Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
221 PM EDT Tue May 25 2021

.SYNOPSIS...
The ridge of high pressure will gradually break down through Friday,
allowing shower and thunderstorm chances to slowly return to the
region. A cold front passage early this weekend will support more
widespread activity with dry and much cooler temperatures by Sunday.
Warmer temperatures return next week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 145 PM EDT Tuesday: A back door cold front is dropping SE
across the Blue Ridge and NE Piedmont. Low clouds developed in
behind this front across a good chunk of the NC Piedmont, but mostly
dissipated across the area as we enter peak heating. Potent cu field
has already developed over the high terrain and should begin to get
its act together across a good portion of the CFWA over the next
couple of hours or so.

The axis of the upper ridge that has been over the area drifts east
to the coast today. A short wave crosses the area in the resulting
southwesterly flow. The low level flow becomes southwesterly as well
with good low level moisture over the area. Scattered diurnal
activity has already started over the ridgetops of the escarpment
and Balsams. Added scattered Pop east of the I-26 corridor outside
of the mountains, with isolated PoP to the west as a differential
heating boundary over the eastern zones evolves throughout the
afternoon/evening hours and sparks a few showers and thunderstorms
east of the mountains. Have gone toward the lower end of a guidance
blend for highs given the initial cloudiness over portions of the
area. Still expect highs around 90 along and south of the I-85
corridor with high thickness values in place.

Convection should diminish through the evening ending in a typical
diurnal fashion. Guidance is a little uncertain on coverage but, low
clouds and fog could become an issue overnight. Won't hit it too
hard for now to see if better alignment develops. Lows should be
around 5 degrees above normal. The upper ridge will continue to
track eastward on Wednesday as sfc high sinks southward and provides
much of the CFWA with a persistent southwesterly low level flow.
This will help kick off more scattered diurnal activity during the
day Wednesday. Coverage will stay mainly confined to the mountains
as the backdoor front fades out and shortwave impulses will remain
just west of the area through the rest of the forecast period. With
fewer clouds in the sky and another day of high thickness values,
expect widespread 90s in locations outside of the mountains, with a
few spots flirting with their record high.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 200 pm Tuesday: The break down of the Southeast upper ridge
will be all but completed early in the short term, as a region of
height falls sweeps through the Eastern Seaboard Wed night/early
Thur. Nevertheless, persistence of a general westerly low level flow
will result in a continuation of the very warm weather, with temps
expected to remain roughly 10 degrees above climo through the
period. Through Thu night, convective chances should remain
primarily driven by the diurnal heating cycle, with scattered
coverage expected to remain primarily confined to the high terrain.
However, a few cells could wander into the foothills Thu afternoon/
evening. By late Friday, a more substantial area of height falls is
expected to approach the eastern states from the Upper Midwest.
Attendant frontal boundary is expected to approach the southern
Appalachians by Friday evening, with pops ramping up to likely
across the NC mountains by 00Z Saturday.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 210 pm Tuesday: A frontal zone is expected to sag southeast
across the forecast area Fri night into early Saturday. In light of
the largely nocturnal frontal timing & weakening instability, as
well as a lack of robust forcing in model guidance, questions abound
as to the degree of convective coverage that will accompany the
front during this time frame. As such, PoPs are primarily
advertised in the token/solid chance range, except for an area of
likely across the far western NC mountains. Convective coverage may
uptick briefly Saturday afternoon, especially across the eastern
zones before the front slides east of the forecast area later
Saturday/Sat night. Drier and noticeably cooler air is then forecast
to overspread the region in the wake of the front, with temps
expected to return to normal, if not slightly-below-normal levels
Sunday, and likely staying there through the end of the period.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
At KCLT and Elsewhere: VFR conditions are expected through much
of the period. High based cu field has developed across the area for
the afternoon. Convergence and differential heating from the cold
front, along with a short wave, has already sparked scattered
diurnal convection over the mountains, with the NC Foothills and
Piedmont expected to get in on the action some time after 18Z. Added
VCTS to KCLT, KAVL, and KHKY TAFs for the expected diurnal activity
today through ~01Z Wednesday. VFR conditions should continue for the
evening with restrictions possibly returning overnight as MVFR vsbys
could develop at KAVL overnight into early Wednesday morning via
model guidance. Some model guidance depict other areas of fog
outside of the mountains, mainly in spots that receive a shower or
thunderstorm during the day today. Light NE wind expected through
the morning with a southerly wind for the afternoon. Light southerly
wind this evening.

Outlook: Under strong ridging, VFR conditions and light winds are
expected to continue over the next few days. The chance of diurnal
convection will gradually increase by late week.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High  91%     High 100%
KHKY       High  99%     High 100%     High 100%     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 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...CAC
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...CAC/RWH

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
403 PM EDT Tue May 25 2021

GAZ010-017-018-026-028-029-262015-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-
403 PM EDT Tue May 25 2021

This Hazardous Weather Outlook is for northeast Georgia.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ033-035>037-048>053-056>059-062>065-068>072-082-501>510-
SCZ001>014-019-262015-
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-
403 PM EDT Tue May 25 2021

This Hazardous Weather Outlook is for the Piedmont, foothills, and
mountains of North Carolina, and the Upstate of South Carolina.

.DAY ONE...Tonight.

Isolated to scattered thunderstorms are expected this evening with
brief heavy rain and cloud-to-ground lightning possible.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
afternoon to
early
Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

MPR

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
513 PM EDT Tue May 25 2021

SCZ013-252145-
Union SC-
513 PM EDT Tue May 25 2021

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN UNION COUNTY UNTIL
545 PM EDT...

At 513 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles south of Union, or near Whitmire, moving northeast at 25 mph.

Locations to be impacted include...
Monarch Mill, Carlisle, Rose Hill State Park, Tuckertown, Santuc and
Adamsburg.

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

LAT...LON 3446 8156 3448 8155 3453 8162 3453 8164
      3456 8168 3455 8172 3456 8174 3479 8152
      3475 8148 3474 8149 3473 8148 3472 8145
      3468 8145 3464 8142 3452 8142 3449 8149
      3445 8154
TIME...MOT...LOC 2113Z 227DEG 20KT 3452 8164

WJM