Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 141745

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
145 PM EDT Thu Sep 14 2017

The remnants of Irma finally will move up the Ohio Valley
through Friday, but still could bring a few showers over our area
today. Weak high pressure will build across the area Friday and
persist into early next week, keeping rain chances low. Hurricane
Jose is forecast to remain over the Atlantic and appears unlikely
to impact the Carolinas or Georgia.


As of 145 PM Thursday: Fcst remains basically on track, although
radar is unimpressive at this time. Think we will see an uptick
in shower coverage with a bit more heating into the mid afternoon,
so precip chances were not changed. Temps seem to be on track.

Otherwise, the remnants of Irma will continue to lift into New
England during the near term, dragging the trailing edge of an area
of deep moisture and WAA across the area. A series of short waves
will rotate around the upper low associated with the remnants and
across the area as well. The combination of moisture and lift will
keep the threat of light showers across the area into the evening.
The greatest coverage will be across the mountains where the best
moisture and lift exist. There will also be some weak instability
over the area. However, the mid level subsidence inversion remains
strong keeping a lid on deep convection. Can`t rule out some
heavier showers, but thunderstorms are not expected. The showers
move out of the area this evening and clouds diminish. This may
set the stage for patchy dense fog overnight in the lingering low
level moisture and developing surface inversion. Highs today will
range from near to 5 degrees below normal. Lows tonight will be
near to slightly above normal.


As of 130 AM Thu: High pressure will remain in place across the
Eastern states Friday and Saturday. No significant dynamic lift
will be present over the CWFA. With the sfc high being centered
to our north, and with Hurricane Jose churning offshore, the mean
flow will be light and largely northerly, keeping diurnal precip
chances below average. Furthermore, a subsidence inversion will
tend to cap off instability, though models do try to develop some
showers over the high terrain. Hence our only advertised PoP will
be slight chance to low chance in that area. Temps will hover near
normal, but a tad warmer Saturday as heights rise within the ridge.


As of 300 AM Thu: Confluent flow on the western side of Hurricane
Jose looks to help reinforce subsident high pressure over the
Southeast in the early part of next week. As Jose continues its
northward trek over the open Atlantic toward the middle of the
week, a deep trough moving from the Pacific into the western CONUS
will reinforce the amplified pattern and Eastern ridging. Our
area should remain largely dry characterized by northerly flow,
with temperatures a degree or two above normal. Precip chances are
only associated with shallow mountain convection. Confidence dips
a bit late in the period due to differences in model depictions
of a low rounding the ridge west of the Great Lakes, and the cold
front extending south into the Mississippi Valley. The current
expectation is that the front either will wash out before reaching
us, or that it will not encroach until after the end of the period.


At KCLT and Elsewhere: Light showers will rotate through the
area through much of the afternoon, with better chances over NC,
but not enough of an impact to cause any restrictions. A VCSH
will be included at the NC TAF sites but not elsewhere. Shower
chances should end with sunset and low clouds should thin out as
the boundary layer stabilizes. A light SW wind should go light and
variable or perhaps northerly at that time. The main problem for the
period will be the potential for fog/low stratus in the pre-dawn
hours. The LAMP guidance is very much in favor of a restriction
in most places, while the NAM fcst soundings even suggest a
restriction down to IFR or less at KCLT. For the time being, we
will stay on the conservative side and keep the MVFR restriction at
KCLT starting at 10Z through 13Z. The usual spots (KAVL/KHKY/KAND)
will get an IFR or tempo for IFR around daybreak. The fog should
clear up and all sites should be VFR after 13Z.

Outlook: Isolated diurnal convection (mainly showers) continues into
the weekend, with morning mountain valley fog/stratus also possible.
Some drying appears likely early next week.

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     Med   75%
KAVL       High 100%     High 100%     High 100%     Med   78%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     Med   75%
KAND       High 100%     High 100%     High 100%     Med   75%

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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