Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
653 AM EDT Mon Aug 16 2021

.SYNOPSIS...
A surface front will remain nearly stationary across the area for
the next few days. The remnants of Fred is expected to generate
heavy rainfall from the Gulf coast to the Tennessee River Valley
Monday night into mid week. Expect cooler than normal temperatures
into mid week. Abundant tropical moisture will continue across the
region through much of the week leading to areas of heavy rainfall
and isolated strong thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 643 am EDT Monday: Still dealing with persistent showers
with heavy rain and embedded thunderstorms caught in the southerly
upslope flow into the Balsam and Black Mtns at daybreak. Will
bump the precip probs way up in those areas for the next few
hours. Elsewhere...probably not much action...but a shower could
form at any time. In fact, showers were blossoming over the wrn
Piedmont already.

As for today...eventually a lull of sorts will set in during the
morning hours over the mtns, unless another weak mid-level impulse
forces some better upslope flow to result in more showers. Similar
to yesterday, the extensive cloud cover may delay destabilization
until the early afternoon, at which time convection will
develop quickly and will probably end up numerous in the mid/late
afternoon. Model guidance shows some vorticity, emanating from the
circulation associated with Fred, moving northward across the region
late in the day, which should help do the trick. Won't rule out a
few strong thunderstorms, but the updraft strength looks poor on
the HREF and profiles are wet with poor lapse rates, so by far the
bigger concern is localized flash flooding. Will not be surprised
if a few locations need a Flash Flood Warning, but confidence in
where the bigger threat might be located precludes issuing a Watch
at this time due to the convective nature of the threat. Temps
will stay on the cool side of normal. As we work into tonight,
the threat for heavy rain will steadily ramp upward mainly over
the upslope areas, particularly southwest NC and the headwaters
of the French Broad River. All ingredients should be in place,
with PW above 2 inches and deep warm cloud depth, we just might
have to wait for something to trigger and focus. Precip chances
increase as a result, mainly after midnight over the southwestern
zones. Temps will stay mild.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 325 AM EDT Monday...The remnants of TC Fred will be tracking
north, generally along the AL/GA border to begin the period. This
system will interact with an existing wedge bndry and push it north
as a warm front thru Wed. Confidence in high rainfall across
the srn escarpment and NE GA has increased, yet the 00z GFS remains
a low QPF outlier as it has the past several runs. The GFS is
indicating convection along the SC coast, which would rob moisture
transport toward the FA, while the other op models generally agree
with high precip rates developing aided by mech lift over the wrn
zones beginning by mid day Tue. This idea is more accepted by the
WPC as well and a Day 2 Moderate risk of excessive rainfall has been
issued for the srn BR escarpment, nw/rn Upstate SC, and NE GA north
of I-85.

Currently thinking about 5-7 inches of rainfall over these regions
with up to 10 inches possible in the favored Lake Toxaway area. This
amt of rain would certainly create flooding issues with small
streams and main-stem rivers like the French Broad by Tue
afternoon/evening. Additionally, with highly moist antecedent conds,
there exists a landslide threat across the srn BR escarpment ridges.
With no sigfnt changes to the QPF forecast anticipated, a Flash
Flood Watch will likely be issued by the day shift today as the
overall threat moves into the 2nd period. This system wont bring
real strong winds, however, low to moderate gusts will develop and
with saturated soils, weak/dead trees could be blown down.

The fcst remains somewhat uncertain going into Wed as the NAM and
ECMWF both linger a high precip amts as the sfc wave elongates
across the Apps, while the GFS takes the better precip well north of
the FA. In any case and considering the degree of soil saturation,
there will likely be additional hydro issues on Wed and the WPC SLT
risk of excessive rainfall looks good across the higher terrain. Max
temps will drop abt 10 degrees below normal Tue and a couple degrees
below normal Wed. Mins will remain abv normal thru the period.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 345 AM EDT Monday...The ext range remains unsettled as an
upper ridge briefly develops overhead Thu, before a couple h5 trofs
and cold fronts work into the area into the weekend. Soundings show
decent sbCAPE and an uptick in deep layered shear ahead of the first
front Fri, which is making the case for a semi-organized squall line
ahead of the sfc bndry progged to cross the NC mtns arnd max
heating. Another upper wave looks to support a sfc front on Sat, but
confidence in the strength and organization of this system is not
great considering the higher h5 heights and weaker trof seen on the
ECMWF. Still, looks like a return to more normal late summer conds
with tstms developing each afternoon thru the weekend. Max temps
will remain at or a bit abv normal each day with mins holding abv
normal as well.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Now that low level moisture is abundant
across the region, with a S/SE low level flow, low clouds and
showery precip could develop at any location at any time through
the period. Away from the mtns, the upslope flow will mainly help
to keep a low cloud ceiling in place, probably variable between
LIFR and MVFR thru mid-morning before the boundary layer starts
to deepen with some heating. Clouds may struggle to scatter/lift
during the middle part of the day. Over the mtns and near the Blue
Ridge Escarpment, showers and a few thunderstorms will continue
off and on. The low clouds should eventually scatter enough for
terminals to go VFR, which the guidance indicates will happen around
18Z. Timing of shower/tstm development is problematic. Going by
the CAMs, that looks like the main wave might pass over the wrn
Piedmont in the late afternoon/early evening, but maybe more like
the early morning hours over the Upstate. Chances are good that
all terminals will get something during the period, so expect
many amendments as confidence increases. Winds should be SE to
S through the period, stronger near thunderstorms. As moisture
increases again late tonight, expect a resurgence of low clouds
down to MVFR, and eventually IFR/LIFR before daybreak Tuesday.

Outlook: Coverage of showers and thunderstorms will become
widespread Tuesday/Tuesday night as the remnants of Fred
pass. Expect numerous restrictions with heavy rain and storms. A
gradual downward trend in diurnal convection is expected during
the latter half of the week. Widespread low stratus and areas of
fog are expected each morning through at least late-week.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       High  89%     Med   70%     High 100%     High  94%
KGSP       Med   78%     Med   70%     High  95%     High  94%
KAVL       Med   72%     Med   75%     Med   70%     Med   72%
KHKY       High  89%     High  80%     Med   65%     High 100%
KGMU       Med   78%     Med   70%     High  95%     High  94%
KAND       Med   78%     Med   70%     High 100%     High  83%

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/SBK
NEAR TERM...PM
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...PM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
632 AM EDT Mon Aug 16 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-171045-
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-
632 AM EDT Mon Aug 16 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 to numerous thunderstorms will develop across the western
Carolinas this afternoon and linger into the evening. A few of these
storms could become quite strong and produce heavy rainfall with the
potential for isolated flooding along with damaging winds.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Deep tropical moisture associated with the remnants of tropical
storm Fred will interact with an old front and the mountains to
produce periodic heavy rainfall through the middle part of the week.
The flood threat will steadily increase as showers and thunderstorms
wet the soil. At this time, the greatest potential for excessive
rain appears to be Tuesday and Tuesday night as a remnant circulation
from Fred moves northward to the west of the region. This could
result in a flash flooding threat, especially in areas that receive
multiple rounds of heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

None.

Krentz

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
733 AM EDT MON AUG 16 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0338 PM     TSTM WND DMG     5 NNE MARSHALL          35.87N 82.65W
08/15/2021                   MADISON            NC   911 CALL CENTER

            AT LEAST A COUPLE OF TREES BLOWN DOWN.

&&

OUTLAW

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
833 AM EDT Mon Aug 16 2021

SCZ001-004-161315-
Greater Oconee SC-Oconee Mountains SC-
833 AM EDT Mon Aug 16 2021

...THUNDERSTORMS WITH TORRENTIAL RAINFALL WILL IMPACT EASTERN OCONEE
COUNTY UNTIL 915 AM EDT...

At 831 AM EDT, Doppler radar was tracking heavy tropical showers
with torrential rainfall across eastern Oconee County,
moving north at 20 mph.

Locations to be impacted include...
Seneca, Walhalla, Salem, Devils Fork State Park, Lake Jocassee, Lake
Keowee, Bad Creek and Oakway.

Very heavy rainfall rates up to 2 inches per hour will be possible in
these areas.

LAT...LON 3502 8303 3505 8290 3503 8292 3501 8291
      3501 8293 3499 8294 3495 8291 3482 8290
      3479 8288 3474 8290 3473 8286 3470 8286
      3470 8285 3467 8285 3465 8283 3464 8283
      3451 8306
TIME...MOT...LOC 1231Z 183DEG 17KT 3483 8295

CSH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
839 AM EDT MON AUG 16 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0815 AM     FLASH FLOOD      SW ROSMAN               35.14N 82.82W
08/16/2021                   TRANSYLVANIA       NC   OFFICIAL NWS OBS

            THE GAUGE ALONG THE FRENCH BROAD RIVER ABOVE CHESTNUT ST
            IN ROSMAN REACHED MODERATE FLOOD STAGE AND IS STILL
            RISING. EMERGENCY MANAGEMENT REPORTED SEVERAL LANDSLIDES.
            HIGHWAY 64 IS CLOSED NEAR FROZEN CREEK JUST WEST OF
            ROSMAN.

&&

TRISHA.PALMER

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
851 AM EDT Mon Aug 16 2021

NCZ056-161330-
Catawba NC-
851 AM EDT Mon Aug 16 2021

...STORMS WITH TORRENTIAL RAINFALL WILL IMPACT CENTRAL CATAWBA
COUNTY UNTIL 930 AM EDT...

At 850 AM EDT, Doppler radar was tracking a tropical showers with
torrential rainfall moving north at 20 mph.

Locations to be impacted include...
Newton, Conover, Maiden, Claremont, Lookout Shoals Lake, Startown and
Oxford.

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.

&&

LAT...LON 3577 8110 3556 8116 3556 8132 3582 8120
      3582 8117
TIME...MOT...LOC 1250Z 198DEG 18KT 3572 8120

CSH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
923 AM EDT Mon Aug 16 2021

SCZ001-004-161415-
Greater Oconee SC-Oconee Mountains SC-
923 AM EDT Mon Aug 16 2021

...HEAVY SHOWERS WILL CONTINUE TO IMPACT EASTERN OCONEE COUNTY UNTIL
1015 AM EDT...

At 922 AM EDT, Doppler radar was tracking heavy showers across the
advised area moving north at 20 mph.

Locations to be impacted include...
Seneca, Walhalla, Salem, Devils Fork State Park, Lake Jocassee, Lake
Keowee, Bad Creek and Oakway.

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.

&&

LAT...LON 3452 8304 3501 8309 3505 8290 3503 8292
      3501 8291 3501 8293 3499 8294 3495 8291
      3491 8290 3488 8291 3482 8290 3479 8288
      3474 8290 3474 8288 3462 8290
TIME...MOT...LOC 1322Z 181DEG 26KT 3493 8297

CSH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
949 AM EDT Mon Aug 16 2021

NCZ056-069-161430-
Lincoln NC-Catawba NC-
949 AM EDT Mon Aug 16 2021

...STORMS WITH TORRENTIAL RAINFALL WILL IMPACT CENTRAL CATAWBA AND
CENTRAL LINCOLN COUNTIES UNTIL 1030 AM EDT...

At 948 AM EDT, Doppler radar was tracking very heavy showers with
torrential rainfall from Lincolnton to Conover, moving north at 20
mph.

Locations to be impacted include...
Newton, Lincolnton, Maiden, Boger City, Crouse and Startown.

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.

&&

LAT...LON 3565 8114 3541 8120 3541 8133 3542 8139
      3569 8128
TIME...MOT...LOC 1348Z 193DEG 17KT 3542 8130

CSH