Flash Flooding and Flood in North Carolina, September 30, 2018

Name: Flash Flooding and Flood in North Carolina, September 30, 2018
Start: 2018-09-30T01:20
End: 2018-09-30T11:30
Location: North Carolina

September 30, 2018 · NWS GSP · 5 events in 4 counties and zones

Heavy rain showers and isolated thunderstorms developed near the Blue Ridge escarpment within a moist southeast upslope flow throughout the 29th. Localized heavy rainfall developed during the evening and into the early morning hours of the 30th, culminating in localized flash flooding across the mountains during the early morning hours.

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

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $20,000
Crop damage: None recorded
Events: 5

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.

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 30, 12:29 AM EST, 51 minutes earlier.

Area forecast discussion, Sep 30, 12:29 AM EST, 51 minutes before

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
129 AM EDT Sun Sep 30 2018

.SYNOPSIS...
Forecast will be dominated by high pressure with some chance for
isolated showers at times over the mountains.  Winds will be light,
and temperatures will remain above normal and humidity will remain
unseasonably high.
.

&&

.NEAR TERM /THROUGH TODAY/...
As of 120 AM EDT Sunday...Convection continues to train along the
escarpment in Buncombe/Rutherford/McDowell counties, and rain totals
continue to add up. Hopefully, rain rates will decrease and this
activity will rain itself out. However, the latest HRRR shows
showers in these areas thru daybreak. Will need to be monitored for
Flash Flood Warning thru the overnight. The other concern is dense
fog developing across the southern Upstate. May need a Dense Fog
Advisory or at least an SPS shortly, if it looks to persist/expand
in area.

Otherwise, lower clouds should be able to fill in and become
widespread again with areas of fog as well.  Sunday morning minimum
temperatures will be warm for late September, on the order of 10 deg
F above normal.

Morning clouds will give way to mixed sun and developing shallow
convective clouds as Sunday wears on. The llvl flow will remain weak
from the east to southeast as ridging aloft builds atop the SE CONUS.
At this point, there remains the possibility of isolated diurnally
fired tstms limited to mainly within the axis of high bl dwpts
acrs the sw cwfa and into the mtns.  Maximum temperatures should be
similar to yesterday, slightly above normal.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
As of 2pm EDT Saturday:  Short term forecast is dominated by a flat
ridge over the South that changes little Monday and Tuesday.  This
will lead to continued above normal temperatures and low chances for
precipitation.  Surface ridge is also fairly stable through Monday
and Tuesday, running northeast to southwest well east of the
Appalachians.  Surface ridge is far enough eastward to limit cold-
air-damming effects, but easterly surface flow is expected Sunday
evening, becoming more southeasterly Monday night as ridge moves a
little farther eastward.  Winds should be fairly light in any case,
at 5 to 10 kts.  Easterly to southeasterly flow will keep some
Atlantic moisture in the area, supporting dewpoints, and giving low
temperatures 10 degrees above normal. Highs will run 5 to 10 above
normal.

Forecast soundings show that, despite decent boundary layer
moisture, mid to upper levels are warm, and the atmosphere is well-
capped, leading to practically no chance of convective activity.
Only chances for significant precipitation Monday and Tuesday are
isolated showers in the mountains, where upslope low-level flow may
be sufficient for some isolate, though weak, showers.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 2pm EDT Saturday:  Upper ridge over the South remains the
dominant feature Wednesday through Friday. A weak disturbance that
crosses the top of the ridge (and has the strongest dynamics well
north of the area) may enhance changes for precipitation over the
mountains Wednesday evening, but soundings are otherwise forecast to
remain capped and convectively stable. Once this disturbance passes,
the ridge recovers on Thursday what little strength it lost, and
even strengthens late in the week.  Surface ridge will remain well
east of the mountains, giving continued fairly light winds, and
continued southerly to southeasterly flow that will keep dewpoints
elevated.  The result will be continued low chances for
precipitation with unseasonably humid and warm conditions, with
highs 10 degrees above normal and lows 15 degrees above normal.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: A moist easterly flow will continue
thru the overnight and the morning hours today, resulting in another
round of MVFR to IFR cigs developing in the next few hours. Dense
fog is developing in the southern Upstate, but not expected to
impact the TAF sites, since they didn't see any rain today. Slow
improvement after daybreak today, and though isolated convection is
possible again this afternoon, not enough to include in any TAFs at
this point.

Outlook: Drier conditions are expected from Monday thru at least
midweek, as high pressure dominates over the Southeast.

Confidence Table...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       High 100%     High  87%     High 100%     High 100%
KGSP       High 100%     Low   50%     Med   75%     High 100%
KAVL       High  91%     Low   56%     Med   75%     High 100%
KHKY       High 100%     High  87%     High  81%     High 100%
KGMU       High 100%     Med   75%     Med   75%     High 100%
KAND       High 100%     High  81%     High  81%     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 and ensemble forecasts
are available at the following link:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

SYNOPSIS...TS
NEAR TERM...ARK/CSH/TDP
SHORT TERM...WJM
LONG TERM...WJM
AVIATION...ARK

Hazardous weather outlook, Sep 29, 4:18 AM EST, 21 hours 2 minutes before

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
518 AM EDT Sat Sep 29 2018

NCZ033-035>037-048>053-056>059-501>506-300930-
Avery-Alexander-Iredell-Davie-Madison-Yancey-Mitchell-Swain-Haywood-
Buncombe-Catawba-Rowan-Graham-Northern Jackson-Caldwell Mountains-
Greater Caldwell-Burke Mountains-Greater Burke-McDowell Mountains-
Eastern McDowell-
518 AM EDT Sat Sep 29 2018

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

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ010-017-018-026-028-029-NCZ062>065-068>072-082-507>510-SCZ001>014-
019-300930-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Macon-Southern Jackson-
Transylvania-Henderson-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-
Union-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-Chester-Greenwood-
518 AM EDT Sat Sep 29 2018

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

.DAY ONE...Today and tonight.

Isolated to scattered thunderstorms are expected to develop today,
before diminishing in the evening. Coverage may be greatest south
of Interstate 85. The primary threat with the thunderstorms will be
cloud-to-ground lightning, gusty winds and locally heavy rainfall.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

In the hours before

Special weather statement, Sep 29, 8:58 PM EST, 4 hours 22 minutes before

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
958 PM EDT SAT SEP 29 2018

NCZ503>506-300245-
McDowell Mountains NC-Burke Mountains NC-Greater Burke NC-
Eastern McDowell NC-
958 PM EDT SAT SEP 29 2018

...A HEAVY RAIN SHOWER WILL IMPACT NORTHEASTERN MCDOWELL AND WEST
CENTRAL BURKE COUNTIES UNTIL 1045 PM EDT...

At 957 PM EDT, Doppler radar was tracking a heavy rain shower 6 miles
northeast of Marion, or near Lake James. This shower was nearly
stationary.

Locations to be impacted include...
Marion, Lake James State Park, Lake James, Nebo, North Cove, Ashford,
Woodlawn and Little Switzerland.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio and tv
stations, as well as local cable tv outlets for additional
information and possible warnings from the National Weather Service.

&&

LAT...LON 3574 8179 3564 8199 3578 8208 3580 8209
      3581 8210 3584 8209 3590 8192
TIME...MOT...LOC 0157Z 059DEG 1KT 3577 8195

TDP

The radar

The Greer radar (KGSP), 63 km away, was scanning. The volume nearest the first event began at 06:20 UTC.

Open the radar archive at this moment

Event by event

4 flash flood, 1 flood. Local standard time, as filed.

Flash Flood, Rutherford

When: September 30, 1:20 AM EST to 3:30 AM EST
Where: Rutherford County, 1.88 mi NW of Chimney Rock to 0.6 mi NW of Chimney Rock
Cause: Heavy Rain
Property damage: $2,000
Reported by: River/Stream Gage
Coordinates: 35.446, -82.277

A stream gauge on the Rocky Broad River at Bat Cave exceeded its established flood stage after 4 to 8 inches of rain fell on the 29th into the early part of the 30th, with the bulk of that falling in just a few hours late on the 29th. Pedestrian bridges and side roads were flooded along the river from the Henderson County line to Chimney Rock Village. Also, public reported a bridge washed out over Buffalo Creek near where it flows into Lake Lure.

Flash Flood, Henderson

When: September 30, 1:20 AM EST to 3:30 AM EST
Where: Henderson County, 0.68 mi WNW of Bat Cave to 0.69 mi E of Bat Cave
Cause: Heavy Rain
Property damage: $500
Reported by: River/Stream Gage
Coordinates: 35.454, -82.291

A stream gauge on the Rocky Broad River at Bat Cave exceeded its established flood stage after 4 to 8 inches of rain fell during the 29th and early part of the 30th, with the bulk of that falling during the evening. A few roads were flooded along the river in the Bat Cave community.

Flash Flood, Buncombe

When: September 30, 2:00 AM EST to 3:30 AM EST
Where: Buncombe County, 4.02 mi ESE of Blue Ridge to 4.35 mi ESE of Blue Ridge
Cause: Heavy Rain
Property damage: $2,000
Reported by: CoCoRaHS
Coordinates: 35.562, -82.262

Cocorahs observer reported flash flooding developed along tributaries of the rocky Broad River in buncombe county after 4 to 8 inches fell in the basin throughout the 29th and the early part of the 30th, with the bulk of that falling during the evening. Affected Streams included grice branch and duck branch, which was responsible for a washed out bridge.

Flash Flood, McDowell

When: September 30, 2:00 AM EST to 3:45 AM EST
Where: McDowell County, 3.04 mi WSW of Old Ft to 3.18 mi SW of Old Ft
Cause: Heavy Rain
Property damage: $5,000
Reported by: Emergency Manager
Coordinates: 35.618, -82.232

EM reported flash flooding along developed along the headwaters of the Catawba River and some of its tributaries after 4 to 8 inches of rain fell on the basin during the 29th and early on the 30th, with the bulk of that falling during the evening. A mobile home was damaged by flood water from a tributary on Catawba River Rd. A private bridge over the Catawba on Denny Bean Rd was also damaged.

Flood, McDowell

When: September 30, 3:45 AM EST to 11:30 AM EST
Where: McDowell County, 3.04 mi WSW of Old Ft to 0.62 mi W of Davistown
Cause: Heavy Rain
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 35.618, -82.232

Although heavy rain ended across the area during the early morning hours, EM reported flooding continued along the upper Catawba and Crooked Creek basins into late morning and early afternoon. Several roads reportedly remained flooded along the Catawba in the Old Fort area, while a culvert was washed out and several private bridges washed out along Crooked Creek.

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
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

Every storm in North Carolina in 2018 Every state in 2018 This day in weather history Warnings in North Carolina, September 2018

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: 787160, 787162, 787165, 787796, 787798.