770
FXUS62 KCAE 281712
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
112 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 slight chance of showers and
thunderstorms late Tuesday through Thursday, mainly northern and
eastern areas.

&&

.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/...
Quiet weather is expected to continue on Monday, with high
confidence in the forecast. Latest ensemble and operation guidance
continues to show our pattern moderating downstream from the active
central Plains. A series of shortwaves and low pressure systems are
forecast to ride northeastward atop the ridge over the eastern US,
with fronts slowly pushing the low-level ridge axis southward. In
turn, our prevailing flow will shift from southeasterly to
southwesterly on Monday. As a result, warm air advection is likely
to be a bit more notable, with 850 hPa temps starting the day in the
12-14C range. This will allow highs to likely jump into the low and
mid 80s, with more sunshine aiding the warming trend. Rain is
unlikely as we`ll see subsidence under shortwave ridging, manifested
in a strong inversion showing up in model soundings between 750-800
hPa. Overnight, look for dry conditions to continue, with lows
in the upper 50s and lower 60s.

A slow moving shortwave trough is forecast to approach the forecast
area on Tuesday. Guidance has slowly trended towards a more
organized trough and a slower progression of said trough on Tuesday.
As a result, there is more forcing aloft for precipitation Tuesday
afternoon. Big however, though. Guidance is split on the amount of
moisture that will be in place ahead of this as the front and upper
level support approaches Tues afternoon/evening. Amongst LREF
guidance, GFS/GEFS are the most aggressive with rainfall chances,
while the ECM/ECE members are least aggressive. The Canadian ens &
operational model (and the early runs of the NAM) are somewhere in
the middle, which seems like a reasonable spot to be in currently.
The fly in the ointment is how much mixing we see by Tuesday
afternoon, which could lower our dewpoints and yield lesser
instability. I think the middle of the road is a good scenario here,
with scattered showers or thunderstorms developing by the afternoon
hours. Guidance (other than the ECM) is suggesting at least ~500
j/kg of CAPE developing for much of the area, which should yield the
chance of thunderstorms. With weak shear, though, anything severe is
unlikely. Highs will likely be in the mid to upper 80s across the
area. Some showers could continue into Tuesday night, with lows in
the low 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Confidence in the long term remains fairly high. Front should slowly
push through the area on Wednesday, with all LREF members showing
afternoon/evening rain chances persisting as the front won`t totally
clear the region and moisture will remain in place ahead of it. Mid-
level ridging will again build in by late week, with temperatures
warming to near 90 Thur/Fri with subsidence aloft keeping us dry and
sunny. By Saturday and Sunday, ensembles and operational models
begin to show a more active pattern developing, with showers and
thunderstorms possible again. So in general, the short and long term
periods are fairly high confidence, especially with regards to above
normal temperatures developing. Confidence is also high that our
best chances of rain/storms will be Tues/Wed, & Sat/Sun.

&&

.AVIATION /18Z 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.

&&

$$