Such larger and longer-burning fires are far from unusual in the drought- and beetle-stricken West. The Rio Grande Forest, for example, had another dry winter. More than half of its hundreds of thousands of acres of mature spruce trees have been killed by beetles, turning the usually fire resistant trees into tinder, Blume said.
Crews in Colorado also are being challenged by the high altitude, which adds to the danger and complexity of launching air assaults in smoke and high winds, said Larry Trapp, a branch director of air operations with Rocky Mountain Type I Incident Command working the east side of Continental Divide. Wolf Creek's summit is 11,904 feet; South Fork's elevation is 8,208 feet. Some peaks in the Rio Grande Forest surpass 13,000 feet.
Among the air resources on the way, he said, is a helicopter with infrared technology that can fly through the smoke to map power lines above the tree line. That will allow more tankers to take to the sky to drop retardant, Trapp said.
About a dozen fires burned elsewhere in Colorado, including a nearly 21-square-mile wildfire near the southern Colorado town of Walsenburg that was 50 percent contained.
Associated Press writer Greg Bull contributed to this report.