Area Forecast Discussion
Issued by NWS Greer, SC

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055
FXUS62 KGSP 221927
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
227 PM EST Wed Nov 22 2017

.SYNOPSIS...
In general, dry high pressure will persist over the area through
early next week. A couple of cold fronts will pass the area
without enough moisture for precipitation. Temperatures will
remain seasonable.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 2pm EST Wednesday:  Weather should be nearly ideal for
Thanksgiving Day.  Front that passed-through on Tuesday is now well
southeast of the area, leaving gusty north-northwesterly to
northeasterly flow and dry advection behind it.  A bit of an upper
trough digs into the Deep South on Thursday, but will have little
moisture to work with at low-levels, and surface low associated with
it will remain well south of the area. Some high clouds look to be
the only impact from this trough.  Good mixing of the BL today that
is generating winds gusts will end with sunset and with the movement
of the center of a large surface high pressure area that becomes
centered along the mountains by Thursday morning. Winds on Thursday
will thus be much lighter and somewhat variable. Thursday will be a
dry and crisp fall day with temperatures slightly above seasonal
normal.

Fog that was seen this morning is unlikely on Thursday as BL drying
has dropped dewpoints 10 degrees or so.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 200 PM Wednesday...With sfc high pressure across the area
Thursday night, latest guidance continues to depict the development
of a sfc low in the Gulf of Mexico which is progged to move across
northern FL and hug the FL/GA/Carolina coast throughout the day on
Friday, per the GFS/ECMWF. With split flow, this track would allow
for NW flow aloft to persist across our forecast as seen from fcst
soundings suggesting PWATs to remain at or below one half of an
inch. However, the latest NAM, west of both the GFS and ECMWF,
continues to track this system a bit northward and inland up through
GA/SC. If this track were to evolve, fcst soundings are highlighting
PWATs at or just above one inch. For this forecast package, am going
to stick with the drier trend of the GFS/ECMWF. With nearly clear
skies overnight Thursday, anticipate temperatures to dip into the
low to mid 30`s before climbing into the upper 50`s to around 60
degrees on Friday.

Expect temperatures to be slightly warmer/near-normal Friday night
as limited moisture allows for mid to high clouds to increase ahead
of an approaching cold front. Per latest guidance, anticipate the
front to push through the area Saturday morning. With limited
available moisture and weak forcing, have kept precipitation out of
the forecast attm. As clouds gradually decrease behind the front and
flow aloft becomes nearly zonal, expect temperatures on Saturday to
climb into the lower 60`s, though cooler across the mountains.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 2:15 PM Wednesday: An Upper level northwesterly flow will be
in place Saturday night, following the earlier surface cold frontal
passage. This will signal a trend toward cooler temperatures across
our forecast area (FA) for the latter half of the weekend. The GFS
does show some very shallow moisture in the northern mountains of
North Carolina briefly on Saturday night, but its depth appears to
shallow for any precipitation.

High pressure will move from the Ohio and Tennessee Valleys Sunday,
into our FA Sunday night and Monday. Aloft the flow remains dry
northwesterly, although easing by late Monday.

The surface high will continue moving south and east of the region
Tuesday, while the flow aloft backs to the southwest. This will
signal the start of a warming trend, but still dry.

In the latter part of the forecast the models diverge on how fast to
move a cold front into our area Wednesday. The GFS was fast, while
the European was slower. The slower European was backing and cutting
off parts of the upper level flow. This far out in the forecast
suggests a compromise is in order. We will have some low end POPS in
the mountains and part of the foothills of western North Carolina,
parts of northeast Georgia, and a sliver of the mountains in upstate
South Carolina Wednesday.

Temperatures Wednesday will be tricky depending on how fast any mid
week front enters the picture.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere:  Region is behind major front with some gusty
north-northwesterly winds and dry advection with only a few clouds
aloft.  Satellite shows some high clouds streaming across South
Carolina, but coverage will not exceed SCT.  Mostly clear skies are
allowing mix-down of gusty winds this afternoon which will relax at
nightfall and be calmer and more variable tomorrow as surface high
pressure becomes centered over the area.  Stronger gusts of 15 to
25kts are over North Carolina and the Mountains today.  10 degree drop in
dewpoints behind the front is expected to nearly eliminate the
chances for fog Thursday morning, any any chance for precipitation
for at least the next 24 hours.

Outlook: Expect VFR through the forecast period as dry/cool
conditions prevail.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
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:

www.weather.gov/gsp/aviation

&&

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

&&

$$
SYNOPSIS...DEO
NEAR TERM...WJM
SHORT TERM...SGL
LONG TERM...TS
AVIATION...WJM



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