912
FXUS62 KCAE 120620
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
220 AM EDT Mon Aug 12 2024

.SYNOPSIS...
Temperatures cool off slightly this week with daily chances of
afternoon showers and thunderstorms continuing.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Key Message(s):

- Isolated showers and thunderstorms through daybreak, mainly north
of Columbia.

Forecast remains largely on track early this morning. Another
shortwave upstream from the Carolinas is expected to continue to
provide at least weak lift, with CAMs consistently showing enough
instability to support convection across the northern half of the
forecast area for much of the night. This has generally occurred,
and thankfully precip is moving off to the northeast at a decent
pace. Temps will be fairly similar to what they have been -
generally mid 70s across the area.

&&

.SHORT TERM /6 AM MONDAY MORNING 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 SUNDAY/...
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 /06Z MONDAY THROUGH FRIDAY/...
Generally VFR conditions expected outside of brief restrictions in
diurnally driven thunderstorms and early morning stratus/fog.

Convection is north of the terminals early this morning with mainly
mid and high level clouds across the area. With shallow low-level
moisture, near calm winds overnight and decreasing high clouds, fog
and low stratus may develop toward dawn. Have included a mention of
restrictions in the TAFs, possibly as low as LIFR/IFR but improving
by 12/14z. As the air mass becomes moderately to strongly unstable
this afternoon, scattered thunderstorms are expected to develop once
again. Outside of convection, sfc winds will be variable at 5 to 10
knots.

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

&&

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

&&

$$