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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KCAE 201041
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
641 AM EDT Sat Apr 20 2024

.SYNOPSIS...
Moisture increases into Saturday as a cold front moves toward
the area. With strong heating each afternoon, diurnally driven
isolated showers and thunderstorms are anticipated to develop.
The front becomes stationary near or slightly south of the area
Sunday. Deep moisture and lift across the area will result in
numerous showers Sunday and Sunday night. Temperatures Sunday
and Monday are expected to be well below normal.

&&

.NEAR TERM /THROUGH TONIGHT/...
A lingering surface trough has led to showers and storms which has
shifted to the eastern area early this morning. Slightly drier air
is shifting into the western portion of the forecast area which
should allow any lingering convection to decrease towards sunrise.

A cold front remains to the northwest of the forecast area this
morning which is expected to slowly shift into the area through the
day. Anomalously warm 850mb temperatures remain in place and cold
advection will lag the front leading to above average temperatures
once again, especially across the southern portions of the forecast
area. Highs in the low 80s in the north to upper 80s south. As far
as the convection potential is concerned for today, HREF guidance
does indicate that the strongest instability will mainly favor the
Coastal Plain but still indicates moderate destabilization over the
forecast area with 50 to 70 percent of members showing sbCAPE > 1000
J/kg south of I-20. Upper level forcing will be limited with zonal
flow aloft but with the front in the area, there likely will be
sufficient forcing for at least scattered showers and storms with
the highest coverage in the southeastern area where the moisture
will be a bit higher. Some HiRes guidance is indicating a capping
inversion potentially hanging on until mid-afternoon. As a result,
convective coverage will likely be highest late afternoon into
evening. Severe weather potential is low with the highest deep layer
shear remaining a bit farther north of the highest instability.

Tonight, a shortwave trough over the Deep South will begin to shift
towards the forecast area with increasing PVA and deep layer
moisture. Rain chances will continue to increase into Sunday morning
with isentropic lift associated with the stalled boundary. Overnight
lows expected to remain mild as a result, mostly in the mid to upper
50s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
An approaching shortwave trough over the MS Valley will promote
continued moisture advection and increasing isentropic lift as
the surface boundary sinks south of the area. Expect periods of
rain to overspread the forecast area through the day which
should strengthen in situ wedge conditions and result in
possible falling or near steady temperatures, which will be much
cooler than previous days with max temperatures ranging from
the upper 50s north to mid 60s south. Overall rain amounts
expected to be somewhat light ranging from around a quarter to
half an inch. Chances of rain decrease Sunday night as
isentropic lift weakens and shifts east of the forecast area and
deeper moisture shifts eastward with PWATs falling below an
inch. Any convection is expected to remain south of the forecast
area closer to the frontal boundary.

Drier air works into the region on Monday as the upper trough
axis moves over the region. There is a chance for afternoon
showers to develop in response to steep mid level lapse rates
from cold 500mb temps moving over the region but limited
moisture available will be a limiting factor and the best
chances should be closer to the Coastal Plain. Expect widespread
clouds to linger on Monday which will limit max temperatures
and keep them well below normal in the 60s. Clearing skies and
some cool advection should support cool temperatures Monday
night in the lower 40s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The extended forecast period generally remains unchanged with
dry weather expected during this period. 500mb ensemble means
show some weak height rises in the wake of the departing trough
off the east coast with somewhat zonal westerly flow.
Temperatures should be a bit warmer than Monday but still remain
below normal with highs in the lower to mid 70s.

A shortwave trough will move from the Great Lakes region to New
England and the Mid-Atlantic coast Wednesday and Wednesday
night. This will push a frontal boundary through the forecast
area by Thursday morning. Ensemble mean PWATs are forecast to be
near normal but with the Gulf of Mexico moisture cut off, most
of the moisture should be above 700mb and expect the front to
come through dry. Max temperatures will return to the upper 70s
to lower 80s on Wednesday ahead of the front with some
compressional heating and plenty of sunshine but highs on
Thursday will be slightly cooler again behind the front.
Ensembles show 500mb ridging on Friday although the GFS ensemble
is a bit flatter than the ECMWF ensemble.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
VFR conditions through the TAF period.

Some passing high clouds over the terminals early this morning.
Winds increase out of the northwest late this morning. With a
cold front in the area isolated to scattered showers and
storms develop late this afternoon into this evening. Coverage
is expected to be limited, so have not included mention in the
TAF. Tonight, moisture will continue to increase with higher
chances for rain and lowering ceilings. There is a possibility
of restrictions around 12z, especially at the Augusta terminals
but with highest confidence after 12z, have left the mention of
restrictions out of this TAF issuance.

EXTENDED AVIATION OUTLOOK...Increasing confidence in
ceiling and visibility restrictions Sunday into Monday with
possible developing wedge conditions.
-- End Changed Discussion --

&&

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

&&

$$