Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 011823

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
123 PM EST Thu Dec 1 2016

Dry and cooler conditions will persist through Saturday. Moisture
should return from the west for the latter half of the weekend and
possibly linger into early next week.


As of 115 PM EST Thursday:  A rather quiet near term in store for
the region as high pressure builds in from the west and a cold front
surges out to sea over the western Atlantic, all beneath developing
quasizonal flow aloft.  As such, drier/cooler air advecting into
the region will lead to lowering of T`s/Td`s through the period
amidst modest sfc/llv westerly flow.  With that, minimal llv
moisture will continue to lift orographically along the TN line
leading to upslope induced cu today/tonight, while the remainder
of the fcst area remains mostly sunny/clear through tonight.
Diurnal cooling will allow T`s to fall back to near normal levels
by morning, warming to normal for highs on Friday.  Skies will
remain mostly sunny on Friday, with the exception of a few high
cirrus streaming in aloft along the mean westerly H5 flow.


As of 315 AM EST Thursday: the end of the week looks quiet enough,
for the most part. Nearly zonal flow aloft will gradually buckle as
an upper ridge slowly amplifies to the west on Friday and Saturday.
This will support dry high pressure over the Southeast on Friday
that gradually gets assimilated by another surface high coming
across the Plains on Saturday. Temps both days will be very
similar...slightly below normal.

Changes will take place Saturday night as the upper ridge axis moves
overhead. Expect isentropic lift to spread northeast across the
region along with moisture return from the Gulf, aided by upper
divergence from the right entrance region of a jet streak passing to
the north. Expect that precip will attempt to develop from the west,
at least across the mountains and wrn half of the fcst area in the
pre-dawn hours on Sunday. Think we can fine tune the timing a bit,
based on the SREF and GEFS, to keep precip chances from moving in
until after 00Z Sunday, and to delay the eastward expansion of
likely precip until after 12Z Sunday. Temps are problematic as
initial dry air will allow for boundary layer cooling. Fcst
soundings, in particular the NAM, suggest that precip will reach the
ground as snow at elevations above about 3K feet around daybreak
Sunday, altho the GFS is not as cool. Think a compromise is in order
that would result in some snow chance at elevations above about 3500
feet if precip develops after midnight, but for the time being no
accumulation is expected as precip amts are minimal.


As of 225 AM EST Thursday: the medium range fcst picks up at 12z on
Sunday with flat upper ridging in place over the southeast and a large
H5 cutoff low over NW Mexico. This low eventually becomes absorbed by
the mean flow and morphs into a decent looking shortwave. The models
have the shortwave passing just to our NW on Tuesday as the upper ridge
steadily amplifies. Ridging is expected to remain in place until the
end of the period with a broad upper trof approaching the fcst area
late in the week. At the sfc, the pattern evolution remains somewhat
uncertain compared to the upper levels. The models are delaying the
development of a Northern Gulf of Mexico low until Monday/Tuesday with
the system not moving to our north until late Tuesday. In the wake of
the low, things dry out on Wednesday. Another cold front appears to
approach the CWFA from the west by the end of the period on Thursday,
but timing varies between the models.


At KCLT and Elsewhere:  VFR through the period as high pressure
builds leading to cooler/drier air advecting into the region.
With that expecting skies to remain mostly skc with the exception of
a few high cirrus streaming in.  Winds are expected to remain wswly
this afternoon as lee troffing persists before veering back wnwly
through the overnight hours.  Given continuation of the llv/mlv
pattern on Friday, am once again expecting lee trof development
which could allow for backed wsw flow, however left from taf at
this point.

Outlook: Dry high pressure persists over the region thru
Saturday. Precip and restrictions may return as soon as Sunday,
as another cold front moves into the region. There may be a brief
lull in these impacts Monday, before low pressure develops along
the front to our west and brings a second shot of moisture overhead
Mon night into Tue.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     Low   24%
KGSP       High 100%     High 100%     High 100%     Low   24%
KAVL       High 100%     High 100%     High 100%     Low   24%
KHKY       High 100%     High 100%     High 100%     Low   24%
KGMU       High 100%     High 100%     High 100%     Low   24%
KAND       High 100%     High 100%     High 100%     Low   24%

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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