452
FXUS62 KCAE 211450
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
1050 AM EDT Fri Jun 21 2024

.SYNOPSIS...
Moisture will increase across the area over the weekend as low
pressure approaches from offshore. This will lead to mainly
scattered diurnally driven showers and thunderstorms focused
in the southeast Midlands and CSRA through Sunday. A weak cold
front will move into the area late Monday and possibly enhance
diurnally driven showers and thunderstorms through midweek. Well
above normal temperatures are expected by Sunday into early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- Tropical wave/low pressure will bring increased moisture
  today and tonight.
- Isolated to scattered showers and thunderstorms across
  eastern Midlands this afternoon and early evening.

An expansive upper level ridge is centered over the Tennessee
Valley, while at the surface high pressure extends from the
mid-Atlantic coast into the central/western Carolinas. In
addition, an area of low pressure continues to organize off the
Florida/Georgia coasts late this morning, but lacks the
deep/organized convection necessary to be classified as a
tropical cyclone.

The airmass is very dry across the area, with a northeasterly
flow in place at the surface. However, moisture associated with
the low pressure system offshore will spread inland across the
coastal plain this afternoon. Precipitable water values
generally range from 1.00-1.25 inches, but a sharp gradient will
develop by the end of the day with precipitable water values
rising to 1.75-2.00 inches across the eastern Midlands and lower
CSRA.

Satellite imagery depicts increasing cumulus clouds across the
eastern Midlands late this morning where the moisture has been
on the increase, and expect this cloud cover to spread farther
inland as the day progresses. High resolution mesoscale models
show diurnally driven isolated to scattered showers and
thunderstorms across the eastern Midlands and lower CSRA this
afternoon and early evening, but rain-free conditions should
persist within the drier airmass and beneath stronger subsidence
aloft farther inland. Temperatures should warm into the lower
to mid 90s today, perhaps coolest near the I-95 corridor where
cloud cover should be most extensive.

Skies should clear out after sunset with any rain chances
quickly diminishing. Low temperatures tonight will be around 70
degrees.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:

- Tropical wave/low pressure moving inland south of the area.
- Increasing chance for afternoon and evening thunderstorms.
- Above normal temperatures expected.

Saturday and Saturday night...Upper level ridging, centered to
the west of the area extends into the area. The westward moving
tropical wave/area of low pressure should be moving inland
mainly south of the area across coastal GA into Florida
Saturday. Precipitable water increases to 1.80 to near 2.00
inches (around 120 percent of normal) in the lower Savannah
river area and southeast Midlands Saturday afternoon. The air
mass is a little drier in the north Midlands and SC Piedmont.
Warm advection and moisture flux focused in the southeast
Midlands. Instability overall appears limited. Showers and
thunderstorms possibly enhanced along a sea breeze front, so
have chance pops in the southeast Midlands. Lower chance of
showers and thunderstorms to the northwest as mid level capping
should be stronger/moisture possibly more limited. Temperatures
slightly above normal in the low to mid 90s for high temps.

Sunday and Sunday night...Moisture appears to increase across
the area and the upper ridge retrogrades a bit to the west.
Perhaps some weak short wave troughs will rotate around ridge to
provide lift. Still think higher chance of afternoon and evening
thunderstorms remains across the CSRA and southeast Midlands
enhanced by sea breeze with capping stronger to the northwest.
Instability remains weak but stronger near the coast. 850mb
temps warm a degree or two so temps should be a little warmer
with most areas rising into the mid 90s. Heat index values in
the 100-105 degree range. Muggy overnight temps in the low to
mid 70s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
KEY MESSAGES:

- Heat builds into next week with heat indices remaining 100.
  Warmest day appears to be Wednesday with heat index values
  near 105 or a little higher.
- Typical scattered afternoon/evening thunderstorms are
  expected.

The NAEFS and ECMWF EFI point to temperatures above normal, but
not significantly, with the warmest day Wednesday. Early in the
week, an upper trough over New England with trough axis along
the coast. Area in northwest flow aloft with rather strong
downslope flow Monday. Upper ridge is now centered in the
southern Plains to Desert southwest. A weakening cold front will
be approaching from the north late Monday then stall near the
area or south of the area Tuesday. Scattered mainly diurnally
driven showers and thunderstorms Monday, lower pops Tuesday as
drier air moves in behind the front. Ensembles showing upper
trough in the Tennessee Valley moving into the southeast
late Wednesday into Thursday. This trough should drive a weak
cold front toward the area. Moisture appears to increase again
with ensemble precipitable water > 1.5 inches probabilities in
the 80-90 percent range by Thursday. Overall instability weak to
moderate mid week and deep shear should increase. Convergence
along front support at least scattered showers and
thunderstorms. Temps should cool a bit by Thursday.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Skies over the terminals are clear at daybreak as high pressure
remains in control of our weather. An area of low pressure to
our southeast will approach the Georgia and Florida coasts
today, likely resulting in scattered cumulus and/or
stratocumulus moving in from the east later this morning. In
addition, a few showers or thunderstorms are possible by the
afternoon but overall confidence is low. Have maintained VCSH
at OGB which is the most likely terminal to see showers and
perhaps brief restrictions. Will need to monitor trends and see
if the rain chances extend further north and west to the other
terminals. Any lingering showers should quickly diminish with
the loss of daytime heating giving way to clear skies. Easterly
winds are likely to continue through the TAF period.

EXTENDED AVIATION OUTLOOK...Brief restrictions possible in
isolated to scattered afternoon and evening thunderstorms on
Saturday with increasing chances Sunday through Tuesday.

&&

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

&&

$$