Debris Flow — Swain, North Carolina

2013-01-16 · near Smokemont, Swain, North Carolina

Event narrative

A large landslide destroyed a 200 foot section of highway 441 in the Great Smoky Mountains National Park. It was estimated the road would take months to repair, thus indefinitely shutting down the Park's only paved throroughfare. Seven to 10 inches of rain fell across the North Carolina section of the park from the 14th through the 17th.

Wider weather episode

A deep long wave trough developed over the western states around January 10th. The trough gradually moved east over a period of several days. As it approached the eastern states, it took on a positive tilt, with the surface cold front stalling across the south Appalachians for several days. Heavy rain periodically fell from late on the 13th through the evening hours of the 17th. The trough eventually filled, but not before a trailing southern stream upper low brought a last shot of heavy rain to the region during the overnight hours over the 17th. The rain changed to snow in some areas before ending. Perceptible water (PW) amounts were upwards of 300 percent of normal. In fact, PW readings at Atlanta and Greensboro were among the highest on record for January. Over a four day period, rainfall amounts ranged from 4 to 10 inches across the southern Appalachians. The heaviest totals were recorded across the southwest mountains, including the Smokies, Snowbird and Nantahala Mountains. Several automated rain gauges recorded 8 to 10 inches of rain in the headwaters of the Nantahala and Oconaluftee Rivers. The prolonged heavy rain resulted is several landslides across the North Carolina mountains. Roads and homes were damaged by these debris flows. While several instances of stream and main-stem river flooding were reported, the prolonged nature of the rainfall kept the flooding from becoming more extensive or damaging than it otherwise would have been.

View location on OpenStreetMap → (35.5940, -83.3600)

Source: NOAA Storm Events Database, event_id 431945. Narrative written by the NWS forecast office that issued the report.