Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 220841

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
341 AM EST Wed Nov 22 2017

In general, dry high pressure will persist over the area through
early next week. A couple of cold fronts will pass the area without
enough moisture for precipitation. Temperatures will remain


As of 335 AM: A weak cold front moves across the area early this
morning with high pressure building in tonight. Skies have cleared
as showers and deep moisture have moved east of the area. This has
allowed areas of dense fog to develop across portions of the area.
The forecast is tricky with the front moving through as at some
point, winds will pick up from the N or NW and drier air moves in.
It looks like the wind and drying will be delayed somewhat, so there
will be enough overlap of dense fog and timing necessitating a dense
fog advisory over the NC Piedmont and eastern and southern Upstate.
Any dense fog will likely remain patchy elsewhere. The dense fog
could even erode early over western portions of the advisory as the
front moves through. Fog should burn off relatively quickly after
sunrise with the front moving in with mostly sunny skies for the
bulk of the day. Expect gusty winds to develop with mixing by late
morning across NC and possibly the Upstate. Highs will be around 5
degrees below normal across the mountains and near normal elsewhere.

Winds taper off quickly this evening with mostly clear skies
remaining in place as high pressure builds into the area. Lows will
be around 5 degrees below normal.


As of 245 AM Wed: The base of an upper trough will cross the
Appalachians during Thanksgiving Day, though it is associated
with very little moisture of its own. A shortwave will begin to
separate from this trough over the eastern Gulf of Mexico at that
time. This will be reflected as a sfc low, which will approach
the Florida Peninsula gradually thru Friday. You may recall that
we had been following the models` various depictions of moisture
advection preceding this low Thursday or early Friday, spreading
precip from the Atlantic up into portions of the CWFA. As of this
morning`s 00z cycle, none of the major models indicate this is
likely enough to warrant PoPs. However, a wrinkle: the operational
NAM deviates from GFS/EC/CMC and most SREF members, suggesting
the low will take a more westerly track over the GA/SC coast. As
a result it shows precip spreading into our area early Saturday
morning. This is being discounted with this package. NAM temp
profiles would support freezing rain given subfreezing sfc temps
(which blended min temps do not indicate). But no PoP is being
included in this package for this part of the fcst.

Aside from the sfc low possibility, it is looking likely
Thanksgiving Day and "Black Friday" will be marked by rather
uneventful weather. Weak mid to upper level flow will persist as we
are caught in the weak deformation zone between the aforementioned
features, and little forcing overall. Max temps Thu will be several
degrees cooler than today, with Friday early morning temperatures
ranging from around 30 over much of WNC to the mid to upper 30s
over the western Upstate and NE GA. Near-normal temps return Fri
aftn and Sat mrng.


As of 315 AM Wed: Another northern-stream upper trough moves
into the northeastern CONUS Saturday. The accompanying cold front
initiates NW flow, which will linger into Monday. The global models
indicate the front will lack enough moisture for a mentionable PoP
even along the Tenn border. However, min temps will dip several
degrees below normal Monday morning. The expansive high behind the
front will drift eastward and offshore by Tuesday, suggesting the
cold snap will be brief. Eventually this should set up return flow
and precip chances toward the middle of the week, though after
the end of Day 7.


At KCLT and Elsewhere: A mix of restrictions exist across the area
as showers and deep moisture move east of the area. Expect some
variation of low clouds and/or fog to remain or redevelop early this
morning. MVFR is expected most locations with IFR likely at normally
more foggy sites. IFR possible elsewhere. Restrictions should burn
off shortly after daybreak with VFR through the rest of the period.
Light northerly wind early this morning picks up in speed and
becomes gusty across much of the area. Winds go NE and drop off
slightly in speed this evening.

Outlook: Expect VFR through the forecast period as dry/cool
conditions prevail.

Confidence Table...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       Med   62%     High 100%     High 100%     High 100%
KGSP       Low   55%     High 100%     High 100%     High 100%
KAVL       Med   63%     High 100%     High 100%     High 100%
KHKY       Med   73%     High 100%     High 100%     High 100%
KGMU       Low   57%     High 100%     High 100%     High 100%
KAND       Low   54%     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 and ensemble forecasts
are available at the following link:


NC...Dense Fog Advisory until 9 AM EST this morning for NCZ035>037-
SC...Dense Fog Advisory until 9 AM EST this morning for SCZ007>009-


SHORT TERM...Wimberley
LONG TERM...Wimberley
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