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000
FXUS62 KGSP 221523
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1123 AM EDT Sun Jul 22 2018

.SYNOPSIS...
A broad upper low will drop south across the Ohio Valley today, then
settle across the Deep South Monday through Wednesday. This low
will remain nearly stationary and support moist unsettled weather
across the region. The low will weaken late in the week, as another
cold front approaches from the northwest.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1110 AM: The forecast appears on track this morning with only
minor adjustments to a slightly delayed start on scattered
convection along the ridge tops.

Otherwise, the western Carolinas and northeast GA will be positioned
to the west of the deep moisture associated with broad warm conveyor
belt region, and to the east of the mid-level deformation zone, this
afternoon through tonight. However, this should allow most of our
area to receive decent insolation this afternoon, albeit with
temperatures remaining a couple of degrees below climo under the
anomalously low heights. Despite significantly weaker mid-level
lapse rates, the atmosphere is expected to become moderately
unstable this afternoon. Thus, the favorable location to the east of
the upper trough axis, the approach of the next mid-level speed max
rotating around the cyclone, along with W/NW low level upslope flow
across the TN Valley/southern Appalachians should allow the high
terrain to light up with numerous convective coverage by mid-
afternoon.  Mean W/SW winds in the cloud-bearing layer will tend to
sweep high terrain convection into the NC foothills and western
Piedmont by late afternoon, so while likely pops are carried north
of I-85 in NC, pops taper to only 30% across much of the northeast
GA and Upstate Piedmont.

Establishment of weaker mid/upper level flow in the vicinity of the
trough axis, along with generally unidirectional profiles will shunt
the substantive shear east of our area today, which combined with
anticipated modest levels of instability will limit the severe
convective potential to perhaps a couple of pulse events, certainly
much less of a threat than on Saturday. Locally heavy rainfall may
be of slightly higher concern, but even then, PWATS will be quite
subdued through the near term, basically right around climo.

Convection will diminish in coverage through the evening, but
gradually developing low level southeast flow may allow for showers to
linger near the escarpment into Monday morning. Min temps are
expected to be a bit below climo.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM EDT Sunday: An upper low will continue to slowly drift
south and weaken Monday, settling roughly over central GA by
Tuesday. This will keep the forecast area within a favorable region
for weak, though persistent deep-layer Q-vector convergence. The low-
level flow will gradually back from southwesterly to southeasterly
by late Monday, bringing in Atlantic moisture into the region. The
00z models seem to be shifting a bit east with the plume of very
moist PWATs, keeping it along the Mid-Atlantic coast. We should
still have periods of numerous showers with some embedded tstms,
capable of producing torrential downpours. Isolated flooding
concerns will likely exist starting Monday evening thru at least
Tuesday night, perhaps more focused across the eastern half of the
CWFA. Temps will feature a below average diurnal range under plenty
of clouds. Highs a couple categories below normal and lows at or
slightly above normal.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 330 EDT AM Sunday: The weak upper low over the Southeast will
finally open up and shear out, as a northern stream trough digs into
the Great Lakes on Wednesday. That trough may close into another
upper low and stall out, keeping a trough axis just west of the
CWFA thru the end of the work week. An associated cold front will
push in from the NW and stall out along a SW-NE axis across the
Southeast. This will likely keep above climo PoPs thru at least
Friday. The latest GFS and ECMWF keep unsettled weather across the
CWFA right thru next weekend. Overall, temps are expected to return
to near climo and convection should be more diurnally driven than
during the middle of this week.

&&

.AVIATION /16Z SUNDAY THROUGH THURSDAY/...

...AMD NOT SKED CARRIED AT KAND DUE TO ASOS OUTAGE...

At KCLT and Elsewhere: Scattered to numerous coverage of showers and
thunderstorms is anticipated again this afternoon/evening, with the
best chances existing across the NC mtns/foothills, warranting
categorical mention of SHRA/VCTS at KAVL and KHKY this afternoon,
TEMPO at KCLT, and Prob30s elsewhere. The potential exists for
multiple rounds of showers and storms at all terminals later today,
so the convective mention is carried for 6+ hours at most sites.
Lingering low level moisture will pose another threat of fog and/or
patchy low cigs early Monday, but restrictions will be most likely
in areas that receive rainfall this afternoon/evening. Since we
don`t know that for sure attm, will generally pass the buck for
adding late night/early Monday restrictions.

Outlook: An active/wet period is expected to continue through the
middle part of next week as a slow-moving storm system impacts much
of the East. Numerous showers and thunderstorms are expected during
this period. While there will likely be an afternoon/evening peak in
coverage on most days, higher-than-normal chances will also exist
during the overnight and morning hours.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High 100%     High 100%     High 100%     High  97%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High  98%     High 100%     High  94%     High  84%
KHKY       High 100%     High 100%     High 100%     Med   72%
KGMU       High 100%     High 100%     High 100%     High  98%
KAND       High 100%     High 100%     High 100%     High  92%

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...ARK
NEAR TERM...HG/JDL
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...HG/JDL