817
FXUS62 KCHS 190028
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
828 PM EDT Thu Jul 18 2024

.SYNOPSIS...
A cold front will approach our region on Friday and likely
stall to our north and west through the weekend. High pressure
will return next week, with weak troughing inland.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Convection across the forecast area has weakened over the last
hour or two. Now turning attention to showers/storms in the
upstate region. Convection and associated outflow/cold pool
continues to congeal a bit while making an eastward advance
toward our area. Will see how it well the convection can
maintain as we get into the nighttime cooling cycle. But latest
timing suggests showers and some thunderstorms will reach the
western part of the forecast around 10 pm.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
The mid-levels will consist of broad troughing over the eastern half
of the U.S. on Friday. High pressure starts to build into our region
from the western Atlantic on Saturday, prevailing into Sunday. This
will yield southwest flow overhead. At the surface, a cold front
will approach our region Friday morning, then stall just to our
north and west Friday afternoon and evening. The front should lift
back to the north and inland Friday night, remaining further to our
north and west this weekend. There will be deep moisture across the
region. PWATs will mainly be over 2", with hints that they could
briefly get as high as 2.5" at times through the weekend. The
highest PWATs are most likely just ahead of the front on Friday.
High temperatures are forecasted to be in the lower to middle 90s
each day across most of our area, except cooler at the beaches. The
combination of heat and moisture will generate plenty of
instability, causing scattered to numerous convection each afternoon
and evening. The most coverage and intensity should be on Friday,
due to the vicinity of the front. Otherwise, it should be a bit
lower during the evening and overnight periods this weekend. As for
the severe threat, a strong to marginally severe thunderstorm cannot
be ruled out each day. The main hazard would be damaging winds.
Locally heavy rainfall is also possible in areas where there is
storm training. Though, steering flow should help move the storms
along each day. Also, heat indices should approach 105-108 degrees
along the coast each day. But the duration and coverage should not
be enough to warrant Heat Advisories, especially considering
afternoon convection will cool temperatures down. Overnight lows
will be in the 70s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A summertime pattern will persist with High pressure in the western
Atlantic and troughing along or near the Southeast U.S. This
synoptic flow will keep abundant moisture across the region. With
highs in the 90s, instability will generate afternoon convection,
trending lower during the overnight hours.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Showers and storms have diminished across the local region at
this juncture with VFR conditions dominant. However, there is a
broken line of showers and storms across the Midlands that may
roll down through the coast later this evening and overnight,
although weakening in time. 00Z terminal forecasts have VCSH,
03-07Z for KCHS/KJZI and 05-10Z at KSAV. Thunder is not out of
the question, but probabilities are too low to include in the
forecast at this juncture.

Quiet weather Friday morning. Another round of showers/storms is
likely Friday afternoon, largely after 18Z. Forecast features
VCTS at the terminals.

Extended Aviation Outlook: Convection could produce brief
flight restrictions, especially each afternoon/evening.

&&

.MARINE...
Rather stout winds have developed across the SC nearshore waters
and Charleston Harbor within the last few hours, with Small
Craft Advisory gusts likely to persist through the evening
hours. Have hoisted an SCA for those areas through 1 am. Winds
are still expected to weaken through the overnight hours.

Meanwhile, showers and thunderstorms over the upstate of SC
will head southeast and approach the waters this evening.
Thunderstorms appear likely across the Charleston nearshore
adjacent waters late tonight. Some of these storms may bring
strong wind gusts, Special Marine Warnings may be needed.

Extended Marine: A cold front will approach our region on Friday,
likely stalling to our north and west through the weekend. High
pressure in the western Atlantic is expected to return next week
along with weak troughing inland. This will yield a typical
summertime wind pattern for our coastal waters. Each day, expect
some backing of the winds. The strongest gusts will be along the
land/sea interface and across the Charleston Harbor due to the
afternoon sea breeze. Each night, expect some veering of the winds.
Stronger winds are possible near the coast due to the formation of
the nocturnal jet. Seas should average 2-4 ft.

Rip Currents: The combination of a 2 ft swell every 8-9 seconds and
gusty onshore winds with the afternoon sea breeze will support an
enhanced risk of rip currents through Saturday. Internal
calculations and RCMOS point towards it being a borderline
Low/Moderate Risk. We opted to maintain the Low Risk, but this may
need to be raised if any of the above parameters along with the
longshore current are stronger than anticipated.

&&

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

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 1 AM EDT Friday for AMZ330-350.

&&

$$

NEAR TERM...Adam/Haines
AVIATION...Adam/Haines
MARINE...Adam/Haines