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000
FXUS62 KGSP 220729
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
329 AM EDT Mon Apr 22 2024

.SYNOPSIS...
High pressure will move over the Southeast today, with much
drier weather expected compared to Sunday. Warmer weather returns on
Tuesday with dry conditions persisting over the area. Warm
temperatures will linger through the workweek despite a weak cold
front tracking across the western Carolinas on Wednesday. This front
may lead to rain showers Tuesday night into Wednesday, especially
over the immediate Tennessee Border.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 305 AM EDT Monday: The arrival of high cloudiness and some
lower dewpoint air filtering in from the west has taken care of
most of the remaining fog over the western Piedmont. A few patches
may persist, perhaps even locally dense, for the next few hours,
but nothing that would warrant an advisory. Meanwhile...the high
clouds across the NC mountains have put the brakes on the cooling
temps, putting the Frost Advisory in jeopardy. Probably not much
sense in canceling it at 3 am, so we will let it ride for now.
The high clouds should slowly translate eastward through
daybreak as the axis of a deepening short wave moves over the
fcst area.

The upper wave is expected to close off into a compact upper low
over the Coastal Plain of NC this afternoon...far enough east to
not have much of an affect on the fcst area beyond veering the
flow around more northerly. Sunny sky can be expected for the
balance of the day, which should allow for a nice rebound in the
high temps on the order of 7-10 degrees compared to Sunday. There
is some minor concern about the afternoon RH, which is forecast
to drop to around 30 pct, but it is not the best situation for
dewpoint mixing out. The upper low moves offshore tonight and a
weakening sfc high will move over the srn Appalachians by Tuesday
morning. This should set us up for a decent radiational cooling
night, with low temps about ten degrees below normal. This raises
the possibility of frost development after midnight. As the fcst
is constructed, only a patchy frost mention is supported over the
nrn foothills of NC because the dewpoint remains too high, so no
Frost Advisory will be issued. Be on the lookout for it, though,
because a small change in the fcst later today could point toward
more frost potential.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 200 AM EDT Monday: Surface high pressure sets up shop over
the southeastern CONUS Tuesday as heights recover following the
departing shortwave trough. Weak south-southwesterly WAA and 850
mb winds supporting a west-northwesterly downslope component will
allow the airmass to modify as the surface high gradually shifts
offshore. Afternoon highs will return back to near-normal values
under partly to mostly sunny skies. A stout shortwave trough with
an attendant frontal boundary will slide across the Northern Great
Plains and into the Great Lakes region by Tuesday. The trailing
front will encroach the region Tuesday night and is forecasted to
produce showers along the front over the NC/TN border just before
daybreak Wednesday. Otherwise, the front will push into the region
under a mostly moisture starved environment. Increased clouds
and continued south-southwesterly flow will allow overnight lows
Tuesday to uptick back to near-normal values. Timing discrepancies
occur with the timing of the fropa on Wednesday amongst the model
guidance. As of now, the latest trends indicate the front won`t
make a clean sweep until late Wednesday evening. In this case, the
models are picking up on some form of QPF response along the front
with PWAT values surpassing 1.00" across the CLT Metro, Upstate SC,
and northeast GA during peak heating. Confidence isn`t the best in
this scenario, but due to back to back trends per model guidance,
decided to go with a mentionable PoP for portions of the Piedmont
zones. Afternoon highs on Wednesday are expected to run a few ticks
above normal. Dry air entrainment will filter in Wednesday night
as the front slips south of the CFWA and continental surface high
settles over the Great Lakes region. Overnight lows on Wednesday
will continue to run near climo, with a light north-northeasterly
breeze.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 315 AM EDT Monday: The short-term frontal boundary is expected
to stall across the Deep South and Southeast, but south of the
CFWA. As a result, surface high pressure over the Great Lakes will
remain in control Thursday and Friday as the front remains south of
the area and the surface high shifts across the northeastern CONUS
and eventually offshore the Northeast Coast by Friday. Temperatures
will run at or slightly below normal Thursday and Friday due to a
persistent northerly component. A digging upper trough will traverse
across the Four Corners region and into the High Plains by Friday,
inducing surface cyclogenesis across the central CONUS. In this
case, the stalled boundary will gain warm frontal activation and
eventually lift north of the CFWA the end of the workweek. Model
guidance are consistent with the overall synoptic pattern over
the region as an upper ridge develops over the Eastern Seaboard,
while the CFWA resides under a warm sector regime. In this case,
expect temperatures to rise a category or two above normal by
D6/D7. Uncertainty still resides with precip potential, but most
of any precip will develop to our north and west, but not enough of
a spark over the CFWA to maintain mentionable PoPs in the extended
forecast period at this time outside of the immediate TN border.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: We will have to deal with some pesky fog
first thing, but the plan is for enough dry air to move in before
the start of morning ops to take care of mixing out the fog. So,
some MVFR/IFR is possible at KCLT and KHKY for the next few
hours. Otherwise, after that, VFR at all terminals. A high-based
stratocu ceiling east of the mtns will move east through daybreak
and scatter out. Once an upper trof axis moves through early in the
day, sky should be essentially clear and we are left with a wind
forecast. Direction should be N to NNE for most of the daytime,
then going light/variable with sunset as high pressure builds in.

Outlook: Expect dry, VFR conditions to continue thru Tuesday as
high pressure builds over the region from the west.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Frost Advisory until 9 AM EDT this morning for NCZ051-058-062.
SC...None.

&&

$$

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