At least some debris flow is ongoing in the Malibu area, with portions of the Pacific Coast Highway closed. The same storm system driving severe weather elsewhere in the country is fueling one of the most widespread and potent rounds of rain in Southern California since the historic January fires.

The storm, which forecasters said could produce tornadoes, is expected to strengthen Friday and move towards the central US.

A powerful storm dropping drenching rain on flood-prone Southern California is raising concern among forecasters that it could produce a dangerous, widespread outbreak of tornadoes, damaging winds and fires along with a blizzard as it crosses the entire United States in the coming days.