Area Forecast Discussion
Issued by NWS Greer, SC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS62 KGSP 231118

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
718 AM EDT Sun Oct 23 2016

High pressure will prevail across the southeast today. A dry
cold front will move through on Monday...with strong high pressure
building back in from the north through the middle of the week.
Another front is expected to move across the region on Thursday or
Thursday night.


605 am update: temps have just about bottomed out over the CWFA with
a few sites reporting freezing temps as of the last hour. Most automated
sites are also reporting winds of 5 kts or less which should allow
some decent frost to develop in the spots that are cold enough. The
frost advisory will be allowed to expire at 9 am as temps warm. Other
than that, skies are clear with a nice day expected to unfold over the
next several hours.

As of 255 am Sunday morning: clear and mostly calm conditions have
settled over the area over the past few hours. We`re still seeing
some decent wind gusts over portions of the higher terrain, especially
over the far northern NC mts, but these should largely subside during
the next few hours. Low temps appear on track with areas of frost
expected over the higher terrain, especially in sheltered mt valleys.
Some patchy frost could also develop over the Northern Foothills
and down into the Southern Piedmont of NC, but only if temps can
cool enough.

Otherwise, dry high pressure will continue to dominate our synoptic
pattern today and into Monday. This will allow clear skies and relatively
low dewpts to persist thru the near term period. Still expecting a
shallow lee trough to develop later this morning as the center of the
high moves farther east. This should cause low lvl winds to become swly
across the lower terrain by 15z or so and remain swly well into the
evening. The high temp fcst required little modification with the latest
guidance still suggesting values in the lower 70s across most of the
lower terrain and mid to upper 60s across most of the higher terrain.


As of 215 AM Sunday, the early part of the week still looks quiet
weather-wise. We still expect a reinforcing cold front to move
across the region on Monday, but too late to keep temps from
climbing up above normal in the afternoon. High pressure should
build in behind the front on Monday night and Tuesday to bring the
temps back down close to normal. The next high will dominate our
weather into the middle part of the week as an upper ridge axis
approaches from the west. It will remain dry.


As of 250 AM EDT Sunday...our primary concern out in the medium
range continues to be the passage of the next upper trof/sfc cold
front later in the week. The operational GFS has flipped back to a
lower amplitude solution that keeps the upper trof progressive,
compared to last nights run at least. Meanwhile, the ECMWF remains
consistent with its higher amplitude trof and ability to tap at
least a little bit of Gulf moisture. Agree with the previous
assessment that the ECMWF is probably a bit more overdone, but see
no reason to make many changes to the precip probability, which
reaches the chance range over much of the fcst area Thursday
afternoon and evening. Either way, precip amts will be minimal at
best. The models suggest that fcst timing can be fine tuned a bit,
with little chance of the system arriving before sunrise on
Thursday. So, the small chance will be taken out of the fcst on
Wednesday night. Oddly enough, high temps may warm a category or so
in the wake of this system east of the Mtns, because of downslope
warming under the ensuing NW flow aloft. Min temps do not look cool
enough for any frost/freeze concerns.


At KCLT and elsewhere: VFR conditions expected thru TAF period.
Dry high pressure will allow clear skies to prevail and temperatures
to moderate. Winds are starting out light and variable this morning
and are expected to back to SWLY by late morning/early afternoon as
lee trofing sets up over the region. Speeds should also increase a
bit, but sustained values should not get above 10kts or so for any
site. KAVL winds will likely veer back around to NWLY by early Monday
morning and also increase in speed as the pressure gradient begins
to tighten again.

Outlook: dry high pressure will persist over the Southeast for the
beginning of the work week, with another reinforcing Canadian High
moving over the region on Tuesday and lingering into midweek.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
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:


GA...Frost Advisory until 9 AM EDT this morning for GAZ010.
NC...Frost Advisory until 9 AM EDT this morning for NCZ033-048>053-


AVIATION...JPT is the U.S. government's official web portal to all federal, state and local government web resources and services.