California ? Fast-moving thunderstorms brought new waves of rain on Sunday to Southern California, following days of drenching weather and heavy mountain snowfall and raising fears of mudslides and flooding.

Officials said the rain brought a threat of serious slides on hillsides stripped of vegetation by last year’s wildfires. Mud and rock slides prompted authorities to shut a highway through a burned area near San Diego.

The storm system also soaked parts of Northern California and snow forced the closure of the main artery between Sacramento and Reno, Nev., CalTrans officials said. Eastbound Interstate 80 was closed Sunday night, about 50 miles northeast of Sacramento. Westbound traffic was being held at the Nevada state line.