689
FXUS62 KCHS 210153
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
953 PM EDT Thu Jun 20 2024

.SYNOPSIS...
A tropical wave will approach the Southeast coast tonight and
shift inland along the northeast Florida and southeast Georgia
coastline on Friday. High pressure will then become the primary
weather feature into the middle of next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Late this evening, the forecast appears on track. The update
will feature slight changes to sky cover.

Tonight, the forecast area will remain between a sfc ridge
centered over the western Carolinas and a tropical wave off the
coast of FL. NHC indicates a 50 percent of tropical cyclone
development over the next 48 hrs, see NHC for latest
information. Satellite water vapor shows a deep area of dry air
across the forecast area, expected to remain through tonight.
Latest runs of the HRRR, indicates that showers will struggle to
make it west of the Gulf Stream tonight. The updated forecast
will decrease PoPs across the land based zones tonight, with
showers over the marine zones. Low temperatures are forecast to
range from the mid 60s inland to the low to mid 70s along the
coast.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Friday and Friday night: The forecast for Friday will really hinge
on the tropical disturbance (AL92) and its progression inland during
the first part of the day. While the disturbance could still
strengthen and possibly develop into a Tropical Depression, the
impacts really don`t change much either way. The main impact will
come in the form of increased shower and thunderstorm activity as
the envelope of deep tropical moisture spreads inland. We expect to
see scattered to numerous showers and thunderstorms load up across
the coastal waters and then rotate onshore through the mid to late
morning hours. The best rain chances will be along the immediate
coast, especially the southeast Georgia coast which will be closer
to the center of circulation. As the day progresses, the best
coverage should shift inland and also shrink to the southwest,
favoring the southeast Georgia coast and all of interior southeast
Georgia. Rainfall amounts from this increased coverage will be
highly dependent on where individual shower/storm elements pass as
this will not be a large shield of precipitation. No significant
change to expected amounts, with 0.25-0.50 along the coastal
corridor with some potential for locally higher amounts along the
immediate coast (especially the GA coast). There are no severe
weather concerns. Winds will again be breezy thanks to the onshore
flow on the northside of the circulation, but gusts will be less
than previous days. High temperatures should mostly top out in the
upper 80s, with low 90s possible for interior southeast Georgia.
Overnight, rain chances should diminish, though we could still see
isolated to scattered development across southeast Georgia, closer
to the remnant circulation.

Saturday and Sunday: We will begin to transition back to a more
typical summertime pattern with the subtropical high extending into
the area from the east. However, there will still be the remnant
circulation from the disturbance across south Georgia as well
as the nearby deeper moisture profiles. The Saturday time period
is now within the hi-res model window and the overall consensus
is for the best convective coverage to be across southeast
Georgia closer to the remnant circulation and associated deeper
moisture. Therefore, the forecast has 60-70 percent chances in
the afternoon hours for southeast Georgia. For Sunday, we should
transition to a more typical diurnal thunderstorm pattern with
40-50 percent chances everywhere. Neither day looks to be
particularly supportive of severe thunderstorms, though you can
never count out boundary interactions producing a stronger
storm. Temperatures will begin a warming trend over the weekend,
with highs getting back into the low to even mid 90s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The early to middle part of next week looks hot with a return to
more typical diurnal coverage of showers and thunderstorms. The
forecast generally has rain chances peaking in the afternoon and
evening, then gradually transitioning to favor the Atlantic coastal
waters through the overnight hours. High temperatures are forecast
to rise into the mid to upper 90s, which will push heat index values
considerably higher than they have been. In fact, we expect to see
widespread 100-105 degree heat index values each afternoon Monday
through Wednesday. As the highest dew points reside within the
coastal corridor, we could see heat index values rise to around 108-
110, and we might have to consider Heat Advisories.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
0Z TAFs: Gusty east winds should gradually subside to 7-10 kts
by 1Z. Conditions tonight are forecast to remain VFR. Around
daybreak Friday, scattered to numerous showers with embedded
thunderstorms should develop along the coast, tracking inland
during the daylight hours. Each TAF will feature a mention of
VCSH by 12Z with predominate showers by 14Z. HREF indicates that
thunderstorm probabilities will peak between 15-19Z, highlighted
with TEMPOs.

Extended Aviation Outlook: Conditions should mostly be VFR. There
could be brief rounds of flight restrictions each afternoon and
evening with showers and thunderstorms.

&&

.MARINE...
Tonight: Pressure gradient will remain tight tonight between inland
high pressure and a tropical wave approaching the Southeast coast.
Northeast winds will generally average in the 15-20 knot range with
higher gusts to 25 knots. Seas will build to 5-7 feet out 20
nm and 7-8 ft beyond. These conditions will support a continuation
of Small Craft Advisories through the night across all marine
zones outside of the Charleston Harbor. For the Harbor, wind
gusts should subside some later this evening with the Advisory
scheduled to come down at 8 PM.

Friday through Tuesday: A tropical disturbance is expected to shift
onshore on Friday somewhere along the northeast Florida and
southeast Georgia coast. The circulation around this feature will
drive elevated northeasterly to easterly flow across the waters into
Friday evening. Seas should peak early Friday, then gradually
diminish through Friday night. Ongoing Small Craft Advisories remain
in effect, with ending times spanning the afternoon through the
evening as seas relax. Thereafter, conditions across the local
waters will transition to a more typical summertime pattern.
Southerly to southwesterly flow will tend to be strongest along the
land/sea interface with the diurnal sea breeze and sea will
typically be in the 2-4 ft range.

Rip Currents: Persistent onshore flow and lingering elevated seas
will again produce a High Risk of rip currents at all beaches on
Friday. Lifeguards continued to indicate hazardous swimming
conditions at area beaches, and these conditions are expected to
continue through Friday. As we get into Saturday, winds and seas
will relax and overall conditions should improve. However, we will
advertise a Moderate Risk of rip currents for Saturday. High
Surf: While there can be some occasional 5 foot breakers in the
surf zone today, most breakers will be 3 or 4 feet, so no High
Surf Advisory is required. Even so, some coastal areas will
experience erosion.

&&

.TIDES/COASTAL FLOODING...
Tide levels will continue to be elevated through Friday thanks
to persistent onshore flow and elevated seas. However,
astronomical tide values aren`t particularly high which will
reduce the overall coastal flooding risk. The Friday evening
high tide (~8:30 pm) will be elevated but should fall short of
the threshold for minor coastal flooding.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents through Friday evening for GAZ117-119-
     139-141.
SC...High Risk for Rip Currents through Friday evening for SCZ048>051.
MARINE...Small Craft Advisory until 4 PM EDT Friday for AMZ350-352.
     Small Craft Advisory until 7 PM EDT Friday for AMZ354.
     Small Craft Advisory until 11 PM EDT Friday for AMZ374.

&&

$$

NEAR TERM...NED
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...NED
MARINE...BSH/ETM