Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1009 PM EDT Wed Jun 9 2021

.SYNOPSIS...
A moist southerly flow off of the Gulf of Mexico will continue into
the second half of the week. An upper level trough will set up over
the eastern states through the weekend as weak cold fronts drift
south across our region.  Expect scattered to numerous afternoon and
evening showers and thunderstorms into the start of the weekend
with somewhat drier conditions by late in the weekend and early
next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 10pm EDT Wednesday:  Showers have been on the decline this
evening, in the typical diurnal pattern, as expected.  With
lightning absent across the CWA at this time, except for one cell in
Greenwood County, the ratio of thunder to rain in the forecast was
adjusted in the direction of rain.  Going into Thursday morning, and
with all of the moisture and recent rains, some patches of fog and
low clouds are a reasonable bet until a couple hours after daybreak.

The upper pattern will gradually modify thru the period as an old
upper low drifts eastward across the Midwest/upper OH Valley region
and weak upper ridging slides underneath it and across the Deep
South. This will continue to veer the low-lvl flow around to a more
SWLY direction today and gradually begin to wean our CWA from the
gulf moisture feed. Mid/upper-lvl forcing will be very weak thru the
period, so convective evolution will trend back toward a more
climatological pattern today and tomorrow. Expect convection to
eventually drift eastward off the Blue Ridge later this afternoon
and out over the Piedmont/Upstate this evening. The best convective
coverage will be concentrated over the mtns/foothills again this
aftn/evening and then over the western Piedmont later this evening.
Fcst soundings continue to show an uptick in the amount of sfc-based
CAPE with a bit less moisture in the boundary layer, so that might
give us a better chance for a few more pulse-type severe multicells.
But, localized flash flooding still remains the bigger concern.
Convection should linger well into tonight and possibly into the
overnight,  before finally dying off. Low temps overnight will
remain about a category above normal. Highs tomorrow should top out
near normal, if not slightly above.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 130 PM Wed: A light SW to WSW'ly flow will continue thru Friday
on the periphery of a subtropical sfc ridge over the western
Atlantic. A slowly moving shortwave initially will be to our
northwest over the lower Ohio Valley; confluent flow downstream of
this feature will maintain a better-defined sfc high near New
England. The shortwave looks to be timed to enhance convective
initiation Friday, and its height falls will help lapse rates improve
slightly compared to the previous day. Thus, our PoPs will trend a
bit upward. Moist profiles appear to keep damaging wind risk on the
low side, though slow-moving storms producing torrential rainfall
will continue to pose a localized excessive rain threat.

As the wave continues to move east Friday night into Saturday, the
front will sag slowly southward across the CWA. This does not look to
induce any real airmass change for Saturday, but it will turn
925-700mb winds toward NW and allow some drying aloft. It will also
bring slightly lower sfc dewpoints. Accordingly, PWATs will end up
closer to a median value for mid-June, though still elevated; peak
diurnal PoPs fall back more into the chance range. We will trade some
of the flash flood threat for more microburst threat as the models
begin to bring higher DCAPE and sfc-midlevel delta-theta-E back to
the area.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 200 PM Wed: We will remain under a relatively dry northerly
flow regime Sunday following the departure of the front, and a
downward trend likely will continue in PWATs. Deep layer lapse rates
remain conducive to diurnal instability, though deeper mixing appears
to make initiation less likely overall. PoPs mostly peak in the
chance range on Sunday with temps about normal. The GFS depicts large
DCAPE greater than 1000 J/kg across the CWA, with marginal
sfc-midlevel delta-theta-E values around 20 K across much of the
area, still with weak 0-6km shear. Thus, a seasonable risk of
damaging microbursts could persist.

A stronger cold front should push south of the Great Lakes on Sunday,
at the leading edge of an appreciably drier continental airmass, and
beneath a deepening NE CONUS trough. Though there are some timing
differences in the deterministic global models, the general idea
appears to be that diurnal convection along the front will
effectively push it a bit farther south each afternoon/evening early
next week. The GFS is more aggressive than the ECMWF or Canadian GDPS
in depicting this; it actually shows deep convection being completely
suppressed over the CWA Monday within the drier post-frontal
environment, which seems like a little bit of a stretch in light of
the other models' solutions. The synoptic fropa looks most likely to
occur Tuesday or Tuesday night, timed with a vort lobe rotating
around the aforementioned trough, and thus don't want to go too low.
Nevertheless, in light of blended guidance, precip chances are being
lowered for Mon-Tue compared to our previous fcst: typical chance
range values for the mountains and slight-chance Piedmont on Monday,
and still mostly at least slight-chance Tuesday. Temps will trend
above normal. Partial thicknesses are rather high, and with downslope
flow and lack of a front on Monday, that looks to be the warmest day
with lower 90s across much of the Piedmont.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere:  Current round of showers and some thunder,
more numerous over the mountains, continues this evening, with
activity expected to decline after dark. A similar round is
anticipated all areas on Thursday.  Using high res-models and radar
trends, the only TAF location likely to directly see a thunderstorm
is KAND, though chances are non-zero elsewhere.  Very moist low-
levels of the atmosphere, along with recent rains, will give a good
chances for lowered CIGS and possible fog prior to sunrise tomorrow,
and this is mentioned in all TAF locations.  With vague frontal zone
across the region, winds will be light to VRB overnight, with a more
definite southwesterly direction expected during the day tomorrow.

Outlook: Scattered to numerous diurnally-driven convection and
associated flight restrictions will continue thru much of the week.
Overnight/morning fog/low cigs are possible, especially over the
mtn valleys and locations that receive heavy precip.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High 100%     Low   55%     Med   77%     High 100%
KGSP       High 100%     Low   55%     High  80%     High 100%
KAVL       Low   47%     Med   77%     High  83%     High 100%
KHKY       High  93%     Med   73%     High  83%     High 100%
KGMU       High 100%     Low   55%     Med   79%     High 100%
KAND       High 100%     Low   55%     High  94%     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 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...JPT/WJM
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...WJM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
348 AM EDT Wed Jun 9 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-100800-
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-
348 AM EDT Wed Jun 9 2021

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

.DAY ONE...Today and tonight.

Scattered showers and thunderstorms are likely again this afternoon
and evening. The main impacts that can be expected are cloud-to-
ground lightning, gusty winds, and heavy downpours. Localized
flooding is possible with any storms that produce high rainfall
rates.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1009 PM EDT Wed Jun 9 2021

SCZ012-019-100245-
Laurens SC-Greenwood SC-
1009 PM EDT Wed Jun 9 2021

...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL LAURENS AND
CENTRAL GREENWOOD COUNTIES UNTIL 1045 PM EDT...

At 1008 PM EDT, Doppler radar was tracking a strong thunderstorm near
Greenwood, moving east at 20 mph.

Locations to be impacted include...
Greenwood, Ninety Six, Cross Hill, Lake Greenwood State Park, Lake
Greenwood, Greenwood State Park, Ninety Six Historic Site, Coronaca,
Dyson and Epworth.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall may flood areas with poor drainage, such as ditches
and underpasses. Avoid these areas and do not cross flooded roads.

&&

LAT...LON 3408 8220 3426 8223 3433 8185 3430 8190
      3424 8191 3421 8194 3420 8194 3419 8192
      3418 8192 3418 8191 3416 8191 3413 8187
      3409 8192 3408 8192
TIME...MOT...LOC 0208Z 266DEG 17KT 3418 8212

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1044 PM EDT Wed Jun 9 2021

SCZ012-019-100315-
Laurens SC-Greenwood SC-
1044 PM EDT Wed Jun 9 2021

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN LAURENS AND EAST
CENTRAL GREENWOOD COUNTIES UNTIL 1115 PM EDT...

At 1044 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles west of Newberry, or 6 miles east of Cross Hill, moving east at
25 mph.

Locations to be impacted include...
Cross Hill, Lake Greenwood State Park, Greenwood State Park, Lake
Greenwood, Joanna, Kinards, Mountville and Dyson.

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.

&&

LAT...LON 3435 8201 3443 8174 3436 8179 3435 8181
      3435 8183 3432 8186 3430 8190 3424 8191
      3421 8194 3420 8194 3419 8192 3418 8192
      3418 8191 3417 8191 3416 8201
TIME...MOT...LOC 0244Z 259DEG 24KT 3430 8186

KRENTZ