Topline
Los Angeles is forecast to receive desperately needed rain this weekend, providing relief to first responders battling four active fires in the region while also creating the risk of new hazards including mudslides, toxic runoff and flash flooding in and near scorched areas.
There are four active fires in Los Angeles as of Friday, all of which are at least 56% contained. ... [+]
Key Facts
The National Weather Service issued a flood watch effective from 4 p.m. Sunday to 4 p.m. Monday for areas in or near burn scars created by the Palisades Fire, Eaton Fire, Hughes Fire and Bridge Fire, the latter blaze of which burned 56,000 acres last fall.
The flood watch warned of a 10% to 20% chance of “significant flash flooding and debris flows” in the impacted areas.
The NWS forecasts light to moderate rain in Los Angeles beginning Friday night and expects the region to receive a half inch to an inch and a half of rain during the weekend, noting the low pressure system bringing rain may produce “elevated winds” across Southern California.
Firefighters attempting to increase containment on the Los Angeles areas scorched by a wave of fires will likely benefit from the rain, but the NWS added the areas will need to be monitored for burn scar flash flooding and debris flows as showers materialize.
California Gov. Gavin Newsom has deployed hundreds of debris flow specialists to Southern California ahead of the rain, with personnel prepositioning flood resources to protect communities and natural resources.
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What Communities Are At Risk Of Flooding And Mudslides?
Communities located in or near the flood watch areas include Malibu, the Pacific Palisades, Castaic, Altadena, Kinneloa Mesa, Sierra Madre and Glendora.
What Is A Burn Scar And Why Are They Dangerous In Rainy Conditions?
A burn scar is an area of land scorched by fires. Burn scars lack the vegetation needed to anchor soil into the ground and “can be as water-repellant as pavement,” according to the NWS, potentially creating debris flows containing rocks, mud, boulders, trees and even homes and vehicles depending on the path of the flow. The combination of rain and burn scars can also create toxic runoff that enters the ocean or waterways.
How To Tell If You Are At Risk For Flash Flooding And Mudslides
The NWS says a good rule of thumb to determine risk is to look uphill. If you see a burnt-out area, you are at risk. Residents in areas of risk are encouraged to have evacuation plans in place, learn alternate routes if nearby roads are blocked by mud or water and clear debris from drains and gutters near their homes.
How Is California Preparing For Potential Flooding And Mudslides?
The Department of Water Resources has created debris dams and pre-deployed over 250,000 sandbags, 777 plastic sheeting rolls and 5,650 super sacks (extremely heavy, industrial-sized bags), according to Newsom and the department. Over 400 California Conservation Corps members will be working on watershed protection near burn scar areas, placing silt fencing, straw wattles and compost socks to filter contaminants within rainwater runoff.
Surprising Fact
The last time Los Angeles received more than a tenth of an inch of rain was last May, when Downtown Los Angeles received 0.13 inches, according to the Los Angeles Times.
Key Background
Burn scars and flooding have impacted Southern California in years past. In 2018, 23 people in the city of Montecito, located just east of Santa Barbara, died as a result of mudslides that were up to 15 feet deep and contained house-sized boulders. The fires in Los Angeles this month that have created flooding risks began on Jan. 7 with the Palisades Fire, which has burned more than 23,000 acres. Four active fires remain in Los Angeles including the 14,000-acre Eaton Fire, the 10,400-acre Hughes Fire and the 45-acre Sepulveda Fire. First responders have gained significant containment on all the fires and will benefit from the rain this weekend, marking Los Angeles’ first significant rainfall in months as the region has remained largely dry since last May.
Further Reading
California Wildfire Updates: Rain Expected This Weekend As Hughes Fire Reaches 56% Containment (Forbes)
