Fire crews in Washington state working tirelessly to contain destructive blazes in the Spokane area are preparing for a new bout of flame-fueling winds and intense heat that will arrive on Friday and continue through the weekend.

Why Spokane's wildfires spread so fast, what caused them and why Washington is facing a major fire crisis.

The cluster of three blazes ranked as the top firefighting priority in the U.S. as a whole, including the drought-parched Pacific Northwest, where dozens of major wildfires have…