246
FXUS62 KCAE 210013
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
813 PM EDT Thu Jun 20 2024

.SYNOPSIS...
Dry weather and near normal temperatures will continue through
tonight as synoptic situation remains relatively unchanged.
Unsettled conditions are possible tomorrow and into the weekend
as moisture moves in from the Atlantic. Well above normal
temperatures are expected by Sunday into early next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...

KEY MESSAGE:

- Seasonably warm and dry overnight.

Little change in the overall pattern and the surface high
remaining in control of the region. Easterly winds will become
light and variable overnight. Can`t completely rule out some
ground fog south of I-20 towards daybreak, but the threat is
low.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...

KEY MESSAGES:

- Tropical wave will pass south of us Friday.
- Increasing chance for afternoon and evening thunderstorms.

Westerly moving tropical wave/low pressure center is forecast
to move ashore northern Florida or southeastern Georgia during
the day on Friday, pushing westward by the evening hours.
Initially, our forecast area will have quite a bit of subsidence
north of this feature as we`ll still be stuck underneath the
mid and upper level ridge. As a result, the day is initially
expected to be dry and warm. By the afternoon hours, however, a
surge of PWs is forecast by all guidance, with HREF members
generally showing the highest PWs >1.5" approaching the I20
corridor and points southward. This is the area most likely to
see rain between 2p and 8p, though it should remain generally
scattered in nature. Thunderstorms are possible but generally
expecting things to remain sub-severe. I do want to note that
the well- performing HRRR has been consistently showing no
precip developing but it also is mixing the boundary layer
substantially more than its fellow CAMs (even those that have
had that bias in the past) so tend to think that is the outlier.
Highs will likely end up in the lower 90s, maybe a touch cooler
in the coastal plain where clouds are likely to develop earlier
in the day. Showers/storms will likely hang around for a bit
after sunset, diminishing as the night goes along. Look for lows
in the upper 60s.

Saturday looks fairly similar, as the plume of higher PWs is
expected to fully overspread the forecast area by this point. Given
hot temperatures and rich boundary layer moisture, we should see
scattered showers/thunderstorms develop across the forecast area
again on Saturday. Again, generally expecting these to remain
sub-severe but can`t rule out a strong storm here or there. Highs are
likely to be in the low to mid 90s, with overnight lows again in the
upper 60s or lower 70s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...

KEY MESSAGES:

- Heat builds into next week with heat indices above 100.
- Typical scattered afternoon/evening thunderstorms are
  expected.

Guidance continues to show fairly conflicting signals in terms
of heat in the long term. The ridge that has been parked across
the OH Valley and Mid Atlantic regions is expected to shift
westward and yield troughing as the next work week approaches.
The first signs of this are expected by Sunday as heights will
begin falling across the Carolinas. Heights should continue to
remain at or below 588dm by Monday and Tuesday as the western
CONUS ridge builds and persistent troughing looks like it may
set up. LREF Members support the operational models in showing,
leading to higher confidence than normal in the pattern
evolution through early next week.

However, the sensible weather that results from this in the forecast
is conflicting to say the least. The trough is forecast and expected
to yield a surface low into the northeast CONUS by Monday, pushing a
weakening cold front towards the FA by Monday afternoon and the
overnight hours. PWs will still be near to slightly above normal
both Sunday and Monday, with scattered to potentially numerous
thunderstorms expected both days given the favorable setup. This
conflicts with models also showing high chances at temps in the
upper 90s to around 100F for highs by Monday. This is also shown on
Tuesday despite the cold front likely stalling near the area. Part
of this looks like it could be westerly or northwesterly flow that
develops in the base of this trough advecting warm (20-22C) 850 hPa
temps across the area Sun-Wed of next week. Given the expectation
that daily showers/thunderstorms will be a risk, and lowering 500
hPa heights, it is hard to believe NBM guidance that temps will make
it to near 100F any day next week, let alone multiple days. Have
capped forecast highs around 98F as that makes conceptual sense
given the forecast as it stands right now. However, while we may
not get as hot as some of the guidance suggests, it will feel
above 100 due to the increasing low level humidity.

Lows will likely be in the 70s given surface moisture in place.
Overall, it does look hot but nothing too crazy for June in the
southeast. By the middle of next week, things still look to be
active with a building western CONUS ridge, so expect daily
chances at rain to continue into Wednesday and Thursday.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR conditions expected through the TAF period.

With high pressure generally in control tonight into Friday,
conditions are expected to remain vfr through the period. Late
afternoon cumulus will be dissipating towards sunset once again.
Winds should diminish to less than 5 knots, but should still be
enough mixing near the surface to keep them from going
completely calm for long periods. In addition, the mixing will
also help to inhibit any fog formation late tonight. Friday will
see an increase in low-level moisture as an area of low pressure
off the coast begins tracking closer to the region. This may
only produce more scattered to occasionally broken vfr clouds
through the afternoon. As for rainfall potential Friday, most
guidance keeps the activity much closer to the coast through
much of the day, but can not completely rule out an isolated
shower approaching ogb late in the afternoon as the sea-breeze
moves inland more.

EXTENDED AVIATION OUTLOOK...Brief restrictions possible in
isolated to scattered afternoon and evening thunderstorms Saturday
with increasing chances Sunday through Tuesday.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...