983
FXUS62 KCHS 021609
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1209 PM EDT Tue Jul 2 2024

.SYNOPSIS...
A stalled front will linger near the area today before
dissipating offshore. A hot and humid air mass will build over
the region during the latter half of the week. A weak cold
front could approach the region by Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
This Afternoon: The front has now drifted south the Altamaha
River, however shower activity has been slow to wane. Showers
with a few tstms will linger south of I-16 for a few more hours
before most of the activity dissipates. Near term pops were
adjusted slightly and the mention of tstms was cut back even
more given the mostly stable conditions that are in place. Gusty
northeast winds will persist along the South Carolina beaches
into Tybee Island, GA, due to pinched gradient conditions behind
the front. Highs in the coastal corridor and south of I-16 were
also nudged down a bit more. Skies are trying to clear for areas
near the CSRA and Southern Midlands, so the warmest conditions
will be found well inland. The risk for flooding rainfall along
the Georgia coast is steadily diminishing.

Tonight: Latest guidance has trended a bit more toward holding onto
precip activity south of the front across southeast Georgia.
However, diurnal heat loss should result in most convection to wane
during evening hours. Additional showers and thunderstorms could
redevelop across coastal waters and make a run toward the coast
late. At this time, scattered showers and thunderstorms remain in
the forecast across coastal areas through much of the night to
account for this possibility. Low temps should range between the low-
mid 70s inland to upper 70s near the beaches.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
High pressure off the mid-Atlantic coast will extend across the area
on Wednesday, while a stalled front lingering nearby eventually
dissipates. Aloft, a mid level ridge will build over the Southeast.
Best potential for convection will be near the southern South
Carolina coast and across southeast Georgia where deepest moisture
resides. Further inland and to the north should not see as much
activity. Highs will be in the upper 80s to lower 90s. Lows
Wednesday night will range from around 70 inland to upper 70s at the
beaches.

Mid level ridge will dominate the pattern aloft Thursday and Friday.
The surface will feature high pressure offshore and a trough of low
pressure inland. Mainly just isolated to perhaps scattered diurnally-
driven showers and thunderstorms are expected each afternoon and
evening. Otherwise, temperatures and humidity will be on the rise.
Highs will be in the low to mid 90s on Thursday, with heat indices
topping out in the 100-105 range. Friday will be a bit hotter, and
heat indices could approach local Heat Advisory criteria of 108
degrees in spots. Lows will be in the 70s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
Guidance is in good agreement in the extended. Mid level ridge will
hold over Southeast coast into the weekend, before weakening. At the
surface, a trough of low pressure will persist inland with high
pressure offshore. It should get a bit more convectively active than
previous days with better instability and possibly weak upper
support. Current forecast highlights chance PoPs (generally 40-50%)
each day with coverage peaking in the afternoon and evening. We are
continuing to monitor the potential for excessive heat. Highs temps
mainly in the mid to perhaps upper 90s combined with elevated dew
points will make it feel even hotter. Heat indices are forecast to
approach or exceed 108 in many locations, with some potential to
even hit 113. Excessive heat headlines could eventually be needed.
Convection could disrupt temperature trends.

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
02/18Z TAF Discussion:
KCHS/KJZI: VFR through the period. There is a chance near MVFR
cigs could develop near KJZI after midnight as shower activity
off the lower South Carolina coast tries to develop. VCSH was
highlighted at KJZI 08-14z for now.

KSAV: MVFR cigs will improve to VFR 20-21z. VFR should then
dominate through late evening. After that, the risk for MVFR
cigs will increase again as shower activity off the coast draws
closer to the coast.

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

&&

.MARINE...
Winds are howling over the waters north of the Savannah River
Entrance this morning where pinched gradient conditions are
occurring. Gusts in excess of 30 kt have been observed at times.
The Small Craft Advisory was extended south to include the
Edisto Beach to Savannah nearshore waters and a Marine Weather
Statement was issued to address winds near 30 kt at the Savannah
River Entrance where especially rough conditions are likely. The
advisory runs through 4 PM.

Today and Tonight: A fairly enhanced pressure gradient has developed
across northern SC waters off the Charleston County coast outside of
convection. Given recent obs across local waters a Small Craft
Advisory is now in effect until 2 PM for gusts around 25-30 kt and
seas up to 4-6 ft. Thereafter, guidance continues to indicate that
the gradient will begin to relax while a ridge of high pressure
persists aloft. Otherwise, expect northeast winds between gusting
around 20 kt outside shower/thunderstorm activity across southern SC
nearshore waters and nearshore GA waters, and more easterly and
light south of a stalled front/boundary across offshore Georgia
waters. Overnight, the front should begin to drift south of local
waters and/or dissipate, but showers and thunderstorms will continue
to pose localized higher wind gusts and reduced vsbys at times until
that occurs. Outside of this activity, winds should gradually weaken
(10-15 kt) and seas should subside to 2-4 ft.

Wednesday through Sunday: Northeast/east winds initially will turn
southerly by late week. Marine conditions should stay solidly below
small craft advisory criteria with speeds 15 knots or less and seas
no higher than 4 feet.

&&

.TIDES/COASTAL FLOODING...
Charleston Harbor: Minor coastal flooding is likely at Charleston
Harbor this evening (606 PM) as departures remain around +1.48 ft
above astronomical (as of 1030 AM). Taking a look at the latest P-
ETSS and ETSS guidance shows models running behind at initialization
with a a 0.5/ 0.7 ft anomaly needed for correction. This is likely
due to guidance not handling the tight pressure gradient/ stalled
cold front along the coast well. Given the above, the latest
forecast for Charleston Harbor is for a 7.2 ft high tide this
evening (606 PM) with potential upside to 7.4 - 7.6. A coastal flood
advisory will likely be needed. Another round of coastal flooding is
then possible Wednesday evening as winds veer around from the
southeast.

Fort Pulaski: Tidal departures continue to increase this morning and
now are up to +1.67 ft above astronomical (as of 1030 AM). Forecast
guidance also is running behind this morning, and this is likely due
to global guidance (which the ETSS and P-ETTS use as forcing) not
capturing the tightening gradient along the coast with multiple
offshore reporting sites observing wind gusts just shy of 30 mph.
The current forecast high tide at Fort Pulaski this evening (608 PM)
is 9.3 ft. There is some upside potential here as the tight pressure
gradient from the stalled frontal zone remains in the region.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Coastal Flood Advisory from 4 PM this afternoon to 8 PM EDT
     this evening for SCZ049-050.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for AMZ350-
     352.

&&

$$