A powerful storm is bearing down on California as an atmospheric river drops through the state. While the fast-moving system will affect nearly the entire state on Thursday, of high concern is Southern California as intense rains fall on the heels of devastating wildfires — downpours that could trigger damaging floods and debris flows.

As heavy rain from a large storm subsided, officials in Southern California said rock and mudslides remain a threat.

Another storm will impact Northern California starting Thursday morning. That event is forecast to be somewhat less impactful than the high winds and mudslides on Tuesday that caused a home to collapse in Sonoma County,