Severe Thunderstorm Warning 288, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
235 PM EDT Wed Aug 5 2020

.SYNOPSIS...
Expect a more typical summertime pattern of mainly afternoon and
evening showers and thunderstorms through early next week.
Temperatures will be near normal for this time of year.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 233 PM: Deep convection underway across the mtns, but still
quiet east of the Blue Ridge. Environment is characterized by
2000-3500 J/kg of sfc-based CAPE and dCAPE of at least 800 J/kg, so
there is some concern for a few pulse severe storms this afternoon
and evening as updrafts become more robust. No major changes at
this time, other than a few tweaks to the precip probs.

The weather situation remains persistent over the next 24 hours
with a SW flow aloft as an upper trof axis remains to our west. One
weak short wave will move slowly overhead this evening, while low
level flow remains light from the S to SE. This should keep some
convection going well into the overnight period, possibly all night
long near the Blue Ridge Escarpment where some weak mechanical lift
will persist. Thus, we hold onto some small precip chances. Min
temps will be near normal. Thursday should turn out similar to
today, with another favorable environment for deep convection
that initiates over the higher terrain by midday and expands from
there. Precip probs should be well above climo again. Sfc-based
CAPE in excess of 2500 J/kg, sfc-delta Theta-e in excess of 30,
and low shear point to another afternoon with possible pulse severe
storms. High temps will be near normal.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 200 pm EDT Wednesday: Thursday night into Friday, an
upper trough will continue to set up shop over the eastern CONUS
with the axis of it just west of the southern Appalachians.
With an associated frontal boundary expected to remain stalled
across the eastern fringe of the cwa, isolated showers and
thunderstorms should linger through the overnight and early
morning hours on Friday, mainly in the mountains and NC
Piedmont. With the help from the right entrance region of a 200
mb jet streak located over the central Appalachians on the
eastern side of the trough, some divergence and forcing aloft
will kick-off a round of convective development early Friday
afternoon, starting in the higher elevations. With the front
still expected to remain stalled near the far eastern zones and
diurnal instability in place, scattered convective coverage and
above climo pops will be likely, especially from the mountains
to the NC Piedmont. Most of the activity on Friday will be
diurnal, but the axis of the trough gradually moves over the
region late Friday into early Saturday before lifting out to the
north and east. This opens the door for a few showers and
storms to linger past sunset Friday. As for Saturday, the front
will sag southward and the overall flow pattern flattens out a
bit and begins to become more zonal. Drier air will filter in as
a W to NW flow overtakes the area. With higher heights building
in from the south, temperatures will be at or slightly above
climo for Saturday. Not to mention, convective development will
be somewhat suppressed compared to Friday, but moderate
instability from daytime heating and PWAT values >1.25" for most
locations should keep isolated to scattered diurnal convective
coverage in the forecast during the first half of the weekend.
Model guidance picks up on a wave or two of elongated shortwaves
to move across the cwa during the same time period and allows
pops on Saturday to stay a tad bit above climo due to the mid-
level energy and typical summertime nature.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 2pm EDT Wednesday: Not a lot of change in the day-to-day
sensible weather Sunday through Wednesday as near climo summertime
conditions continue. High and low temperatures vary by a few degrees
each day, along with generally light winds, and at least some chance
for afternoon thunder each day.

Some weak embedded shortwaves in WNW upper flow will, at times, give
a little forcing that will elevate POPs to above climo levels.  At
the same time, weak surface features do not give any strong fetch of
new moisture into the area.  So CAPE will remain at 1000 to 2000
j/kg in the afternoons, along with low-levels of deep-shear, to give
limited chances for severe.  Most likely severe weather will be
isolated microburst activity, typical of this time of year.

EC and GFS models agree on general weak dynamical pattern, with the
latest GFS model having a stronger shortwave entering the eastern
CONUS Monday night.  However, most of the energy with this wave
crosses well north of the CWA, with only some difficult-to-nail-down
increase in POPs Tuesday evening.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
At KCLT and Elsewhere: VFR through the evening hours outside
of scattered/numerous thunderstorms. All sites get a TEMPO for
thunderstorms with an MVFR restriction based on the latest model
guidance, mainly during the mid/late afternoon hours. Guidance
suggests the convection will carry on into the overnight, so
this will be re-evaluated and amended later on. Wind should be
light from the SE to S with scattered cu away from storms and
outflows. Low level moisture will remain rich overnight. Valley
fog looks like a near certainty, so KAVL was taken down to at least
LIFR in the pre-dawn hours. Other sites could also have an MVFR or
IFR restriction at that time, but confidence is lower. Expect more
of the same on Thursday, with light SW wind and more convection
from midday onward.

Outlook: Afternoon/evening showers and thunderstorms will be
possible thru the rest of the work week. Morning restrictions will
also be possible, especially over the usual mountain valleys.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     Med   78%     Med   79%
KGSP       High 100%     High 100%     High  85%     High  88%
KAVL       High 100%     Med   75%     Med   77%     High  83%
KHKY       High 100%     High  90%     Med   67%     High  81%
KGMU       High 100%     High 100%     Med   69%     High  87%
KAND       High 100%     High 100%     High  88%     High  81%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables 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...PM
SHORT TERM...CAC
LONG TERM...WJM
AVIATION...PM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
449 AM EDT Wed Aug 5 2020

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-060900-
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 NC-
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-Union SC-Chester-Greenwood-
449 AM EDT Wed Aug 5 2020

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

.DAY ONE...Today and tonight.

Scattered to numerous thunderstorms are expected to develop across
the region this afternoon and evening. Any of these thunderstorms may
produce cloud to ground lightning, heavy downpours, and gusty winds.
One or two of the thunderstorms may become severe, producing damaging
wind gusts.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
326 PM EDT Wed Aug 5 2020

SCZ013-052000-
Union SC-
326 PM EDT Wed Aug 5 2020

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL UNION COUNTY UNTIL
400 PM EDT...

At 326 PM EDT, Doppler radar was tracking a strong thunderstorm 12
miles southwest of Union, or 7 miles west of Rose Hill State Park.
This storm was nearly stationary.

Locations to be impacted include...
Cross Keys and Sedalia.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

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 3457 8177 3457 8180 3458 8180 3458 8181
      3459 8182 3459 8184 3460 8184 3460 8185
      3468 8182 3469 8181 3462 8171 3456 8176
TIME...MOT...LOC 1926Z 141DEG 4KT 3461 8180

KRENTZ

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