598
FXUS62 KCAE 220012
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
812 PM EDT Mon Jul 21 2025

.SYNOPSIS...
Quiet night expected tonight as showers and storms diminish,
followed by increased convective coverage Tuesday as a frontal
boundary moves through the region. Temperatures return to normal
for mid- week followed by another wave of heat to end the week.

&&

.NEAR TERM /UNTIL 7 AM TUESDAY MORNING/...
Key Message(s):

- Isolated storms will continue to diminish over the next few
  hours, leading to a quiet night.

Convection has been primarily confined to areas along and south
of I20 this afternoon. This area was south of a moisture
gradient that was evident in satellite imagery and SPC RAP
Analysis, with a stark instability gradient from north to south
in the forecast area. Cumulus has generally been flat, with some
isolated storms developing, north of I20 but in general
everything in this area has struggle to establish. The southern
Midlands and CSRA had stronger convection, which is now
beginning to wane due to a combination of the sun setting and
convection stabilizing the atmosphere. So overall, the weather
looks to remain quiet tonight after the isolated storms that
are out there now diminish. Lows will likely end up in the mid
70s again.

&&

.SHORT TERM /7 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Key message(s):

- Noticeably cooler on Tuesday as a frontal boundary sinks
  south through the area.

- Mostly cloudy with showers and thunderstorms expected,
  especially across the south where a few stronger thunderstorms
  cannot be ruled out.

A shortwave trough moving off the New England coast will drive
a weak cold front through the forecast area on Tuesday. PWAT
values will be above normal with values over 2.25 inches pooling
along and just ahead of the southward sinking frontal boundary.
The combination of surface heating and excessive moisture is
expected to result in more cloud cover through the day with much
higher coverage of diurnal showers and thunderstorms. Severe
potential appears to be a bit lower than previous days but
cannot rule out an isolated strong to severe storm. However,
slow moving nature of storms and possible back building and
training of storms could result in increased flash flood
potential and WPC has the forecast area outlooked in a slight
risk of excessive rainfall. Temperatures should be cooler with
highs ranging from the upper 80s north to the mid 90s in the
CSRA. Daytime temperatures should be notably lower with forecast
highs in the upper 80s to lower 90s. A few locations in the CSRA
may see heat index values close to criteria but elected to hold
off on an advisory for tomorrow given lower confidence in these
areas reaching 108 degrees given the aforementioned clouds and
rain. The threat of showers and thunderstorms should end from
northeast to southwest Tuesday night as the backdoor cold front
slowly passes through, ushering in a drier air mass.
Temperatures fall into the lower to mid 70s by daybreak
Wednesday.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Key message(s):

- Near to slightly below normal temperatures expected Wednesday
  through Friday. Rain chances are highest in the south.

- Upper ridge and surface high pressure return for the weekend
  with warming temperatures and higher heat indices.

The frontal boundary is forecast to stall near or just south of
the CWA on Wednesday, likely resulting in a sharp moisture
gradient. While the northern Midlands should enjoy lower
dewpoints and dry conditions, the moisture remains in place
across the southern Midlands and CSRA, with isolated to
scattered showers and thunderstorms expected. The central
Midlands, including the Columbia area, are located in the
transition zone so the weather here will be determined by how
much progression south the front makes. Regardless, the entire
forecast area should see near to below normal daytime
temperatures, putting a temporary end to the high heat index
values. The latest guidance shows moisture pushing back in from
the south and east on Thursday with high rain chances, though
temperatures should be similar to Wednesday.

Confidence is increasing that an upper ridge will build back
over the region Friday and into the weekend, while surface high
pressure moves west towards the Southeastern US. This should
allow temperatures to gradually warm through the remainder of
the extended with decreasing rain chances. Will have to watch
the heat index once again as atmospheric heights overhead
increase and the high humidity remains in place.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
VFR conditions are generally expected overnight with potential
restrictions associated with convection during the afternoon and
evening Tuesday.

There remains some scattered cumulus that are starting to
diminish across the region this evening and satellite imagery
shows convective debris clouds over the eastern Midlands and
into the CSRA. Radar has quieted down fairly quickly around the
TAF sites with only some vicinity showers for AGS/DNL and some
weak showers slowly pushing toward CAE/CUB from the north. 4-7
kt winds are a bit variable with multiple outflow boundaries
working across the area, but should become a bit lighter and
turn toward NNW to N overnight and finally toward the NE into
Tuesday morning, peaking around 6-8 kts Tuesday afternoon. This
is due to a weak front nearing the region into Tuesday morning
before it likely stalls out near the eastern Midlands Tuesday
afternoon/evening. With winds expected to remain slightly
elevated overnight due to the approaching front, model guidance
is not showing much of a signal for fog/stratus tonight, though
it cannot be ruled out at the typical prone sites of AGS/OGB.
With the frontal boundary in the area, greater coverage of
showers and storms are expected after 18-20z tomorrow and to the
end of the period where the greater potential for restrictions
should be by OGB, but all TAF sites will have a shot at seeing
convection and thus I have put a PROB30 group at all sites.

EXTENDED AVIATION OUTLOOK... Patchy early morning fog/stratus
possible through the extended. Rain chances become more
seasonal for the remainder of the period.

&&

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

&&

$$