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000
FXUS62 KCHS 282345
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
745 PM EDT Wed Jul 28 2021

.SYNOPSIS...
High pressure will build over the area through Saturday,
bringing dry and hot conditions. A cold front will then stall
over the area Sunday through the middle of next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Radar has become little more active in the past hour as the last
few showers and storms form on northern fringe of the southward
moving deep layer moisture region. Expect scattered showers and
thunderstorms to gradually taper off through the evening over
the extreme southeast part of the forecast area/Altamaha river
basin. Otherwise, no major changes to the previous forecast.
A warm and muggy night is expected, with lows in the mid 70s
most area, even upper 70s near the coast. Model soundings show
near saturation in the lowest few hundred feet. This moisture,
combined with a wet ground from previous rainfall, light winds
and clearing skies is expected to lead to patchy fog late
tonight.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
An upper ridge will expand to the east during the period,
bringing hot temperatures and mainly dry conditions. The warmest
temps are expected Friday through Saturday once a 15-20 kt
westerly flow develops at 850 mb. A somewhat drier airmass will
move in, with PWs at or below 1.75" most of the time. This,
combined with strong mid-level subsidence, will prevent
convection from developing Thursday and Friday. A slight
increase in moisture late Saturday, combined with a weak
shortwave, could spur a few showers and tstms to develop or move
in from the northwest.

The hot temps and heat indices are the main concern during the
period. Although far inland dewpoints should mix down to the low
70s each day, a fairly good sea breeze will surge dewpoints into
the mid/upper 70s across the eastern half of the area during the
afternoons. Temps forecast to reach the low to mid 90s Thursday
and mid/upper 90s Friday/Saturday. We`re currently showing heat
indices of 105-109F on Thursday with a significant area of
110-114F Friday and Saturday. A few areas closer to the coast
where hot temps intersect with particularly high dewpoints could
touch 115F at times Friday and Saturday. We will likely require
Heat Advisories for much of the area Friday and Saturday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
An upper ridge will set up to our west late this weekend into
the middle of next week while a front stalls over the area. A
wet period is anticipated with numerous showers and tstms each
day, including during the overnight hours.

&&

.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
Tonight: The threat for showers/thunderstorms seems to be over
for all sites. VFR conditions expected for the first part of the
night. However, main concern continues to be the potential for
at least patchy fog at all sites. Have continued previous MVFR
vsbys, but continue to monitor for the potential for IFR vsbys
and CIGS, especially KCHS and KJZI. Any restrictions will
improve back to VFR after 13z Friday.

Extended Aviation Outlook: Flight restrictions are possible in
afternoon/evening showers and thunderstorms Saturday and Sunday.

&&

.MARINE...
Tonight: No significant changes to the previous forecast. Quiet
marine conditions will prevail with generally light and variable
winds of 5-10 knots or less. Seas will average 2-3 feet.

Fairly persistent SW flow anticipated Thursday through early
next week. Winds could get close to Small Craft criteria Friday
afternoon due to a tightening gradient ahead of a cold front.
Winds along the coast each afternoon will back slightly and
strengthen with the sea breeze.

&&

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

&&

$$

NEAR TERM...RFM
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...ETM/JRL
MARINE...ETM/JRL