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bag out of his line pack.
    â€œProbably the worst thing that’s happening now is what’s called urban interface—that is, houses in the forest,” he said. “When it’s a question of saving structures rather than just trees, we’re more likely to take risks. Basically, if you’re protecting a structure and the fire’s coming at you, you don’t retreat. You stay put and try to work the fire around either side.”
    Root ate methodically, clearly in no hurry to resume cold-trailing. His bag lunch, delivered by helicopter, seemed geared toward the taste of grade school boys: bologna sandwiches, candy, cookies, more candy, and a couple of apples. As we talked, one of the Cromans came in low over us and started to ease itself down over the helispot. Dangling below it was a car-size bladder bag of water called a blivet. The pilot, looking down out of his side window, placed the blivet gingerly on the crest of the ridge and then released it from the tether. Root didn’t take his eyes off it.
    â€œSometimes when they punch off, the load goes downhill,” he explained. I realized that we were, in fact, directly below one and a half tons of water. He took a last look at it as he ate his sandwich.
    â€œThis is a pretty unexciting day, but last night was interesting. We were at the bottom of this slope—you never want to be above a fire—and rocks and trees were burning loose and just rolling past us. You could hear them coming. Someone would yell, ‘Rock!’ and then there’d be total silence while people tried to spot it and get out of the way. Logs would roll to the bottom and ignite the hillside, and the fire would come right back up at us. The night went by fast.”
    According to Root, all over the West, fire conditions were about as dangerous as they could get. The drier the fuels, the hotter they burn and the faster the fires spread, and fuel moisture levels that should be at 15 or 20 percent are down in the single numbers. Low relative humidity and unstable air (wind) compound the problem. Fires are generally slow-moving creatures, moving a few chains an hour. But sometimes they can explode up a hillside or across a canyon, and the mountains all around us, scorched by seven years of drought, were as likely as they’d ever been to produce such behavior.
    â€œI’ve never seen it so dry,” said Root, fingering the yellow cheatgrass around us. “One little ember in this stuff, and it ignites; last night every ember was taking. The fuels in Washington and Oregon are drier than what you’d buy at a lumber store. Now all it takes is one lightning strike in thousand-hour fuels for it to catch. That’s almost unheard of.”
    Thousand-hour fuel is a piece of wood between three and eight inches thick. The thousand hours mean that if the fuel were completely saturated with water, it would take a thousand hours for it to lose 63 percent of its weight through evaporation. Conversely, if it were bone-dry, it would take a thousand hours to soak up 63 percent of its weight in moisture. Sixty-three percent is used as a benchmark because it is midway between two points—above 78 percent and below 58 percent—where moisture absorption or evaporation happens in a predictable, linear fashion. In that middle range, however, wood gains or loses moisture in a very complex way, and 63 percent is at the mathematical center point of that nonlinear range. Grass and twigs dry out or saturate almost immediately—one-hour fuels. Sagebrush and other small growth are considered ten-or hundred-hour fuels. Thousand and ten-thousand-hour fuels include everything else, up to ponderosa pine with six-foot diameters. It is very rare for thousand-hour fuels to be as dry as one-hour fuels, but they are. Everyone was worried. As one hotshot said, “There are no small fires anymore.” Everything that ignites tends to explode.
    Fuel moisture levels can