Debris Flow in San Miguel County, Colorado

Early in the afternoon of August 18th, Law Enforcement reported a mudslide on Colorado State Highway 145 at mile marker 83, or about 3 miles north of the town of Sawpit or 1.5 miles south of the town of Placerville. This is an area well known for mudslides and debris flows with heavy rainfall thanks to very steep terrain. Time of incident was based on radar data, as Law Enforcement report came in after the fact. Road was closed for a short while to facilitate cleanup.

With above normal moisture in place across eastern Utah and western Colorado, and passing shortwaves adding some extra lift and instability, round after round of daily showers and thunderstorms had already been ongoing for 2-3 days prior to August 18th. This meant that, by the afternoon of the 18th, the atmospheric profile was fully saturated, meaning any stronger shower or storm could produce heavy rainfall and high rainfall rates. In addition, there was some indication that training of storms would be possible during the afternoon hours, heightening the risk for heavy rain, flash flooding, and debris flows.