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000
FXUS62 KGSP 241332
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
932 AM EDT Wed Apr 24 2024

.SYNOPSIS...
High pressure off the Southeast Coast will give way to a weak cold
front moving down from the north today. The 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 showers. After that, expect a warming trend through
the weekend as high pressure takes over.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 929 AM EDT Wednesday: A weak cold front continues to approach
the area from the west with a band of showers slowly pushing into
the mountains along the Tennessee border. Large dewpoint depressions
and considerable dry sub-cloud layer air will limit how much
precipitation actually reaches the ground. Nonetheless, light rain
is likely across the mountains with coverage waning to the east this
afternoon owing to a lack of stronger forcing and deeper moisture. A
few minor adjustments were made to the forecast, otherwise no major
changes were needed.

Lowering cloud deck in association with the main frontal zone has
pushed into the NC mountains and will begin to spew further south
and east through the morning hours. Precip along the the boundary
has reached the immediate TN border and will overspread portions of
the mountains over the next few hours. Shortwave trough currently
resides over the Great Lakes region with the attendant frontal
boundary draped from the Great Lakes through the OH Valley and mid-
MS Valley. With surface high pressure set up shop just offshore the
Southeast Coast, weak southwesterly WAA will continue to filter into
the CFWA, ahead of the front. Expect increased cloud cover east of
the mountains by late morning into the early afternoon and
overspreading a good chunk of the area. The frontal boundary is
expected to sag south through the CFWA during peak heating, which
will help to generate a few showers along the boundary east of the
mountains. Coverage will be minimized due to the lack of forcing and
moisture as the better DPVA will reside north of the area, in the
vicinity of the parent low. CAMs still kick off some showers later
in the afternoon and in the evening for the CLT Metro and eastern
Upstate, which increases confidence enough to at least put a
mentionable PoP in these zones. Afternoon highs will run near-
normal, but could fluctuate by a few degrees depending on the extent
of cloud cover along the boundary as it pushes through the CFWA. The
boundary is expected to complete a full fropa by midnight tonight as
a continental surface high settles over the Upper Great Lakes region
and filters in a dry northerly wind behind the front. Cloud cover
will gradually scour out from north to south overnight, with mostly
clear skies for much of the area by daybreak Thursday. Overnight
lows are forecasted to run at or a few ticks below normal for most
locations.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 303 AM Wednesday: A weak cold front should stall out to
our south on Thursday as a surface high moving past to our north
ridges down and gives as a pretty springtime day with temps
a few degrees on the cool side of normal. On Thursday night,
that high pressure center will move to the Hudson R Valley, in
a decent position to function as a parent high to the formation
of a cold air damming wedge across the fcst area. Meanwhile, the
old front will start to lift back northward in response to the low
pressure system wrapping up over the central Plains. The forecast
becomes uncertain, though, because the all the players don`t seem
to be reading from the same script. The main problem might be the
building mid/upper ridge axis overhead on Friday, which keeps the
mid/upper forcing away to the west and minimizes the development
and impact of isentropic lift at low/mid levels. The end result is
a relatively low chance of precip, particularly east of the mtns
where it would be needed to lock in a wedge air mass. Instead, we
just end up with a slightly cooler day with some showers around,
mainly over the mtns. If we get more precip than expected, then
high temps will have to be cut down accordingly. Any precip that
develops should diminish overnight on Friday night.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 227 AM Wednesday: Not much to get excited about out in the
Medium Range. The upper pattern progression slows to a crawl
over the weekend, keeping the axis of a mid/upper ridge over
the area from the Appalachians to the East Coast, and all the
energy lifting northeastward out of the upper troffing over the
Plains off to our west through at least Monday. This pattern will
support a surface high pressure center migrating from off the
nrn Mid-Atlantic Coast on Saturday morning to a position off the
Southeast Coast on Monday. While the high position is favorable for
cold air damming on Saturday, once the sun comes up and warms the
boundary layer, the static stability is no longer high enough and
the low level flow veers around to the east and southeast. Expect
a few ridgetop showers in the afternoon on Saturday, which will
be included. There is some indication of a weak impulse coming
in from the Atlantic to give us some shower activity on Sunday,
but the chance of that is too remote to include just yet. Monday
also looks basically dry. Instead, the main deal will be warming
temps through the weekend and into the first half of next week,
creeping upward a few degrees each day and ending up on the order
of ten degrees above normal by Monday and Tuesday. Eventually,
by Tuesday, the axis of the upper ridge goes positive and gets
pushed off the East Coast as the deamplifying upper trof finally
lifts out of the Plains and across the Great Lakes. This should
push a dying cold front toward the region on Tuesday, possibly
through the region Tuesday night, accounting for a chance of
precip during that time period. We always look for severe storm
possibilities with springtime frontal passages, but this one looks
fairly unimpressive at this time. In fact, looking ahead a bit,
the model blend barely makes a bump in the temps.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: VFR conditions will prevail at all TAF
sites through the forecast period. Cirrus continues to filter
in across the area, while a lowering cloud deck begins to push
across the NC mountains. Expect this cloud deck to thicken and
overspread the region through the morning hours. Low VFR cigs are
forecasted with this deck as a cold front approaches the terminals
from the northwest during the day. With high pressure centered
offshore the Southeast Coast, southwesterly winds will filter in
ahead of the front with low-end gusts possible during peak heating.
Showers will accompany the boundary and the latest guidance are
indicating slightly better coverage. Showers will come close to KAVL
and decided to keep a PROB30 mention for showers during the mid-
morning and early afternoon hours. Showers may develop along the
boundary east of the mountains and could affect KCLT, KHKY, and the
Upstate sites during peak heating, mainly after 18Z. Confidence is
just high enough for a VCSH mention at KCLT as trends continue to
support more shower development along the front as it slips through
the area during the daytime period. Winds will shift to a
northwesterly component at KAVL this morning and this wind shift
will impact the rest of the terminals later in the afternoon and
evening as winds toggle to a north-northwesterly direction and
eventually northeasterly by the very end of the forecast period,
behind the front with clouds slowly diminishing.

Outlook: Dry weather returns Thursday into this weekend, but this
is subject to change as a warm front lifts north of the area by
Saturday with possible restrictions.

&&

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

&&

$$

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