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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 202156
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
556 PM EDT Sat Apr 20 2024

.SYNOPSIS...
Much cooler temperatures and widespread light rain is expected
overnight into Sunday with drier weather returning by Monday. Warmer
weather returns by Tuesday and continues through the workweek.

&&

.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
As of 545 PM EDT Saturday: Over the past couple of hours we saw
a cluster of thunderstorms develop west of the I-77 corridor and
move east. A couple of these storms became severe. The southern-
most storm produced a very impressive hail core that dumped 2 inch
hail in and around Rock Hill, SC. This activity has moved east of
our CWA, but we`re currently seeing some new cells develop over
roughly the same area mentioned above. More than likely, this
activity will remain sub-severe, but any storm that manages to
become severe will have the potential to produce damaging wind
gusts and large hail. The rest of our fcst area remains precip
free early this evening. Convective activity should wane after
sunset with the loss of daytime heating.

Otherwise, drier conditions are expected this evening thru late
tonight as the eastern periphery of dry high pressure extends into
the western Carolinas. However, rain chances will gradually ramp
up across the forecast area overnight into late Sunday morning as
an in-situ CAD develops and isentropic ascent increases. Lows to-
night should be 3 to 5 degrees above climo thanks to increasing
clouds and rain. Rain will linger thru much of the day on Sunday
before gradually tapering off from west to east late Sunday aftn
into early Sunday evening. Thus, have categorical to likely PoPs
from early Sunday morning thru late Sunday aftn. Thunderstorms are
not expected to develop thanks to the CAD. Highs on Sunday will end
up 15 to 20 deg below climo thanks to the wedge and will struggle
to reach into mid to upper 50s east of the mountains.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 100 PM EDT Saturday: Rainfall directly associated with the
southern stream wave will pull away from the area Sunday evening
with just a small lingering pop early in the Piedmont areas. A
vigorous mid level trough will swing quickly through on Monday. This
system will have little moisture with which to work, so the main
impact will be just keeping conditions cooler than climo for Monday.
Flat mid level ridging and weak surface high pressure will be the
main weather influences for Monday night and Tuesday.

Temperatures Sunday night and Monday night will be cool with lows in
the 30s in the mountains and lower to middle 40s in the Piedmont.
Right now, it looks like temperatures will remain just above and
frost/freeze concerns in the mountain valleys, but this will need to
be watched closely. Highs Monday will be nearly 10 degrees below
climo warming to around 3 degrees below climo on Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 115 PM EDT Saturday: A mid level trough will move from the
Great Lakes into the Northeast for the middle of the week. This will
push a weak and mainly dry cold front into the area on Wednesday.
Mid level heights will quickly rebound from this trough for Thursday
and Friday. Another system will impact the area late in the week
with some showers possible by Friday, mainly in North Carolina.
Temperatures for the middle to end of the week should be pretty
close to climo.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Sfc high pressure will dominate through late
this evening leading to mostly dry conditions. However, isolated
thunderstorms may develop late this afternoon into early this
evening thanks to ample daytime heating. Thunderstorms look to
develop around/near KCLT, KGSP, and KGMU from roughly 21-24Z so have
introduced TEMPOs at these terminals. Could not rule out the
possibility of an isolated strong to severe storm impacting any of
the aforementioned terminals. Dry conditions will return around
sunset due to the loss of daytime heating. The rest of the terminals
should remain dry this afternoon and early evening. A few terminals
are reporting low-end gusts this afternoon; KAVL, KGMU and KAND.
Intermittent low-end gusts should stick around through this
afternoon before gradually diminishing this evening. The exception
will be KAVL where low-end gusts may linger through late this
evening before tapering off. Winds will start out W`ly across the SC
Upstate terminals early this afternoon before gradually turning N`ly
this evening. Winds will start out NW`ly at KHKY and KCLT early this
afternoon before gradually turning N`ly this evening. Winds east of
the mountains will gradually turn NE overnight and will remain NE
through Sunday. Winds will remain NW at KAVL through the entire 18Z
TAF period. Both restrictions and rain chances will return overnight
into early Sunday morning as in-situ cold air damming develops. Cigs
will gradually lower from west to east early Sunday morning becoming
IFR by late Sunday morning. -RA will linger through the end of the
18Z TAF period for all terminals thanks to isentropic ascent. No
thunderstorms are expected with stable cold air damming in place.
Cigs may lift to low-end MVFR levels early Sunday afternoon but
confidence on this is low at this time.

Outlook: VFR and dry conditions return Sunday night into early next
week as high pressure builds into the region from the west.

&&

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

&&

$$

SYNOPSIS...SCW
NEAR TERM...AR/JPT
SHORT TERM...SCW
LONG TERM...SCW
AVIATION...AR/JPT