Debris flows and flash floods strike California as atmospheric river sweeps through
An atmospheric river triggered multiple debris flows and flash floods across California after it brought heavy rains and mountain snow to much of the state on Thursday, February 13, 2025. Multiple flood alerts and evacuation warnings were issued, with the local authorities reporting widespread damage and multiple rescues.
A boulder that fell on the road due to the heavy rains in California on Thursday February 13, 2025. Image credit: LASDHQ
Millions of California residents were placed under flood alerts as an atmospheric river (AR) brought heavy rain and mountain snow through Thursday, February 13, triggering flash floods and debris flows that caused widespread damage across the region.
Flood warnings were issued for Los Angeles and flood advisories were in effect for areas around San Francisco as thunderstorms moved through, bringing winds of 97 km/h (60 mph) on Thursday evening, February 13.
The fast-moving cold front delivered 25 – 50 mm (1 – 2 inches) of rain across the flatter coastal and valley regions, while coastal slopes received 75 – 150 mm (3 – 6 inches). Interior areas recorded approximately 13 – 25 mm (0.5 – 1 inch) of rainfall.
The cold front generated heavy convective cells, producing rainfall rates of 25 – 32 mm (1 – 1.25 inches) per hour, which led to urban flooding and debris flows in burn scar areas. The snow and flooding also created hazardous travel conditions across the region
The front moved out of the region by late Thursday, prompting the authorities to lift up all warnings and alerts in the region.
Multiple mobile homes sustained damage in Ventura County, northwest of Los Angeles. The California Department of Transportation (CALTRANS) closed a section of the Pacific Coast Highway between Santa Monica and Malibu until further notice due to the significant risk of mudslides and debris flow.
The California Highway Patrol reported two interstate closures due to flooding. Southbound Interstate 680 to westbound Interstate 580 was shut down because of water covering the roadway.
A Los Angeles Fire Department vehicle was swept off the roadway and into the ocean by a debris flow along the Big Rock Road in Malibu at around 17:00 LT on Thursday. Additional water rescues were reported across Southern California, but no significant injuries were recorded.
Officials in Santa Barbara County issued an evacuation warning for areas in and near the Lake Fire burn scar ahead of the rain event, due to the potential for flash flooding, debris flows, and mudslides. Residents were advised to be prepared for immediate evacuation.
The Santa Cruz Sheriff’s Office ordered evacuations for some areas east of Watsonville, California, due to runoff threats shortly after 08:00 LT on Thursday. Several roads in the area were closed due to flooding.
Voluntary evacuation orders were issued for areas near burn scars in Orange County, while the San Bernardino Sheriff’s Office mandated evacuations for communities affected by the Line Fire.
Santa Barbara, Los Angeles, and Riverside remained under a Level 3 out of 4 flash flood risk through Friday, February 14.
A winter storm has been affecting higher elevations since Wednesday night. A winter storm warning remains in effect for the Sierra and White Mountains through Friday night.
Forecasts indicate snowfall of up to 2.1 m (7 feet) in the Sierra Nevada by the weekend.
Travel was expected to be extremely difficult on Thursday due to heavy snowfall and gusty winds reaching 97 km/h (60 mph). The most hazardous travel conditions were anticipated during the Thursday morning and evening commutes.
References:
1 Area Forecast Discussion – NWS– February 13, 2024
I am an Assistant Editor and Severe Weather & Science Journalist at The Watchers, specializing in real-time severe weather coverage, geophysical event reporting, and research-driven scientific analysis. You can reach me at rishav(at)watchers(.)news.
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