Debris Flow — Okanogan, Washington

2021-08-20 · near Ruby, Okanogan, Washington

Event narrative

Heavy rainfall, with reports of 0.40 - 0.50 in one hour, occurred in the early evening hours of August 20th outside the town of Conconully. The brief heavy rainfall lead to 4 to 6 inches of debris flow on the roadway. Some local observation sites reported a total 0.75 - 1.25 of rainfall after a long, evening of showers. Additionally due to the heavy rain, a roadway in Twisp was covered in mud and gravel. There were CoCoRaHS and spotter reports of over 2.0 of rain in Twisp that evening.

Wider weather episode

Showers and thunderstorms developed across the Inland Northwest in the afternoon and evening of August 20th. The northern counties received the greatest rainfall totals where stationary thunderstorms brought heavy downpours to the area that evening. There were numerous 12 hour observations of 1 to 2 rain reported across Okanogan, Ferry, and Stevens Counties.

View location on OpenStreetMap → (48.5264, -119.6818)

Source: NOAA Storm Events Database, event_id 978298. Narrative written by the NWS forecast office that issued the report.