Another powerful storm system that could cause more flooding and mudslides is rolling across Southern California. Forecasters say the region could experience its wettest Christmas in years, increasing the risk of debris flows in areas scorched by wildfires in January. Heavy rain and gusty winds were blamed for at least two deaths on Christmas Eve. On Wednesday, a falling tree killed a San Diego man. Farther north, a Sacramento sheriff’s deputy died in what appeared to be a weather-related crash. Residents around burn scar zones from the Airport Fire in Orange County are under evacuation orders.