692
FXUS62 KCAE 241814
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
214 PM EDT Tue Jun 24 2025

.SYNOPSIS...
Hot and humid conditions, with dangerous heat index values, are
expected through Wednesday under the continued influence of a
strong upper ridge. Rain chances increase for the mid to late
week as ridging begins to break down. A few thunderstorms may
become strong to severe on Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):

- Dangerous Heat Continues with Heat Index Values 105-110

Heat indices have climbed this afternoon into the triple digits and
will likely continue to increase over the next couple of hours. A
Heat Advisory remains in effect and will continue to be in effect
through tomorrow evening as temperatures and heat indices remain
above seasonal average across the forecast area. A few showers
have developed early this afternoon east of the area near a
surface trough but overall subsidence continues to dominate over
our area with the cumulus field that has developed remaining
flat. An isolated shower or storm could sneak into the
easternmost portion of the forecast area before sunset but most
of the area is expected to remain dry. Remaining warm tonight
with lows generally in the mid-70s.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Key Message(s):

- Dangerous heat expected to continue Wednesday

- Numerous severe thunderstorms expected Wednesday afternoon and
  evening, with hail and damaging winds likely

A really interesting and potentially hazardous weather day is on tap
for Wednesday as a very unique atmospheric set up materializes
across the area. Heat will continue to remain at least during the
first half of the day as slightly more moisture is expected during
the morning hours, coupled with similar temperatures. Temps by mid-
afternoon are expected to be up near 100F again and with dewpoints
69F-72F across the area, heat index values are likely to be in the
105F-110F. As such, have extended the Heat Advisory through 8pm on
Wednesday to account for the dangerous heat expected through the day
tomorrow.

As all of this heat continues across the Carolinas, a shift in the
synoptic pattern driving this is forecast to take place over the
next 36 hours. WV imagery reveals a westward moving upper level low
north of the Bahamas, forecast to encroach upon the Carolinas
tonight and tomorrow. As it does so, it is forecast to create a
strong mid/upper level height gradient, yielding fairly strong E-W
oriented upper level jet streak. This is forecast to propagate
westward through the day, with favorable upper level divergence
noted in the exit region across the Carolinas. As this upper low
approaches us, a plume of really robust mid-level lapse rates are
forecast to overspread the region. Values of 7-8 C/km in the 700-500
hPa layer are expected, with some values of up to 8.5C/km to
possible within this layer. These are, frankly, extreme mid-level
lapse rates for really any time of the year locally, but especially
for late June when the max observed value at CHS is 6.5 C/km for
June 25. Given surface temps in the upper 90s & dewpoints in the
upper 60s or low 70s, extreme values of CAPE are expected tomorrow
afternoon. Guidance is uniform in showing values of SBCAPE in the
4000-5000 j/kg range, with MLCAPE values of 3000-4000 j/kg by 18z.
RAP/NAM/GFS/REFS/HRRR forecast soundings are all concerning,
showing those CAPE numbers in addition to DCAPE values of
1200-1400 j/kg, 0-3km Theta-E lapse rates of 35-40 (this is a
microburst environment differentiator; values of ~25 are
sufficient for severe microbursts typically). Genuinely, this is
one of the more extreme microburst environments that this
forecaster has observed locally.

Despite there being little to no shear, the robust thermodynamic
environment should foster clustering of convection, with multicell
clusters yielding strong cold pools where they develop. This could
allow convection to develop into weakly organized lines of storms,
capable of numerous instances of damaging winds. The CAMS are almost
all showing this possibility, raising the level of confidence in
this scenario taking place. As such, wind damage is certainly
the primary hazard with this setup. Wind gusts of 60-70 mph are
expected, with intense microbursts potentially yielding stronger
gusts. Given the intense CAPE and steep lapse rates, at least
some instances of marginally severe hail are possible as well.
Expect convection to get going between 1p and 3p as peak heating
arrives & favorable upper level lift pushes in ahead of the
low. Storm motions will be pretty funky, likely moving from
northeast to southwest. This is a fairly robust set up and a
hazardous weather day in general. Be prepared for both hazardous
heat & then a quick switch to hazardous thunderstorms tomorrow
afternoon. Things should gradually settle down on Wednesday
night and into early Thursday, with seasonal lows in the low
70s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Key Message(s):

- Typical summertime pattern with near to slightly above normal
  temperatures and daily chances for showers and thunderstorms.

Beyond Wednesday, things look quite seasonal. The upper low will
push inland and help to degrade the intense ridging aloft from
south to north. The same forecast is expected daily from
Thursday through the end of the period as temperatures are
likely to be in the low to mid 90s, with lows in the lower 70s.
Afternoon showers and thunderstorms are expected to yield some
strong to severe storm threat, but this will be much more
seasonal compared to Wednesday`s setup.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
VFR conditions are expected to prevail through the TAF period.

Cumulus field has developed across the area with generally light
and variable winds. Winds will remain mostly variable through
the day, becoming near calm around sunset. With a loss of
daytime heating, also expect the cumulus to dissipate tonight.
Synoptic pattern does not favor widespread fog tonight as
temperatures will struggle to cool overnight, remaining in the
mid 70s. Cannot completely rule out fog at fog prone AGS or OGB
but it remains highly unlikely.

EXTENDED AVIATION OUTLOOK...Scattered to widespread
thunderstorms Wednesday afternoon through evening. Diurnally
driven scattered thunderstorms each afternoon through the
weekend.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...Heat Advisory until 8 PM EDT Wednesday for SCZ016-018-020>022-
     025>031-035-037-038-041-115-116-135>137.
GA...Heat Advisory until 8 PM EDT Wednesday for GAZ040-063>065-077.

&&

$$