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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 021136
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
636 AM EST Tue Mar 2 2021

.SYNOPSIS...
Dry high pressure will build over from the north today. Low pressure
will develop near the Florida panhandle this evening along a stalled
front and move to the South Carolina coast by daybreak Wednesday.
This system will spread moisture northward into the region tonight,
with some light wintry precipitation possible in the North Carolina
mountains overnight. Dry high pressure will return Wednesday into
Friday before a moist Gulf Coast low pressure system possibly
affects the southeast Friday night into Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 615 am EST: Surface high pressure moving east across the
central Appalachians today will permit cooler and drier air to spill
southward into the region. Quite a bit of high clouds could persist,
especially across the southern half of the area today, as a closed
low pressure system over the OK/AR region sends cirrus downstream
over a shallow ridge axis into our area. Will maintain max
temperatures some 5 to 10 degrees below climatology as the dry
conditions are countered by lingering high clouds and cooler
thicknesses.

The upstream 500 mb low/trough will move east through the lower MS
River Valley this evening and approach the base of the southern
Appalachians overnight. This will induce a surface wave along the
stalled frontal boundary near the Florida panhandle, with the low
center transitioning to the SC coastal waters toward daybreak
Wednesday. Questions remain over how far north precipitation
associated with these features will be able to work back into the
area, with the greatest chances in southern/southeast sections.
Precipitation coverage and intensity will be lowest where profiles
are coldest - generally north of I-40. Given the drier and cooler
profiles over the mountains, light snow is the currently favored
precipitation type there for the overnight hours, especially at the
higher elevations, although a light wintry mix is possible at times.
There is slightly better potential for overlap between the deeper
moisture and colder temperatures in the southern NC mountains. We
will currently feature an inch or less of snow in these southern
mountain locations, mainly along the higher ridges. Areas from
Franklin to Waynesville, and especially along the higher ridges in
between, will need to be monitored closely in case the moisture
trends a bit farther north. For now, will keep accumulations sub-
advisory and continue a mention in the HWO.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 115 AM Tuesday...Precip will likely linger during the early
part of the short range as there is some potential for the upper
trof axis to slow down and allow for weak mlvl deformation while a
weak sfc low traverse up the Atl coast and brings in back-side
moisture. Not anticipating much rain accum and any additional snow
amts would be across the wrn NC mtns in developing upslope flow. Max
temps will be tricky Wed with the models indicating winds oriented
for good downslope warming adjacent to the BR escarpment. So, have
the highest temps bisecting the middle of the FA from the SW to the
NE. Weak hipres continues to build in Wed night and with good rad
cooling expected, there could be a localized dense fg threat as
noted in the latest soundings and supported to some degree by MOS
output. A dry day is in store Thu with max temps reaching well abv
normal, esp east of the mtns, as deep subs develops overhead and
combines with a w/ly downslope warming component. With mostly clear
skies and little wind, the overnight periods will see mins drop to
normal levels or a little below each night.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 220 AM Tuesday...The op models continue to agree pretty well
with the large scale pattern over the ext range. A strong ulvl ridge
acrossthe Rockies will traverse east thru Monday, which will supoort
stg Canadian hipres building south across the ern CONUS underneath a
deeply dry subs zone. The GFS is somewhat of an outlier compared to
the CMC/ECMCF solns in depicting a weak trailing sfc trof across the
Apps as it/s parent sfc low gets surpresed south of the area Fri
night into Sat. This scenario has been noted in the ECMWF a couple
runs ago, so will give some credence to this possibility and have
bumped up rain PoPS to low-end chance Fri night across NE GA and the
wrn Upstate. Periods of -snsh and flurries are possbile across the
higher elevations of the central and southern NC mtns into Sat.
However, any snow accums would be very light to negligible as
moisture looks to remain very shallow and transient. A reinforcing
sfc high builds down the east coast Sat night and continues
widespread dry conds into Mon. Afternoon RH values will likely drop
into the l30s or less outside the mtns each afternoon and low-end
fire-wx concerns may be had by the late weekend depending on any
precip realized Fri night and Sat. Otherwise, it looks this may be a
good period for prescribed burns by forestry officials. With winds
remaing genrally n/ly to e/ly, yet insol remains high, max temps
shud be held right arnd normal thru the period, while mins also
persist arnd seasonal levels.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
At KCLT and elsewhere: Anticipate mainly cirrus ceilings for the
first half of the TAF period. Winds will be some flavor of northerly
this morning, toggling more southeasterly through the afternoon.
Better moisture will return north of a developing Gulf Coast low
center overnight, with the best precip chances across the Upstate
sites for the overnight hours. Cigs should fall into the MVFR, or
possibly IFR range, there overnight. The moisture will strike more
of a glancing blow across the NC sites overnight into Wednesday
morning, but with a RA/SN mix possible from KAVL to KHKY if the
precip survives that far north as the low center transitions to the
SC coastal waters. A window of mainly light rain is more likely at
KCLT. Will keep the NC TAF sites with mainly lower end VFR cigs for
now with any light precip. Winds will adjust back to NW at KAVL and
NE at the foothill and Piedmont terminals tonight.

Outlook: Dry and VFR conditions will return from the west on
Wednesday and persist through Friday. Moisture could return with a
Gulf Coast low pressure system toward the weekend.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     Low   58%

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
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...SBK
NEAR TERM...HG
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...HG