Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 241837
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
237 PM EDT Sat Jun 24 2017

.SYNOPSIS...
A cold front will move southeast across the western Carolinas and
northeast Georgia this evening and then settle southeast of the
region overnight. Drier and cooler air will start to spread in from
the northwest through the day on Sunday, with these conditions
persisting through much of the week. Moisture will slowly return
around an offshore ridge of high pressure toward the end of the week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 230 PM EDT: A broad 500 mb trough will persist over the
eastern CONUS through the near-term period. A cold front moving
southeast in the mean trough will pass east of the Blue Ridge by
evening, then settle southeast of the forecast area overnight. A
soupy pre-frontal airmass, with precipitable water values above two
inches across the eastern half of the area, will keep a heavy rain
and isolated flash flooding threat in place with any convection that
trains over a location. The convection developing off the Blue Ridge
will be the predominant rain maker through early evening as the
boundary moves southeast. Profiles continue to look a bit too warm
and moist for much in the way of severe weather, but mid levels will
begin drying from the west late this afternoon with a slow uptick in
surface to mid-level theta e lapses. Dewpoints in the lower 70s will
keep sbCAPE values in the 2000 to 2500 J/kg range southeast of the
front, but lapse rates will remain weak. Gusty winds and locally
heavy rainfall will remain the primary threats, with the focus
steadily shifting to the I-85 corridor and points southeast from
late afternoon through early evening.

Deeper layer drying will develop from the west overnight as the
frontal boundary gradually settles southeast of the region. Weak
northwest flow moisture may keep lower clouds banked up against the
southern Appalachians into Sunday morning, but little to no
continued shower activity is expected. Max temperatures may be
comparable to, or slightly higher than, today in the improving
sunshine, but humidity will be far more pleasant as dewpoints tumble
into the 50s and lower 60s.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 115 PM EDT Saturday: Mean upper trough continues to make
progress into the Eastern Conus allowing dry air through a deep
layer to overspread the region Sunday night and Monday. Still
expecting a precipitous tumbling of sfc dwpts and below normal
temperatures.  Upper trough axis progresses into the region on
Tuesday with s/wv energy progged to advect through it`s base.  Short
range model consensus is trending a tad more responsive with this
feature, and may wind up ringing out some showers acrs NW NC.
Tuesday should wind up being the coolest day of the week thanks to
more the way of cloudiness and an increase in northerly llvl flow.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 1230 PM EDT Saturday: Upper heights atop the SE Conus begin to
rise on Wednesday with llvl return flow just getting under way as
llvl ridge axis shifts to the coast. Little in the way of sensible
wx to speak of featuring temperatures and humidity levels below
climo. This trend continues into Thursday with an upward bump in max
temps and dwpts, but the atmosphere still should remain effectively
capped.  A return to summertime warmth and humidity is expected for
Friday and Saturday within the progressively more moist, unstable
and less suppressed enviroment featuring daily thunderstorm chances.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
At KCLT: Convection continues to increase in coverage over the
foothills as the cold front slowly crosses the southern Appalachians
this afternoon. HRRR timing of the thunderstorms suggests peak
coverage around KCLT from 20Z to 00Z and this is featured in a
TEMPO. Although cigs should be primarily VFR going forward, any
precipitation will quickly take restrictions back into MVFR given
the moist airmass in place, and winds may become briefly gusty.
Anticipate a wind shift circa 04Z with fropa and strong drying
overnight into Sunday as winds trend northerly.

Elsewhere: Convective coverage will increase off the Blue Ridge this
afternoon and affect most terminal locations between 19Z and 00Z,
slightly earlier at KAVL and KHKY. MVFR cigs should lift to VFR this
afternoon but trend quickly back down to MVFR in any heavier showers
given the moist airmass. TEMPO gusts are likely at the foothills
sites near any thunderstorms. Expect clearing and drying from the
northwest post fropa during the overnight hours. Southwest winds
this afternoon will turn NW with fropa through the evening hours and
trend N to NE overnight into Sunday. Expect little more than a few
stratocumulus on Sunday with weak northwest flow moisture around
KAVL but drier across the foothills.

Outlook: The cold front will move away to the southeast through late
Sunday, with drier weather developing through most of next week.
Moisture will slowly return around an offshore ridge on Thursday.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High  95%     High 100%     High 100%     High 100%
KGSP       High  94%     High 100%     High 100%     High 100%
KAVL       High  99%     High 100%     High  91%     High  95%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High  92%     High 100%     High 100%     High 100%
KAND       High  92%     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...HG
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...HG


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