615
FXUS62 KCHS 161820
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
220 PM EDT Tue Jul 16 2024

.SYNOPSIS...
High pressure will persist offshore, while a weak trough
resides inland through mid week. A cold front will approach the
region late week and likely stall nearby.

&&

.NEAR TERM /THROUGH TONIGHT/...
17Z SPC mesoanalysis 1-2K J/Kg MLCAPE across the forecast area
with minimal CINH. Afternoon satellite image shows building Cu
primarily along and west of the I-95 corridor and showers west
more inland toward the Midlands. Another batch of showers/storms
is ongoing farther south toward the JAX ea. But thus far,
shower/storm development is lacking across our forecast area.

Still monitoring trends. Despite the instability, low level
convergence across the forecast area does appear to be a bit
more limited as compared to the last few days. It`s noteworthy
that recent high-res guidance has and remains rather minimal
with convection this afternoon, particularly the HRRR. That
said, it wouldn`t take much to trigger convection. Will see how
convection/outflows progress upstream and locally along the
marine layer over the next few hours.

Tonight: Convection will gradually wind down with rain-free
conditions prevailing after midnight. It will remain warm and
humid with lows from the mid 70s well inland to the lower 80s
at the beaches and Downtown Charleston.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
Ridging aloft will begin to break down on Wednesday as a broad
trough amplifies into the southeastern states. At the surface a
cold front will begin to approach the region, likely stalling in
the vicinity of the Carolinas late in the week. PWATs ahead of
the cold front will increase to over 2 inches along with
moderate to strong instability. With some synoptic forcing from
the approaching front combined with the local sea breeze,
scattered to numerous showers and thunderstorms are forecast to
develop each afternoon, with PoPs generally increasing as the
week progresses. While the threat for organized severe
thunderstorms is low, with DCAPE values forecast around 800 J/kg
a strong to marginally severe thunderstorm cannot be ruled out.

Conditions Wednesday and Thursday are expected to be hot and
humid, with slightly cooler high temperatures on Friday as the
cold front approaches. Heat Index values on Wednesday and
Thursday are forecast to reach 105-107, with some locations
reaching 108F. Heat Advisories may be required for portions of
the forecast area. However, afternoon convection may hinder
temperatures from reaching their full potential. Friday high
temperatures are forecast to reach into the low to mid 90s, with
Heat Index values of 102-105, below Heat Advisory criteria.
Overnight low temperatures will provide little relief, only
dipping into the mid 70s inland and upper 70s to around 80 along
the coast. The record high minimum temperatures could be
challenged at all three of the climate sites, see the Climate
section for more details.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
Broad troughing aloft will prevail this weekend, with high
pressure extending into the forecast area from the Atlantic
early next week. At the surface, a front is forecast to linger
in the vicinity of the Carolinas through the weekend, yielding
elevated PWATs. Between lingering forcing from the nearby front
and the afternoon sea breeze circulation scattered to numerous
showers are forecast each afternoon. Guidance continues to be
rather bullish with PoPs through the long term period, so the
current forecast maintains chance to likely PoPs, still above
climatology. With above normal precipitation chances and
increased cloud cover through the period temperatures are
forecast to return to near normal, or even slightly below normal
through the weekend.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
16/18z TAF Discussion:
KCHS/KJZI/KSAV: VFR for much of the period through 17/18z. There
remains is a risk for afternoon showers/storms this afternoon
although nothing has developed near the local terminals thus
far. KSAV may still have the best shot for direct impacts from
convection late in the afternoon with lower chances at
KCHS/KJZI. Forecast has maintained VCTS and TEMPO for TS at KSAV
afternoon 22Z. But confidence is on the lower side.

Extended Aviation Outlook: Scattered afternoon showers/tstorms
could produce brief flight restrictions at all terminals this
week.

&&

.MARINE...
Today: Modest nocturnal surging should end prior to daybreak.
South to southwest winds will prevail today with sea breeze
enhancements likely near the land/sea interface and Charleston
Harbor as the sea breeze moves inland. Speeds will average 10-15
kt, but may be closer to 15 kt with gusts to 20 kt at the
beaches and Charleston Harbor. Seas will average 2-4 ft.

Tonight: Another modest noctural surge is expected, especially
for the South Carolina waters north of the Savannah River
Entrance. Winds will range from 15-20 kt in the South Santee-
Edisto nearshore leg to 10-15 kt with gusts to 20 kt over both
Georgia marine zones. Winds will remains somewhat tempered in
the Charleston Harbor, but should still hold in the 10-15 kt
range. Seas will average 2-4 ft.

Wednesday through Saturday: High pressure will prevail across
the marine zones while a cold front approaches the inland zones.
This will yield a slightly pinched pressure gradient between
the approaching cold front and the high pressure over the marine
waters. Overall, conditions are expected to remain below Small
Craft Advisory criteria. However, there is a chance that the
Charleston nearshore waters could see wind gusts to 25 knots on
Wednesday. Otherwise, generally S winds are forecast, 10-15
knots. Slightly stronger wind speeds are possible along the
direct coastline in association with the afternoon sea breeze.
Seas should average 3 to 4 ft.

&&

.CLIMATE...
Record High Minimum Temperatures:

July 16:
KCHS: 78/2023
KCXM: 82/2021
KSAV: 82/1883

July 17:
KCHS: 78/2023
KCXM: 82/2021
KSAV: 80/1883

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 7 PM EDT this evening for GAZ116>119-
     138>141.
SC...Heat Advisory until 7 PM EDT this evening for SCZ043>045-
     047>052.
MARINE...None.

&&

$$