048
FXUS62 KCAE 190024
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
824 PM EDT Sat May 18 2024

.SYNOPSIS...
Scattered showers with isolated thunderstorms move through
overnight as a cold front drops through the area. Abundant
moisture across the region will keep rain chances likely
lingering into Sunday, especially across the CSRA. 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 7 AM/...
Current surface analysis shows a cold front is making its way
south through North Carolina toward our forecast area. This
front is kicking off some shower and thunderstorm activity. As
this front continues to move south, expected the scattered
showers and storms to continue moving along with it as it moves
through the forecast area. As we lose daytime heating, I do
anticipate the storms become more isolated in nature, however,
which has already been seen on radar. Another more washed out
front is being noted over the North Carolina mountains that has
also sparked some shower and storm activity. Not anticipating
that this activity moves away from the mountains and the
activity we see will likely be from the first front. The severe
threat is minimal at best for our forecast area.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Sunday and Sunday Night: Upper trough axis will swing through
the forecast area utilizing above normal PWATs which should
bring showers and isolated thunderstorms to the forecast area.
Expect scattered showers over the western Midlands Sunday
morning shifting southeastward through the day with a transition
to a more convective nature by early afternoon with some
surface heating. Hi-res CAM guidance in reasonable agreement
showing more widespread showers and thunderstorms across the
CSRA and southeast Midlands during the afternoon hours. Drier
and more stable air will move southward through the day so pops
will be decreasing from north to south through the afternoon
hours.

Abundant clouds and rain should limit temperatures tomorrow
with highs expected to range from the lower to mid 70s northern
Midlands to upper 70s to near 80 in the CSRA and southeast
Midlands. Clouds should begin to clear out from the north
overnight as drier air works into the region and some cool
advection will support overnight lows in the upper 50s to lower
60s.

Monday and Monday Night: High pressure will build over the
region with some rising 500mb heights in the wake of the
departing shortwave trough off the southeast coast. PWATs drop
to at or below an inch with forecast soundings showing a
subsidence inversion around 700mb and this should provide dry
and fair conditions. Temperatures should rebound a bit with
highs in the lower 80s under mostly sunny skies. Overnight lows
again expected in the upper 50s with reasonable radiational
cooling expected.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Continued benign weather expected early in the extended
forecast period through mid week before some unsettled weather
returns by the weekend.

Ensemble guidance in fair agreement showing an amplified 500mb
pattern on Tuesday with a deep upper trough over the
intermountain west and off the southeast coast with an upper
ridge extending from the lower MS Valley through New England.
This upper ridge will build eastward over the forecast area by
Wednesday and although it weakens and flattens a bit on Thursday
due to a shortwave trough moving into southeastern Canada, the
ridge should still dominate over the southeastern states. At the
surface, high pressure centered off the New England coast will
ridge into the Carolinas and southeastern states Tuesday into
Wednesday and gradually shift eastward offshore by Thursday.
Ensemble mean PWATs are forecast to be below normal (around
70-80% of normal) Tue/Wed before PWAT values rise back above
normal on Thursday with the return deep southerly to
southwesterly flow as the surface high shifts further offshore.
This should result in a rain free forecast Tue/Wed followed by
low chances of convection returning by Thursday, mainly
diurnally driven.

Friday into Saturday, chances of rain increase as low pressure
lifts into southeast Canada pushing a cold front toward the
forecast area on Friday with ensembles showing sufficient
moisture (PWATs around 120% of normal) available and some weak
shortwave energy moving into the region. It is uncertain whether
or not the front will make it all the way into the forecast
area or not given it will be late May but nevertheless a
boundary in the area may still provide a focus for convection.
Temperatures during this period are expected to be near to above
normal with the upper ridging in place, warming through the
week.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR conditions expected for the next couple of hours before
restrictions develop tonight behind a backdoor front.

Calm before the in-situ wedge is present across the region
currently, with convection to our west, south, and north today but
really not across our area. That has worked out with just mid and
high level clouds remaining in place all day. However, a backdoor
front is noted currently across northeastern NC and southeastern VA.
It is slowly moving southwestward, with guidance approaching the
Columbia terminals between 04z and 06z tonight. Confidence is high
that MVFR and IFR conditions will develop as some cold air advection
develops along with north and northeasterly surface flow. Some
stratus is expected and shown by guidance ahead of the front, but
that is a bit less certain that what follows the front.
Additionally, approaching upper level trough along with this front
should yield at least scattered rain showers everywhere tonight,
helping to usher in IFR and even periodic LIFR at times. Upstream
obs behind the backdoor front give confidence to the forecast. So
overall it looks like a very restricted period for the TAFs.
Thinking is that showers should hang on, especially at AGS/OGB/DNL,
into late morning or even the afternoon. Low clouds almost certainly
will last longer than guidance suggests they will at this point,
which is why this forecast keeps lower MVFR at all sites through the
end of the period. There is a chance that CAE/CUB see some clearing
late in the day but this will likely be brief at the end of this
forecast period.

EXTENDED AVIATION OUTLOOK...Periodic restrictions from showers
and thunderstorms continue through Sunday night. Conditions
should improve on Monday.

&&

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

&&

$$