California is being walloped by a powerful winter storm carrying thunderstorms, strong winds and heavy snow in the mountains. Millions of residents in Los Angeles County were facing a flash flood warning as rain pounded the region. Residents in some areas scarred by last year's devastating wildfires faced an evacuation warning. Meanwhile, state emergency officials are deploying rescue resources for flooding and debris flows. Forecasters expect extreme Sierra snow through late Wednesday. The storm comes amid a snow drought across much of the American West.
