North Carolina, 2020

Flood in North Carolina, September 17 to 18, 2020

September 17 to 18, 2020 · NWS GSP · 1 event in 1 county or zone

Moisture associated with the remnants of Tropical Cyclone Sally moved into western North Carolina during the evening of the 16th and continued into the morning of the 17th. 2 to 4 inches of rain fell across much of the area in about 20 hours, resulting in minor flooding across the upper French Broad basin.

Where it happened

Every event with a place to put it. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

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The toll

Deaths
0
Injuries
0
Property damage
$500
Crop damage
None recorded
Events
1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS GSP wrote it up.

Moisture associated with the remnants of Tropical Cyclone Sally moved into western North Carolina during the evening of the 16th and continued into the morning of the 17th. 2 to 4 inches of rain fell across much of the area in about 20 hours, resulting in minor flooding across the upper French Broad basin.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Greenville-Spartanburg, SC wrote its last area forecast discussion before the first event at Sep 17, 1:33 PM EST, 2 hours 17 minutes earlier.

Area forecast discussion, Sep 17, 1:33 PM EST, 2 hours 17 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
233 PM EDT Thu Sep 17 2020

.SYNOPSIS...
Rainfall associated with Post Tropical Depression Sally will impact
much of the area tonight, tapering off by early Friday morning.
Thereafter, dry and cool high pressure will dominate the weather
through the middle of next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 225 PM EDT Thursday: The main plume of heavier showers and
embedded thunderstorms have largely pressed east of the area ahead
of schedule. A combination of deformation zone of showers typical of
winter storms will continue to support periods of moderate to
briefly heavy rainfall focused across the NC Piedmont. A few
isolated heavier showers have developed in the dry slot across
eastern GA into the Upstate of SC. It seems mid-level capping is
keeping the convection low based, thereby limiting the heavy
rainfall and lightning threat. Have trimmed back the ongoing Flash
Flood Watch for our GA counties and Macon and Jackson counties in
NC, but held onto other areas in the watch as many areas in the
watch continue to see rising streams and rivers from earlier heavy
rainfall.

The deformation rain will follow the parent low east of the area
this evening into tonight with perhaps a few terrain induced showers
hanging on during this time across the mountains with showers also
dwindling near the I-77 corridor. Low clouds and patchy fog may be
slow to clear tonight especially across the mountains thanks in part
to the wet soils. In fact, patchy dense fog is likely across
sheltered mountain valleys such as the Little Tennessee.

Downsloping northerly flow and sunny skies will support one more
warmish day Friday with widespread highs into the 70s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 300 PM Wednesday: Cooler and drier air will begin filtering
in during the short term period. A post-frontal environment with
a general N to NE flow will prompt CAA into the area. A sfc high
will slide from the Upper Great Lakes region to New England during
the period, which will increase the NE wind component through
the weekend. Clouds will stick around on Saturday due to residual
moisture from Post-TC Sally and a slight Atlantic fetch. Expect
sunny skies Sunday as the cooler, drier air becomes relatively
persistent and allows any clouds to dissipate by then. PoPs
will be virtually nonexistent, while temperatures dip way below
average. Temperatures will be close to early November values rather
than mid-September. A true fall airmass will be in store for the
entire cwa.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 300 PM Wednesday: A pleasant weather pattern should prevail
through much of the extended. With a dip in the jet streak putting
the area in the left entrance region starting out the forecast
period, cooler air will be able to sink down through the atmospheric
column and keep temperatures below-normal for a good chunk of
the medium range. With a ~1032 mb sfc high set up shop over the
northeastern CONUS during the first half of the period, low-level
N to NE flow will continue to nose down the Eastern Seaboard. By
the middle part of next week, the sfc high will drive southward,
while weakening as it approaches the Mid-Atlantic and OH Valley. By
the end of the extended, the east side of a developing ridge will
dig down into the northeastern CONUS and suppress the sfc high to
the TN Valley. Dry air will still be in place, but higher heights
coming in from the west will gradually raise temperatures throughout
next week. This set up will keep PoPs to a minimum and allow for
dry conditions to settle in through most of the period. However,
temperatures will start out way below-climo Monday and Tuesday
with a ~5+ degree bump up between Wednesday and Thursday as we
creep back to around normal by then. A warmer airmass is expected
to work back into the region by the latter half of next week.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Shower coverage and intensity will continue
to diminish from southwest to northeast through around 12Z. IFR to
low MVFR cigs will prevail during this time with IFR or lower fog
possible for mountain valleys. Drier air filtering into the region
should allow for rapid cig/vsby improvement around or just
after 12Z. Northerly winds will be gusty at times.

Outlook: Conditions will gradually improve during the day on Friday
with VFR expected through the weekend and into early next week.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High  84%     High  80%     Med   79%     High  83%
KGSP       Med   77%     Med   75%     High  80%     High 100%
KAVL       High  82%     Med   62%     Med   76%     High  85%
KHKY       Med   77%     High  81%     High  86%     High  99%
KGMU       High  84%     Med   65%     Med   76%     High 100%
KAND       Med   62%     Med   65%     Med   75%     High  95%

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...Flash Flood Watch through Friday morning for NCZ035>037-056-
     057-064-065-068>072-082-502-504-506>510.
SC...Flash Flood Watch through Friday morning for SCZ001>014-019.

&&

SYNOPSIS...SCW
NEAR TERM...65
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...65
Hazardous weather outlook, Sep 17, 1:17 PM EST, 2 hours 33 minutes before
Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
217 PM EDT Thu Sep 17 2020

NCZ035>037-056-057-064-065-068>072-082-502-504-506>510-SCZ001>014-
019-181830-
Alexander-Iredell-Davie-Catawba-Rowan-Transylvania-Henderson-
Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-
Greater Caldwell-Greater Burke-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-
217 PM EDT Thu Sep 17 2020

...FLASH FLOOD WATCH IN EFFECT THROUGH FRIDAY MORNING...

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

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flash Flood Watch.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flash Flood Watch.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062-063-501-503-
505-181830-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Madison-Yancey-
Mitchell-Swain-Haywood-Buncombe-Graham-Northern Jackson-Macon-
Southern Jackson-Caldwell Mountains-Burke Mountains-
McDowell Mountains-
217 PM EDT Thu Sep 17 2020

This Hazardous Weather Outlook is for northeast Georgia and western
North Carolina.

.DAY ONE...This afternoon and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

In the hours before

Local storm report, Sep 17, 10:09 AM EST, 5 hours 41 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1109 AM EDT THU SEP 17 2020

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

1030 AM     FLASH FLOOD      WALHALLA                34.78N 83.06W
09/17/2020                   OCONEE             SC   911 CALL CENTER

            911 CALL CENTER REPORTED TREES DOWN AND A ROAD CLOSURE
            DUE TO RISING WATER ON TULIP DR

&&
Local storm report, Sep 17, 10:15 AM EST, 5 hours 35 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1115 AM EDT THU SEP 17 2020

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

1030 AM     FLASH FLOOD      1 ESE SENECA            34.68N 82.94W
09/17/2020                   OCONEE             SC   911 CALL CENTER

            911 CALL CENTER REPORTED TREES DOWN AND A ROAD CLOSURE
            DUE TO RISING WATER ON S JONES ST

&&
Local storm report, Sep 17, 2:06 PM EST, 1 hour 44 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
306 PM EDT THU SEP 17 2020

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

0300 PM     NON-TSTM WND DMG 4 N PAW CREEK           35.34N 80.94W
09/17/2020                   MECKLENBURG        NC   SOCIAL MEDIA

            SOCIAL MEDIA REPORTED TREE DOWN CAUSING POWER LINES TO
            FALL ON FORESTWINDS LN

&&

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 flood. Local standard time, as filed.

Flood, Transylvania

When
September 17, 3:50 PM EST to September 18, 3:00 AM EST
Where
Transylvania County, 0.6 mi ENE of Calhoun to 0.37 mi ESE of Calhoun
Cause
Heavy Rain
Property damage
$500
Reported by
River/Stream Gage
Coordinates
35.253, -82.640

A stream gauge on the Little River exceeded its established flood stage after 2 to 3 inches of rain fell throughout the basin in about a 20-hour period. The main impact was to lowlands along the stream and to Cascade Lake Rd, which was covered by more than a foot of water in spots. Minor river flooding also developed on the French Broad at Blantyre during the evening of the 17th and continued for almost 48 hours.

What these are

Flood
Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in North Carolina in 2020Every state in 2020This day in weather historyWarnings in North Carolina, September 2020

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 922150.