Bootleg Fire: What Makes It So Hard to Contain?

U.S.|Why is the Bootleg Fire so hard to contain?

• July 21, 2021

In his four decades of firefighting, Joe Hessel has rarely seen a wildfire prove as difficult to bring under control as the Bootleg Fire, the sprawling blaze that over the past two weeks has scorched almost 400,000 acres in southern Oregon.

And what has made this fire different than most, he said on Wednesday, was back-to-back days of what firefighters call extreme fire behavior.

“It’s not unusual to get a few days in a row, or a day here and there, of extreme fire behavior,” said Mr. Hessel, an incident commander with the Oregon Department of Forestry team that is trying to suppress the Bootleg Fire.

“But on this incident, it’s been 13 or 14 days in a row,” he said. “When you have that type of fire behavior, it’s hard enough to keep up with it, let alone get ahead of it.”

So, what do firefighters mean by extreme fire behavior? Generally, it includes some or all of the following:

• a high rate of spread

• flames growing through the branches and leaves on trees as well as shrubbery, unaided by the blaze on the ground

• the existence of fire whirls, which are vortexes of hot air and gases rising from a ground fire and carrying debris, flames and smoke into the air. They range from less than one foot to more than 500 feet in diameter. The largest resemble the intensity of a small tornado.

• the presence of a convection column, which sends gases, smoke, fly ash, particulates and other debris produced by a fire straight into the air, spreading vertically, instead of horizontally.

Fires with one of more of these characteristics are hard to forecast because they generate their own weather. The intensity and extreme heat can force wind to go around them, create clouds and sometimes form so-called fire tornadoes.