Debris Flow — Ada, Idaho

2025-08-26 · near Barber, Ada, Idaho

Event narrative

On the east side of the Valley Fire burn scar, heavy rainfall with a peak rain rate of 7 inches per hour caused a slurry of mud, ash, and debris to flow down eastern Highland Valley Rd, depositing nearly a foot of debris on the road with running water estimated at 12 inches high. The road would have been impassable while water was running, and the debris flow ran down the length of the valley. No impacts along Hwy 21.

Wider weather episode

Monsoonal moisture surged into the region over a three day period, the most intense of which was the 26th. High atmospheric moisture content combined with weak flow in a monsoonal pattern to produce very moist storms moving very slowly. Additionally, as terrain served as the main trigger for convection, storms would train over the same spots for much longer than normal. Precipitable water was at near record levels around 1.2 inches.

View location on OpenStreetMap → (43.5537, -116.0455)

Source: NOAA Storm Events Database, event_id 1295132. Narrative written by the NWS forecast office that issued the report.