Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 240543

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
143 AM EDT Mon Oct 24 2016

High pressure will remain across the area today before a dry cold
front crosses through on Monday. Strong high pressure will quickly
build back in from the north through the middle of the week...with
another frontal passage expected late Thursday.


As of 130 AM...looks quiet through daybreak as dry high pressure
lingers across the Deep South. Clear conditions with light winds
expected, which could allow some fog to develop in the little TN
River valley. Low temperatures across the mtns will reflect an inverse
lapse rate, ranging from around 40 within the valleys to the mid 40s
across the ridges.

Not much change to earlier thinking for the next 24 hours. A dry
backdoor cold front is expected to slip southward across the NC
Foothills and Piedmont during the late morning to midday period,
passing across Upstate SC during the early afternoon. Sfc winds will
veer as the front approaches during the morning hours. Only a
few cirrus clouds will be possible with the passage of the front.
The timing of weak CAA in the wake of the front will favor temps
climbing up to two categories above normal. High pressure will build
back in from the NW behind the front tonight, but temps are not
expected to be as cool as the air mass was behind the last front. At
this point, the frost threat looks minimal.


As of 215 PM Sunday, much of the short term will be characterized by
a non or slowly-progressive pattern, with a long wave trough along,
or just off the East Coast, and mean ridging across the central
Conus. This will result in an expansive surface ridge associated
with Canadian high pressure gradually build into the area through
the period. Resultant (relatively) low thickness values/easterly
component to the low level flow will result temps near to a little
below climo through the period. Other than some occl cirrus (esp
toward the end of the period, as a short wave trough ejects from the
central Plains), skies should remain cloud-free.


As of 215 pm EDT Sunday: Overall the extended is pretty quiet, but
we`ll start the period with a shortwave pushing a front down the
Mississippi Valley, approaching the Southern Appalachians Thursday
morning. Of the operational models, the GFS is faster but all
generally bring the front through sometime late Thursday. Moisture
is fairly anemic and guidance seems to be pulling back on the
southern edge of the moisture. The GFS has a little more
precipitation ahead of the front, the ECMWF lingers it a little
longer, but in the end we`re talking slight to low chance pops and
storm-total generally less than 1/2".

Expect a cloudy and cool day Thursday, and with winds swinging
around to the northwest and the downsloping component, should
actually see temperatures warmer Friday into the weekend despite
being behind the cold front. Mass fields diverge between the
operational models but looks like some sort of shortwave will pass
through during the weekend, and have kept the slight chance pops
that we had already advertised across the northern mountains
Saturday night. Not enough model consistency late in the period to
hang our hats on anything specific so just kept with a blend with
slightly above-normal temperatures and continued dry.


At KCLT and elsewhere: VFR conditions expected thru TAF period.
A dry cold front will slide southward across the western Carolinas
during the day, complicated by the development or presence of a lee
trof. With little moisture to work with, only a wind shift is
expected with the fropa. Winds will shift from SW to W or WNW by
midday, then veer further to NW Monday evening. The biggest problem
will be a cross-wind at KCLT thru the middle part of the day. Have
opted to keep wind direction WSW thru much of the daytime hours
because of the lee trof, with a shift to WNW not until 22Z based on
the LAMP guidance. Only a few wisps of cirrus will stream by from
the west periodically through the period. The other trouble spot
might be KAVL. There could be some fog development around daybreak,
but think that will be confined more to the little TN River valley.
Strong winds aloft this morning above a strong temperature inversion
may result in several hours of low level wind shear. Once the
boundary layer deepens, the shear will go away and the wind gusts
will begin, around 16Z or so.

Outlook: Dry high pressure will persist over the Southeast through
Wednesday. Then a fast-moving cold front will cross the area
Thursday or Thursday night, but with limited moisture. Dry
conditions return for next weekend.

Confidence Table...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     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:




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