Debris Flow in Okanogan County, Washington

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.

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.