SoCal Braces For Major Winter Storms
What happened
Southern California is preparing for a series of winter storms this week that are forecast to bring heavy rainfall. The system poses a significant hazard, especially in mountain regions, and will likely impact travel and daily routines across Los Angeles.
Why it matters
The incoming weather is fueled by an atmospheric river, a concentrated plume of moisture flowing from the tropics capable of carrying a volume of water vapor equivalent to the flow at the mouth of the Mississippi River. When these "rivers in the sky" make landfall and are forced upward by mountain ranges, they cool rapidly, releasing massive amounts of rain or snow. This torrent will test Los Angeles County's sprawling and aging flood control infrastructure, a network that includes 18 dams and 487 miles of flood-control channels. Engineers have expressed concern that infrastructure designed based on 20th-century weather patterns is being pushed to its limits by more frequent, extreme storms. A key risk for electrical systems comes from high winds associated with these storms, which frequently lead to widespread power outages. A major storm in February 2024, which set a daily rainfall record in Los Angeles, knocked out power for around 300,000 homes and businesses across the state. The region's topography and recent wildfire history create significant risks of mud and debris flows in burn scar areas. In response, state and local agencies often pre-deploy resources, including specialized personnel and concrete K-rails, to divert potential flows and protect vulnerable communities. The high concentration of impervious surfaces in Los Angeles—accounting for over 60% of its land cover—intensifies runoff and increases the burden on the storm drain system. This has led to initiatives to retrofit the urban landscape with more absorbent, "sponge city" infrastructure to capture and manage stormwater locally.
Key numbers
- This torrent will test Los Angeles County's sprawling and aging flood control infrastructure, a network that includes 18 dams and 487 miles of flood-control channels.
- Engineers have expressed concern that infrastructure designed based on 20th-century weather patterns is being pushed to its limits by more frequent, extreme storms.
- A major storm in February 2024, which set a daily rainfall record in Los Angeles, knocked out power for around 300,000 homes and businesses across the state.
- The high concentration of impervious surfaces in Los Angeles—accounting for over 60% of its land cover—intensifies runoff and increases the burden on the storm drain system.
What happens next
- This torrent will test Los Angeles County's sprawling and aging flood control infrastructure, a network that includes 18 dams and 487 miles of flood-control channels.
- The system poses a significant hazard, especially in mountain regions, and will likely impact travel and daily routines across Los Angeles.
Quick answers
What happened in SoCal Braces For Major Winter Storms?
Southern California is preparing for a series of winter storms this week that are forecast to bring heavy rainfall. The system poses a significant hazard, especially in mountain regions, and will likely impact travel and daily routines across Los Angeles.
Why does SoCal Braces For Major Winter Storms matter?
The incoming weather is fueled by an atmospheric river, a concentrated plume of moisture flowing from the tropics capable of carrying a volume of water vapor equivalent to the flow at the mouth of the Mississippi River. When these "rivers in the sky" make landfall and are forced upward by mountain ranges, they cool rapidly, releasing massive amounts of rain or snow. This torrent will test Los Angeles County's sprawling and aging flood control infrastructure, a network that includes 18 dams and 487 miles of flood-control channels. Engineers have expressed concern that infrastructure designed based on 20th-century weather patterns is being pushed to its limits by more frequent, extreme storms. A key risk for electrical systems comes from high winds associated with these storms, which frequently lead to widespread power outages. A major storm in February 2024, which set a daily rainfall record in Los Angeles, knocked out power for around 300,000 homes and businesses across the state. The region's topography and recent wildfire history create significant risks of mud and debris flows in burn scar areas. In response, state and local agencies often pre-deploy resources, including specialized personnel and concrete K-rails, to divert potential flows and protect vulnerable communities. The high concentration of impervious surfaces in Los Angeles—accounting for over 60% of its land cover—intensifies runoff and increases the burden on the storm drain system. This has led to initiatives to retrofit the urban landscape with more absorbent, "sponge city" infrastructure to capture and manage stormwater locally.
