San Gabriel Mountains brace for strong thunderstorms, possible debris flow

SAN GABRIEL, Calif. - 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.

The NWS later reported that at 1:39 p.m. Sunday, Doppler radar was tracking "strong and nearly stationary thunderstorms over the San Gabriel mountains, extending from Acton to Falling Springs. ... Wind gusts up to 50 mph and half inch hail are expected, as well as frequent lightning, and heavy downpours capable of localized flash flooding."