s along with sfc dewpts in the mid-upper
70s will likely support areas experiencing heat index values above
108 degrees each afternoon Monday through Wednesday. Heat index
values could even approach Excessive Heat Warning criteria (113F)
across parts of the area Tuesday and Wednesday afternoon.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
Prevailing VFR through at least tonight. There is potential for
brief impacts from isolated/scattered showers and thunderstorms
at KCHS and KJZI this afternoon. Late tonight into Friday,
flight restrictions will be possible in MVFR ceilings and in
showers/thunderstorms again. Further south at KSAV, prevailing
VFR through 18z Friday. Low chance for restrictions in
showers/thunderstorms on Friday.

Extended Aviation Outlook: Scattered afternoon showers/thunderstorms
could produce tempo flight restrictions at CHS/JZI/SAV terminals
each afternoon early next week.

&&

.MARINE...
Tonight: Winds will largely be out of the south and east
through tonight. Conditions remain well below small craft
advisory criteria with speeds 10 knots or less and seas 2-3
feet.

Friday/Saturday: Mainly light and variable winds Saturday morning
become more uniformaly moderate S to SW winds later Saturday through
Sunday as weak high pressure moves onshore. Moderate SSE medium
period swell from breezy winds several hundred miles offshore will
spread into the waters Friday and Friday night, gradually increasing
seas from 2-3 ft Friday morning to 3-4 ft Saturday.

Sunday through Tuesday: Conditions are expected to remain below
Small Craft Advisory levels through early next week, but the
pressure gradient should slightly tighten between high pressure
centered offshore and trough that persists inland. In general,
southerly winds will be in place with temporary increases to around
15kt, mainly near the coast where sea breeze circulations develop,
then shift inland. Seas will range between 2-4 ft.

Rip Currents: Moderate SSE swell directed mainly north of Cape Fear
will work into Charleston County coast Friday. The modest increase
in swell will bump the rip current risk to Moderate for the
Charleston County beaches.

&&

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

&&

$$

NEAR TERM...ETM
SHORT TERM...CEB/DPB
LONG TERM...DPB
AVIATION...CEB/ETM
MARINE...CEB/ETM