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557
FXUS62 KCAE 231850
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
250 PM EDT Mon Sep 23 2024

.SYNOPSIS...
High pressure building over the SE US will keep warm conditions
over the Southeast into the first half of the work week.
Multiple shortwaves crossing the region will bring chances for
precipitation through much of the week. Confidence remains on
the lower side in the forecast beyond midweek as there is still
uncertainty associated with the evolution of an upper trough
moving toward the region and the track of a likely developing
tropical system in the Gulf.

&&

.NEAR TERM /THROUGH TONIGHT/...
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Key Message(s):

- Upper ridge persists with above normal temperatures
- Isolated afternoon convection this afternoon and evening

Satellite showing wedgelike cloud cover across much of the
western Midlands and Pee Dee region. This will continue to have
an impact on temperatures, with readings most of the afternoon
mostly in the 70s. With enough breaks in the clouds, and some
sunshine still possible later this afternoon, highs may still
top out in the lower 80s there. Further south, plenty of
sunshine has brought current temperature well above normal, with
readings already around 90 degrees. With plenty of time left
this afternoon, highs still expected to reach the low to middle
90s across the central Midlands and majority of the CSRA. In the
areas with sunshine, a weak capping inversion should be eroded
later this afternoon. There is some weak to moderate
instability, and with a weak shortwave moving out of GA this
afternoon, can not rule out a few isolated showers or
thunderstorms.

Showers and/or storms that do develop should dissipate by 06z.
Issue tonight will mainly revolve around redevelopment of
stratus deck if the wedge develops back southward. Blended
guidance is showing this scenario, with the cloud deck making it
into the central Midlands again. Light northerly winds under the
clouds expected, with light and variable winds south. In
addition, can not rule out some light rain or drizzle across the
northern Midlands and Pee Dee late tonight into Tuesday morning.
Overnight lows down around 70 degrees.
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&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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Key Message(s):

- Upper ridge continues to bring above average temps.
- Marginal Risk for Severe Weather Tuesday Afternoon and Evening
  north of Columbia.

The upper level ridge axis will shift slightly eastward Tuesday with
above average temperatures continuing. Models do indicate the
potential for lingering stratus through the morning across the
northern portions of the forecast area once again, so there will be
at least somewhat of a temperature gradient with highs in the low
90s in the south to mid 80s across the north. Bit of a question mark
as to the development of showers and storms Tuesday afternoon as
HREF mean soundings show the potential for a capping inversion
across the area, but also weaknesses in the ridge and some weak
convergence across the northwestern portions of the area. As a
result, isolated to widely scattered showers and storms are
possible with highest coverage in the NW. Some of these storms
may be a bit organized with deep layer shear approaching 30
knots near the SC/NC border. A marginal risk for severe weather
remains in place north of Columbia.

The upper ridge continues to shift eastward Wednesday with a
deepening trough over the lower Mississippi Valley that there
remains good consensus among models will develop into a cut-off low
pressure system. Even some of the faster guidance keeps an impacts
from PTC Nine well to our south through Wednesday. This will lead to
fairly uneventful weather Wednesday with temperatures above normal,
although likely a few degrees cooler than Tuesday and little chances
for rain.
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&&

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

- Likely tropical system continues to develop in the Gulf, but
  uncertainty remains in its track.
- Chances for precipitation increase toward the end of the week.

National Hurricane Center is issuing advisories on Potential
Tropical Cyclone Nine. High confidence that PTC 9 will develop into
a tropical cyclone in the northwest Caribbean or southeast Gulf of
Mexico and move north towards the Gulf Coast. Increasing confidence
in the storm making landfall as a hurricane but uncertainty remains
in the track as it interacts with an upper low moving in the
Mississippi Valley. Most guidance (global models and ensemble
members) do generally take the center west of the area but exact
impacts depends on how close the center moves towards the area
and the degree of weakening as it moves inland. For now, the
biggest impact will likely be moderate to potentially heavy
rainfall that could develop as early as Thursday afternoon,
although most ensemble members at this point favor heaviest rain
Thursday night. With the current track of the storm, however,
tornado potential as well as strong winds are possible with
ensemble guidance indicated highest potential for gusts above
40mph in the CSRA (around 50 percent chance probability).
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&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
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Generally VFR conditions expected through the day and into the
early overnight hours at all sites. Mvfr/ifr conditions possible
at cae/cub late tonight into Tuesday morning.

Clouds associated with surface wedge pattern will remain north
of all terminals this afternoon and into the early portions of
the overnight hours, leading to vfr conditions. Guidance is
indicating that the stratus deck associated with the wedge will
redevelop southward late tonight into the central Midlands, with
the greatest impacts being located at cae/cub towards Tuesday
morning. Ifr conditions are forecast to develop by sunrise at
cae/cub, lasting through around 14z once again. After that,
mixing along the edge of the cloud area should help to improve
conditions back to vfr at those two locations after 14z. All
other taf locations will remain outside of the overcast low
cloudiness, with vfr conditions expected through the period.
Winds out of the south through the afternoon and evening, then
more light and variable after sunset. Winds turning back to
southerly then after mixing starts Tuesday after 14z.

In regards to rainfall restriction, guidance does show isolated
showers/storms developing in areas receiving plenty of sunshine
this afternoon, with brief impacts possible at all terminals
through sunset.

EXTENDED AVIATION OUTLOOK...Restrictions along with strong winds
becoming possible Thursday through Saturday associated with a
potential tropical system moving west of the forecast area.
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&&

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

&&

$$