For the second time this year, Southern Californians are evacuating their homes as heavy rain threatens new destruction in areas still recovering from last month’s devastating wildfires.

According to The Weather Channel, the storm raises major concerns for flash flooding and debris flows, especially in areas recently scorched by wildfires, including the Eaton and Palisades fire zones in Southern California.

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.