238
FXUS62 KCAE 111820
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
220 PM EDT Sun Aug 11 2024

.SYNOPSIS...
Hot temperatures and high humidity have led to triple digit
heat indices again today for many locations. Scattered
afternoon and evening thunderstorms are also likely, with
isolated flash flooding and a strong to severe storm or two
possible. River flooding is expected to continue over the next
several days. Temperatures then cool off slightly early this
week with daily chances of afternoon showers and thunderstorms
continuing.

&&

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

- Isolated flash flooding and severe thunderstorm potential this
  afternoon

Rest of the afternoon: A frontal boundary remains draped over
the region today as an upper short wave translates through the
area. Along the coast, a seabreeze front is beginning to move
westward toward the area. These features are acting as
triggering mechanisms for shower and thunderstorm activity this
afternoon. Some showers have already formed over the forecast
area. Expect the development to continue and drift generally
eastward. High PWAT values around 2 inches, especially for the
eastern portions of the forecast area, will likely lead to
locally heavy downpours. Slow storm movement and the potential
for training cells today could lead to isolated flash flooding.
Considered a Flood Watch as offices to our east have some
watches out for the afternoon and the potential, but with the
convective nature of activity today, don`t think there will be
enough coverage of thunderstorms to warrant a watch. Therefore,
did not issue a watch for today. Much like yesterday, SPC
mesoanalysis is indicating 2500-3000 J/kg of mixed level CAPE
along with DCAPE values over 1000 J/kg over the area. One minor
difference between yesterday and today is that there is a bit
more bulk shear expected this afternoon along our northern most
counties. These parameters could lead to an isolated strong to
severe thunderstorm, with the highest threat over the northern
most counties due to the shear there. The main threat will be
strong winds. Temperatures may have hit the peak for many as
cloud cover continues to increase. Most places will see highs in
the lower to mid 90s.

Tonight: Hi-res guidance has been fairly consistent with another
shortwave moving through the region tonight, bringing the chance
for another round of showers and thunderstorms. This round is
expected to track over the northern half of the forecast area,
so have increased PoPs there somewhat to around 40%. This
activity could linger into the early morning hours as well.
Another typical warm and muggy night is in store with lows in
the mid 70s expected.

&&

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

- Showers and thunderstorms expected across the eastern half of
  the forecast area on Monday
- Increasing chances of showers and thunderstorms Tuesday

Zonal upper level flow will persist over the CONUS through much
of the short term with some amplification noted late Tuesday and
Tuesday night as ridging builds over the central US and weak
troughing over the eastern US. At the surface the weak and
diffuse boundary will be over the eastern Midlands on Monday
continuing to act as a focusing mechanism. Instability will
again be moderate to strong Monday afternoon with pwat values
remaining in the 2.0 to 2.2 inch range over the central and
eastern Midlands. This will again make for showers and
thunderstorms during the afternoon and evening with much of the
anticipated activity along and south of I-20. Wind gusts will be
the main threat for severe thunderstorms as DCAPE values will
again push toward 1000 J/Kg. The other concern remains the
potential for locally heavy rainfall combining with already
saturated or nearly saturated soils. WPC has much of the central
and eastern Midlands in a marginal risk of excessive rainfall
and with the anticipated convective coverage this seems
reasonable. With sunset expect much of the activity to dissipate
however with the instability and remaining outflow boundaries a
few cells could develop into the early overnight hours. High
temperatures Monday will range from the mid to upper 80s in the
far northern Midlands to the low 90s in the southern Midlands
and CSRA. Lows Monday night will be in the low to mid 70s.

On Tuesday the pattern begins to shift as the upper levels
amplify over the central and eastern US which will put the area
under NW flow aloft. Although this will be ushering some drier
air into the area models are indicating a short wave which will
be moving through the northern portions of the forecast area
which should trigger convection once again for the afternoon and
evening hours. Much will depend on the location of the short
wave as it moves through the region however with slightly drier
air aloft DCAPE values during the afternoon will be rising to
over 1000 J/Kg producing a wind threat from thunderstorms. With
the lower pwat values Tuesday afternoon around 1.8-1.9 inches
the threat of locally heavy rainfall will be slightly lower.
High temperatures Tuesday afternoon will again be in the upper
80s north to low 90s south with overnight lows in the upper 60s
to lower 70s.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Key Message(s):

- Slightly cooler temperatures but seasonably dry weather
  expected throughout the middle part of the week.

The upper level pattern amplification will continue as the ridge
builds over the central US with the trough digging along the
Atlantic Coast. This will keep the forecast area under
northwesterly flow and drier conditions for Wednesday and
Thursday. By late in the week low pressure will be marching into
the western Great Lakes with a frontal boundary extending into
the central Gulf States. This system is expected to slow as it
reaches the Great Lakes with the frontal boundary lingering over
the SE US through the weekend. This will once again bring
showers and thunderstorms back into the area however with the
trough over the eastern US and expected cloud cover temperatures
will be slightly lower. Afternoon high temperatures will be
slightly below normal in the mid to upper 80s.

&&

.AVIATION /18Z SUNDAY THROUGH THURSDAY/...
Generally VFR conditions through the remainder of the TAF
period, with afternoon and evening convection possible.
Potential for restrictions returns around daybreak.

Isolated to scattered convection has begun to develop across the
region this afternoon. This activity is likely to affect
CAE/CUB/OGB over the next 2 to 4 hours, so have included tempo
groups at the respective terminals. This activity could also
produce gusty winds at each of these terminals.Confidence is
low that AGS/DNL will be affected, so just have VCSH there for
now. Once this round of activity exits, another round of showers
and thunderstorms move across the area overnight, but don`t
think the terminals will be affected by this. Near daybreak,
stratus and/or fog could develop once again due to the residual
moisture in the area. Winds are expected to remain generally
light, less than 10 kts at the terminals except in convection.

EXTENDED AVIATION OUTLOOK...Afternoon and evening convection
and associate restrictions will be possible through Thursday.
Early morning fog and stratus could occur, especially at fog-
prone AGS/OGB.

&&

.HYDROLOGY...
Key Message(s):

- Area rivers have crested and are falling.

The Pee Dee at Cheraw and the Wateree River at Camden are
currently at moderate flooding levels, but will fall into the
minor category shortly. Minor flooding will continue on the
Congaree River south of Columbia in the Congaree National Park
through tomorrow morning.

&&

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

&&

$$