Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 231810
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
210 PM EDT Fri Jun 23 2017

.SYNOPSIS...
Shower and thunderstorm coverage will increase from the west into
early Saturday morning. Light showers will linger Saturday morning
as the front slowly crosses the area, and thunderstorms may
redevelop just ahead of the cold front over the piedmont.
Unseasonably cool and dry conditions will spread over the forecast
area in the wake of the front and persist through the middle of next
week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 145 PM EDT: Satellite and surface observations show the
remnant Cindy circulation over the mid Mississippi River Valley this
afternoon, and all models agree in the system getting gradually
absorbed into the broad northern stream trough later this afternoon
and this evening. The deep fetch of tropical moisture ahead of the
system stretches from central MS to central TN and this band will
move east toward the southern Appalachians through the evening
hours. Meanwhile, conditions remain quiet this afternoon across the
western Carolinas and NE GA. Despite plentiful dewpoints around 70
degrees F, little to no triggering is apparent and piedmont sbCAPE
values above 1000 J/kg cannot be realized due to CINH and capping in
the profiles under the southeast ridge. This should change from the
west as the Cindy remnants arrive later this evening, with the
phasing system crossing the Appalachians quickly around Midnight and
then swinging east of the forecast area through the early morning
hours. The latest convection-allowing models have activity reaching
the western mountains around 00Z and moving quickly east of I-77
after 06Z. The 50+ kt low level jet will traverse the area centered
around 03Z, with peak low level shear over the mountains 00Z to 03Z
and over the piedmont 03Z to 06Z. This would be the best window for
any marginal severe weather and gusty winds mixing to the surface.

A surface cold front will then arrive from the west in the wake of
the Cindy remnants on Saturday, and only slowly move southeast
across the region Saturday afternoon. The slower cold front
progression will yield 2000 to 3000 J/kg sbCAPE over much of the
eastern foothills and lower piedmont. Scattered, strong pulse type
storms and locally heavy rainfall will be possible in the southeast
half of the area through late Saturday afternoon.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 305 AM EDT Friday: the short-term fcst picks up at 12z on
Saturday with longwave upper trofing digging down across the Great
Lakes and steep upper ridging over the West and East Coasts. The
upper lvl pattern is not expected to change much thru the period
with the trof axis remaining just to our NW and the ridge amplifying
to our west. At the sfc, a robust-looking cold front will be moving
thru the CWFA by early Sat, with widespread showers and thunderstorms
likely as it does. The models are hesitant to move the front south
of the CWFA on Saturday and keep the bndy just to our southeast thru
Sunday. By the end of the period early Monday, strengthening Canadian
high pressure to our NW finally pushes the bndy offshore. Precipitation
chances will steadily diminish Sat night thru early Sun with the rest
of Sunday expected to be dry and a bit cooler.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 145 PM EDT Friday: Not much change from the previous fcst. The op
guidance remains in general good agreement with the synoptic pattern
which features a strong upstream ridge enforcing good subsidence
across the FA. There is a strong h5 s/w depicted to cross the area
on Tue...but with nil moisture to work with...will anticipate only
mid/high level clouds with this feature. The atmos remains rather
stable thru most of the period as a Canadian high slowly crosses
overhead. There could be some limited mtn-top convg shra/tstms
developing late Thu however confidence is too low attm to include in
the fcst grids. The best chance for precip will be Fri thru the
period when a cold front approaches from the west and by that time
the Bermuda high will be back in it/s normal config allowing sw/ly
moist adv and seasonal sfc heating. Shower and tstm activity will be
limited mainly to the higher terrain aided by mech lift. Max/min
temps will begin the period a couple cats below normal with a
gradual increase to near normal levels by the weekend.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: SCT VFR cumulus with heating will continue
through late day until the Cindy remnants and associated moisture
begin to cross the area from the west from 00Z in the mountains to
06Z to 08Z east of KCLT. SHRA/TSRA chances will ramp up through the
evening hours. Anticipate a period of MVFR cigs late evening through
overnight, with a window of IFR toward daybreak in abundant low
level moisture. SW winds will continue and remain gusty until the
upper wave/Cindy remnants pass early Saturday, with a weakening
gradient as the frontal boundary settles into the region. SHRA/TSRA
chances will start to increase again with fropa near the end of the
period.

Outlook: A passing cold front will move southeast of the area
through the late weekend, with drier weather developing through most
of next week.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High  80%     High  80%
KGSP       High 100%     High 100%     High  86%     Med   75%
KAVL       High 100%     High 100%     Med   68%     Med   63%
KHKY       High 100%     High 100%     High  85%     Med   70%
KGMU       High 100%     High  93%     Med   70%     Med   75%
KAND       High 100%     High 100%     High  82%     High  86%

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...SBK
NEAR TERM...HG
SHORT TERM...JPT
LONG TERM...SBK
AVIATION...HG



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