How investigators found the tree that started the Black Mountain Fire in Grand County | VailDaily.com
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How investigators found the tree that started the Black Mountain Fire in Grand County

Amy Golden
Sky-Hi News
This image shows a tree that was struck by lightning, which investigators believe ignited the Black Mountain Fire. Investigators were able to quickly pinpoint the cause of the fire thanks to reduced fire behavior.
Black Mountain Fire Facebook page/Courtesy photo

GRANBY — After determining that lightning ignited the Black Mountain Fire, investigators have shared photos of the tree where they think the fire began.

Images shared Friday, Sept. 3, show a tree struck by lightning that investigators say caused the fire. The bark and wood had separated from the tree, and the tree was split at the bottom, both of which are common evidence of a lightning strike.

With the Black Mountain Fire burning just a few miles away from the East Troublesome Fire burn scar, many have wondered why the cause of this new fire was found so much faster.



The East Troublesome Fire, which ignited Oct. 14, 2020, was determined to be human-caused, but fire officials have not released any further information.

Mike De Fries, spokesperson for the incident management team working the Black Mountain Fire, explained that determining the cause of the Black Mountain Fire in less than a week was possible because of a number of specific circumstances.

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“This is a different fire, and it all just happened to work out that the timing was such that they could come back with a cause within a number of days in this particular case,” De Fries said. “Every wildfire, every fire has unique circumstances, and there are often very good reasons why a cause is announced at a certain point.”

Investigation of the Black Mountain Fire began by examining the available evidence, such as pictures, video and drone footage. Using images and mapping data, fire behavior analysts pinpointed the source of the Black Mountain Fire to an approximate location, De Fries explained.

Investigators also knew that there had been a number of recent lightning strikes in the area. That’s not enough to determine the cause of a fire, though.

“You may know where the fire started in general, but this is still an active incident,” De Fries said. “However, fire activity has calmed. In that area where the fire started, things cooled to the point where, at some point late (last) week, they could actually hike in, and examine and get right up close in the area where the fire started. We still have to have boots on the ground to help determine the cause.”

Images shared Friday, Sept. 3, show a tree that was struck by lightning, which investigators say ignited the Black Mountain Fire. The fire was discovered Aug. 29.
Black Mountain Fire Facebook page/Courtesy photo

From there, investigators looked at burn intensity and traced the fire back to the beginning. In this case, a tree that was struck by lightning happened to be right there.

While humans are thought to be the cause of most wildfires, U.S. Forest Service data analyzing wildfires in the western U.S. from 1992 to 2015 found that lightning caused 44% of fires, but lightning-ignited wildfires were responsible for 71% of the area burned.

“As for why that is, there could be a number of reasons,” De Fries said. “There could be a lightning-caused fire that nobody noticed because often times it’s very remote and the fire has time to take off.”

When lightning strikes a tree, sap boils, steam is generated and cells explode in the wood, leading to physical damage and often the ignition of a fire. The Black Mountain Fire was first reported Aug. 29 but was burning too aggressively for initial attack crews to extinguish it.

As of Monday, Sept. 6, the Black Mountain Fire remained at 416 acres and containment had increased to 48%.


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