Computer model paints sobering fire picture
They came to life at about the same time, but luck played a prominent part in holding the fire near the Eagle County Landfill to 40 acres, compared with the blaze at Glenwood Springs that so far has burned more than 10,000 acres, and two dozen trailer homes.
The Wolcott fire, just north of the county landfill, was snuffed quickly with the aid of six air tankers and ground crews Saturday afternoon. It could have been much, much worse.
It’s a wonder people in charge of fighting fires sleep at all, with conditions as dry as they have been. They say it’s not a case of if a big fire will happen here, but when. There are eight large fires now in Colorado burning more than 125,000 acres.
The fires took off during what firefighters call “red flag days” – with humidity measured in single digits, temperatures in the 80s and wind gusts up to 45 miles-per-hour from a storm front passing to the north. In conditions like that, a small fire can quickly become a large, out-of-control fire if set in the right place.
“Conditions are on the extreme end of things,” said Phil Bowden, who coordinates firefighting for the Bureau of Land Management from Dotsero to the Eisenhower Tunnel. “We definitely dodged a bullet there (in Wolcott). A change in fuel type from pinon and juniper to slower-burning sagebrush also helped.”
The Wolcott fire actually was sparked by a lightning strike during a rain shower a week ago Monday. The warm, dry winds fanned a smoldering snag into flames five days later.
A computer-generated fire model paints a sobering picture of the potential of this fire to have roared out of control like the other big Colorado fires. The computer model, called Behave, is used by firefighters to predict fire behavior based on the fuel, terrain, and weather conditions.
In the Wolcott model it used light brush as a fuel type with fuel moisture of 5-10 percent for light fuels and 12 percent for heavier fuels, fanned by a 10 mile-per-hour wind and temperatures in the 80s – the same conditions present when the fire started. The computer model is static and does not include changing fuel types or changing slopes. For comparison purposes, moisture content of a 2 x 4 purchased at a lumber store averages 12 to 15 percent.
According to the model, In just two hours that fire would have been 2,100 acres with an elliptical perimeter measuring 8.5 miles. At four hours it would have reached 8,500 acres, and at eight hours it would have reached 34,000 acres (53 square miles) with a perimeter of more than 15 miles. in. That stretches from Wolcott to State Bridge.
“That’s a fire similar in size to the Hayman Fire on the Front Range,” Bowden said. “In a different place and with different fuels, it would have been another story.”
The Hayman Fire, which started Sunday northwest of Pikes Peak, is now bearing down on Denver’s southwestern suburbs and displacing thousands of people in its suspected path. At 87,000 acres as of 4 p.m. Tuesday, it is the state’s largest wildfire in history. It was a wind-driven crown fire that raced through treetops at its height. Such fires cannot be controlled until they either burn themselves out or weather conditions slow them down.
Bowden also ran a computer model for the Dowd Junction area, where the fuel is heavier. That model, based on the same dry conditions and wind, and steep slopes showed that a fire that stayed on the ground and didn’t leap to the crowns of trees, forecast a fire growing to 2,200 acres after eight hours.
Area fire crews are jumpy. Monday, they responded to the report of a fire in the Whiskey Creek area south of Eagle-Vail that turned out to be blowing clouds of pollen from the lodgepole pines. Several smoke reports were called in from Eby Creek north of Eagle, but those were from the Glenwood fire.
Based on the conditions, vigilance is necessary.
A 5-acre fire erupted on Porphyry Mountain near Fulford, south of Eagle, on Tuesday. Fire officials said this fire likely started with a lightning strike from the same storm that eventually led to the Wolcott fire Saturday.
“We have to be ready to jump on fires quickly,” Bowden said. “In conditions like this, you don’t want anybody getting in the way of something like this. The best thing you can do it to get people out of the way.”
Holy Cross District Ranger Cal Wettstein has been assisting firefighting efforts in Glenwood Springs, and he’s seen what happens when a fire roars through a community.
“It’s really sobering when you talk to people who have lost their homes,” he said.