Flash Flood — Buncombe, North Carolina

2024-09-27 · near Shumon, Buncombe, North Carolina

Event narrative

Rainfall rates began to intensify as tropical rainbands near the center of Helene swept across the area during the morning hours after 10-17 inches of rain fell across much of the county, with amounts over 20 inches reported in the eastern part of the county. Devastating flash flooding developed along numerous streams, especially across the eastern half of the county. This included the French Broad River, which was already in moderate flood stage at Asheville, but began to rise rapidly during this time, culminating in historic and devastating flooding in the River Arts District, where numerous structures were inundated and damaged, and multiple structures were swept away. The Asheville gauge crested at just under 25 feet during early afternoon, exceeding the record stage by more than a foot, a record that had stood since the Great Flood of 1916. In addition, significant flooding was reported along the Ivy River in the Barnardsville community and vicinity, where multiple structures and numerous roads were inundated. The Broad River also saw significant flooding in the southeast part of the county, impacting several structures and multiple roads. Otherwise, numerous tributaries of these larger streams also overflowed their banks. More than 300 landslides were identified across Buncombe County, with some of those causing additional structural damage. Multiple fatalities were reported throughout the area, most due to drowning, but some due to landslide-related destruction. Damage to transportation infrastructure due to the combination of flooding and downed trees was widespread, with some communities inaccessible for days. Damage to the water infrastructure resulted in running water being unavailable in Asheville for days. Once the service was restored, boiling water advisories were in effect for almost two months.

Wider weather episode

Tropical Cyclone Helene began organizing over the western Caribbean on the 23rd and 24th of September before rapidly intensifying as it moved north through the eastern Gulf of Mexico on the 25th and 26th. A plume of moisture extending from the intensifying storm interacted with a slow-moving cold front to produce a band of widespread heavy rain showers and embedded scattered thunderstorms over the southern Appalachians and vicinity on the 25th and 26th, resulting in a predecessor heavy rainfall and flash flooding event over these areas. Helene made landfall in the Florida Big Bend and moved quickly N/NE through Georgia before turning toward the N/NW once the remnant center reached northeast Georgia. Tropical rainbands around the center of Helene swept over areas with already-saturated soils over the mountains and foothills during the early morning of the 27th, resulting in extreme rainfall and record, catastrophic flash flooding across multiple basins with headwaters near the Blue Ridge escarpment. Due to its quick movement, Helene was still a strong tropical storm when the wind field reached the western Carolinas and northeast Georgia. Frequent wind gusts of 55 to 70 mph, with occasional gusts of 80 mph...and likely as high as 100 mph across the higher elevations combined with saturated soils to produce widespread damage to trees and electrical infrastructure. Across the mountains, some east and southeast-facing slopes above 3000 feet saw canopy-loss of 80% or more. Hundreds of trees fell on houses, vehicles, and power lines throughout the area, resulting in several fatalities. Almost all customers in several counties lost power for at least a brief period. Most people were without power for at least a couple of days, while thousands were without power for a week or more.

View location on OpenStreetMap → (35.5400, -82.2300)

Source: NOAA Storm Events Database, event_id 1218194. Narrative written by the NWS forecast office that issued the report.