Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 180702

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

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.


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, latest IR imagery from GOES16 indicates a patchy
yet thinning area of stratocu across portions of the fcst area east
of I26, which is expected to sct somewhat over the next few hours.
Recent hi-res guidance does favor patchy fog development along
portions of the I77 corridor this morning, especially near I40
where a few sparse showers were observed last evening, however
likely to remain above DFA criteria.  Otherwise mtn valley fog
is expected in the usual prone areas, and is already occurring in
the Little TN valley where Franklin is down to 1/2sm visb.

Moving into Monday, 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.


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

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.


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.


At KCLT and Elsewhere: VFR conditions expected to dominate at
all sites for the majority of the period, aside for fog and low
stratus in the mtn valleys and possibly over the NC piedmont.
Guidance favors lingering low/mid stratocu for a few more hours
around the region, eventually sct`ing toward daybreak.  However,
the same guidance also indicates development of low clouds in
association with fog along the I77 corridor.  Therefore did include
MVFR tempo`s at KCLT/KHKY with few008 for now, although an amd might
be needed later for sct or bkn 008.  Otherwise carried a fairly
fog/cig restricted taf this morning at KAVL given recent days mtn
valley fog conditions.  Lastly, did also include a tempo at KAND
for MVFR fog, although think chances there are low.  Beyond that,
any restrictions will clear up by mid/late morning leading into
another dry and low vfr cu day amidst light nely flow.

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...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       High  91%     High  87%     High 100%     High 100%
KGSP       High  96%     High  96%     High 100%     High 100%
KAVL       Low   37%     High  87%     High 100%     High  95%
KHKY       High  90%     High  96%     High 100%     High  95%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High  86%     High  96%     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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