747
FXUS62 KCAE 300813
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
413 AM EDT Tue Apr 30 2024

.SYNOPSIS...
A shortwave trough aloft will push through the area Tuesday and
bring scattered showers-storms in the afternoon and evening.
Drier air will fill in for Wednesday and Thursday but temps
will again push back in the mid-upper 80`s as ridging develops
aloft. Shower-storm chances will gradually increase for Friday
over the weekend as low level moisture returns and some weak
troughs cross the region.


&&

.NEAR TERM /THROUGH TONIGHT/...
A robust short wave trough is evident over Mississippi this
morning. It is already becoming a little negatively tilted.
Moisture is increasing ahead of the trough across the Deep South
into Georgia. Precipitable water will increase to around 1.4
inches, possibly a little higher in the CSRA and southeast
Midlands as the surface ridge that is centered offshore weakens.
The trough will move through South Carolina late this afternoon
and this evening although appears to de- amplify a bit.
Relatively strong upper lift expected ahead of the trough.
Despite increasing high cloudiness, sufficient diabatic heating
and modest warm advection should result in afternoon
temperatures mainly in the low 80s. This will result in weak to
possibly moderate instability with surface based CAPE likely
above 500 J/kg especially in the CSRA and southeast Midlands
based on latest CAMS. Overall mid level lapse rates appear weak
limiting instability. Deep layer shear appears moderately high
with HREF 0-6km values 25 to near 30 knots. The latest CAMS
suggest scattered convective coverage, perhaps a little more
coverage in the CSRA and southeast Midlands, less northwest into
the SC Piedmont/north Midlands. Went ahead and raised the pops
a bit across the area late this afternoon through the early
evening when best forcing is expected. Severe threat appears low
due to mainly weak instability. The showers and thunderstorms
should diminish by around 03z but kept pops through the
overnight with showers moving to the east. Overnight lows mainly
in the low 60s.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Excellent model-ensemble consensus is seen through the end of
the week with deep ridging quickly building into the region
as the 500 mb shortwave from Tuesday lifts northeast by early
Wednesday. Dry and warm northwest flow from the surface through
250mb will help clear skies out on Wednesday and some downslope
component flow will help further push temps back above average,
in the mid- upper 80`s. The associated moisture gradient from
the Tuesday trough passage will slide south to the GoM coast,
driving dew points down into the 50`s throughout the day as
surface winds remain out of the north- northwest. As we move
into Thursday, broad ridging will deepen across the SE CONUS
and the ridge axis will set up nearly directly overhead. So
while the dry northwest flow will weaken, general subsidence
will continue and skies will remain mostly clear again Thursday.
Temps again expected in the mid-upper 80`s. Surface high
pressure will strengthen a bit off the coast so surface winds
will turn more out of the east in the afternoon and allow dew
points to push back into the 60`s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Broad ridging aloft is likely to dominate the long term period
with gradually increasing low-mid level moisture; NAEFS
highlights the relatively anomalously warm and moist setup
through this period well with 50-90th percentile heights,
temps, and PWAT`s. GEFS and EC members then consistently show a
series of weak shortwaves sliding to our northwest starting
late Friday through the end of the period. Given the warm and
moist airmass in place thanks to the mid-level ridging and
southwest surface flow, this shortwaves should serve as
sufficient lift to trigger some scattered-widespread showers-
storms each day in the long term. GEFS and EC particularly focus
on Saturday-Monday afternoons for likely convection.
Instability and shear look to be limited overall in this period
however thanks to mediocre low-mid level lapse rates and very
weak flow aloft. Joint probability in the LREF suite of > 500
J/kg CAPE and > 15 knots 0-6km shear remains less than 10%
through the period (probs for greater than 500 J/kg alone are
around 40-50% each day). So weakly forced showers-storms are
probable in the afternoons, with limited severe threat.
Regardless of precip chances, confidence is high in well above
average temps through the end of the period with high temps
running about 10 degrees above average, especially as we move
into next week.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
VFR conditions expected through the early afternoon.
Restrictions possible late this afternoon into the evening as
convection moves through the area.

High pressure offshore is extending into the area. The ridge
will weaken this afternoon as an upper trough approaches the
area. Satellite indicating mid and high level clouds will
increase across the area through the morning. Some mixing in the
boundary layer and less nocturnal cooling expected so fog not
expected early this morning. The air mass will become weakly to
moderately unstable by this afternoon. Scattered to broken
cumulus possible late morning through the afternoon but should
remain VFR. Ceilings more likely to be mid level. Convective
models show scattered convection developing ahead of the upper
trough late this afternoon into the evening. Brief restrictions
possible mainly 20z-01z time period. Patchy light showers
possible through 06z Wednesday.

EXTENDED AVIATION OUTLOOK...Restrictions possible Tuesday night.
Additional restrictions become possible again by Saturday ahead
of a frontal boundary.

&&

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

&&

$$