Debris Flow in Montezuma County, Colorado

Heavy rainfall to the northeast of Mesa Verde National Park fell on the afternoon of August 25th, with estimated rainfall rates in excess of 2 inches per hour for around 10 minutes. That puts the rainfall total along County Road 41, in this area, at 0.25-0.35 inches. The debris flow resulted in the closure of the road and damage to the road in at least 2 locations.

A strong southwesterly jet aloft was in place of eastern Utah and western Colorado, not only advecting rich monsoonal moisture into the area, but also providing enhanced lift a some decent wind shear. All this to say the environment was perfect for stronger, and more organized convection to form during the afternoon hours of August 25th. With the above normal moisture and indications of potential training thunderstorms, as well as the fact of the unusually supportive environment itself, the local Grand Junction office issued a Flash Flood Watch for portions of the area, in addition to a moderate risk of excessive rainfall from the Weather Prediction Center and a slight risk of severe weather from the Storm Prediction Center, prompting a Severe Thunderstorm Watch.