Area Forecast Discussion
Issued by NWS Greer, SC

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251
FXUS62 KGSP 181030
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
630 AM EDT Mon Sep 18 2017

.SYNOPSIS...
High pressure will remain in control of the weather pattern across
northeast Georgia and the western Carolinas through much of the
week, leading to above normal temperatures and generally below
normal precipitation chances. Meanwhile, Hurricane Jose will remain
over the western Atlantic with no impacts expected across the
southern Appalachians and surrounding areas.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM EDT Monday:  Fog development has been hampered by
slower than expected erosion of early morning stratocu across the
NC/SC piedmont, thus did favor improving visb in the fcst given
eminent sunrise.  Otherwise, the current fcst trends look good
thereby warranting no sig changes to the near term.  Did make
some minor tweaks to t/td over the next hour/two to align with
recent ob trends, and left the remainder of the fcst as it was
for this update.

As of 255 AM EDT Monday:  An amplified synoptic pattern remains
prevalent this morning as sharp H5 ridging prevails over the eastern
CONUS, while troffing sets atop much of the country west of the
MS river.  At the surface, large scale 1022mb high pressure centered
over Wisconsin dominates beneath the upper ridge, while a stationary
front lays across the Ozarks northeastward into the OH Valley.
In addition, Hurricane Jose remains a category 1 storm with a
northward movement of approx 9mph, with no impacts to be expected
across northeast GA and the western Carolinas.  Speaking of closer
to home, not much change from previous days forecasts as mid 60s
dewpoints mix out with heating and subsidence prevents widespread
convection.  That said, do have token slight chance pops over the
northern NC mtns/fthills where ridgetops showers are possible.
Skies are expected to remain mostly clear, aside for a few patchy
fair wx cu this afternoon which in turn will yield max temps in
the mid/upper 80s across the lower terrain and 70s to lower 80s
in the mtns/valleys.  All in all, another nice day in store for
the region.  Any residual showers and or cu should dissipate this
evening with loss of heating, leading into another evening of
patchy fog outside the mtns and possibly dense fog in the valleys.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 200 AM EDT Monday: With Hurricane Jose drifting northward over
the offshore waters of the Mid-Atlantic on Tuesday, a shallow ridge
of high pressure will remain in place over the southern Appalachians
and surrounding areas. Any isolated afternoon shower coverage should
be similar to previous days late Tuesday, but with a slight increase
in thunder potential as lapse rates improve somewhat over the
mountains.

A very weak mid-level trough will develop from the mid OH valley
across the Appalachian mountain chain on Wednesday, but with
generally westerly mid-level flow persisting over our region. 850 to
500 mb lapse rates should increase to 6.5 to 7.0 deg C across the NC
mountains for slightly better late day PoPs and thunder chances than
on Tuesday. Expect temperatures to be about one to two categories
above climatology through the short-term period, with Wednesday
afternoon likely featuring the warmest temperatures of the week.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 210 AM EDT Monday: Weak upper troughiness will extend
southwest from the offshore location of Jose near southern New
England to the central Gulf coast, while a prominent ridge wraps
over the top from the southern plains to the Midwest through the
Great Lakes. At low levels, flow may acquire a more easterly to
southeasterly component into the southern Appalachians late Thursday
through Friday. This could lead to more clouds, slightly cooler
temperatures (still above climo, though), and a steady uptick in
diurnally favored PoPs along the eastern side of the mountains
through late Friday.

Current indications are that Hurricane Maria will likely remain off
the southeast coast through next weekend. This track would keep our
region in a drier subsidence zone through the end of the long term
period, with temperatures remaining above climatology.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
At KCLT and Elsewhere: VFR conditions expected to dominate at all
sites through the vast majority of the taf cycle, aside for fog
and low stratus at KAVL once again on Tuesday morning.  Deep layer
ridging will prevail today with any early morning restrictions to
erode quickly leading into only a few low vfr cu this afternoon.
Winds at all sites will be predominately light and out of the ne,
however some sites could see light/vrb.  Any low vfr cu could
linger into the overnight hours, with another round of mtn valley
fog/cigs possible, thus did include such at KAVL.  Also favored
MVFR fog restrictions at KHKY, with the remaining sites all VFR.

Outlook: Isolated, mainly high terrain diurnal showers will
remain possible through early week, with better mountain shower
coverage building Wednesday through Friday. Morning mountain valley
fog/stratus are also expected each day.

Confidence Table...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       Med   77%     High 100%     High 100%     High 100%
KGSP       High  91%     High 100%     High 100%     High 100%
KAVL       Low   26%     High 100%     High 100%     High  91%
KHKY       High  91%     High 100%     High 100%     High  91%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High  83%     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:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...HG
NEAR TERM...CDG
SHORT TERM...HG
LONG TERM...HG
AVIATION...CDG



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