Flash Flood in Caldwell County, North Carolina

Stream gauges indicated flash flooding developed across western Caldwell County, particularly Johns River, Yadkin River and their tributaries after 7-12 inches fell across the western half of the county over three days. Flash flooding first developed along Wilson Creek, followed by flooding developing downstream along Johns River. After briefly subsiding during the evening, flash flooding rapidly redeveloped and became catastrophic as tropical rainbands around the remnant center of Helene swept across the area around sunrise. In addition to Wilson Creek and Johns River, major flash flooding also developed along the Yadkin River during this time. Hundreds of structures and roads were inundated and damaged or destroyed throughout the area. Several landslides were also discovered, primarily near the Avery and Watuaga County lines.

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.