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000
FXUS62 KGSP 160717
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
317 AM EDT Thu Aug 16 2018

.SYNOPSIS...
An upper level trough of low pressure will develop west of the
Appalachians today and persist well into the weekend as a stalled
surface front lingers north of the region. Moisture will increase
ahead of this system to produce a lengthy period of unsettled
weather from Friday onward. A weak cold front will approach slowly
from the northwest early next week and likely arrive in the region
on Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 235 AM: Mountain valley fog and patchy fog outside of the
mountains will dissipate this morning leaving copious cirrus and
some mid cloud overhead. The ridge axis overhead moves east today as
a short wave trough moves toward the area. The best short wave
energy crosses the mountains late this afternoon and early evening.
Low level flow turns southwesterly but isn`t very strong. Not much
in the way of low level forcing develops outside of the mountains,
and what does develop is mainly south of the CWFA. The main forcing
will be weak terrain triggering across the mountains. Scattered
coverage develops there as better moisture returns in the S to SW
low level flow. Can`t rule out an isolated cell along the southern
tier of the CWFA, but most of the area outside of the mountains will
remain dry. Convection will linger into the evening then diminish
overnight. However, the moist weakly forced atmosphere may lead to
lingering isolated showers across the mountains overnight. Highs
should top out a few degrees above normal. Lows will be a few
degrees above normal as well.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 145 AM Thursday: An active pattern will continue across the FA
thru the short term period. A broad ulvl trof will deepen and slowly
cross the ern CONUS with the mean axis remaining west of the mtns.
This will leave the area in broad lift with continuous pockets of
small-scale dPVA traversing thru the flow. In the low levels...sw/ly
moisture adv will continue and the column will remain quite moist.
The deep moisture will help keep instability elevated until late
afternoon Fri when sbCAPE increases over 1500 J/kg....altho shear
parameters will be low. The wrn zone will be under gun for stronger
storms aided by mech and dyno lift...so will continue the mention
of possible svr activity in the HWO inline with the latest SPC Day 2
products. Saturday has similar looking profiles with relatively more
deep layered shear so will anticipate isol/sct stg/svr convec within
the better large scale lift or wrn half of the FA. Hydro could also
be an issue during this time with continued activity over the same
localized areas esp across the far wrn zones. Max temps will be arnd
or little cooler than climo due to the high cloud cover and
precipitating storms.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 200 AM Thursday: Little change was made to the going mid-range
fcst as the guidance continues to show a broad and moist ulvl trof
dominating the pattern early on. Soundings begin highly saturated
Sun and this could be a problem hydro-wise as the overall steering
flow weakens during the day and the previous days will likely have
generated a broad area of precip coverage. The mid-levels dry out a
little Mon into Tue as a h5 ridge traverse the area...but enuf llvl
moist flux will keep an active pattern in the works. Surface based
CAPE and bulk shear are not impressive...so will expect a pulse tstm
mode with a few stg/svr storms possible. Basically a nominal
summertime sensible weather fcst is in store to begin the work week
with max temps remaining a little below normal.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Quite a bit of mid cloud and cirrus across
the area this morning. Still expect mountain valley fog to develop
after the mid cloud dissipates. Have gone with persistence at KAVL.
MVFR fog possible at the normally more foggy sites of KHKY and KAND.
Any restrictions should dissipate relatively quickly after daybreak
with cirrus remaining and cumulus developing for the afternoon. Best
chance of any convection will be across the mountains, so PROB30 has
been retained for KAVL. Convection should diminish during the
evening but cumulus will linger. Light and variable wind becomes SW
for the afternoon then light S to SW during the evening.

Outlook: Increasing coverage of diurnal thunderstorms us expected
from Friday through the upcoming weekend and into early next week.
Restrictions will be limited mainly to areas in heavy showers and
low clouds/fog across the mountain valleys each morning.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High  86%     High 100%     High 100%     High 100%
KHKY       High  86%     High  96%     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:

www.weather.gov/gsp/aviation

&&

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

&&

$$
SYNOPSIS...HG
NEAR TERM...RWH
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...RWH