Flash Flood — Transylvania, North Carolina

2021-08-16 · near Powelltown, Transylvania, North Carolina

Event narrative

Stream gauges indicated and an NWS flood survey confirmed significant flash flooding developed near the upper reaches of the French Broad River after as much as a foot of rain fell in the headwaters in less than six hours. Multiple structures along the river were inundated in the town of Rosman, including on Depot St, Highway 178, Main St, and Chestnut St. This was the worst flooding along this portion of the French Broad in almost 30 years, while the stream gauge at Rosman registered its 4th-highest level on record. (Continuous observations at that site date back to 1935). Newspaper reported significant flash flooding also occurred upstream of Rosman along the North Fork of the French Broad in the Balsam Grove community, where vehicles were swept downstream and multiple structures were damaged or destroyed. In addition, flash flooding developed along the Davidson River in Pisgah Forest, briefly inundating portions of Davidson River Rd and Deavor Rd.

Wider weather episode

Increasing moisture and southeast upslope flow well in advance of landfalling Tropical Cyclone Fred resulted in development of numerous showers across the high elevations of the Balsams and surrounding hours during the overnight and early morning hours. Heavy rain showers moving repeatedly over the same locations resulted in locally very high rainfall amounts of as much as 12 inches in just a few hours. This resulted in the most significant flash flooding along the upper French Broad River in almost 20 years. Additional flash flooding developed in Lincoln County later in the day after a small area of excessive rainfall developed over the Piedmont.

View location on OpenStreetMap → (35.1320, -82.8170)

Source: NOAA Storm Events Database, event_id 982259. Narrative written by the NWS forecast office that issued the report.