Powerful storm moves into Southern California after record rainfall to the north

Southern California is expected to get hammered by a new storm Monday as record rainfall hit Northern California over the weekend, causing debris flows and flooding.

The atmospheric river event will probably peak in Los Angeles around midday Monday and could dump half an inch to an inch of rain on downtown L.A.

The atmospheric river, a concentrated stream of water vapor circulating in the middle and lower levels of the atmosphere, could result in localized flooding, and roads may become slippery because of oil residue runoff.

L.A. County mountains could get up to 1½ inches of rain and probably will see gusty conditions, with wind advisories possible.

California

Heavy rain unleashes mud, debris flows in Northern California areas burned by wildfire

Heavy rain in Northern California unleashed mud and debris flows and shut down at least one critical highway by Sunday morning.

The fall rains come as welcome relief after California reported its hottest summer on record and its driest water year in nearly a century, conditions that helped stoke a long and active wildfire season.

Rain was already falling on San Luis Obispo County early Monday. Evacuations were ordered near the Alisal fire zone.

Northern California saw record rains on Sunday. Downtown Sacramento hit an all-time record with 5.44 inches.

The torrential rainfall shut down at least one crucial highway as mud, rocks and unshackled debris flushed down denuded hillsides. Flash flood and excessive rain warnings blared across road signs and phone screens, with some officials declaring that for those in the Dixie fire burn area who had not yet evacuated, it could be too late.

“If you are near a burn scar, it may be too late to evacuate,” officials at the National Weather Service in Sacramento said on Twitter. “Do not attempt to cross a debris flow. Take shelter in the highest floor of your home.”

Multiple debris flows shut down Highway 70 between Jarbo Gap and Greenville, a historic mountainside community in Plumas County that had already lost so much to the Dixie fire. A photo circulating on social media showed a dramatic slide near the community of Tobin, where a huge pile of rock, trees and debris collapsed onto both lanes of the highway.