838
FXUS62 KCAE 250004
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
704 PM EST Sun Nov 24 2024

.SYNOPSIS...
The air mass across the region will continue to moderate through
early in the week with temperatures rising to above normal. A
cold front with limited moisture will move through the area
Tuesday with a few light showers. A stronger cold front will
move through the area Thursday to Thursday night with scattered
to numerous showers. Below normal temperatures expected next
weekend as the coldest air mass of the season moves into the
region.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Key Message(s):

- A cool night ahead with some patchy fog along area rivers.

High pressure is steadily shifting east of the area, allowing
boundary layer flow up through 850mb to increase slightly. This
will allow for just enough turbulent mixing overnight to prevent
ideal cooling and decoupling like we had the last couple
nights. But moisture is still limited, so lows will still fall
to around 40F with good agreement across guidance. Some river
fog looks possible again since the mixing will be light, but the
airmass remains too dry away from rivers & lakes for fog.


&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Key Message(s):

- Warmer weather through Tuesday ahead of a cold front.
- Isolated light showers Tuesday associated with the front.

Monday and Monday night...Low amplitude upper trough over the
northern Plains will move toward the Great Lakes region. This
trough will drive a weak cold front toward the Carolinas and
Georgia by Monday night. The surface ridge will be southeast of
the area with low-level flow increasing from the southwest.
This will lead to warmer temperatures due to warm advection and
continued weak subsidence and a modest increase in moisture
with precipitable water increase to above an inch overnight,
near 1.30 inches in the Piedmont. Highs around 70 and warmer
overnight lows due to an increase in clouds after midnight, low
to mid 50s.

Tuesday and Tuesday night...Timing differences remain with the
frontal passage as the ECMWF upper trough is more progressive and
the front clears the area early in the afternoon. The GFS appears
to hang it up through the afternoon. The grand ensemble mean
favors the faster solution. The models continue to suggest weak
forcing and limited low level convergence as low-level flow
appears westerly. Any qpf will be quite light. The probabilistic
QPF guidance remains fairly bullish on the probability of
measurable rainfall, especially in the western portion of the
forecast area. Amounts will be limited, however, with even high
end (10% exceedance) values less than a tenth of an inch. The mos
consensus suggests slight chance. If the front hangs up, light
showers could linger in the east later in the afternoon, so kept
pops up there. Warm day though with highs around 70 despite
clouds. Dry high pressure building east from the Plains, modifying
and setting up north of the area. Weak cold advection mainly
during the evening, lingering clouds until after midnight. Lows
mainly in the 40s, except upper 30s in the north Midlands closer
to the ridge.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Key Message(s):

- Scattered to numerous and isolated embedded thunderstorms
  for Thanksgiving with breezy winds.
- Significantly colder weather late week into next weekend.

High pressure over the area Wednesday with seasonable
temperatures and air mass dry. A stronger and more potent upper
trough is expected to develop in the eastern CONUS by Thursday
into Friday. There remains significant synoptic differences
among the deterministic and ensembles. Low pressure is expected
to develop along a front in the Tennessee Valley Wednesday
night. ECMWF ensemble is stronger with the surface low
development and more progressive since the upper trough has more
amplification than the GFS and GEPS ensembles. The NBM highest
pops are Thanksgiving day through the evening then lower by
Friday afternoon as the front moves off the coast and upper
trough follows. Kept scattered to likely pops with ensemble qpf
around 0.5-0.75 inch with heaviest rain in the Piedmont. There
is potential for more widespread showers across the area through
Thanksgiving. Thunderstorms will be possible with some
instability noted especially over the southeast Midlands and
CSRA where surface CAPE may exceed 500 J/kg. 850mb south-
westerly winds may be near 50 kts. Strong gusty winds possible,
the ECMWF EHI CAPE and wind are elevated for Thursday.
Significant airmass change behind the cold front with NAEFS mean
indicating that 850mb temps will be below the tenth percentile.
Blended guidance likely not capturing the extent of this cold
air with bias correction indicating the blended highs and lows
are above the 75th percentile of the distribution. So lowered
temps over the weekend, especially min temps.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Low level moisture will increase tonight supporting patchy fog
development tonight. MOS and the HRRR suggest VFR through the
period but similar to the previous night we should at least see
fog near area rivers, including AGS. Therefore we added a TEMPO
group for AGS to cover the typical shallow fog that the site
observes frequently. Fog at the other terminals is less likely.

Winds will pick up out of the SW around 15Z Monday ahead of an
approaching front. No rainfall is expected through 00Z Tuesday,
however with moisture increasing ahead of the front, there may
be some low clouds and ceiling restrictions that develop near
the end of the 24 hour TAF period. At this point confidence is
too low to include in the TAFs.

EXTENDED AVIATION OUTLOOK...LLWS conditions will be possible
Monday night ahead of the approaching cold front. The front will
move through the area Tuesday with light showers possible. A
stronger front will move through the area Thursday to Thursday
night with thunderstorms and gusty winds possible.

&&

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

&&

$$