380
FXUS62 KCAE 212340
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
740 PM EDT Fri Jun 21 2024

.SYNOPSIS...
Moisture will increase across the area over the weekend as low
pressure approaches from offshore. Above normal temperatures
are expected by Sunday into early next week. Heat Advisories
may be possible from Monday through Wednesday. Expect scattered
diurnally driven showers and thunderstorms for much of the
short and long term forecast.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- Tropical wave/low pressure will result in increased humidities.

The center of the tropical low and associated wave will move
onshore near the Florida/Georgia Atlantic border shortly after
sunset. Low level moisture has been surging in from the
southeast on the north side of the wave, and will continue to do
so overnight. Dew points have already risen into the 70s in the
southeasternmost counties, and that should make it to the I-20
corridor by midnight and over the entire FA by morning. The
increase in moisture should help promote some patchy ground fog
in the eastern half of the area toward sunrise.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
KEY MESSAGES:

- Increasing moisture will lead to a chance for afternoon and
evening thunderstorms.

Surface low pressure will move south of the forecast area on
Saturday with deep easterly flow leading to increasing moisture.
PWAT values rise to 1.75 to 2.00 inches, near to slightly above
normal, with highest values to the south. Expect showers and
thunderstorms to develop in the afternoon as the air mass becomes
conditionally unstable through daytime heating. We would expect
coverage to be highest across the southern Midlands and CSRA where
moisture is deeper and due to stronger subsidence to our north. Low
lapse rates point to limited updraft strength and a low threat of
severe weather. Convection should diminish in the evening with loss
of daytime heating, however as moisture advection increases through
the night we may see an isolated shower pop up during the early
morning Sunday.

Temperatures will be around normal in the low to mid 90s. Lows
overnight will be mild in the low to mid 70s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Temperatures rise late this weekend into mid-week.
- Heat Advisory criteria possible Monday through Wednesday.

Daytime temperatures from Monday through Wednesday may be near 100
degrees. Varying levels of moisture during this period limit
confidence in reaching Heat Index values above 105. Daily showers
and thunderstorms could also hinder heating.

Late this weekend, 850mb temps warm leading to daytime highs rising
into the mid 90s for most areas. This warming trend continues into
Monday with highs into the upper 90s to near 100 degrees ahead of a
weak cold front which will bring drier air into the region. Much of
the area will be in northwest flow aloft with rather strong
downslope flow on Monday. The downslope flow would contribute to the
hot temps but would also dry out of the low levels. There may be a
period on Monday where lingering low level moisture combined with
warm temps raise Heat Index values into the 100 to 105 range.
However confidence in reaching Heat Advisory criteria is somewhat
limited by the potential for afternoon showers and thunderstorms.

With drier air over the area for Tuesday, rain chances and dewpoints
will be lower. Highs will still be in the upper 90s to near 100 but
with drier air in place Heat Adv criteria looks less likely. Global
ensemble means favor upper troughing in the Tennessee Valley moving
into the Southeast mid-week, pushing another weak cold front toward
the area. Moisture appears to increase again with over 75 percent of
ensemble member PWAT values over 1.5 inches by Thursday. Increasing
moisture and continued warm temperatures may push Heat Index values
to near Advisory criteria on Wednesday. A cold front pushing into
the Southeast late in the week and increasing cloud/precip chances
should promote slightly cooler weather towards the end of the long
term.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions will prevail at all terminals through early
tonight, then flight restrictions becoming possible later
tonight due to stratus development.

Moisture increasing off the Atlantic associated with low
pressure moving inland near the FL/GA state line. Broken vfr
cloudiness along with a few showers moved into the Midlands and
CSRA. With loss of heating, clouds are expected to become more
scattered early tonight. However, towards 08z most guidance is
showing ifr stratus development across the Midlands, possibly
reaching the CSRA during that time. IFR ceilings seem quite
likely at cae/cub/ogb, and have introduced ifr at those sites at
08z. Kept ifr out of ags/dnl for now, but still expect some
stratus development close by, and went with mvfr conditions at
08z in those locations. Skies forecast to begin improving
towards 14z as better mixing starts, with vfr by late morning at
all sites. Can not rule out an isolated shower early this
evening at any site, and again Saturday afternoon, but due to
low confidence and coverage will not mention in tafs at this
time. As for winds, they will be mainly easterly this evening
before becoming light and variable overnight. A southeasterly
direction with speeds around 5 knots forecast for Saturday as
the region remains north of the surface low still across
southeastern GA.

EXTENDED AVIATION OUTLOOK...Brief restrictions possible in
isolated to scattered evening thunderstorms on Saturday with
increasing chances Sunday through Tuesday.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.

&&

$$