Torrential rains unleashed flash floods and warnings of debris flow across southern California’s fire-scarred areas, as a series of Christmas storms pummeled the state, with downpours and high winds forecast through Friday.Driven by an atmospheric river known as “the Pineapple Express,” which moves heavy moisture from Hawaii to the US West Coast, storms were expected to dump months’ worth of rain in California over a few days.Early Thursday, the National Weather Service (NWS) forecast that southern California, including Los Angeles, the second-most populous US city, was at risk of excessive rainfall.For all the latest headlines follow our Google News channel online or via the app.It warned of a “broad plume of moisture” producing heavy rain in California on Thursday.“Numerous flash flooding events are possible. In addition, many streams may flood, potentially affecting larger rivers. The flooding may include debris flows in or near recently burned areas,” the service said, referring to