Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 240002

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
802 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 5:15pm EDT:  Latest hi-res guidance has showers entering from
the west after 0Z with an initial line of heavier convective showers
passing through by 12Z Saturday morning.  Available convective
energy will be on the decline due to diurnal cooling, but will
remain unstable to some extent through the night

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 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: A round of showers and thunderstorms related
to the remnants of Cindy is expected overnight with timing of most
intense period from around 3z to 8z as system moves across the area
from west to east. 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. Low ceilings down to 800 ft AGL or less are
possible early Saturday due to a very moist boundary layer.
Following a general reduction in showers Saturday morning,
additional showers and thunderstorms are expected Saturday afternoon

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...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       High 100%     Med   75%     High  90%     High 100%
KGSP       High 100%     Low   58%     Med   70%     High  85%
KAVL       High  92%     Med   78%     High  84%     High 100%
KHKY       High 100%     Med   69%     High  97%     High 100%
KGMU       High  93%     Med   61%     High  81%     Med   73%
KAND       High  93%     Low   58%     Med   79%     Med   70%

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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