With thunderstorms emerging, a flash flood warning was issued Sunday night for areas burned by the Franklin fire and a portion of the Palisades fire, including Malibu and part of the Santa Monica Mountains.
At 8:15 p.m., flooding was reported along Pacific Coast Highway, the National Weather Service said.
The weather service issued the flash flood warning at 7:40 p.m. for the area. The warning is set to last through 11 p.m.
“While not immediately likely, a life-threatening debris flow will be possible,” the weather service said.
The warning was issued as radar and rain gauges indicated thunderstorms were “producing heavy rain across the warned area,” which includes Malibu; Malibu Creek State Park, which is near Calabasas; and Malibu Canyon and Las Virgenes roads through the Santa Monica Mountains.
It’s possible that mud, rock and debris flow could affect roads and homes in and below the burned area, the weather service said.
Rainfall rates of 0.39 of an inch per hour have been reported around Pepperdine University, the weather service said, but “higher rainfall rates are likely occurring.”
A rate of half an inch per hour or more is the point at which a debris flow could be triggered in burned areas, forecasters say.
A debris flow can happen when water rapidly flows downhill and, besides mud, picks up rocks, branches and sometimes boulders — something capable of damaging cars and homes. It can be life threatening.
“Severe debris flows are possible across roads. Roads and driveways may be washed away in places,” the weather service said.
A flash flood warning is the highest level of alert about possible floods.
The weather service has already issued a flood advisory for the burn areas around the Palisades, Franklin and Kenneth fire burn areas. A flood advisory means flooding could occur.
The weather service at 8:32 p.m. also issued a flood advisory across a large swath of L.A. County, including the Westside, the 405 Freeway through the Sepulveda Pass, the area around Los Angeles International Airport, and parts of the South Bay, San Fernando Valley and Hollywood Hills. There have been reports of minor road flooding in Venice and Santa Monica, the weather service said.
The Franklin fire burned through the Malibu area, and the Kenneth fire was ignited on the western edge of Woodland Hills and burned to the southwest.
A flood watch, the lowest level of a flood alert, means flooding is possible.
A flood watch took effect at 10 a.m. Sunday and was set to continue through 4 p.m. Monday for the burned areas of the Eaton fire in the Altadena and Pasadena areas; the Palisades and Franklin fires in the Pacific Palisades and Malibu areas; the Hughes fire around Lake Castaic; and the Bridge fire in the San Gabriel Mountains west and southwest of Wrightwood.
