Debris Flow — Lassen, California

2025-07-30 · near Constantia, Lassen, California

Event narrative

Intense rainfall lead to mudslides and rockslides along US-395 north of Red Rock Rd. This caused both lanes of traffic to shutdown.

Wider weather episode

An upper level wave moving through N CA/NV provided plentiful forcing for storms to develop on July 30. In fact, showers lingered overnight the night before across portions of the Sierra and NE CA. These storms produced robust outflows with multiple areas of blowing dust and one true haboob/dust storm. We also had flooding that closed a roadway that afternoon/evening along US-395 near the Red Rock area.

View location on OpenStreetMap → (39.9336, -120.0029)

Source: NOAA Storm Events Database, event_id 1270616. Narrative written by the NWS forecast office that issued the report.