This story originally published Nov. 14 has been updated after Governor Gavin Newsom announced the state would mobilize resources in advance of winter storms.
A dangerous atmospheric river is poised to deliver “excessive rainfall” across Southern California, raising fears that the rain could unleash a threat that has been lingering in the burn scars of wildfires that ravaged Los Angeles communities in recent years.
Called debris flows, these fast-moving slurries of floodwater and sediment can hurtle down slopes carrying cars, trees and even boulders with them…