Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 141047

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
647 AM EDT Sat Oct 14 2017

Drier and warmer conditions return today and Sunday before a more
robust cold front moves across the Carolinas Sunday night and
Monday. Considerably cooler and drier air will spread over the
region in the front`s wake and linger through most of the next
work week.


As of 645 AM EDT: An expansive low deck of clouds is indicated on
satellite imagery and in surface observations across much of the
area. An upper ridge will remain in place over the Southeast through
the period. The moist surface ridge associated with hybrid cold air
damming will weaken through the period, as parent high pressure
moves well off the northeast Conus coast. With nothing to lock the
wedge in place, the cloud cover should gradually erode by noon
giving way to a mostly sunny afternoon. This will allow max temps to
rise to 5 to 10 degrees above normal. With the warm air mass in
place, lows only fall to around 10 degrees above normal tonight,
even with mostly clear skies and light winds. However, this will
also set the stage for fog development overnight. Except for the
Little TN valley, it`s still too early to tell if dense fog
develops, but it is possible.


As of 245 AM Sat: Surface and upper ridging will remain situated
over the Southeast on Sunday, bringing warm temperatures and light
southwest winds. Temperatures will rebound even warmer compared
to Saturday, reaching 8 to 11 degrees above normal. During the
afternoon, heights will begin to fall as a low pressure system
moves east out of the Great Lakes region. A midlevel subsidence
inversion initially is progged, but should weaken with the
falling heights. Models generally produce seasonably modest CAPE
developing at peak heating. As the cold front associated with
that low approaches the mountains, this may enhance convective
initiation. Hence a chance PoP creeps into the NW zones in the
second half of the day.

Rain chances spread thru the remainder of the CWFA Sunday night
along the front, which is depicted as moving more quickly across
the area than models from 24 hours ago; by daybreak Monday it
looks likely to be over the I-85 corridor. Moisture profiles as
viewed in Bufkit lack a deep saturated layer, and assuming fast
frontal motion, QPF is not that remarkable. Most guidance shows
precip ending over the southeast zones prior to 18z Monday, but
our PoP will taper off a little more slowly given potential timing
changes. Cold advection will bring somewhat gusty winds and sharply
cooler temps by Monday afternoon. Consensus of guidance suggests
max temps even a couple degrees below normal.

Mostly clear skies will build in with high pressure behind the
front. Despite continued breezy conditions into early Tuesday,
morning mins will be below normal. Winds may be the limiting factor
for frost development, but at least in the more sheltered mountain
valleys and northern NC foothills, it appears likely enough to
begin a patchy mention in the fcst.


As of 310 AM Sat: Confidence remains high that dry high pressure
will continue to bring seasonably cool and settled conditions to
the CWFA Tuesday thru Friday. A shortwave trough does cross the
area midweek, which is generally shown to invoke cyclogenesis over
the old frontal boundary well off the Southeast coast. Between
this low and the next incoming trough over the western CONUS,
a shortwave upper ridge develops which reinforces a sfc high over
the East and a northerly flow into our area. Temps will moderate
gradually, rising to about a category above normal by Friday. The
most impactful weather during the period may be frost, which could
occur again Wednesday morning, as temps will remain chilly under
even lighter winds than Tuesday morning.


At KCLT and Elsewhere: Ceilings around the region are varying
between IFR and MVFR. IFR locations will improve to MVFR by mid-
morning while MVFR locations remain steady. Expect skies to lift and
scatter out around noon with VFR into the evening. MVFR fog looks
likely overnight outside of the mountains with at least IFR fog and
stratus in the mountain valleys. IFR conditions are possible outside
of the mountains, but guidance cannot agree on vsby or cig
restrictions. Have gone with MVFR fog and no cig restrictions for
now. Light NE wind becomes light and variable this afternoon and
calm overnight. KAVL the exception where light S wind becomes calm
this evening.

Outlook: Any restrictions early Sunday will dissipate by mid-
morning. A cold front, with associated showers and restrictions,
will cross the region from the west early next week, with much drier
and cooler air filtering in behind the front through mid-week.

Confidence Table...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       Low   54%     Med   77%     High 100%     High 100%
KGSP       Med   70%     High  82%     High 100%     High  91%
KAVL       High  80%     High  92%     High 100%     High  86%
KHKY       Med   75%     High  80%     High 100%     High  91%
KGMU       Low   59%     Med   77%     High 100%     High 100%
KAND       High  90%     Med   75%     High 100%     High  91%

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:




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