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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 080209
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1009 PM EDT Fri May 7 2021

.SYNOPSIS...
Drier high pressure will return over the weekend. Expect
warmer temperatures on Sunday as the high moves over the Atlantic
and a southerly flow of air returns.  Another cold front will
approach from the west Sunday night and then move slowly across the
region Monday into early Tuesday. High pressure will set up by mid-
week, but with a moist low pressure system returning from the west
Wednesday night into Thursday.

&&

.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --
As of 1000 PM: The cu filed has dissipated with the nocturnal cycle
in full force to help stable the atmosphere. Post-frontal regime
will be in store tonight with NW CAA filtering in to help
temperatures drop well below-normal as mentioned below.

The unseasonably deep and cold trough overtop the
region will slide offshore into Saturday. But not before a secondary
impulse rides the westerly flow through the region tonight, offering
up another chance of showers and and high elevation snow mainly
confined to the mountains near the TN border. Lows tonight will come
in well below normal with lows in the 40s to near 50.

A weak warm front is progged slowly gain momentum, mainly to the
west of the area Saturday with the main impact being some mid-level
clouds poking into the region from the west. Downsloping NW/W flow
and a develop WAA regime during the day tomorrow will allow for the
area to really dry. With more subsidence and a relatively dry
airmass, the boundary layer will deepen Saturday afternoon and mix-
out the lower levels of the atmosphere. Dew points should mix out
into the 20s and 30s, which would drop RH values to near critical-
levels, but a FDS is not warranted as of now since wind gusts won`t
be as high as they were today. Rising heights and low level
thicknesses will result in several degrees of warming over today
with highs in the 60s across the mountains to 70s elsewhere.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 205 pm Friday: Heights will be on the rise early in the short
term as a short wave ridge progresses across the TN and OH Valley,
albeit in a dampening state in response to falling heights across
the western Conus. Thus, the main story of the early part of the
period will be the warming trend, as temps are forecast to return to
above-normal levels, with widespread maxes in the 80s expected
Sunday afternoon. As the dampening ridge progresses east of the area
late Sunday/Sun night, a frontal zone associated with a region of
height falls to our west will approach the forecast area, bringing
precip chances to mainly the western half of the area by daybreak
Monday, with PoPs ranging from low chance across the foothills and
upper Savannah River Valley, to likely across extreme southwest NC/
the Smokies and vicinity. Frontal zone is forecast to progress
steadily across the forecast area throughout Monday. In general,
deep layer forcing is lacking. However, guidance depicts good Gulf
moisture return in the warm sector, which allows for moderate
destabilization across the Southeast Monday afternoon. As such,
model convective qpf response increases throughout the day, and this
appears good enough to advertise a likely PoP in most areas.
Forecast wind profiles are more or less unidirectional, while the
flow isn`t especially strong in the lowest 3 km or so. The
combination of forecast shear/instability would therefore suggest a
non-zero, but rather marginal threat for severe convection at this
time.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 220 pm Friday: Low amplitude troughing will become established
across the East early in the medium range, allowing for a resumption
of below-normal temps. In fact, Wed forecast max temps are a solid
10 degrees below normal. While global models depict a baroclinic
zone hanging out south of the forecast area during mid-week, with
generally dry conditions suggested for our forecast area,
uncertainty regarding the timing of moisture return atop this
baroclinic zone leaves us to advertise generally small pops Tue into
early Wed. However, chances for moisture return will ramp up quickly
late Wed into Wed night, and pops increase to likely across much of
the forecast area by daybreak Thursday. Although much of the details
will depend upon the track of any surface waves across the region,
the overall pattern is suggestive of strong potential for at least
in-situ cold air damming, and thus the risk for severe convection...
or really any convection at  all appears small. In fact, max temps
will be forecast at 10-15 degrees below normal Thursday. PoPs will
diminish and temps begin to warm again to end the period.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
At KCLT and elsewhere: VFR conditions are expected except KAVL where
brief MVFR or low VFR cigs are possible at times from 03Z to 14Z.
Can`t rule out a brief shower at KAVL during this time, but the
highest chances will be confined to higher elevations especially
near the TN border. Breezy W/NW winds should quickly drop off
tonight, but will probably return at least briefly after 14Z. Only
VFR level cu field is expected on Saturday, while remaining dry. Low
end gusts could work back into the terminals during the
afternoon/evening hours tomorrow.

Outlook: Predominately VFR conditions are expected thru the weekend.
The next shot at widespread restrictions may be with a Monday system.

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 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%     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
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...DEO
NEAR TERM...CAC/Munroe
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...CAC