Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 192310

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
610 PM EST Sun Nov 19 2017

Cool high pressure will move from east Texas to the Carolinas by
Monday evening as the wind becomes light. A weak cold front will
cross the area Tuesday night. Low pressure develops along the Gulf
Coast Thursday then moves up the Atlantic seaboard through Friday.
Another strong cold front arrives next weekend.


As of 605 pm EST: IR cloud tops continue to warm along the TN border
zones of the northern mountains, and no further flurries are
expected going forward as the upslope moisture dissipates.
Otherwise, skies will remain mostly clear at worst through the
period, with perhaps some increasing high clouds occurring Monday
monday afternoon. Temps will remain unseasonably cool with mins
tonight about 10 degrees below climo and maxes Monday afternoon
roughly 5 degrees below climo.


As of 145 PM Sunday: Not much change to the previous fcst. Good
model agreement is had with the ulvl ridge axis slowly shifting east
of the FA early Tue before a broad wave of ulvl energy approaches
from the southwest. This wave is not very dynamic and has little div
or llvl waa ahead of it. It will be mainly an ulvl cloud maker
while some measure of moist isent lift develops in the lower levels.
The NAM continues to be the more aggressive soln wrt the amount of
moisture flux and also earlier than the other op guidance. Have
opted to keep the later arrival time of -shra arnd 15z over the wrn
zones and spreading east throughout the day. PoPs will remain in the
isol/sct range with little precip amounts. Another area of area of
strong high pressure will build in Tue night with the high center
remaining west of the fcst area as the ulvls become loosely

Max temps will remain below normal by about 5 degrees F Tue and
rebound with less cloud cover Wed to near normal levels. Mins will
also begin about 8-10 degrees below normal and bump up a cat or so
Tue night as cloud cover lingers.


As of 130 PM EST Sunday:  The medium range forecast kicks off on
Wednesday night amidst an intruding cold front from the west as
a 1026mb high and accompanying Canadian airmass spill into the
OH/TN valleys.  Meanwhile broad/deep troffing prevails across the
eastern CONUS with a weak H5 shortwave diving through the mean
flow atop the northern GOM leading to cyclogenesis at the surface.
Pattern evolution through the period looks to be highlighted by
the northeastward ejecting surface cyclone along the southeast
coastline beneath the now southern stream H5 wave, while the
Canadian high pressure moves across the Appalachians into the
Delmarva region.  With that, cool/dry surface air will remain in
place Thursday amidst nely flow while the coastal wave continues
tracking northeast.  Moisture from said wave looks like it could
pose some threat potential for wintry ptypes on Friday morning
as the wave moves up the Carolina coastline and diurnal morning
lows remain near freezing across the NC Piedmont.  That said,
there remains some model disagreement with regard to the westward
extent of said moisture as the GFS is a bit more progressive
with the surface wave, and thus keeping it`s associated moisture
tied to the coastline while the ECMWF is a bit further inland.
Therefore given uncertainty, will keep any wintry ptypes out of
the fcst at this time by holding min temps at nlt 33 degrees among
any moisture.  Beyond that the pattern begins to shift across the
southeast as the primary upper wave slides over the western Atl
into Saturday setting up a brief window of warmer wly/swly veered
flow, all ahead of another northern clipper and its associated cold
front which looks to arrive Saturday night into Sunday bringing
another round of potential nwfs to the high terrain.


At KCLT and Elsewhere: Gusty northwest winds may linger through late
evening at KAVL, but with gusts steadily diminishing through the
teens as the gradient weakens in the norhthwest flow. Otherwise,
expect mainly light NW to N winds overnight into Monday morning,
with flow gradually toggling toward southerly midday Monday. Any
clouds going forward should be confined to FEW to SCT cirrus in the
westerly flow aloft Monday afternoon.

Outlook: Expect VFR conditions through Monday night under the
influence of cold and dry continental high pressure. Increasing low
level moisture could result in cig restrictions and perhaps -RA on
Tue/Tue night. Otherwise, dry/cool conditions should persist into
late week.

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:




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