Wind gusts are expected to reach 45 mph across the urban corridor, with isolated gusts up to 60 mph possible in the foothills. Those conditions, layered on top of an air mass that meteorologists describe as unusually dry, are enough to allow a fire to move fast and wide with little warning. Fuels across the plains dried out Thursday after only a light sprinkle earlier in the week, leaving grass and brush in a brittle state that forecasters say is particularly vulnerable.