PLACERVILLE, Calif.—Crews were digging in and burning out fire lines amid another round of high winds that contributed to the fury to a Northern California wildfire. “We have a firefight ahead of us and the wind today is going to make it very challenging,” said Keith Wade, a spokesman with the California Department of Forestry and Fire Protection, or Cal Fire, on Saturday. The Caldor Fire in the northern Sierra Nevada already destroyed dozens of homes, and authorities on Friday closed down a 46-mile stretch of Interstate 50, the main route between the state capital of Sacramento and Lake Tahoe on the Nevada state line. The highway was closed after debris from the blaze fell onto the roadway and because of red flag warnings for 20- to 30-mph winds that by Saturday evening “combined with continued extremely dry fuels will result in critical fire weather conditions in the vicinity of …