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000
FXUS62 KGSP 240243
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1043 PM EDT Fri Oct 23 2020

.SYNOPSIS...
A weak cold front will cross the area slowly on Saturday bringing a
chance for widespread showers. Slightly cooler temperatures Sunday and
Monday will be followed by a return to well above normal temperatures
with the next round of rain possible on Thursday ahead of a strong upper
low.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 1042 PM EDT Friday: Earlier shower activity over the northern
foothills of NC has dissipated, so our attention has turned toward
the west and a line/area of rain and thunderstorms moving east
across the Cumberland Plateau. This activity appears to be on track
to reach the mtns in the pre-dawn hours. Otherwise, patchy fog is
likely again tonight, although may not be as widespread across
mountain valleys in response to increasing cloud coverage. The
warm air mass in place will support lows once again in the 50s to
near 60.

It now appears the a weak cold front pushing into the region
Saturday will stall over the region thanks to a weak disturbance
riding along the front, roughly through I-85 corridor during
the day. This will help to enhance light to occasionally moderate
showers over the region with sufficient instability for isolated to
scattered thunderstorms from late morning though the afternoon. The
clouds and rain should arrive late enough in the day for one more
warm day with highs again near 80 east of the mountains.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 220 PM EDT Friday: The short-term forecast picks up at 00z on
Sunday with a weak, embedded upper shortwave moving over the Southeast
as very broad upper trofing deepens over the Northern Rockies. For
the remainder of the period, the large-scale upper pattern will
continue to amplify as the above mentioned trof digs down across
the Southwest and heights gradually rise over the Southeast as an
upper ridge builds. At the sfc, a moist cold front will be moving
thru the CWFA as the period begins late Saturday. As the front`s
parent low lifts well to the north over Canada, the front will be
fairly slow to move thru the fcst area with the deeper moisture
associated with it lingering well into Sunday. By late Sunday, high
pressure north of New England will slide farther east and a weak
CAD pattern will setup. This will allow shallow moisture to persist
over the area for the remainder of the period. Overall, most of
the fcst area should get some decent QPF, but it`s not likely to
be enough for any hydro concerns. In addition, some sfc-based
instability is expected for Sunday, however it`s doubtful that
any thunderstorms that do develop will become strong/severe.
Otherwise, high temps will be near normal both days with lows
remaining well-above normal.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 205 PM EDT Friday: The extended forecast picks up at 00z on
Tuesday with deep upper trofing digging down across the extreme SW
CONUS as broad upper ridging lingers over the Southeast. By mid-week,
the above mentioned upper trof is expected to separate from the mean
upper flow and a large cutoff low forms over New Mexico/Texas. At
the same time, very broad upper trofing centered over the Great Lakes
region will persist to our north. As for the remainder of the period,
the long-range guidance diverges quite a bit with the fate of the
closed low becoming unclear. At the sfc, weak high pressure will be
lingering over the fcst area as the period begins with an elongated,
nearly stationary frontal bndy to our north and west that stretches
from New England to Texas. Over the next couple of days, the moist
frontal bndy will slowly drift over the Carolinas as weak high
pressure moves further offshore and weak, SLY return flow sets up
over our area. On Thurs, the models try to move a low northward out
of the Gulf of Mexico and track it over the deep south. It remains
unclear how quickly this system will track north/northeastward, but
it will likely bring some widespread precip and unsettled wx to our
area for Thurs and Fri. Some severe wx is also a possibility with
this system as the large-scale forcing appears robust. Temps will
start out well-above normal on Tues and cool to below normal by the
end of the period late next week.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR through the end of operations this
evening. Precipitation and cloudiness ahead of a cold front will
reach the mtns in the pre-dawn hours, but probably not early
enough to prevent fog/low stratus restrictions from developing
in the mtn valleys. Confidence is not high enough to take KAVL
down below MVFR at this point, though. A brief period of low
clouds could also impact KCLT, but again, confidence is not high
enough to indicate anything worse than a scattered cloud below
010. Wind will be light S to SW. On Saturday, an initial band
of precipitation will move in from the west during the morning
hours and may impact KAVL before noon. This will be handled with
a PROB30. The front will slow down and lay out over the western
Carolinas in the afternoon and evening. The initial band of precip
is expected to weaken during midday, and then new showers and a
few thunderstorms are expected to develop across the region in
the afternoon. Confidence is reasonable enough to expect some
precip to affect each site at some point after noon, but the
timing is unclear. For that reason, we employ a PROB30 to give
us a longer time range with which to indicate the associated
restrictions. Chances go up Saturday evening. Expect later TAFs
to refine this with TEMPO groups and prevailing restrictions as
confidence in location and timing improves. Wind should stay SW.


Outlook: Shower activity will continue into Sunday with occasional
flight restrictions continuing through Sunday night. A brief lull
might occur early in the week, but another round of precip and
restrictions is expected during the middle part of the week.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High  97%     High  96%     High 100%
KHKY       High 100%     High  92%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High  82%     High  98%     High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

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

&&

$$
SYNOPSIS...JPT
NEAR TERM...Munroe/PM
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...PM