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000
FXUS62 KGSP 181830
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
230 PM EDT Tue Jun 18 2019

.SYNOPSIS...
Seasonal temperatures and humid conditions will persist over the
next few days while unsettled weather returns ahead of a front
drifting down from the Great Lakes. Drier weather is expected on
Friday, but showers and thunderstorms will return over the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 2:15pm EDT Tuesday:  Thunderstorms are continuing to increase
in intensity and coverage this afternoon, as forecast.  There is
some risk for isolated severe wind reports and isolated flooding
issues.  A half inch to an inch of rain over the next 24 hours is
expected on average, with some locations which fall underneath the
heaviest storms receiving more.  While more rain is expected in the
mountains and foothills, it is likely that all locations will
receive some rain.

Synoptically, mid-level wave with a band of PVA is currently
crossing the region with sufficient forcing, along with a weak
surface trough, to extract a good deal of the nearly 2 inches of
precipitable water in the area.  Skinny skew-t plots with limited
CAPE are suggestive of heavy rain being the main issue, rather than
severe winds, though quick movement of the system will limit overall
flooding potential to isolated locations.  DCAPE has also come down
from recent days. CAM models are indicative of thunderstorms
persisting until around midnight, followed by something of a lull in
activity for Wednesday morning. Despite the progression of the mid-
level trough east and out of the area, it is not replaced by
ridging, but by a broad, weak trough to the west, with continued low-
level moist advection that will keep dewpoints elevated.   Bits of
vorticity will continue to cross the area on Wednesday, leading to
continued showers Wednesday afternoon, though of a reduced intensity
compared with today.

Considerable cloudiness may reduce high temperatures a few degrees
today and tomorrow, but conditions will remain seasonally warm with
humid lows.  With weak, broad trough over the area, winds will be
light and somewhat variable at times, with a general
southwesterly bias.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 140 PM EDT Tuesday: Still a concern for severe tstms on
Thursday, as a decent mid-lvl shortwave passes by during the peak-
heating hours. The strongest forcing will remain north of the area,
and the latest NAM shows a decaying MCS entering the mountains from
the west during the morning hours. This feature helps delay
recovery/destabilization, and as a result triggers the bulk of the
convection to our east. So confidence on the threat is still too low
to mention in the HWO at this time. But if the MCS fizzles before
reaching the FA or is slower in getting here, destabilization of up
to 2500 J/kg of sbcape is expected given dewpts in the upper 60s to
lower 70s. Bulk shear of 30-35 kts and 0-3 kt helicity of 200 or
more may be enough for supercells and/or multicell clusters.
Whatever activity does develop should exit to the east by late
evening. Temps will be near normal Thursday.

Friday, the wave will exit to our east, and heights will begin to
rise with ridging to our west. A dry NW flow should result in a
quiet day, with mostly sunny skies and temps slightly above normal
(upper 80s to lower 90s across the piedmont).

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
As of 130 PM EDT Tuesday: Starting at 00Z Saturday with the 500mb
pattern showing a ridge building over our region to start the
weekend. There are model differences in timing, but the GFS has a
MCS feature moving SE from KY after topping the ridge and reaching
the NC mountains early Saturday. The EC has a shortwave bringing
areas along and north of I-85 convection late Saturday into Saturday
night. The GFS has another MCS arriving on Sunday. All medium range
models have a strong shortwave arriving from TN late Monday
resulting in numerous showers and storms lasting into Monday night
then gradually shifting east as they weaken. The strong shortwave
will knock down the ridge creating a more zonal west to east
movement of systems. Highest CAPEs late Saturday from west of AVL to
the Upper Savannah in the range 2000 to around 3000. The rest of the
afternoons and early evenings will have pockets of around 2000 CAPE
mainly from the Great Smokies to the Upstate.

Temperatures near to 3 degrees above normal with Sunday perhaps the
warmest to hottest day.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Thunderstorm activity is the main issue for
the next 36 hours.  Currently, scattered showers are increasing and
will likely peak tonight, followed by a lull after midnight.  There
is a good chance all locations will receive some thunderstorm
activity this afternoon and evening, with better chances over the
mountains.  Following the lull, thunderstorms are again possible
Tuesday afternoon.  Main issue with storms will be strong and
variable winds in storm outflows. Following the reduction in rain
early Wednesday morning, low ceilings down to IFR will be possible
due to moistened boundary layer.  Winds will be light and variable
outside of thunderstorms with a slight southwesterly trend.

Outlook: Continued afternoon convection with possible flight
restrictions, mainly across the higher terrain, along with
increasing chances for morning valley fog/low stratus are expected
thru the week.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High  81%     Low   55%     Med   74%
KGSP       High 100%     High 100%     Med   70%     High  85%
KAVL       High 100%     Low   55%     Low   39%     Med   69%
KHKY       High 100%     High  83%     Low   42%     Med   79%
KGMU       High 100%     High 100%     Med   70%     High  83%
KAND       High 100%     High 100%     High  81%     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:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...DEO
NEAR TERM...WJM
SHORT TERM...ARK
LONG TERM...DEO
AVIATION...WJM