Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 162315
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
615 PM EST Thu Nov 16 2017

.SYNOPSIS...
Dry high pressure will linger atop the region through Friday.
A strong cold front then crosses the area Saturday night followed by
dry and cooler weather Monday and Tuesday.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 615 PM EST Thursday:  Updated discussion for 00z taf issuance.
All in all the current near term segment of the fcst remains in
line with present trends, therefore opting for no sig changes.
Did tweak sky just a tad given latest sat high cirrus coverage.

As of 2:30 PM Thursday...With the exception of some passing high
clouds, abundant sunshine has allowed for temperatures to climb
quickly throughout the day. Latest obs are reporting temperatures
well in the mid to upper 60`s across most of the area. Temperatures
may climb another degree or two this afternoon before dropping
off quickly after sunset. West-northwest flow aloft will continue
overnight into Friday as sfc high pressure continues to build into
the area. With light winds and thin cirrus overnight, radiational
cooling will be ideal as temperatures are forecast to drop into the
low to mid 30`s, with the upstate a bit warmer in the lower 40`s.
Given dry airmass in place, do not anticipate much in the way of
fog development. On Friday, high pressure continues to dominate
the weather pattern with light winds and afternoon high`s in the
50`s to near 60 degrees.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 230 PM Thursday: A short wave ridge will progress east of the
forecast area early in the period, while a strong short wave trough
is forecast to move east of the Miss Valley by Sat night. Increasing
SW flow responding to large scale height falls will result in
moist/mechanical lift increasing near the high terrain, possibly
resulting in some scattered showers across the SW mtns by Sat
evening. Meanwhile, a fairly sharp/fast-moving frontal zone and
attendant shower band is forecast to cross the area Sat night,
warranting likely to categorical pops across much of the forecast
area.

Freezing/snow levels will fall quickly across western NC in the wake
of the front, while a developing strong NW low level flow acting
upon post-frontal moisture should support at least scattered showers
near the TN border early Sunday morning. Ingredients appear to be
marginally favorable for accumulating snow showers, although the
anticipated duration of the event suggests accumulations would be
very light (perhaps up to an inch) and primarily confined to
elevations above 4000` or so near the TN border. Otherwise, very
gusty winds are expected near the Blue Ridge early Sunday, as
mountain wave scenario unfolds under the influence of increasingly
deep NW flow. Signals in the model guidance are not suggestive of a
high wind event, but an advisory may become necessary for portions
of the Blue Ridge area.

Otherwise, after beginning the period in the warm sector, with temps
right around climo, temps return to well-below (at least 10 degrees)
normal levels by Sunday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 215 PM EST Thursday: The base of a broad upper trough axis
will cross the western Carolinas at the start of the period Sunday
night, but with generally dry profiles up the column. Any lingering
low-level moisture in the NW flow will dry up quickly along the
northern mountains Sunday night. A shortwave ridge will then cross
the region on Monday as heights fall upstream over the plains.
Strong surface high pressure setting up over the mid-South will
cross the southern Appalachians Monday night and exit off the east
coast Tuesday. The GFS is faster to return the plains shortwave to
the southern Appalachians on Tuesday, while the ECMWF keeps the
system to the west over the lower MS River Valley. Very limited
moisture would accompany the wave in any event. Meanwhile, a
reinforcing surface cold front will arrive from the northwest
Tuesday night and then settle southward across the forecast area on
Wednesday. Temperatures will steadily climb to near climo through
Wednesday.

Both the GFS and ECMWF solutions produce more prominent height falls
to the west on Wednesday, with a cutoff mid/upper low possibly
developing by Thursday morning. This could lead to surface low
development over the northern Gulf of Mexico on Thanksgiving day.
The GFS keeps any deeper moisture ahead of this system confined to
the immediate southeast coastline as the system develops eastward,
while the farther west position of the ECMWF Gulf low suggests more
potential for inland moisture over the southeast. For now, profiles
from either solution appear fairly dry atop our forecast area and
will keep Thursday PoP below slight chance.

&&

.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
At KCLT and Elsewhere: VFR through the period at all sites as high
pressure continues to migrate southeast atop/through the region.
With that, lgt nly/vrb flow tonight will gradually veer and increase
out of the ene after sunrise as the center of the high moves over
the central Appalachians.  Furthermore, the high center will shift
southeast into the afternoon hours leading to further veering and
thus lgt sely/sly flow at all terminals.  Deep dry air through
the profile will keep skies mostly skc aside for a few occasional
passing high cirrus.

Outlook: Potential for MVFR/IFR due to increased cloud cover/low
cigs and increasing rain chances with a cold front Saturday night.
Otherwise expect VFR.

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       High  87%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High  94%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     Low   58%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High  94%     High 100%     High 100%     High  83%

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

www.weather.gov/gsp/aviation

&&

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

&&

$$
SYNOPSIS...CSH
NEAR TERM...CDG/SGL
SHORT TERM...JDL
LONG TERM...HG
AVIATION...CDG


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