Severe Thunderstorm Warning 75, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1055 PM EDT Fri Jun 21 2019

.SYNOPSIS...
Showers and thunderstorm activity will return this weekend and
persist off and on through much of next week. Near seasonable
temperatures are expected to prevail through the next seven days.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 11pm EDT Friday:  Upstream convective system is currently in
Eastern TN and is expected to reach the TN border and parts of
Northeast Georgia in the next couple hours, with a severe
thunderstorm watch in effect for the western part of the CWA where
CAPE is elevated.

A Mesoscale Convective Complex (MCC) has developed atop the ridge
over northern Missouri, and convection driven by the associated cold
pool continues to run eastward into southern Illinois, with
additional activity developing over south-central MO. These features
will become the main players in our forecast for the upcoming
nighttime period. Corfidi vector steering flow should drive the
system mainly eastward toward the Appalachians, but with additional
south flank development expected as the cold pool encounters better
instability there. The convection-allowing models have converged on
a solution with more of a direct hit of the MCS on the southern
Appalachians overnight. The HRRR has the system arriving the fastest
(circa 05Z) and surviving east of the mountains through 08Z or so.
The NAMNest and national hi-res solutions are a touch slower, with
varying decay as the system traverses the higher terrain and
encounters stabler air. Given the latest solutions, will feature
more solid chances over the NC mountains for the overnight hours,
and advertise isolated to scattered coverage eastward through the
lower piedmont. The HWO wording has been beefed up accordingly for
mountain areas.

Saturday is a major question mark for the timing and coverage of the
next round of MCS activity, especially in light of the early morning
passage of the decaying MCS late tonight. There are some features
that suggest the afternoon timing will be favored. First, the region
just east of the central CONUS flat ridge, mainly over the lower
Ohio Valley and surrounding areas, will provide a prime area of
genesis for further MCS activity through Saturday. This appears tied
more strongly to weak upper shortwaves or MCVs moving down the east
side of the upper ridge and this activity would time out toward
Saturday afternoon. Also, a boundary will be in place across the
forecast area through the day on Saturday, and peak afternoon
instability will lead to maintenance of the passing MCS, if one
forms. All told, will feature a peak of coverage (likely northwest
to solid chance southeast) for the afternoon hours. The latest Day 2
Slight Risk Outlook looks well placed, with some 3000+ muCAPE likely
south of the stalled boundary. This too will be talked up in the HWO
for mainly wind potential.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 200 PM EDT Friday: The forecast area will remain on the east
side of a mid level ridge axis on Saturday night and Sunday. This
position in the flow looks to be active with convective complexes
moving through and some local development of storms also possible
both periods. A few of the storms may be severe per the SPC Day 2
outlook.

The ridge axis will move across the area Sunday night and east of
the area on Monday. This will lead to a quieter period Sunday night
and most of Monday. A mid level trough moving across the Great Lakes
states is expected to activate a front moving across the Tennessee
Valley on Monday afternoon. Some of this activity will move into the
mountains during the late afternoon hours.

The forecast for Sunday will feature highs in the upper 80s to lower
90s in the Piedmont and mid 80s in the mountain valleys. The overall
pattern suggests that debris cloudiness and possible leftover
convective boundaries may have an impact on these readings. We may
have to make some adjustments once the timing and location of storms
become more clear.

With less cloudiness and the ridge overhead, Monday looks to be the
hottest day of the week. We expect highs in the lower to middle 90s
in the Piedmont and in the mid to upper 80s in the mountain valleys.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 200 PM EDT Friday: A potent upper trough is expected to lift
northeast into the Great Lakes states Monday evening driving a
rapidly weakening cold front through the region sometime Monday
night or Tuesday morning. A few showers and thunderstorms will be
possible with the front.

Moisture will decrease slightly for the middle of next week so the
chance of showers and thunderstorms will be lower than this weekend
which is closer to climo. Temperatures will be near or slightly
above climo.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Very weak pressure gradient in post-frontal
regime is giving generally light northerly to northwesterly winds,
with a few gusts still seen that will fairly quickly die-out
diurnally. Skies are also mostly clear at the moment as moisture has
been shunted southward with the front.  These good VFR conditions
will likely change early Saturday morning as the remnants of an MCS
cross over the Southern Appalachians.  This is expected to give a
period of a few hours of scattered showers to the region, and
possibly some thunder.  By Saturday afternoon, front lifts back
northward bringing increasing moisture, clouds, and chances for
afternoon thunder with it for Saturday afternoon.  Timing of showers
in the TAFs was derived from the HRRR model and other cams.  Latest
radar has upstream MCS, currently over western KY and TN, a little
ahead of schedule.

Outlook: A more diurnally-driven convective pattern is expected
Sunday through Tuesday, with some mid-week drying possible. Mainly
daybreak restrictions will be possible each day, aside from any
thunderstorms.

Confidence Table...

            03-09Z        09-15Z        15-21Z        21-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High  95%     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...SW
NEAR TERM...HG/WJM
SHORT TERM...SW
LONG TERM...SW
AVIATION...WJM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
1051 PM EDT Fri Jun 21 2019

GAZ010-NCZ051-052-058-059-062>064-230300-
Rabun-Swain-Haywood-Graham-Northern Jackson-Macon-Southern Jackson-
Transylvania-
1051 PM EDT Fri Jun 21 2019

...SEVERE THUNDERSTORM WATCH 422 IN EFFECT UNTIL 5 AM EDT SATURDAY...

This Hazardous Weather Outlook is for northeast Georgia and western
North Carolina.

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

A line of thunderstorms may arrive across the North Carolina
mountains from the northwest overnight tonight into early Saturday
morning. Some of these thunderstorms may be strong to severe and
produce damaging winds. The greatest threat for severe thunderstorms
will be along the Tennessee border and over the southwest mountains
of North Carolina.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

NCZ033-048>050-053-065-501-503-505-507-509-230300-
Avery-Madison-Yancey-Mitchell-Buncombe-Henderson-Caldwell Mountains-
Burke Mountains-McDowell Mountains-Rutherford Mountains-
Polk Mountains-
1051 PM EDT Fri Jun 21 2019

This Hazardous Weather Outlook is for western North Carolina.

.DAY ONE...Tonight.

A line of thunderstorms may arrive across the North Carolina
mountains from the northwest overnight tonight into early Saturday
morning. Some of these thunderstorms may be strong to severe and
produce damaging winds. The greatest threat for severe thunderstorms
will be along the Tennessee border and over the southwest mountains
of North Carolina.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

GAZ028-029-NCZ035>037-056-057-068>072-082-502-504-506-508-510-SCZ003-
006>014-019-230300-
Hart-Elbert-Alexander-Iredell-Davie-Catawba-Rowan-Cleveland-Lincoln-
Gaston-Mecklenburg-Cabarrus-Union-Greater Caldwell-Greater Burke-
Eastern McDowell-Greater Rutherford-Eastern Polk-
Greenville Mountains-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Chester-Greenwood-
1051 PM EDT Fri Jun 21 2019

This Hazardous Weather Outlook is for northeast Georgia, piedmont
North Carolina, western North Carolina and Upstate South Carolina.

.DAY ONE...Tonight.

A diminishing line of thunderstorms may push into the region from
the northwest overnight tonight into Saturday morning. Depending on
how quickly these storms diminish as they cross the mountains, one
or
two storms may be strong to severe, especially across western
Upstate South Carolina and northeast Georgia. The primary threat
will
be strong to damaging winds.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorms are expected Saturday afternoon into Saturday evening.
Some of these thunderstorms may be strong to severe. The
primary threat will be damaging winds with an isolated threat of
large hail.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

GAZ017-018-026-SCZ001-002-004-005-230300-
Habersham-Stephens-Franklin-Oconee Mountains-Pickens Mountains-
Greater Oconee-Greater Pickens-
1051 PM EDT Fri Jun 21 2019

...SEVERE THUNDERSTORM WATCH 422 IN EFFECT UNTIL 5 AM EDT SATURDAY...

This Hazardous Weather Outlook is for northeast Georgia and Upstate
South Carolina.

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

A diminishing line of thunderstorms may push into the region from
the northwest overnight tonight into Saturday morning. Depending on
how quickly these storms diminish as they cross the mountains, one
or
two storms may be strong to severe, especially across western
Upstate South Carolina and northeast Georgia. The primary threat
will
be strong to damaging winds.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorms are expected Saturday afternoon into Saturday evening.
Some of these thunderstorms may be strong to severe. The
primary threat will be damaging winds with an isolated threat of
large hail.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.