Debris Flow — Alpine, California

2025-08-26 · near Markleeville, Alpine, California

Event narrative

CalTrans and the California Highway Patrol reports 2 large rocks on the northbound lane of Highway 89 near Markleeville. Also, CHP reported mud, dirt, and rocks at the SR-4 and SR-89 junction south of Markleeville.

Wider weather episode

A high amount of atmospheric moisture in the region interacted with a short-wave trough, allowing for widespread heavy precipitation. This was day four of an extended push of monsoon moisture that produced heavy rain, localized flooding, strong outflow winds.

View location on OpenStreetMap → (38.6900, -119.7800)

Source: NOAA Storm Events Database, event_id 1280328. Narrative written by the NWS forecast office that issued the report.