Debris Flow — Garfield, Colorado

2021-07-31 · near Shoshone, Garfield, Colorado

Event narrative

Multiple debris flows occurred along Interstate 70 within the Grizzly Creek Fire burn scar between mile marker 123 and Hanging Lake Tunnel. Colorado Department of Transportation (CDOT) described the damage from the new flows as extreme. The new debris piles were around 17 feet tall over the roadway and house-sized boulders fell as well. Hanging Lake trail received considerable damage. At least seven bridges were either destroyed, washed downstream or otherwise severely damaged. National Forest officials say it will be at least late-season 2022 before the trail can be reopened.

Wider weather episode

High pressure retrograted in response to a deepening mid-level trough over the center of the nation and parked over western Colorado. Even so, subtropical moisture remained entrenched over the area with precipitable water values exceeding an inch and trending over 150% of the climatological norm. As a result, widespread showers and thunderstorms erupted over western Colorado. Additionally, convergence along the Continental Divide enhanced storm coverage. Heavy rain and training was common with storms which led to numerous reports of flash flooding and debris flows, including over the Pine Gulch and Grizzly Creek Fire burn scars.

View location on OpenStreetMap → (39.5757, -107.2311)

Source: NOAA Storm Events Database, event_id 965545. Narrative written by the NWS forecast office that issued the report.