Residents in burn scar areas should be ready to evacuate if needed. City and county agencies have readied streets for debris flow with K-rails and sandbags, as a storm moves in on Wednesday, Feb.

With heavy rain bringing the risk of dangerous debris flows, the Los Angeles Fire Department has announced evacuation warnings — and mandatory evacuation orders for some specific addresses — in areas recently burned by wildfires.

When hills are healthy, vegetation can anchor the soil in place. But when that is burned off, hillsides become vulnerable to erosion, and slopes can come crashing down.