Colorado Avalanche Information Center releases final report on fatal Berthoud Pass avalanche

44-year-old Brian Bunnell and his teenaged sons were caught in avalanche in Nitro Chute on Berthoud Pass, resulting in the father's death on Dec. 26, 2022. Avalanche debris piled deeply on the uphill side of the large boulder marked in red. The boulder concentrated the debris and increased the consequence of the avalanche, according to the final report released by the Center on Jan. 3, 2023.
Colorado Avalanche Information Center/Courtesy Photo

The Colorado Avalanche Information Center released a final report on the Dec. 26 Berthoud Pass avalanche, which resulted in the death of 44-year-old Brian Bunnell from Lakewood, Colorado.

The slide occurred around 1 p.m. near the summit of Berthoud Pass in the Nitro Chute, an east-facing avalanche path at around 11,500 feet in elevation. The avalanche caught four backcountry tourers — Brian Bunnell and his three teenage sons. On that day, the Center had rated avalanche danger at moderate (a level 2 out 5).

Accident and rescue summary

According to center’s report, Bunnell and his three sons left Winter Park on the morning of Dec. 26 and drove to the top of Berthoud Pass. That same morning, another group of backcountry tourers had triggered a large avalanche at Lift Gully, about 500 feet south of Nitro Chute. It’s unclear if the Bunnells were aware of this previous avalanche.

The report states that once the family entered Nitro Chute, Bunnell made some laps on his splitboard, including traveling to the less steep Big Roll area, while his sons constructed a jump. At about 12:40 p.m., Bunnell returned to where his sons were on Nitro Shute. Two of his sons, who had snowboards, were on foot. Another son was in his skis. As Bunnell rode down, an avalanche released. The slide’s destructive-size scale rating was a D-2 — a level 2 out of 5. The moving debris caught all four family members. One son managed to get out of the flowing snow, another son was only partially buried and dug himself out, and one son and Bunnell were both completely buried.

The two sons who were unburied used their avalanche transceivers to find the others. They followed the signal to the uphill side of a large boulder. They located their brother first and dug down 2 feet to clear his head from the snow. Since he was alert and breathing, they decided to leave him there to find their father.

Three groups of nearby backcountry tourers became aware of the accident and came to help at about 12:50 p.m. Near this time, Grand County dispatch received a 911 call about the avalanche. Grand County Search and Rescue and the Alpine Rescue Team were alerted. Rescue personnel began making their way to the pass, as well as a Flight for Life helicopter.  

After pinpointing his transceiver signal, some members of the group located Bunnell with a probe and dug him out — He was not breathing. Those at the scene performed CPR from about 1:10-1:50 p.m., but they were unsuccessful in their attempts to resuscitate him. 

Search and Rescue personnel arrived at Berthoud Pass just before 1:40 p.m. They recovered Bunnell’s body from the field around 3 p.m.  

Snowpack and weather preceding the avalanche

According to the report, around 11 inches of snow fell around Berthoud Pass over the five days before the accident. Strong winds shifted from the southwest to the northwest and drifted the new snow into thick, dense slabs. This caused a dense slab about 30 inches thick to settle over a layer of “weak, well-formed, chained, striated depth hoar crystals,” the report stated. Wind gusts were strong during this period. Winds averaged 20-30 mph at many points — sometimes getting up to the 70-mph range about 1,500 feet west of the accident site.

“Another wind event overnight on December 25 into the morning hours of December 26 continued to deposit wind-drifted snow onto easterly-facing aspects,” the report stated.

The conditions prompted the center to increase avalanche danger to considerable (level 3 of 5) from Dec. 22-25.

Natural avalanche activity ended on Dec. 25, and avalanche danger dropped to moderate on Dec. 26, when the Bunnell family toured the pass. At this point, the winds had decreased and there was some cloud cover.   

An image of the Dec. 26 avalanche track. Bunnell’s sons were building a jump in the area near the lower left of the image. Debris from the avalanche in Lift Gully and the Berthoud Pass parking lot are visible in the background.
Colorado Avalanche Information Center/Courtesy Photo

Remembering Brian Bunnell

In a Facebook post made by the Bunnell family, they remembered the father of three as an accomplished athlete and avid snowboarder. Bunnell was a high school chemistry teacher and took his family on numerous ski and snowboarding trips. His wife and sons shared his same passion for the outdoors.

“He was a man who loved adventure and family over all else. He lived for both of those each and every day,” the family wrote.

The Bunnells held a memorial service on Tuesday, Jan. 3, at the Origin Hotel Red Rocks in Golden. In lieu of flowers, the family has requested donations in honor of Bunnell to Grand County Search and Rescue or the Colorado Avalanche Information Center.

Avalanche safety education

After describing the accident and conditions, the report offered the following comments to help tourers avoid future avalanche accidents.

“It is a standard avalanche safety practice to expose just one person at a time to any avalanche hazard. The most common way to do this is to travel through avalanche paths or sections of avalanche terrain one at a time,” the report explained. “In this case, all four group members ended up in the same avalanche path.”

Risk increases if more time is spent in an avalanche track like Nitro Chute, and more people remain in that track close together.

“Watch from a distance when others are riding and limit the amount of time you are exposed to avalanche terrain whenever possible,” the report stated.

In this case, the father and son were both buried close to each other. This complicated the transceiver signals the family and other backcountry tourers followed. Rescuers realized they were following the transceiver signal of the brother who was safe, rather than the father’s signal, before they turned the brother’s transceiver off.  

“Rescue becomes much more complex if an avalanche catches multiple people. Fewer members of the group are available to perform a rescue,” the report concluded. “… Knowing how to use your rescue equipment in complex situations and practicing with it often increases the chance you will be able to use the equipment effectively in a real rescue.”

Colorado ranks highest in US for avalanche deaths

The center cautions that avalanches can happen anywhere, not just in remote or expert terrain. Popular or easy-to-access backcountry spots, such as Berthoud Pass, are not necessarily safer. Being near other backcountry tourers or being able to skin up from the highway sometimes gives recreationists a false sense of security.

“All of the fatal avalanche accidents we investigate are tragic events. This one seemed especially so because the accident involved a family with teenage children,” the Center wrote in their report. “We do our best to describe each accident to help the people involved, and the community as a whole better understand them.”

According to the Center, nearly 500 avalanches have been recorded this season, with over 400 this past week. From 1950-2022, Colorado has recorded 312 avalanche deaths, with an average of six people dying each season over the last 10 winters. This exceeds avalanche deaths in other parts of the country. Alaska, which ranks second in deaths, has recorded an average of four deaths each season over the past 10 winters. The center stated the last avalanche death in the Berthoud Pass area before Bunnell’s was Dec. 26, 2020, which was the first in nine years.

Current avalanche danger

The Colorado Avalanche Information Center’s avalanche forecast rates avalanche danger in Berthoud Pass as “considerable,” a level 3 out of 5, for Jan. 4-5.

“You can trigger a dangerous avalanche that breaks wider and runs further than anticipated. You can trigger these avalanches from below a slope or from a distance,” the center writes of current conditions.

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