A flood advisory was issued Sunday afternoon for the San Gabriel Mountains, where urban and small stream flooding caused by excessive rainfall was expected.
The advisory was in effect until 4:30 p.m. Sunday.
“Strong thunderstorms are developing, producing hourly rain rates of 1 inch. These rates will generate flooding of mountain roadways and low-lying areas,” the National Weather Service’s Los Angeles office tweeted.
Residents in the area were advised to move away from recently burned areas.
“The rain will likely trigger shallow mud and debris flows, minor rock falls, and flooding capable of localized damage, especially in steep terrain in and near burn scars,” forecasters warned.
At 1 p.m., the NWS also reported nearly stationary thunderstorms southeast of Acton in Los Angeles County and over Lockwood Valley in Ventura County. The NWS said storms would likely contain heavy downpours with localized flash flooding, strong wind gusts, small hail and dangerous lightning that could trigger grass fires.