807
FXUS62 KCAE 181853
AFDCAE

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

.SYNOPSIS...
Scattered showers and thunderstorms are expected through
tonight 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 TONIGHT/...
An upper level low, part of a broader positively tilted upper
level trough, is centered over western Tennessee early this
afternoon. This upper trough, along with an associated weak
surface low pressure system, will move east toward the area
through this evening. As the surface low passes to the east
overnight, a backdoor cold front will drop through the area.

Shower activity from early this morning has shifted east of the
area, leaving the area rain-free early this afternoon. Convection
is expected to redevelop later in the afternoon into this
evening as forcing ahead of the approaching upper trough
increases across the area. The higher resolution mesoscale
models generally show the greatest coverage of this convection
across the northern Midlands and into the Pee Dee. Then
overnight as the backdoor cold front drops through, scattered
showers will persist, with the focus across the western/central
Midlands and upper CSRA where forcing will be greatest.

The overall severe weather threat appears minimal, as morning
shower activity and abundant cloud cover has limited
instability. However, a few strong or even severe thunderstorms
capable of producing stronger wind gusts and perhaps some hail
could still occur, with the greatest potential across the
northern Midlands and Pee Dee where instability and forcing will
be greatest into this evening.

Late tonight, low ceilings and reduced visibilities are expected
to develop within the light northeasterly flow behind the
backdoor cold front. Lows will be rather mild with temperatures
in the mid 60s due to extensive cloud cover.

&&

.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 /18Z SATURDAY THROUGH THURSDAY/...
Some flight restrictions persist early this afternoon at the
Augusta area terminals, but overall VFR conditions will prevail
through this evening across the area. Showers could develop
later this afternoon and become scattered in coverage into this
evening ahead of an approaching upper trough. However, due to location
and timing uncertainty, have kept mention out of the TAFs for
now. Overnight, ceilings will lower considerably as a backdoor
cold front drops through the area, with IFR ceilings expected
to develop at all terminals after about 08-09Z, with abundant
low level moisture within a light northeasterly flow at the
surface producing reduced visibilities as well. Scattered
showers are possible with the passing upper trough axis late
tonight/tomorrow morning, and have included vicinity showers in
the TAFs as a result.

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.

&&

$$