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Area Forecast Discussion

097
FXUS62 KGSP 291456
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1056 AM EDT WED JUN 29 2016

.SYNOPSIS...
Weak high pressure centered over the Mid West will build over the
southern Appalachian region through the late work week. A slow
moving cold front is expected to become stationary across the
western Carolinas this weekend. The boundary may remain stalled over
the region into early next week, before possibly dissipating on
Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 10:00 AM EDT...Minor adjustments to the current temperature
scheme as values are rising nicely. We left the current convective
development in place, as inhibition should break with development in
the mountains of North Carolina and possibly in the southern part of
the South Carolina upstate. Rather diffuse front becoming difficult
to find in the wind field, and it may just settle into an elongated
surface reflection, or lee side trough.

Meanwhile profiles over the piedmont will be relatively unstable,
generally featuring 1-1.5k j/kg SBCAPE, while also exhibiting
upwards of 30kts 0-6km shear thanks to improved flow aloft.  In
addition to these profile features, guidance favors a weak shortwave
impulse ejecting through the trof base by mid/late afternoon which
could provide some synoptic support for deeper convection, mainly
along the I40 corridor. Convection should then fan out as the day
wears on.

Wouldn`t be surprised to see a few strong to perhaps an isolated
severe storm this afternoon, especially over western NC adjacent to
the approaching H5 vortmax.

The aforementioned front/lee trough will likely struggle to clear the
area tonight, most likely stalling out atop the region.  This will
likely yield continued convection thanks to persistent LLV
convergence in proximity to the boundary, and sustained elevated
cape per soundings.  Thus, will keep pops in the chance range along
the I77/I40 region through midnight before slowly tapering to non
mentionable levels by daybreak Thursday.  Temperatures today will be
a few degrees warmer with high topping out near normal, as well as
tonight`s lows.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 155 AM Wednesday, a series of weak short waves move through
the long wave trof over the eastern CONUS Thursday and Friday. At
the surface, a weak boundary remains stalled just south and east of
the area Thursday. A weak wave moves along the front bringing
southerly low level flow and moisture back into the area. This leads
to increased instability, especially along and east of I-85. An
upper jet max moves through as well bringing divergence and some
shear. The result will be scattered diurnal convection with the best
coverage over the NC Piedmont and SC Eastern Piedmont. Decent DCAPE
values develop as well. The combination of features could lead to an
increase in severe thunderstorm chances, especially along the I-77
corridor. The surface boundary slides a little farther east and
south on Friday. This leads to less low level moisture and only weak
instability. Therefore, only isolated diurnal convection is
expected. Highs Thursday will be a degree or two below normal and
rise to near or a couple of degrees above normal Friday. Lows remain
nearly steady a few degrees above normal.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 305 AM Wednesday, the upper trough over the east coast moves
east of the area Saturday leaving nearly zonal flow in place across
the area through Tuesday. A series of short waves move through the
flow and over or near the area each day. At the surface, a frontal
boundary drops into the area on Saturday. Scattered mainly diurnal
convection will be the result. The front may sag south a little on
Sunday, but a wave of low pressure moving along the front keeps the
front from moving too far south and keeps low level moisture over
the area. Numerous to good chance convective coverage develops
during the day and only slowly tapers off overnight. A stronger low
pressure center moves into the OH valley Monday bringing the front
back north across the area. The guidance shows the potential for an
MCS to develop with this wave, but it remains north of the CWFA.
Still, we should see at least good chance convective coverage. The
front finally begins to dissipate on Tuesday, but yet another wave
moving along it keeps enough low level moisture, and the resulting
instability, across the area for scattered mainly diurnal
convection. Temps will bounce around just either side of normal each
day.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere:  Vfr through the period with the exception of
possible restrictions associated with any afternoon thunderstorms.
Winds will be rather light and erratic with a weak frontal feature,
of some sort, which settles into the region.

Expect VFR cumulus development ahead of primary convective
initiation. Said convection is progged to propagate into the
foothills/piedmont regions warranting thunderstorm at all sites with
ceiling and visibility restrictions.

The guidance insists the front will likely stall across the region
thus leading to possible isolated shra around the region overnight,
however confidence is too low at this point to include in TAFS.
Also, given the stalled front, expecting winds along/behind the
front to veer NW, mainly at KAVL/KHKY, while all other sites remain
out of SW.

Outlook:  A warm and moist airmass will prevail through weeks end
leading to afternoon/evening convection regionwide.  Restrictions
will be possible adjacent to any shra/tsra, as well as morning fog
in the mountain valleys and at locales that experienced recent
rainfall.  Another front will slide southward towards the area
this weekend yielding further increased chance for shra/tsra.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High 100%     High 100%     High 100%     High  94%
KGSP       High 100%     High 100%     High 100%     High  94%
KAVL       High 100%     High  85%     High 100%     Med   75%
KHKY       High 100%     High 100%     High 100%     High  89%
KGMU       High 100%     High 100%     High 100%     High  94%
KAND       High 100%     High 100%     High 100%     High  83%

The percentage reflects the number of guidance members agreeing
with the schedule 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...RWH
NEAR TERM...CDG/TS
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...CDG/TS



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