A powerful storm moved through the Los Angeles region Thursday, flooding streets, prompting evacuation warnings, and threatening mudslides in fire-ravaged areas. By Thursday evening, a debris flow had closed Mulholland Drive,

In the Los Angeles area, the burn scars that carry the highest risk are those from the Eaton and Palisades fires from January and the Bridge Fire from the fall.

Areas charred by last month's wildfires in Southern California now face a new threat from a powerful, but fast-moving Pacific storm. Here's what you need to know about this threat.