Debris Flow in Lewis and Clark County, Montana

Debris Flow July 31, 2025 · Lewis and Clark County, Montana

$11K

Damage as recorded

Where the report was made, with tornadoes recorded within 15 miles over the years.

What the National Weather Service wrote

Jimtown Road and the Riverside Campground was closed due to debris flow from the burn scar flooding. Media also reported a 15 foot debris flow caused by the flooding washed away two trucks and a shed to the shores of Canyon Ferry Lake.

The wider storm

An upper-level shortwave combined with monsoon moisture brought a few severe thunderstorms and localized areas of heavy rainfall to North-Central MT. This resulted in isolated large hail, flooding, and a landspout. A stationary storm developed directly over the Great Falls urban area; this produced heavy rainfall and flash flooding in the city, with one gauge reporting 2.25 inches of rain in an hour. Another thunderstorm produced heavy rainfall over the Horse Gulch burn scar, which caused flash flooding downstream.

Began near Canyon Ferry (46.6033, -111.7392).

Source: NOAA Storm Events Database, event 1285061. Narratives are written by the National Weather Service forecast office that issued the report.

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