393
FXUS62 KCAE 170528
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
128 AM EDT Sat Aug 17 2024

.SYNOPSIS...
A cold front approaches the Southeast US this weekend, moisture
and rain chances return. Drier air and cooler temperatures are
on tap for early to mid next week.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
Key Message(s):

- Some scattered thunderstorms are possible across the northern
  Midlands between 9p-12a.

Scattered-linear thunderstorms are continuing to push southeast
across NC, eventually expected to push down into the Upstate
and potential the Midlands. Water vapor shows the associated
shortwave trough aloft that is triggering this convection with
some modest shear and decent instability. Instability has peaked
across our area, with high temps dropping back down into the
upper 80`s as of 7pm and dew points in the low 70`s; RAP
mesoanalysis paints about 1000 J/kg across the western
Midlands. Surface instability will quickly decrease after about
8pm, and any convection should become elevated as it moves
across the Upstate. HRRR wind swaths support this, with up to 30
mph wind gusts within any line that does stay organized into
the Midlands. All the short range guidance is then consistent in
dissipating any remaining convection across the Midlands
shortly after 04z.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH SUNDAY NIGHT/...
Key Message(s):

- Showers and thunderstorm chances return for the weekend.
- A few thunderstorms may be strong with damaging wind gusts as the
primary severe hazard, particularly on Sunday.

Warm Saturday as upper ridge axis moves offshore and upper trough
moves into the Great Lakes region. Moisture remains high over the
area with PWAT values between 1.7" and 2". Showers and thunderstorms
are expected Saturday in conjunction with a pre-frontal trough with
a cold front still west of the region. Best chance will remain over
the western Midlands closer to the incoming front, mainly in the
afternoon and evening hours. Confidence is on the lower end for
coverage, with a lack of upper support for much of the peak heating
hours. High temperatures Saturday back into the lower 90s, with lows
in the lower 70s.

Better dynamics on Sunday with the front approaching and passing
through the area. Expect additional showers and thunderstorms with
better organization given stronger shear and more upper level
support. Convection could be stronger to marginally severe, mainly
with the threat for damaging winds. Convection may last a little
into the evening hours, but then should end with the front passing
late Sunday night into Monday. Drier air then begins to filter into
the region. Temperatures similar to Saturday, with highs in the low
to middle 90s possible, and lows around 70 Sunday night.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Key Message(s):

- Lower rain chances much of the week with drier air over the region.

Cold front moves east of the area Monday with drier air filtering in
from the west. Upper troughiness hangs around much of the week, but
surface high pressure will translate east across the Great Lakes and
into New England before ridging down the coast mid to late week.
Ensemble mean PWAT values are below 1.5", particularly during the
middle of the week when they may approaching 1". This should set us
up for a drier period along with slightly cooler temperatures, with
highs in the 80s and lows down into the mid to upper 60s.

&&

.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...
VFR Conditions expected through at least 18z. Scattered
thunderstorms in the late afternoon and evening may result in
brief restrictions, but confidence low at this time.

Mid level clouds spreading into the region this evening as
convection upstream dissipates. Guidance indicating a low fog
threat early this morning. High pressure has shifted to the
coast. The upper ridge over the area will be weakening today as
an upper trough over the Great Lakes region amplifies. At the
surface a Piedmont trough will set up and provide some weak low
level convergence. The air mass is expected to become moderately
unstable in the afternoon and moisture appears high. The high
resolution models suggest scattered convection will develop in
the afternoon, after 18z. A few storms may impact terminals
primarily during the 18z Saturday to 04z Sunday, but confidence
low at this time. So, scattered to broken VFR cumulus expected
especially during this period. Winds will be southwest 5 to 10
knots with a few higher gusts in the afternoon.

EXTENDED AVIATION OUTLOOK...Scattered showers and thunderstorms
are expected Sunday afternoon and evening, possibly strong to
severe and restrictions possible.

&&

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

&&

$$