Debris Flow — Lewis, Idaho

2017-12-30 · near Kamiah, Lewis, Idaho

Event narrative

Heavy rain and snow melt saturated the ground and caused a Debris Flow near Kamiah. The mudslide cut and temporarily closed Idaho Highway 64 between Nez Perce and Kamiah.

Wider weather episode

A stationary front fed by a rich plume of Pacific moisture followed by the passage of a surface low pressure brought heavy snow to the mountains and valleys of north Idaho beginning on the 28th of December and continuing through the 30th. As the surface low pressure approached a tongue of warm air aloft produced freezing rain in addition to snow in the Coeur D'Alene area. The warm front never migrated any farther north and the mountains and valleys of the northern Idaho Panhandle received heavy snow until the storm ended. South of the warm front, over the Idaho Palouse region and the valleys of the central Panhandle heavy rain fell with St. Maries reporting 1.26 inches of rain, Potlatch receiving 2.21 inches and Lewiston 1.33 inches. This rainfall combined with melting low elevation snow triggered mudslides and debris flows as well as forcing Paradise Creek near Moscow briefly above Flood Stage.

View location on OpenStreetMap → (46.2500, -116.1000)

Source: NOAA Storm Events Database, event_id 725866. Narrative written by the NWS forecast office that issued the report.