Northern California is bracing for renewed and expanding flood threats following deadly inundation over the weekend. Officials have issued flood watches across much of the state through Christmas week as a powerful atmospheric river continues to steer moisture ashore. The Bay Area, Sacramento Valley, and Sierra foothills may experience several more inches of rain, which could strain already saturated soils and waterways, leading to urban flooding, debris flows, and mudslides. Southern California has been upgraded to a rare high risk of flash flooding around Christmas Eve, particularly near wildfire burn scar areas where evacuation warnings are in effect.