Debris Flow in Montrose County, Colorado

Heavy rains resulted in erosion of the Highway 141 bridge at mile marker 85.6 over Mesa Creek, roughly 8 miles northwest of Uravan. CDOT closed Highway 141 in both directions on August 12 at 1010 MST, nearly 24 to 36 hours after the inciting debris flow and scouring due to the compromised bridge.

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.