Severe Thunderstorm Warning 201, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
224 PM EDT Sat Aug 17 2019

.SYNOPSIS...
A weak area of high pressure will be across the area through the
weekend into next week. Moisture will increase through the first
half of next week, as a Bermuda high strengthens over the western
Atlantic Ocean.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 215 pm: Strong insolation, improved low-to-mid-level lapse
rates and surface dewpoints that are a couple of degrees higher than
in recent days are combining to yield sbCAPE in the 2000-3000 J/kg
range across much of the forecast area this afternoon. Isolated to
widely scattered convection has been firing within this air mass
across the favored high terrain areas for the past 1-2 hours. Robust
dCAPE (AOA 1000 J/kg) indicates cells should output some robust
outflow, with isolated microbursts possible with the stronger
storms. Locally heavy rainfall to the tune of up to 2" in an hour
has also occurred, mainly due to cells anchoring along terrain
features. However, mean cloud-bearing winds of around 10 kts
suggests these types of quasi-stationary or very slow moving cells
should be relegated to said terrain features. Convection will
continue to gradually increase in coverage over the next few hours,
with at least isolated activity developing/spreading out into the
Piedmont along outflow boundaries. Convection should begin steadily
diminishing by early evening, and dissipate for the most part by
late evening. Min temps will remain a couple of degrees above
climo.

Not much change in the air mass or overall pattern is expected on
Sunday, with weak W/SW flow aloft and a nebulous surface pattern,
with the old frontal boundary focusing convection closer to the
coast. Mid-level lapse rates will remain respectable, perhaps even
improve a bit, and strong insolation and seasonable dewpoints will
yield another round of moderate-to-strong instability. Deep
convection should again fire across the usual high terrain areas
during early afternoon, and 30-50 pops are carried across much of
the mtns. At least isolated outflow-driven convection will waft into
the Piedmont again by late afternoon, warranting 20-40 pops there.
Max temps will again by a few degrees above normal.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 200 PM EDT Saturday: Mid level heights will start out in a
westerly flow pattern Sunday night and Monday. By Tuesday, there
will be mid level ridging centered across the southern plains and
over the Atlantic Ocean near Bermuda. A weakness between the two
ridge centers will exist across the southeastern states allowing for
a more active convective pattern to develop starting on Tuesday.

High temperatures will be in the lower 90s in the Piedmont and mid
to upper 80s in the mountain valleys on Monday. However, with
increased moisture and convection, highs will be a few degrees
cooler on Tuesday.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 200 PM EDT Saturday: The medium range still looks fairly
unsettled, as a weakness in the upper level ridge lingers over the
region thru midweek. High moisture content as indicated by
precipitable water values approaching 2 inches by late week suggest
that some locally heavy rain will be possible by late next week.
Temperatures will be near to slightly below climo due to increased
cloud cover and rainfall potential.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Convective parameters indicate chances are
higher for showers and storms than they've been over the past
several days, and indeed isolated/widely scattered convection has
begun firing across the high terrain for about the past hour.
Gradual expansion in coverage is expected as cells develop/move
slowly east along outflow boundaries from the high terrain.
VCTS/VCSH is warranted at all terminals by mid-afternoon (earlier at
KAND, where an isolated shower had already developed at 18Z TAF
time). Trends will have to be closely monitored for inclusion of
tempos for TSRA, but coverage is not expected to be quite high
enough to warrant a mention attm.

Otherwise, light/generally vrbl winds will continue through much of
the forecast period. Fog and/or low stratus will likely develop
again early Sunday morning in the mtn valleys and perhaps across the
Piedmont. However, restrictions have had difficulty developing at
the TAF sites (except for very brief periods) and so will feature a
VFR forecast for now, hinting at the restrictions potential with 6SM
at KAVL/KCLT/KHKY.

Outlook: Moisture and instability will gradually increase through
the middle of next weak, resulting in a steady uptick in afternoon/
evening  convective coverage each day, especially during the middle
part of the weak as a cold front approaches from the northwest.
Early day fog and stratus will be possible each day across the
mountain valleys.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High  97%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High  85%     High  90%
KHKY       High 100%     High 100%     High  84%     High  99%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High  99%     High  95%

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...JDL
SHORT TERM...SW
LONG TERM...SW
AVIATION...JDL

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
449 AM EDT Sat Aug 17 2019

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-180900-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Alexander-
Iredell-Davie-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Catawba-
Rowan-Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union-
Caldwell Mountains-Greater Caldwell-Burke Mountains-Greater Burke-
McDowell Mountains-Eastern McDowell-Rutherford Mountains-
Greater Rutherford-Polk Mountains-Eastern Polk-Oconee Mountains-
Pickens Mountains-Greenville Mountains-Greater Oconee-
Greater Pickens-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Chester-Greenwood-
449 AM EDT Sat Aug 17 2019

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

.DAY ONE...Today and tonight.

Isolated to widely scattered thunderstorms are expected to develop
this afternoon across the area, especially near the Blue Ridge
escarpment. Cloud-to-ground lightning, brief heavy downpours, and
locally gusty winds will be the primary threats.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
115 PM EDT Sat Aug 17 2019

NCZ504-171745-
Greater Burke NC-
115 PM EDT Sat Aug 17 2019

...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT SOUTHEASTERN
BURKE COUNTY UNTIL 145 PM EDT...

At 114 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall 11 miles southeast of Morganton, or 5 miles east
of South Mountains State Park, moving east at 15 mph.

Locations to be impacted include...
South Mountains State Park and Pleasant Grove.

Wind gusts up to 40 mph and pea size hail will be possible in these
areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.

&&

LAT...LON 3563 8148 3561 8151 3557 8154 3556 8158
      3557 8158 3557 8163 3564 8165 3571 8151
TIME...MOT...LOC 1714Z 250DEG 12KT 3561 8156

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
120 PM EDT Sat Aug 17 2019

NCZ033-501-171745-
Caldwell Mountains NC-Avery NC-
120 PM EDT Sat Aug 17 2019

...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT WEST CENTRAL
CALDWELL AND SOUTHEASTERN AVERY COUNTIES UNTIL 145 PM EDT...

At 120 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall 10 miles southeast of Newland, or 6 miles
southeast of B.R. Parkway-Linville Falls To Grandfather. This storm
was nearly stationary.

Locations to be impacted include...
Edgemont.

Wind gusts up to 40 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.

&&

LAT...LON 3601 8169 3591 8172 3594 8178 3595 8178
      3595 8180 3597 8182 3597 8183 3598 8185
      3603 8183
TIME...MOT...LOC 1720Z 282DEG 3KT 3598 8179

KRENTZ