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761
FXUS62 KCAE 211035
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
635 AM EDT Sat Sep 21 2024

.SYNOPSIS...
High pressure building over the region, resulting in generally
dry and warm conditions through Sunday. A return to more
seasonable conditions is expected early to mid week along with
daily slight chances for showers.

&&

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

- Patchy fog possible early this morning.
- Above average temperatures this afternoon.


Through sunrise: Satellite imagery indicates there are a few
pockets of fog and stratus developing across the forecast area.
Expect fog and stratus to continue developing through the pre-
dawn hours. After sunrise, the fog and low clouds are expected
to dissipate rather quickly.

Rest of today and tonight: A dirty ridge continues to slowly
build over the area as an upper trough slides further eastward.
As a result, temperatures are expected to be about 5 degrees
above average for this time of year, topping out in the upper
80s to lower 90s. A shortwave is forecast to rotate around the
periphery of the dirty ridge overnight, bringing shower or
thunderstorm activity to North Carolina and Virginia. Confidence
is low, but there is a small (~10%) chance that some of the
activity is able to extend down to our neck of the woods. Have
left mention of any rain out of the forecast grids for the time
being. Tonight, temperatures are expected to be seasonably mild
in the mid to upper 60s for lows.
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&&

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

- Upper ridge dominates over the area with above temps

The upper ridge axis will build over the forecast area this
period while shortwave energy dives southeastward through the
Mid-Atlantic region on Sunday and shifts the upper trough off
the coast further eastward. Surface high pressure centered over
New England will remain in place across the Carolinas. Forecast
soundings continue to show a capping subsidence inversion and
this should limit convection both days, although on Monday
afternoon there could be isolated showers or thunderstorms
approach the northern Midlands associated with some weak
shortwave energy rounding the top of the upper ridge, but think
it will remain to the north at this time. The rising 500mb
heights should support continued above normal temperatures with
highs expected in the lower to possibly mid 90s on Sunday.
Monday high temperatures may be a bit cooler across the northern
Midlands due to slightly cooler 850mb temps but highs should
range from the mid 80s north to lower 90s south.

&&

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

- Chances of rain increase on Wednesday with limited confidence
- Continued above normal temperatures

The extended forecast features a lot of uncertainty regarding
the evolution of the upper level pattern and possible tropical
development in the Gulf of Mexico. Medium range ensembles
diverge on the 500mb pattern evolution beyond Thursday after
being in reasonable agreement earlier in the week. The upper
ridge axis shifts east of the forecast area Tuesday afternoon
allowing for increasing chances of rain with deeper
southwesterly flow and PWATs rising to around 130-150 percent of
normal. The GEFS brings a deeper upper trough to the east coast
by Thursday with upper ridging over the Northern Plains and
south central Canada, while the EPS splits off some of the
energy from the base of the upper trough and closes it off over
the Southern Plains by Thursday.

This leads to lower confidence in the forecast, especially the
pop forecast, but it seems reasonable that chances of rain will
increase later in the week given increased moisture and may be
reasonable to expect isolated diurnal convection late in the
week. The other uncertainty in the forecast revolves around a
possible low developing in the southern Gulf of Mexico and
possibly approaching the Gulf Coast by the weekend. The GFS and
its ensembles have been trending toward a faster solution and
bringing a system to the central Gulf coast sometime next
weekend while the ECMWF and its ensembles have been slower and
further west with this feature, but the latest 00z run of the EC
has trended toward the GFS so this will be a feature of
interest to watch in the coming days.

Temperatures are expected to remain above normal and warm with
NBM probabilities of max temperatures above 85 degrees at 80% or
higher across most of the area through Thursday. Slightly
cooler temperatures expected by Friday with increasing clouds
and possible rain.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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Generally VFR conditions anticipated through the TAF period.

Satellite imagery and surface observations indicate some patchy
fog has developed in portions of the area. However, AGS is the
only terminal affected thus far. There remains potential for
some fog at the terminals through 13z or so, with the exception
of DNL where the dew point depression is 3 degrees. Should fog
form at any of the terminals, it will likely dissipate quickly
after sunrise. VFR conditions persist after that. Winds are
anticipated to be light, generally 5 kts or less.

EXTENDED AVIATION OUTLOOK...No significant impacts to aviation
expected through Wednesday.
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&&

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

&&

$$