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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 231345
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
945 AM EDT Tue Apr 23 2024

.SYNOPSIS...
High pressure over the Southeast Coast today will bring warmer
temperatures with dry conditions persisting over the area. The high
will give way to a weak cold front moving down from the north,
but we will scarcely notice any change in the temperatures and
most places will not get rain through mid-week. The front may
come back northward on Friday. After that, expect a warmup through
the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 943 AM EDT Tuesday: Early morning shallow ground fog has since
mixed out as the boundary layer warms and mixes/deepens. A few high
cirrus will continue to stream across the area with a quiet forecast
on tap for today. No changes were needed with this update and the
ongoing forecast remains on track.

Otherwise, a digging shortwave trough over the Northern Great Plains
with an attendant boundary will inch closer towards the CFWA from
the northwest throughout the period. Scattered cirrus in association
with this feature is currently drifting over the area. Surface high
pressure currently centered over the Southeast has allowed for winds
to go light and variable over much of the CFWA. In this case,
temperatures have dropped well into the 40s and 30s under good
radiational cooling conditions. Factor in tight dewpoint depressions
as well and the ongoing Frost Advisory remains on track. The surface
high pressure will gradually pull offshore the Southeast Coast
during the daytime period in response to the incoming frontal
boundary and allow for weak south-southwesterly WAA to filter into
the region. A few high clouds will be possible, but a very pleasant
day overall is expected as afternoon highs return to near-normal
values and an uptick of 8-10 degrees compared to Monday. The
boundary layer will be able to mix out very well and could drops RH
values below 30% and provide some low-end gusts during peak heating
across portions of the CFWA. Decided not to go with a Fire Danger
Statement at this time, but could eventually be issued for northeast
Georgia later in the morning if trends come in a bit drier.

The aforementioned shortwave trough will swing into the Great
Lakes region later today as the trailing front encroaches
the region. Increased cloud cover will move into the mountains
overnight, especially along the immediate TN border. Enough moisture
and forcing along the boundary should instigate an area of precip
along the NC/TN border by daybreak Wednesday, but QPF response will
remain low. Winds remain elevated overnight as the boundary layer
struggles to fully decouple under southwesterly flow. Overnight
lows will run ~10 degrees higher tonight compared to Monday night
as a result and thus, Frost issues will not be a concern.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 305 AM Tuesday: The main feature of interest will be a weak
cold front that gets pushed southeastward across the forecast
area on Wednesday by a short wave passage to our north, which
takes the axis of a rather broad and low amplitude upper trof
across the region as well. The best chances for precip will be
along the TN border early on Wednesday as moisture gets pushed
upslope from the WNW, but otherwise the forcing is meager and the
moisture shallow, so places east of the spine of the Appalachians
are likely to remain dry as the front moves through. The NAM seems
overdone at this point, but isolated showers east of the mtns in the
afternoon remain a low possibility and could be added into later
packages. Otherwise, we will barely notice the passage of this
boundary as temps climb back up to around normal for Wednesday and
Thursday. Sfc high pressure moving across the Great Lakes region
will build into the region for Thursday and give us a nice Spring
day. It won`t last though, as model guidance amplifies the pattern
starting Thursday night, with a lead short wave lifting northeast
out of the upper trof coming out over the High Plains. The old
front will start to lift back northward toward us overnight,
with perhaps enough moisture return to bring a slight increase of
precip chances toward daybreak Friday. Low temps should be warm
enough to keep frost from forming.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 223 AM Tuesday: A short wave riding over the top of the
mid/upper ridge just to the west on Friday should activate the old
front and lift it northward as a warm front across the NC mtns,
with enough forcing to account for some shower activity over the
higher terrain. Temps will be a bit tricky as the position of a
sfc high and the pattern suggest wedge, even though the guidance
blends do not seem to bear this out. If anything, the temps are
more likely to end up cooler than what shows in our forecast for
highs Friday, so look for a trend in the next few cycles. Once we
get past Friday, the bulk of the forecast through the weekend,
at least, will feature an amplifying upper ridge over the east,
supporting a sfc high that migrates down to a position between the
Southeastern US and Bermuda. This evolution should allow for warmth
and moisture to move steadily back in from the Gulf/Atlantic,
with temps climbing about a category each day Saturday through
Monday. In this pattern, it`s hard to suppress all the convection
over the mtns, so each afternoon will probably have a small chance
of ridgetop showers. Eventually, the axis of the upper ridge
will reach the East Coast on Monday and we will start to feel
the effects of the upper trof moving in from the west. However,
the trof will be deamplifying the whole way, losing a lot of the
forcing and with the sfc cold front dying out as it reaches the
mtns Monday night. Precip chances increase during the late part
of the forecast, but for now, nothing more than warm season climo.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR conditions will prevail through the
forecast period as high pressure centers over the area, which has
allowed all TAF sites to go light and variable for winds. A band of
cirrus is pushing in from the northwest and have included this in
the prevailing line for all terminals. High pressure will gradually
push offshore during the daytime period and allow for winds to pick
up out of the southwest by mid-morning. Factor in good mixing in the
boundary layer and low-end gusts will overspread all TAF sites
during peak heating, so included this at KCLT and elsewhere. Winds
will remain elevated tonight, but low-end gusts should diminish
after sunset. An increase in cloud cover will begin to overspread
the region after daybreak Wednesday as a cold front encroaches the
region from the northwest later Wednesday.

Outlook: Dry VFR conditions are expected to continue through tonight
as high pressure remains over the region. A cold front will approach
our area from the NW early Wednesday and move through during
the day. This system could bring some brief flight restrictions.
Drying returns Thursday into this weekend, but this is subject to
change as a warm front lifts north of the area by Saturday.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
GA...None.
NC...None.
SC...None.
-- End Changed Discussion --

&&

$$

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