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222
FXUS62 KCAE 180748
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
348 AM EDT Sat May 18 2024

.SYNOPSIS...
A few showers will be possible tonight with periods of showers
and thunderstorms expected today and into Saturday night. Rich
moisture across the region will keep rain chances likely
lingering into Sunday. Cooler and drier air moves in for Monday
and Tuesday with temperatures rebounding during the middle of
next week as another ridge moves in from the west.

&&

.NEAR TERM /THROUGH TONIGHT/...
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The radar early this morning shows a few areas of light showers
moving across the forecast area. Rainfall amounts tonight so far
have been are minimal, between a Trace and a few hundredths of
an inch. However, showers and thunderstorms now over Alabama
are expected to move northeast towards the forecast area with
rain chances increasing towards daybreak. Temperatures are on
track to fall into the mid-60s to around 70 degrees.

For today, a positively tilted trough centered over Arkansas
will slowly move east approaching the CWA towards daybreak.
At the surface, weak low pressure will move east in tandem with
the trough. Southwesterly flow ahead of this system will advect
moisture into the region. The day begins wet for at least the
southern half of the FA as the previously mentioned area of
showers and thunderstorms passes through. Gulf coast convection
may be sufficient to limit shower and thunderstorm development
this afternoon in the Midlands and CSRA once this first round
moves out and there may be a break in the activity today until
the approaching trough provides enough lift to trigger showers
and thunderstorms, especially over the northern half of the CWA.
This solution is shown in many of the CAMs and PoPs have been
adjusted based on these trends.

In terms of the severe threat, confidence in strong to severe
thunderstorms has decreased across the FA. While modeled
soundings show modest speed and directional shear, CAPE values
have decreased, likely due to the ambiguous instability and
lack of a significant lifting mechanism until this evening.
Having said that, there are some hints of an inverted V
signature in the soundings meaning any thunderstorms that do
develop later today could produce strong wind gusts with a non-
zero hail and tornado threat. The SPC Day 1 outlook decreased
the severe weather threat to Marginal (1/5) across our FA which
aligns with what is being shown in the guidance.

Temperatures will likely struggle to warm due to persistent
cloud cover and periods of showers and thunderstorms. Forecast
highs range from the mid-70s to near 80 degrees. Any convection
this evening should gradually wane as the best lift moves out.
It will remain cloudy though with temperatures falling into the
lower to mid 60s.
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&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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Sunday and Sunday night...Highly positively tilted upper level
trough will be just west of the forecast area at daybreak and
gradually move eastward through the day reaching the coast by
Sunday evening. At the surface a weak boundary will be sinking
southward with winds turning northerly with passage and the
atmosphere becoming increasingly stable indicating wedge-type
conditions. The boundary will push into the northern Midlands
and Pee Dee by daybreak through the central Midlands during the
mid morning then begin weakening as it reaches the southern
Midlands and CSRA by mid afternoon. Although much of the
forecast area will see increasing stability there will be some
instability in the far eastern Midlands into the southern CSRA
which could generate a few thunderstorms if there are enough
breaks in the clouds to allow for sufficient heating. Overall
have lowered pops and increased clouds which has also resulted
in afternoon high temperatures also coming down a few degrees
with low 70s in the north and upper 70s to around 80 in the
southern Midlands and CSRA. Sunday night the upper trough will
continue slowly moving offshore with high pressure building in
at the surface. Model soundings indicate plenty of dry air
overtaking the region Sunday night however moisture will be
trapped near the surface resulting in partly to mostly cloudy
conditions overnight. With the continued northerly flow low
temperatures Sunday night will be in the upper 50s to around 60.

Monday and Monday night...Upper level ridging will be
approaching the region Monday and Monday night as the upper
level trough becomes nearly stationary over the western
Atlantic. High pressure will control the surface with dry air
dominating the mid and upper levels. Mid level lapse rates will
be 5.5 C/Km at best so any cumulus which form will be vertically
limited. Northerly flow will persist over the region so
although there will be partly to mostly sunny skies allowing for
plenty of sun expect afternoon highs in the upper 70s to low
80s. With little change for Monday night expect another night of
partly cloudy skies and overnight lows in the upper 50s to
around 60.
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&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
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Upper level pattern remains amplified yet progressive through
the long term. Upper level ridging and weak surface high
pressure will remain in control of the area through Wednesday
night with the next frontal boundary currently expected to move
into the region Thursday. As it typical for this time of year
the front will struggle to reach the forecast area and stall
just to the northwest. This will result in the front acting more
as a focusing mechanism for showers and thunderstorms Thursday
and Friday with the highest pops over the northern Midlands.
Temperatures through the long term will be near to slightly
above normal.
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&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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Restrictions Possible this Morning...

Scattered showers continue to move across the region,
periodically bringing light rain to the terminals. Rainfall
amounts have been very light and no restrictions are currently
being reported. Additional showers and embedded thunderstorms
currently in Alabama will move northeast towards the terminals
during the next few hours bringing restrictions. Have omitted
thunder chances until confidence in impacts increases. Guidance
has backed off on the lowered ceilings this morning and TAFs
have been adjusted accordingly. Ceilings will likely lower at
least temporarily during the next few hours as the rain
approaches but may not fall into the IFR category as previously
thought. The ceilings should improve around midday with a return
to VFR conditions in the afternoon. However, additional showers
and thunderstorms will be possible across the region later
today. Maintaining VCSH after 21Z due to low confidence in
thunderstorm timing.

EXTENDED AVIATION OUTLOOK...Periodic restrictions from showers
and thunderstorms continue through Sunday night. Low ceilings
are also possible Sunday morning. Conditions should improve on
Monday.
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&&

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

&&

$$