Nearly 170,000 people live in Altadena, Pasadena and Sierra Madre at the foot of the San Gabriel Mountains, and many are potentially in the path of debris flows. Heavy rainfall expected on Thursday and Friday has triggered warnings about fire-scarred hillsides unleashing torrents of mud, boulders and debris from the torched slopes. The National Weather Service issued a flash flood watch for late Thursday, with the greatest risks in areas burned by the Eaton, Palisades, Franklin, and Bridge fires. In Santa Barbara, people in the Lake Fire’s burn areas were told to prepare to evacuate as a storm approaches today.

Other debris flow and wildfire impact news:

• The Washington Post: Worst rains since L.A. fires will fuel landslide risk. What to know about the storm.
• The New York Times: Strong storm expected to soak Southern California, raising fears of mudslides
• Los Angeles Times: ‘High risk of flooding, debris flow’ on Thursday as powerful rainstorm hits Southern California
• California Governor’s Office of Emergency Services: News release: Be prepared for mudslides and debris flows in burn scar areas
• Office of Gov. Gavin Newsom: News release: With biggest winter storm of the season looming, California takes early, proactive steps to protect communities and harden burn scar areas
• CalMatters: More than 2 million Calif. acres face ‘high’ or ‘very high’ fire danger