An “atmospheric river” continued to batter parts of Northern California on Tuesday, causing widespread flooding. The heavy rains prompted the National Weather Service to warn of a dam failure outside Carson City, Nev., saying that it was “not a drill” and that residents should “move to higher ground now.” But less than 90 minutes after issuing the alert, the agency changed its report to say the retention basin in Dayton, Nev., had not failed. Instead, it was full and overflowing into drainage areas, the weather service said.