Debris Flow in Ouray County, Colorado

Heavy rain from thunderstorms in Ouray caused town flooding as well as the flooding of several creeks including Oak, Cascade and Skyrocket Creek. These creeks filled with debris, rock and silt, resulting in trail closures and large boulders/rock slides and mudslides on Highway 550 at mile marker 94, 94.5 and 94.6 specifically but generally between mile markers 94 and 95 approximately 2 miles north-northwest of Ouray. Storm total rainfall ranged from 1.5 to 1.7 inches in Ouray. Daily spot forecasts were requested by emergency management for both Ridgway and Ouray for extensive cleanup efforts for several days following the debris flows.

Deep monsoonal moisture remained in place with convection ongoing during the morning hours. This led to a later start to convection on the afternoon of August 11th but precipitable water values climbed to over an inch as deep monsoonal moisture continued to increase from the south, combined with a shortwave trough and sufficient lift from an upper level jet helped provide support for stronger storms towards the late afternoon and evening that led to 1 to 2 inch per hour rainfall rates on top of already saturated soils leading to significant debris flows and flash flooding, especially across southwest Colorado.