Driven by an atmospheric river known as "the Pineapple Express," which moves heavy moisture from the tropical climes of Hawaii to rain on the West Coast, the storm is expected to deliver months' worth of rain over the next few days. California Governor Gavin Newsom declared a state of emergency in several counties, including Los Angeles, to facilitate the rapid mobilization and allocation of resources if needed. "Life-threatening flash flooding continues over Southern California today and tomorrow; heavy mountain snow and high winds are also ongoing," the National Weather Service (NWS) said, adding that "lives and property are in great danger."

The first burst of heavy rain hit the region Tuesday night, leaving Los Angeles with fallen trees and some debris in the streets, as well as minor flooding that hampered traffic. The rainfall intensified early on Wednesday, leaving thousands of people in southern California without power due to downed lines caused by the fury of the Christmas storm. Late Wednesday the first storm moved out of the Los Angeles area, "but another storm is expected to move in later tonight into Christmas Day," weather officials warned.

Some communities already received 10 inches (25.4 centimeters) of rain in the first storm, forecasters said. Across the state, some 80,000 homes and businesses had no electricity heading into Christmas Eve, according to tracking site Poweroutage.us. Fire burn scars and the communities near them across the state are under special alert, including the coastal areas of Pacific Palisades and Malibu, as they are still recovering from the devastating wildfires in January. Due to fire damage, the terrain is susceptible to mudslides from heavy rain. While many were still hoping to drive to spend the holidays with family, transportation officials were busy announcing road and freeway closures due to flooding, fallen trees and mud flows across Southern California. (Bssnews)