By Keith Coffman
DENVER (Reuters) - A trio of wind-driven wildfires roared unchecked across 76,000 acres of national forest in southwest Colorado on Monday and firefighters held the line against flames threatening the mountain town of South Fork.
Crews have been hampered in battling the West Fork Complex fires - which consist of three separate blazes - by the steep mountainous terrain and winds in excess of 50 miles an hour (80 km/h) on some ridgelines.
South Fork, the town of 600 residents evacuated last week as flames crept to within a few miles of the community, is located 170 miles southwest of Denver.
The three lightning-sparked fires have scorched a 119-square-mile (308 square km) swath through the San Juan and Rio Grande national forests.
For the fifth straight day, the National Weather Service has issued a red-flag warning for the burn area, citing extreme fire danger due to high winds, hot temperatures and low humidity.
"You will not see significant gains until we get some help from the weather," incident commander Pete Blume of the U.S. Forest Service told reporters on Monday.
Crews have cut lines with bulldozers around South Fork and so far no structures have been lost, Blume said, adding that there is no timetable for when residents can return home.
A smoke plume from the fires, which are being fueled by large stands of dry, beetle-killed timber, has billowed 30,000 feet into the air, leaving a smoky haze over much of southern Colorado.
Nearly 900 firefighters are battling the blaze from the ground and air.
Further east in Huerfano County, fire officials said they have 15 percent containment on a separate wildfire that has charred 13,000 acres.
The so-called East Peak Fire, burning 10 miles southwest of the town of Walsenburg, has destroyed 14 homes and outbuildings, according to a statement from the Rocky Mountain Incident Team.
(Editing by Alex Dobuzinskis; Editing by Carol Bishopric)