Perimeter

Fire crews dig a perimeter around a fire near Big Sky last week. 

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Officials said Tuesday night that weather and fuel conditions were appropriate for a prescribed burn the day the Porcupine fire sparked south of Big Sky.

The Porcupine fire started Thursday about a mile away from where Forest Service crews were conducting a prescribed burn to regenerate aspen stands. It quickly spread through grass and timber, reaching approximately 650 acres in two hours. Firefighters had it fully contained by Sunday, when a winter storm hit Big Sky.

Though Forest Service officials initially thought an ember or a spot fire from the burn caused the wildfire, they now say conditions at the time didn’t seem to support the theory. They requested an investigation.

“As I came off the hill, I noticed the great distance between the prescribed fire and the wildfire,” said Caleb Schreiber, incident commander for the Porcupine Fire. “It just didn’t seem likely to me that the prescribed fire would have caused a wildfire at that point.”

Schreiber said the usual precautions were taken before Mary Erickson, Custer Gallatin National Forest forest supervisor, ultimately OK’ed the prescribed burn. Crews conducted a test fire and recorded the conditions on the day of the burn. They ordered spot forecasts from the National Weather Service.

The forecasts showed weather conditions were favorable at the burn site, though a red flag warning had been issued in a neighboring county, Schreiber said.

Spot forecast records from Thursday morning indicate that conditions at the are of the prescribed burn were warm, and increased winds were expected Thursday afternoon. Gusts were expected to reach 25 mph.

Three days prior, officials had checked fuel conditions at the site, finding pockets of snow throughout the area. Spot forecasts at that time indicated wind conditions would improve.

“The burn plan and the burn itself takes a great deal of work and effort,” Schreiber said. The plans are continually refined and updated based on maps and data.

Corey Lewellen, Bozeman District Ranger, said the prescribed fire behaved normally, with no spot fires showing up between the area of the burn and the wildfire.

“At the end of the day, there is risk with prescribed fire,” he said.

When crews working on the prescribed burn heard reports of a wildfire, they immediately stopped what they were doing and attempted to suppress it, Schreiber said. Firefighting crews from the Big Sky Fire Department and the Forest Service, deputies from the Gallatin County Sheriff’s Office, helicopters from the DNRC and other county resources aided in the response.

Because the available fuels were primarily grass, the wildfire grew rapidly but quickly diminished, Schreiber said.

Gallatin County Sheriff Brian Gootkin said warnings were issued to 33 homes, but no evacuation orders were issued. No structures were damaged by the fire, which scorched 50 acres of Forest Service land and approximately 600 acres owned by Montana Fish, Wildlife and Parks.

There is no timeline for the fire investigation, according to Gootkin.

“Only in 2020 are we talking about a fire in Big Sky in November,” he said. “We are working with the Forest Service, we will find out what happened, and we will let you know.”

The prescribed fire was part of an ongoing project to restore aspen stands and remove hazardous fuels, Lewellen said. It was intended to improve forest health, and was expected to benefit foraging for elk.

The Forest Service is now working with FWP to determine how the wildfire might have impacted winter range for elk, according to Lewellen. Some foraging areas were lost, he said.

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Helena Dore can be reached at hdore@dailychronicle.com or at 582-2628.

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