Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1058 AM EDT Sat Jun 5 2021

.SYNOPSIS...
Bermuda high pressure will be present in the western Atlantic while
a cutoff low tracks across the south-central United States early
next week. This setup will lead to an increase in shower and
thunderstorm coverage late this weekend into next week. This
summerlike pattern continues into middle to late next week leading
to daily diurnal shower and thunderstorm chances.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1045 am: The next 24 hours looks like a transition to a more
typical warm and humid June/early summer weather pattern, with an
upper low over the srn Plains and a Bermuda High. As this happens,
we should be subjected to an influx of moisture from the Gulf of
Mexico, which is essentially underway, with surface dewpoints in the
upper 60s and even lower 70s already being observed across upstate
SC and northeast GA. Forcing will be weak, but thermodynamics,
light southerly upslope flow and differential heating combined with
weakly diffluent upper flow should be enough to allow at least
scattered deep convection. Initiation should beginning early in the
afternoon across the favored high terrain areas, and perhaps in the
more unstable air across the Lakelands. SCT convection should then
overspread the remainder of the area during mid/late afternoon.
Surface-based CAPE should max out at around 1500 J/kg (give or take)
by mid-afternoon. A pulse-type severe storm will not be ruled out,
neither will locally heavy rain, but weak shear will preclude
substantive convective organization. High temps will be a few
degrees above normal. The deep convection may persist well into the
overnight period on the strength of the slowly developing moisture
transport in the southerly flow, so a chance of showers and storms
was kept. Low temps will remain warm.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 230 am Saturday: A summerlike pattern can be expected
during the short term forecast period thanks to Bermuda high
pressure in the Atlantic and a cut off low in the south-central
United States. With the western edge of the subtropical high in the
western Atlantic extending into the eastern United States and the
upper low off to our west, southerly flow will be present at the low
levels across the Deep South and the Carolinas. As a result, an
intrusion of Gulf moisture will lead to daily shower and diurnal
thunderstorm chances late this weekend into early next week. With
this warm, humid airmass in place, above climo PWAT values equal to
or greater than 1.7 inches are portrayed by both the GFS and ECMWF.
High PWATs, deep warm cloud depth, and weak winds at the sfc and
aloft are all ingredients needed for locally heavy rainfall. With
these ingredients noted in soundings, any pulse thunderstorms that
develop could lead to heavy rainfall. Although we have relatively
dry soils, (with some counties in our CWA being abnormally dry per
the U.S. Drought Monitor), heavy rainfall could present some hydro
concerns. Wind shear is expected to be minimal meaning severe wx is
not anticipated. Thus pulse thunderstorms will be the main
convective mode. Sunday high temps look to be slightly below/near
normal across the SC Upstate and NE GA while highs across western NC
will be near/slightly above normal. Monday highs are expected to be
near/slightly below normal across the entire CWA. Calm winds along
with dewpoints in the upper 60s/low 70s outside the mtns will lead
to muggy conditions Sunday and Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 330 am Saturday: No major changes are anticipated during the
extended forecast period as the summerlike pattern will continue
with Bermuda high pressure remaining in place across the western
Atlantic. The continuation of the influx of Gulf moisture will lead
to above normal PoPs throughout the extended period. Showers and
diurnal thunderstorm chances are forecast each day. Throughout much
of the extended period, a warming trend can be expected with the max
temps. No relief in sight in regards to the muggy conditions as
dewpoints will remain in the upper 60s/low 70s outside the mtns.
Warm cloud processes along with calm winds will carry on into next
week meaning that locally heavy rainfall remains a concern for at
least the first half of the extended period.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Prevailing VFR through the early morning
hours on Sunday, most likely. For today, a light S wind will
develop by mid-morning. Scattered cu should develop early in the day
underneath a mid/upper level ceiling. There could be a brief period
of MVFR broken ceilings in some locations in late morning before
the boundary layer deepens and lifts the cloud base above 030,
but the chance of that was too low to include right now. Scattered
thunderstorms are expected to develop in the late afternoon into
the early evening across the region, so a PROB30 was carried at all
TAF sites. The model trend has been toward more coverage, so this
will be evaluated for a possible TEMPO with later issuances. Low
level moisture will increase tonight. Guidance shows an MVFR/IFR
cloud deck developing in the pre-dawn hours on Sunday, with fog
possible in locations where it rains. For now, the TAFs were
limited to the MVFR ceiling restriction.

Outlook: Chance of diurnal convection and associated restrictions
increases Sunday, then continues each day early in the week. Morning
fog/stratus possible, especially in the mountain valleys.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High 100%     High 100%     High 100%     Med   69%
KGSP       High 100%     High 100%     High 100%     Med   67%
KAVL       High 100%     High 100%     High  90%     High  84%
KHKY       High 100%     High 100%     High 100%     Med   73%
KGMU       High 100%     High 100%     High 100%     Low   51%
KAND       High 100%     High 100%     High  98%     Low   51%

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...AP
NEAR TERM...JDL/PM
SHORT TERM...AP
LONG TERM...AP
AVIATION...PM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
331 AM EDT Sat Jun 5 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-060745-
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-
331 AM EDT Sat Jun 5 2021

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

.DAY ONE...Today and tonight.

General pulse thunderstorms are expected across the forecast area
today. The main impacts with these thunderstorms are cloud-to-ground
lightning and locally heavy rainfall.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
213 PM EDT Sat Jun 5 2021

SCZ012-051845-
Laurens SC-
213 PM EDT Sat Jun 5 2021

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN LAURENS COUNTY UNTIL
245 PM EDT...

At 212 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles southeast of Laurens, or near Cross Hill. This storm was nearly
stationary.

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

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.
Isolated flooding of low-lying areas may result.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

&&

LAT...LON 3422 8197 3424 8198 3424 8201 3429 8207
      3445 8198 3441 8175 3436 8179 3435 8181
      3435 8183 3432 8186 3430 8190 3424 8191
      3420 8195
TIME...MOT...LOC 1812Z 285DEG 3KT 3431 8192

HG