202
FXUS62 KCAE 281836
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
236 PM EDT Sun Apr 28 2024

.SYNOPSIS...
Weak high pressure centered northeast of the region will remain
in control through Monday along with a warming trend. A weak
front is expected to bring a chance of showers and
thunderstorms late Tuesday into Wednesday, mainly northern and
eastern areas. Above normal temperatures persist into the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
SE flow continues today advecting moisture into the forecast
area. However the moisture will be shallow with PWAT values
around 1.2 inches from the GOES-16 derived imagery. The onshore
flow should promote mostly cloudy skies but a considerable
inversion aloft, along with some dry air, should prevent
rainfall. The subsidence inversion is lower today than is was
yesterday based on the 12Z CHS sounding. Yesterday the inversion
began at about 700mb versus today`s is lower at about 850mb.
This should prevent the shallow showers from developing that we
saw yesterday. This evening low clouds will begin to diminish
with sunset with mid and high clouds also clearing tonight. This
could allow low stratus or fog to develop early Monday morning.
High temperatures this afternoon will be in the upper 70s to
low 80s with lows tonight in the mid 50s.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Monday and Monday Night: Generally quiet weather expected with
an upper ridge axis over the forecast area. All of the active
weather remains off to the northwest as a series of shortwaves
move through the western OH and MS/TN Valleys on the west side
of the upper ridge. Atmospheric moisture over our area with be
slightly lower on Monday compared to today with PWATs falling
below an inch through the day as low level flow shifts from
southeasterly to more south or southwesterly. Due to low level
moisture trapped beneath the subsidence inversion, would not be
surprised to see some stratus in the morning. However, once any
stratus burns off there should be some sunshine through the
afternoon. Model forecast soundings indicate a strong subsidence
inversion around 850mb which will limit instability. 850mb
temps should warm a couple of degrees and with more sunshine
this should result in warmer max temperatures in the lower to
mid 80s. Dry weather continues Monday night with slightly warmer
overnight lows in the upper 50s to around 60 degrees. It would
not be surprising to see some predawn stratus develop along the
Coastal Plain and move into the forecast area early Tuesday
morning.

Tuesday and Tuesday Night: Ensemble and global guidance is in
reasonable agreement bringing shortwave energy into the forecast
area from the TN Valley late Tuesday and Tuesday night which
will bring an increase in rain chances. There are some timing
differences among the faster GFS and slower ECWMF but this
shortwave trough is forecast to amplify a bit as it moves into
the area with the existing upper ridge shifting offshore and
another upper ridge building over the MS Valley in response to
deep upper troughing over the intermountain west by Tuesday
night.

Atmospheric moisture is forecast to increase to slightly above
normal on Tuesday combining with upper forcing that moves in
later in the afternoon to support at least scattered showers and
thunderstorms across the region into Tuesday night. Deep
southwesterly flow should yield some instability but the degree
of instability may depend on how long it takes to erode the
capping inversion around 700mb, and nevertheless should support
possible thunderstorms, though the chance of severe
thunderstorms seems unlikely.

Temperatures should warm further with max temperatures in the mid to
upper 80s, while overnight lows Tuesday night are expected to be in
the upper 50s west to lower 60s east with lingering cloud cover and
possible showers.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
There is somewhat lower confidence in rain chances on Wednesday
as the slow moving upper trough traverses toward the coast due
to timing issues with the guidance. Kept some low pops across
the eastern Midlands, lower CSRA and Pee Dee region to account
for possible slower timing. The western portion of the forecast
area should have lower chances as some drier air begins to work
into the region with a weak surface front/trough slowly pushing
through the area by Wednesday evening.

Ensemble guidance is consistent in showing another shortwave
ridge building over the forecast area on Thursday and persisting
into Friday with forecast soundings showing a strong subsidence
inversion around 700mb. This will support continued above
normal temperatures through the extended forecast period.
Chances of rain will increase again over the weekend as
shortwave energy from the west effectively weakens the upper
ridge and 500mb flow becomes more zonal in nature giving way to
additional shortwaves interacting with above normal moisture
resulting in scattered showers and thunderstorms. Depending on
the amount of instability available over the weekend, strong to
severe storms cannot be ruled out and CSU ML probabilities are
highlighting a potential threat, although confidence remains low
this far out. Wednesday through Friday look to be the warmest
days of the period with highs in the mid to upper 80s and cannot
totally rule out a 90 degree reading, but with increased
moisture and clouds and possible storms over the weekend, highs
should be slightly cooler.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Stratus and fog possible early Monday morning.

A subsidence inversion aloft will hinder vertical growth and
prevent showers at the terminals today. Clouds will diminish
with sunset as some drier air moves into the area. Clearing
tonight and light winds could promote fog and stratus
development early Monday morning. The highest confidence is in
AGS experiencing its typical river-valley-based fog but all
sites could see restrictions from 09Z to 15Z Monday. After 15Z
winds will pick up out of the south with a few cumulus and high
clouds.

EXTENDED AVIATION OUTLOOK...Restrictions possible in early morning
fog or stratus. Then there is at least a slight chance of
afternoon showers and thunderstorms Tuesday onward.

&&

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

&&

$$