316
FXUS62 KCAE 260915
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
415 AM EST Tue Nov 26 2024

.SYNOPSIS...
A cold front with limited moisture moves through the area
today with scattered light showers possible. A stronger cold
front is expected to move through the area sometime on
Thanksgiving with the potential for scattered to numerous
showers and isolated storms. Behind this front, below normal
temperatures are expected for the weekend into early next week
as the coldest air mass of the season moves into the region.

&&

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

- An approaching cold front will bring a few showers to the area
this morning.
- Above normal daytime temperatures continue.

A weak upper trough located across the Great Lakes will move into
New England today, while a mid-level shortwave and attendant cold
front are advecting toward our area. This weak cold front is
identified in abundant clouds on satellite imagery, and by a line of
showers extending from western NC southwest into AL. As such,
temperatures this morning remain mild in the mid to upper 50s in
many locations. Southwesterly moisture advection is slowly
increasing moisture ahead of the showers, but overall PWATs still
remain around a modest 1". HREF member solutions bring the front and
showers through the area generally between 7 AM and 11 AM this
morning. It should be noted, however, that many of these solutions
show a marked weakening of the line compared to how it presents on
radar at the current time. This is likely due to needing to overcome
drier area both at the surface and aloft. Dynamics are generally
weak with the main shortwave remaining north of the area. LREF
probabilities of at least 0.01" remains above 50% through the
morning across the Midlands and CSRA. In general, QPF`s should
remain on the lower side, generally less than 0.2" with most places
picking up only a couple of hundredths. Conditions clear out fairly
quickly after the front passes through around 21z-00z this evening,
with PWATs falling quickly back under 1" and dewpoints dropping back
into the low 40s and upper 30s.

Temperatures will still be warm this afternoon with highs around 70.
Cold advection is weak behind this front, and winds should remain a
bit elevated through the period. Some weak/shallow moisture flux
overnight may result in a few low clouds and temperatures may stay
up a bit with lows generally in the 40s with cooler spots north and
warmer across the CSRA.


&&

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

- Dry and mild conditions anticipated for Wednesday.
- A stronger cold front expected on Thanksgiving, bringing
  scattered to numerous showers and possibly thunderstorms.

Wednesday and Wednesday night: Zonal flow aloft and surface high
pressure are expected to be in place Wednesday morning, allowing
for dry and seasonable conditions. The high pressure is forecast
to slide eastward through the period as a cold front approaches.
An upper trough also closes in on the region through the day.
As a result, flow transitions to southwesterly, allowing for
some warm air advection and an increase moisture overnight
Wednesday. Despite the increase in moisture and warm air
advection, Wednesday and Wednesday night are expected to remain
dry. Temperatures are forecast to be slightly above normal in
the afternoon and quite mild overnight.

Thanksgiving and Thanksgiving night: The aforementioned front
and trough move toward and through the region on Thanksgiving.
However, uncertainty remains in the timing of the frontal
passage, which will play a role in the chance for thunderstorms
and potential for severe weather. To account for the
uncertainty, have left chance PoPs in the forecast for each of
the 6 hour periods. In general, the ECMWF and its corresponding
ensemble mean move the front through earlier in the day, while
the GFS and its corresponding ensemble mean move the front
through later in the day. Other guidance land in between. If the
front moves faster as the ECMWF suggests, the threat for severe
weather would be limited. If it is later as the GFS suggests,
daytime heating would allow for some CAPE values of over 500
J/kg to build up. The GEFS probability of CAPE greater than 500
J/kg is moderate (40-50 percent) in the afternoon. 0-6 km bulk
shear is forecast to be around 50 kts, which is plenty to
support severe weather should the front move through later in
the day. This front is also expected to act as the initial surge
of cold air in the days following Thanksgiving. However,
temperatures for Thanksgiving and overnight are expected to be
above normal.

&&

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

- Confidence increasing in the coldest air of the season.

After the front moving through on Thanksgiving, strong and
prolonged cold air advection are expected through the weekend as
shortwaves moving through the upper trough bring reinforcing
pushes of cold air. The NAEFS and ECMWF EFI suggest that
temperatures could be near the climatological low. As of now,
the NBM indicates confidence is very high (80-90%) of lows
dropping below 25F Monday night, with a moderate chance
(~40-50%) of near record lows (upper teens). Needless to say,
any locations with active growing seasons are very likely to be
over this weekend.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
VFR conditions through the night giving way to possible MVFR/IFR
conditions with a passing front later today.

Satellite imagery shows increasing cloud cover from the west
associated with an approaching cold front. Radar imagery indicates
showers are just starting to enter northwest SC. Expect lowering
CIGS over the next few hours as the front and showers move through
the state. The front is expected to push through the region around
mid morning with some low VFR CIGS just ahead of it, followed by
possible MVFR and IFR CIGS behind the front from 14z-19z. There is
some uncertainty regarding how low CIGS will get, and if IFR
conditions will occur at all. A return to VFR is then expected
this afternoon as clouds clear and lift. Winds generally light
and variable overnight then shifting to the west and eventually
northwest behind the front this afternoon around 6 to 10 knots.

EXTENDED AVIATION OUTLOOK...Another stronger cold front will
move through the area Thursday and Thursday night with
thunderstorms and gusty winds possible.


&&

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

&&

$$