Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 231823

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

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


As of 220 PM EDT: Satellite and surface observations show the
remnant Cindy circulation over far western TN/KY this afternoon, and
all models agree the system will get gradually absorbed into the
broad northern stream trough. The deep fetch of tropical moisture
ahead of the system stretches from central TN to eastern MS 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, especially over the higher terrain.

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.


As of 215 PM EDT Friday: Will plan on basing the Saturday evening
pop timing by extrapolating the NAMNest sfc refl which is progging
scattered deep convection translating acrs the piedmont 21-02z. Sfc
front should then translate to the coastal plain before sunrise
Sunday.  Broad upper troughing builds into the eastern conus
starting on Sunday with an influx of drier continental airmass
expected atop the cwfa. Sunday afternoon sfc dwpts should be around
10 deg F lower than Saturday`s values.  Upper trough continues to
build toward the eastern seaboard on Monday while a persistent llvl
northerly flow allows for further drying.  Sfc dwpts should fall
into the 50s, impressive values for late June.


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.


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, centered around 00Z in the
mountains and 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
from the northwest on Saturday. SHRA/TSRA chances will start to
increase again with the front 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:




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