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840
FXUS62 KCAE 201045
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
645 AM EDT Fri Sep 20 2024

.SYNOPSIS...
High pressure and ridging build into the area today, bringing
warmer temps and limiting rain chances to mainly the northern
Midlands. Dry and warm conditions continue through Sunday, then
become more seasonable early to mid week.

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

- Patchy dense fog this morning.
- Warming trend begins today with just a slight chance of rain
  north.

Satellite imagery is indicating some patchy fog across the
forecast area, mainly the northern half. Visibilities of 1 mile
are being reported at this hour, but the more dense fog has been
staying out of our area so far this morning. Any fog that is out
there is anticipated to mix out fairly quickly after sunrise.

The axis of an upper trough has shifted just to our east as
ridge builds in from the southwest, putting us into a northwest
flow regime. At the surface, high pressure continues to filter
in from the north. The upper ridge and trough are expected to
drift eastward through the day as the surface high pushes
southward. As a result, a generally dry and warm day can be
expected for much of the area. The one fly in the ointment is
that a weak shortwave within the northwest flow could be just
strong enough to bring a slight chance (~15%) of few showers or
an isolated thunderstorm to the northern Midlands this
afternoon. After daytime heating wanes, the chance for any
precipitation diminishes. Afternoon highs are expected to be a
few degrees warmer than Thursday, while overnight lows should
be similar to Thursday night.
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&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Key Message(s):

- Upper ridge builds over the area this weekend with warming temps

Upper ridging centered over the OH/TN Valleys will build over
the Carolinas this weekend as an upper trough over the four
corners region lifts northeastward toward the Central Plains.
Surface high pressure centered over New England and the Mid-
Atlantic will continue to ridge into the Carolinas through the
weekend. There is the possibility of isolated showers developing
in the northwesterly flow aloft late Saturday but moisture is
limited with PWATs around 1.2-1.5 inches.

Most guidance keeps any showers north of the forecast area, so
will continue to carry a dry forecast. Forecast soundings show a
strong subsidence inversion which should further limit
instability and rain potential. 850mb temperatures rise a few
degrees over the weekend and expect highs to be near to above
normal Saturday and above normal on Sunday. NBM probabilities of
max temps greater than 90 degrees on Sunday are over 50 percent
across much of the southern half of the area.

&&

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

- Generally benign weather with near to above normal temperatures
- Chances of rain increase on Wednesday with limited confidence

Ensemble guidance shows positive 500mb height anomalies with an
upper ridge remaining over the Carolinas into midweek with high
pressure in control at the surface but shifting offshore by
Tuesday. This should lead to continued warm temperatures with
highs in the mid 80s to low 90s. More uncertainty arrives in the
forecast by midweek as ensembles and deterministic models
handle a potential tropical system moving into the Gulf of
Mexico near the end of the forecast period.

The GFS and its ensembles are a bit deeper with the next upper
trough moving through the Ohio Valley on Wednesday which picks
up a system moving into the Gulf, while the EC and its ensembles
are less amplified and do not have that system in the Gulf of
Mexico until later in the week beyond the forecast period.
Regardless, moisture increases over the region and low chances
of rain return to the forecast on Wednesday. Temperatures
expected to remain above normal but cool a bit by mid week with
the approaching upper trough.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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VFR conditions expected for much of the period with
restrictions from the pre-dawn hours through mid morning.

Satellite imagery shows some pockets of fog and stratus across
the region this morning. None of the 5 terminals have been
affected up to this point; however, the potential remains for
MVFR or IFR conditions through about 13z at all terminals except
DNL. After sunrise, the stratus deck and fog is expected to
dissipate, leaving VFR conditions through much of the rest of
the TAF period. Light northeast winds expected today, then
diminish and shift more easterly after about 00z.

ADVISORIES... SC...None. GA...None.
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&&

$$