It was late evening when the wind over a brush-choked canyon in northern California unexpectedly shifted and roared downhill.The Rattlesnake Fire had been burning since midday on the Mendocino National Forest. The fresh, violent wind picked up embers from the fire and spun them down into the depths of the canyon, blowing into a thunderous torrent of fire.The sight mesmerized veteran firefighters. Long, fatal minutes passed before they remembered a...