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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 030259
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
959 PM EST Wed Dec 2 2020

.SYNOPSIS...
A moderating high pressure area will be in control of our weather
through Thursday. A low pressure system will cross the area this
weekend. A return to cool and dry weather is expected next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --
Evening Update...Expect quiet conds overnight with temps cooling
efficiently in a deeply dry and stable airmass. Current obs are
running close to the fcst curve, so no changes will be made to min
temps. Some mtn valley and lake fog is possible arnd daybreak, other
than that most areas will remain fog free.

Quiet weather continues into Thursday. A closed low that was
dropping into the Southern Plains will be come elongated while
drifting our general direction. Weak surface high pressure will
settle into the area tonight supporting nearly ideal radiational
cooling conditions with the dry air in place, light winds and mostly
clear skies. Have under model guidance a bit for overnight lows as a
result, yielding lows generally in the 20s. These conditions may
also be favorable for lake fog development. Added a fog mention for
now for larger lakes, although dense fog may also be possible.

West southwest flow aloft Thursday associated with a progressive
short-wave ridge will shut off any lingering cold air advection atop
the region, allowing temperatures to continue to rebound, with near
normal high temperatures well into the 50s. Mid to high level clouds
will increase from the west in earnest through the afternoon,
perhaps curtailing putting a lid on afternoon heating for far
western areas.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 200 pm Wednesday: Model guidance continues to exhibit
improving  agreement regarding southern stream upper low that is
expected to begin wobbling east from the southern Great Plains near
the start of the short term period. It is looking increasingly
likely that this feature will accelerate across the lower Miss and
TN Valleys in response to a digging northern stream wave Friday
through early Saturday, possibly phasing into the northern stream
before it moves off the Mid-Atlantic coast late in the period. With
this evolution, cyclogenesis is expected across the inland Southeast
Friday, with surface low likely tracking quickly from the Deep South
through the Carolinas late Friday through early Saturday. This will
place the best deep layer forcing and moisture profiles very close
to our CWA, warranting increasing pops beginning around daybreak
Friday, reaching categorical by late Friday evening.

Based upon the forecast track of the cyclone center across, or very
close to the CWA, it will be a struggle for the warm sector air mass
to make significant headway into the forecast area, and as such,
instability will be weak to non-existent, with what little there
will be likely confined to the far southern periphery of the CWA.
Having said that, there will be a non-zero threat of high shear/low
CAPE severe convection in that area Fri night. The absence of
instability along with quick movement of the system should result in
respectable, but hardly excessive rainfall, with most locales likely
seeing .5-1.0 inch.

As the cyclone becomes increasingly wrapped up as it moves away
from the area, cold advection and lingering moisture from the TN
Valley into the southern Appalachians should result in at least a
brief period of northwest flow snow showers on Saturday morning,
with minor accums appearing to be a possibility across the higher
elevations near the TN border. Max temps will be near to a little
below normal, and mins a little above normal through the period.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 220 pm Wednesday: A rather complex/split upper air flow
pattern will persist through the medium range, with troughing
generally predominating over the East. As such, temps are forecast
to be a handful of degrees below normal through the period. Dry
conditions will predominate, although a very potent clipper system/
upper low is forecast to dig well into the Southeast on Monday. This
will undoubtedly bring another round of northwest flow rain/snow
showers to the mountains. Interestingly, because they are digging
the trough so far to the south, with the speed max actually passing
south of the forecast area based on some solutions, the global
models are beginning to depict some precip breaking containment into
the Piedmont and foothills Mon afternoon/evening. IF this were to
happen, p-type east of the high terrain could be very interesting,
as it appears mid-level thickness values would be more than adequate
for frozen precip. For now, we are opting to continue a dry forecast
for much of the area Mon/Mon night.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
At KCLT and elsewhere: VFR conds will continue thru the period over
all sites. Strong and deeply dry hipres will build across the fcst
area and make for steep sfc-based inversions overnight, however, any
fog development will likely be held to areas near lakes and a few
valley drainage locales. KAVL should maintain VFR VSBY. Winds go
calm overnight, then setup after inversion mixes out to weak s/ly to
se/ly across the non mtns and nw/ly at KAVL.

Outlook: VFR conditions will prevail until the next system
approaches the area Thursday night into Friday.

Confidence Table...

            03-09Z        09-15Z        15-21Z        21-00Z
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...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...JDL
NEAR TERM...Munroe/SBK
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...SBK