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000
FXUS62 KGSP 250731
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
331 AM EDT Thu Apr 25 2024

.SYNOPSIS...
A weak cold front should stall to our south tonight and Thursday as
high pressure moves past to our north. The front will move back
northward on Friday and wash out across our area, but giving us a
cooler day because of clouds and a few showers. After that, expect a
warming trend through the weekend and into next week as high
pressure takes over.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 315 AM EDT Thursday: The trailing cold front has completed a
full fropa across the CFWA and is expected to stall south of the
region throughout the daytime period with surface high pressure
nosing into the region as the center of the high settles over the
Great Lakes region. Weak upper troughiness will be replaced by an
incoming upper ridge by the end of the period, with associated vort
energy. The stalled boundary will undergo warm frontal activation at
this time as a deepening low moves across the central High Plains,
while the vort energy helps the warm front to gradually lift north
back into the region by daybreak Friday. The aforementioned high
will slide over the northeastern CONUS and allow winds to return
to a east-northeasterly component overnight, which will set the
stage for a wedge-like configuration to filter into the CFWA. At
the same time, the favorable upslope locations along the eastern
Blue Ridge Escarpment will generate a few light showers by the
end of the period before showers become more widespread during the
short-term, mainly across the mountains. Afternoon highs today will
run at or slightly above normal with mostly sunny skies and a weak
downslope component present. Increasing high clouds will filter in
very late into the daytime period, but will thicken overnight and
start across the eastern BR escarpment and I-40 corridor before
spreading further south into the CLT metro and eastern Upstate by
daybreak Friday. As a result, overnight lows are expected to run
near-normal for most locations.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 312 AM Thursday: Friday continues to be the most troublesome
part of the forecast, as guidance continues to put a sfc high
somewhere off the coast of southern New England, in a good spot to
support a hybrid cold air damming wedge. The problem is that the
synoptic guidance continues to amplify the mid/upper ridge right
overhead during the day, which limits the amount of forcing. The
GFS still has some productive-looking mid-level isentropic lift,
but low levels are nothing to get too excited about. The CAMs
go out far enough to include Friday, but limit most of the good
chances of precip production to the mtns. That being said, a trend
seems to be forming that would have more clouds and probably more
shower activity with a light S/SE wind at 850 mb. So, we have
cut high temps another few degrees and increased the coverage of
relatively modest precip probs, which points us in the direction
of possibly not getting out of the 60s Friday afternoon. Light
S/SE upslope flow continues into Friday night so a precip chance
will be kept near the Blue Ridge Escarpment. By Saturday, the high
pressure center should start to migrate south and the isentropic
lift will diminish and move away, so we should be able to lose
some of the cloud production and consequently see the start of
a warming trend. High temps still look right around normal, with
some sun in the afternoon.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 201 AM Thursday: The upper pattern is expected to be slowly
progressive through the Medium Range, slow enough that the severe
weather expected over the Plains/MS Valley region over the weekend
never really makes it to us because the pattern also deamplifies
and loses energy. While all that is going on to our west Sunday
into Monday, the axis of the high amplitude upper ridge moves to
the East Coast and supports sfc high pressure off the Southeast
Coast. No big changes there...the pattern allows temps to climb
maybe a category above normal Sunday and then 5-7 degrees or so
above normal Monday. The upper ridge gets pushed offshore by a
strong shortwave lifting out of the deamplifying and approaching
trof Monday night into Tuesday. That sets us up for some forecast
uncertainty with regard to the passage of a dying cold front on
Tuesday. This boundary will have the mid-level support of a vort
lobe moving through during the day, which should be supportive
of at least scattered showers and thunderstorms, so most of the
forecast area along and N/W of I-85 gets a chance, but yet the
guidance blend brings the high temps up to about 10 degrees above
normal. Depending on the trend of the guidance, expect some movement
up or down to both. The severe storm potential looks no better than
average. Even if the boundary sags through the region, the air mass
change looks insignificant, so the forecast for Wednesday looks
basically the same with another shot at scattered storms during
peak heating, and temps still around ten degrees above normal.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: VFR conditions will prevail through the
majority of the forecast period. The cold front has sagged south of
the terminals with winds going light. Winds have shifted to a north-
northeasterly component for the TAF sites, with KAVL maintaining a
north-northwesterly wind. Skies are mostly clear for most locations,
but mountain valley fog will be possible overnight, but should stay
away from KAVL. Mostly sunny skies will be in store Thursday with
winds turning the dial to a south-southeasterly component by peak
heating as the direction becomes influenced by surface high over the
Northeast. Model guidance maintains a northeasterly component at
KCLT, which is little surprising, but decided to make winds more
easterly than northerly. The front will stall south of the area and
act as a wedge boundary overnight. This would set the stage for an
increase in clouds overnight tonight, with possible restrictions at
the NC TAF sites by or just before daybreak Friday and in all of the
Upstate sites at or just after daybreak Friday. Advertising MVFR at
the moment for KCLT, but could be lowered to IFR in the 12Z TAF
update with a mention at all terminals. Winds will increase as a
result and all TAF sites will gain an easterly component overnight
as well.

Outlook: Rain and associated restrictions develop Friday as a warm
front lifts north across the area. Clouds linger Saturday, along
with the potential for isolated mountain convection which lingers
into Monday.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$

SYNOPSIS...PM
NEAR TERM...CAC
SHORT TERM...PM
LONG TERM...PM
AVIATION...CAC