Heavy rainfall has hit Southern California, prompting authorities to urge drivers not to travel and advising residents living in hillside and valley areas devastated by last year's wildfires to move to safer zones. Due to an atmospheric river, an atmospheric flow laden with massive amounts of water vapor evaporated from the Pacific Ocean and blown ashore, some areas saw rainfall rates of 2.54 cm or more per hour. According to the U.S. National Weather Service, the storm is expected to last through Christmas and into Friday, creating unsafe driving conditions during the typically busy holiday period. The weather service stated that the 'life-threatening' storm conditions are expected to persist over Southern California until Christmas. City of Los Angeles officials urged residents to comply with evacuation orders for about 130 homes deemed particularly at risk of mudslides and debris flows in areas destroyed by last year's wildfires, the Pacific Palisades area. The heavy downpours were accompanied by gale-force winds, weather experts said, which could cause trees to fall and power lines to be cut. Weather experts issued a rare tornado warning for a small part of eastern Los Angeles County due to thunderstorm activity over the Alhambra area.
