215
FXUS62 KCAE 211854
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
254 PM EDT Fri Jun 21 2024

.SYNOPSIS...
Moisture will increase across the area over the weekend as low
pressure approaches from offshore. Above normal temperatures
are expected by Sunday into early next week. Heat Advisories
may be possible from Monday through Wednesday. Expect scattered
diurnally driven showers and thunderstorms for much of the
short and long term forecast.

&&

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

- Tropical wave/low pressure will result in increased moisture
  through tonight.
- Isolated to scattered showers and thunderstorms across eastern
  Midlands into early this evening.

An expansive upper level ridge remains centered over the
Tennessee Valley. Meanwhile at the surface, high pressure
continues to ridge in north of the area from the western
Atlantic. In addition, low pressure off the Florida/Georgia
coast lacks the organization necessary to be considered a
tropical cyclone, but any additional organization could result
in a tropical depression forming and NHC has this area
highlighted in a 60% chance of formation. While this low is
expected to move onshore somewhere along the GA/FL coast tonight,
its impacts to the local area will be minimal, other than
resulting in a significant increase in moisture.

Surface winds this afternoon into this evening will remain
easterly, around 8-12 mph, between the high pressure to the
north and the low pressure off the southeast coast. Already
seeing a notable increase in moisture across the easterly
Midlands/lower CSRA where precipitable water values should rise
to 1.75-2.00 inches by late in the day. Farther inland, the
airmass will remain dry through the afternoon with precipitable
water values around 1.00-1.25 inches, but these areas will
experience that increased moisture as well later tonight.

Strong subsidence and dry air has resulted in mainly sunny skies
across much of the area this afternoon. However, extensive
cumulus/strato-cumulus has formed across the eastern Midlands,
along with isolated showers, in the area of deepest moisture.
Expect isolated to scattered showers and thunderstorms across
the eastern Midlands into early this evening, before diminishing
with the loss of daytime heating. The additional moisture should
result in partly to mostly cloudy skies later tonight as
stratus develops across much of the area.

Temperatures should warm into the lower to mid 90s today,
perhaps coolest near the I-95 corridor where cloud cover should
be most extensive. Low temperatures tonight will be mild in the
lower 70s.

&&

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

- Increasing moisture will lead to a chance for afternoon and
evening thunderstorms.

Surface low pressure will move south of the forecast area on
Saturday with deep easterly flow leading to increasing moisture.
PWAT values rise to 1.75 to 2.00 inches, near to slightly above
normal, with highest values to the south. Expect showers and
thunderstorms to develop in the afternoon as the air mass becomes
conditionally unstable through daytime heating. We would expect
coverage to be highest across the southern Midlands and CSRA where
moisture is deeper and due to stronger subsidence to our north. Low
lapse rates point to limited updraft strength and a low threat of
severe weather. Convection should diminish in the evening with loss
of daytime heating, however as moisture advection increases through
the night we may see an isolated shower pop up during the early
morning Sunday.

Temperatures will be around normal in the low to mid 90s. Lows
overnight will be mild in the low to mid 70s.

&&

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

- Temperatures rise late this weekend into mid-week.
- Heat Advisory criteria possible Monday through Wednesday.

Daytime temperatures from Monday through Wednesday may be near 100
degrees. Varying levels of moisture during this period limit
confidence in reaching Heat Index values above 105. Daily showers
and thunderstorms could also hinder heating.

Late this weekend, 850mb temps warm leading to daytime highs rising
into the mid 90s for most areas. This warming trend continues into
Monday with highs into the upper 90s to near 100 degrees ahead of a
weak cold front which will bring drier air into the region. Much of
the area will be in northwest flow aloft with rather strong
downslope flow on Monday. The downslope flow would contribute to the
hot temps but would also dry out of the low levels. There may be a
period on Monday where lingering low level moisture combined with
warm temps raise Heat Index values into the 100 to 105 range.
However confidence in reaching Heat Advisory criteria is somewhat
limited by the potential for afternoon showers and thunderstorms.

With drier air over the area for Tuesday, rain chances and dewpoints
will be lower. Highs will still be in the upper 90s to near 100 but
with drier air in place Heat Adv criteria looks less likely. Global
ensemble means favor upper troughing in the Tennessee Valley moving
into the Southeast mid-week, pushing another weak cold front toward
the area. Moisture appears to increase again with over 75 percent of
ensemble member PWAT values over 1.5 inches by Thursday. Increasing
moisture and continued warm temperatures may push Heat Index values
to near Advisory criteria on Wednesday. A cold front pushing into
the Southeast late in the week and increasing cloud/precip chances
should promote slightly cooler weather towards the end of the long
term.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions will prevail at all terminals through this
evening, with flight restrictions possible later tonight at some
terminals due to stratus.

High pressure prevails this afternoon, but moisture will
continue to increase from the coastal plain through the night as
an area of low pressure off the GA/FL coast shifts inland.
Scattered to broken cumulus will remain at VFR levels at KOGB
into this evening, however there is a vicinity shower in the
forecast as convection is possible through about 23Z. Later
tonight, low ceilings due to stratus is depicted by the NBM and
and other guidance. As a result, the TAFs currently show a
period of IFR ceilings at KOGB and MVFR ceilings at KCAE and
KCUB from about 09-14Z. KAGS and KDNL should remain VFR however.
Easterly winds are generally expected at all terminals through
the forecast 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.

&&

$$