Hail in North Carolina, June 16, 2017

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
525 PM EDT Thu Jun 15 2017

.SYNOPSIS...
A deep ridge over the Atlantic will continue to transport warm,
moist air into the area through the weekend and into early next
week, keeping chances of afternoon showers and thunderstorms in the
forecast. A cold front approaching the area will increase chances
for storms on Monday, with some rain chances hanging around next
week as the front stalls near our area.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 515 PM: convective coverage has steadily expanded across the
CWFA over the past few hours, with most of the activity occurring
over the higher terrain and into the foothills. A robust MCS
continues to move eastward across portions of Alabama and Georgia,
but that system should remain to our south as it approaches the
area. Otherwise, with the shortwave providing a slight enhancement
to lift overnight, PoPs were allowed to diminish slowly, but a lull
is expected across the area during the early morning hours. Patchy
fog will likely develop again, though convective debris and other
cirrus associated with the shortwave may be enough to prevent it
from being as solid

From a synoptic standpoint, things look appreciably more favorable
for convective development over our area tomorrow. The shortwave
will be passing over the area during peak heating; no significant
DPVA is suggested by the NAM or GFS, but its presence leads to
steeper lapse rates than we've seen most of this week so far.
Furthermore, some degree of low level convergence is resolved with
the prefrontal (and/or lee) trough. Likely PoPs are fcst over most
of the CWFA. Prog soundings continue to look dry enough to expect a
nonzero threat of damaging wind.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 130 PM EDT Thursday: Slightly better upper level forcing will
be over the region on Saturday with a weak trough axis and
associated vorticity maximum arriving from the west. This could lead
to more non-diurnal scattered coverage early in the period Friday
night through Saturday morning. However, peak heating should still
yield the best convective coverage Saturday afternoon as sbCAPE
values surge to 2000 to 2500 J/kg around the region. Westerly flow
will increase a bit on Sunday as the digging northern stream trough
amplifies toward the Ohio River Valley - with a lingering vorticity
lobe in the weakness atop our region. The initiation of the
strongest convection should once again occur along and east of the
Blue Ridge on Sunday afternoon and sbCAPEs may be a touch higher
Sunday compared to Saturday. Meanwhile, south to southwest low level
flow will continue to pump moisture into the region and precipitable
water values and the associated localized flooding threat will
remain elevated all weekend. Expect well above climo PoPs both days
this weekend with min temps well above climo and maxes around climo.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 130 PM EDT Thursday: Uncertainty in the medium range is
increasing due to a number of factors, though overall it appears we
will remain in a wet pattern. A surface cold front will approach
the area Monday night as an upper level longwave trough digs into
the east coast, suggesting that we may not see a diurnal lull in
pops Monday night into Tuesday morning. Frontal passage will occur
some time during the day on Tuesday, and most solutions agree this
will not be clean. There is disagreement as to exactly where the
front may get hung up, but at least the southern half of our
forecast area will hold on to pops through Tuesday. The upper and
surface ridges over the Atlantic will retreat a bit by Wednesday, so
an Atlantic moisture fetch will set up over the Carolinas. With the
surface boundary washing out somewhere close to our area, high-end
chances for diurnal convection will remain through the end of the
week.

The other wildcard at the moment is the erratic behavior of the
trough/tropical wave feature somewhere in the Gulf at the end of the
period. Direct impacts for our area appear unlikely, but the remnant
moisture from the system could serve to either increase or decrease
QPF towards the end of the period depending on its track and where
moisture transport is best. The system will be watched, but
regardless of its track, the medium range will remain muggy and
rather wet. Minimum temperatures will run roughly 5 degrees above
average, with maximum temperatures near average.

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Winds will be rather variable this aftn
with a weak pressure pattern across the region, plus the possible
influence of a shortwave approaching from the west. By evening
SW-ly winds are expected to prevail. Diurnally driven TSRA are the
initial impact weather expected during the period. Said storms
will spread generally from the mountains into the foothills and
Piedmont over the course of the aftn, with profiles favorable
for strong to severe winds to develop in some. A second wave of
activity could develop in a convergence zone over the Upstate in
the late afternoon or early evening, aided by the shortwave, and
per several meso model runs and sfc analysis. Hence VCSH/VCTS are
kept into the evening as needed. Dry air above the sfc should once
again limit fog mainly to areas where soils are wet from antecedent
rainfall. KAVL/KHKY saw restrictions this morning and are expected
to see them again; guidance hints that KCLT may also be affected.

Outlook: Chances for SHRA/TSRA will remain elevated
through the weekend, possibly resulting in afternoon/evening
restrictions. Chances for morning vsby restrictions increase as
well, mainly over the mtn valleys, but also possible outside of
the mtns where any precipitation has fallen.

Confidence Table...

            21-03z        03-09Z        09-15Z        15-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     Low   53%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     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...Carroll
NEAR TERM...JPT/Wimberley
SHORT TERM...HG
LONG TERM...Carroll
AVIATION...JPT/Wimberley