2022/12/26 - Colorado - Nitro Chute, north of Berthoud Pass

Published 2023/01/03 by Mike Cooperstein, Austin DiVesta, Ethan Greene, Spencer Logan - Colorado Avalanche Information Center

On December 1, the Berthoud Summit SNOTEL, less than a quarter of a mile east of the accident site, measured a snow height of 20 inches. The snowpack was almost entirely composed of weak faceted crystals. There was very little snowfall until December 21.

In the five days preceding the accident, around 11 inches of snow fell around Berthoud Pass. Strong winds shifted from the southwest to the northwest and drifted the new snow into thick, dense slabs on easterly-facing aspects. There was now a dense slab about 30 inches (80 centimeters) thick resting on a layer of weak, well-formed, chained, striated depth hoar crystals. The avalanche danger rose to CONSIDERABLE (Level 3 of 5) on December 22 and remained elevated until December 25, when the loading event finished, and natural avalanche activity ended.

On December 27, CAIC investigators observed a crown profile in Nitro Chute. They found a 55-inch (140 centimeter) deep snowpack. The bottom 18 inches (45 centimeters) was composed of two to four-millimeter chains of depth hoar. The depth hoar was Fist hard on the Hand Hardness Scale. On top of the depth hoar was a 2-inch (5 centimeter) crust that was breaking down and faceting. A One-finger hard slab of small (0.5 millimeter) rounded crystals made up the next 25 inches (60 centimeters) of the snowpack. The snowpack’s top 8 inches (20 centimeters) was composed of broken stellar crystals with a thin layer of heavily rimed new snow just below the surface. Snowpack stability tests produced propagating (ECTP25) planar sheers in the depth hoar layer about 15 inches (38 centimeters) above the ground.

A father and his three teenage sons left Winter Park on the morning of December 26 and drove to the top of Berthoud Pass. They parked just below the summit on the north side. The three sons planned to build a jump while their father (Rider 1) made some laps on his split-board. The teenagers (Riders 2 and 3, and Skier 1) traveled into the Nitro Chute area – one with a split-board, one with a snowboard, and one with skis. They chose a spot about midway up the track of Nitro Chute and began to dig and pack snow for the jump. Rider 1 skinned up and rode down through an area locally known as Big Roll, which is less steep than Nitro Chute and sees quite a bit more backcountry traffic.

Several hours before the fatal avalanche, another group of backcountry travelers triggered a large (Destructive size 2) avalanche in an area locally known as Lift Gully. This avalanche ran over a commonly used route below the West Side cliffs. Lift Gully is about 500 feet south of Nitro Chute, with a similar aspect and elevation to the accident site. Investigators do not know if the father and sons noticed the avalanche in Lift Gully.

At about 12:40 PM, Rider 1 rode onto Nitro Chute. As he descended the avalanche released washing him downhill. Riders 2 and 3 were on foot, and Skier 1 was wearing his skis. All three were on the slope in the avalanche track. The teens saw the flowing snow and tried to get out of the way, but were all caught in the moving debris. Skier 1 moved downhill and to the side and managed to get out of the flowing snow. Riders 2 and 3 tried to run out of the avalanche path. Rider 2 managed to get to the edge and was just partially buried when the debris stopped. Rider 3 was pushed downhill in the moving snow. When the avalanche stopped, Riders 1 and 3 were missing.

Rider 2 and Skier 1 turned their avalanche transceivers to receive and began to search for their father and brother. They followed the signals to the uphill side of a large boulder in the runout zone. They were able to pinpoint one signal and began to dig. After digging down about two feet, they located Rider 3 and were able to excavate his head from the snow. He was buried vertically with his head toward the surface. He was alert and breathing. 

A group of two backcountry tourers saw the avalanche and came to help. Another group of three tourers in the trees below heard people yelling, asked if the group needed help, and skinned uphill to the accident site. A third group of two people in the parking lot on the east side of the Pass saw the fresh avalanche. One headed toward the accident site while the other waited for emergency personnel to arrive. All three groups arrived on the avalanche debris within a few minutes of each other, around 12:45 PM. The two boys had just uncovered their brother's head, but their father was still missing. The responders decided to leave Rider 3 partially buried in place and start searching for the Rider 1. 

Grand County Dispatch received a 911 call about the avalanche at 12:50 PM. Grand County Search and Rescue and the Alpine Rescue Team were alerted. Search and rescue (SAR) personnel made their way to Berthoud Pass. 

The responders spread over the debris to search for the Rider 1's transceiver signal. After several minutes they realized they were getting two transceiver signals close to where Rider 3 was still partially buried. One responder dug down and turned Rider 3’s transceiver off. The father's transceiver signal indicated he was buried very close. The responders were then able to pinpoint the second transceiver signal and locate Rider 1 with a probe. They uncovered his snowboard, and then quickly moved to digging him out of the snow. Rider 1 was buried about one and a half feet deep, face down, with his head downhill. When they reached his head and turned him over, he was cyanotic and not breathing. It was around 1:10 PM. 

A CAIC forecaster was in Lift Gully investigating the earlier avalanche and saw the toe of the new avalanche at 1:15 PM. He alerted the CAIC dispatcher and made his way to the avalanche. The other responders were performing CPR on the father when he arrived. 

A Flight For Life helicopter took off at 1:28 PM with an estimated flight time of 12 minutes to the avalanche. The first SAR personnel arrived at Berthoud Pass just before 1:40 PM and staged in the parking lot.

The responders performed CPR for almost 40 minutes. They discontinued CPR around 1:50 PM. It had been about an hour since the avalanche occurred. 

The responders descended to the search and rescue staging area at the highway. At around 3:00 PM, rescuers recovered the father's body from the field.

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. We do our best to describe each accident to help the people involved, and the community as a whole better understand them. We offer the following comments in the hope that they will help people 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. In this case, all four group members ended up in the same avalanche path. Three by deciding to build a jump below an avalanche-prone slope, and one by riding through the area while other people were in it. When the avalanche released, it caught all four people in the group and completely buried two. 

Minimizing the time exposed to a hazard decreases the risk of that hazard. By building a jump in an avalanche track, the teens spent a significant amount of time exposed to potential avalanches. A standard avalanche safety practice is to avoid waiting or regrouping in the avalanche track or runout zones. Choose places to eat lunch or build jumps outside of terrain connected to steep slopes above. Watch from a distance when others are riding and limit the amount of time you are exposed to avalanche terrain whenever possible.

Rescue becomes much more complex if an avalanche catches multiple people. Fewer members of the group are available to perform a rescue. Searching for multiple people is always more complicated than searching for one. The chance of a close proximity burial increases if people are caught within a short distance from each other. Close proximity burials can make transceiver searches more difficult and increase the time of rescue. After the rescue, responders who assisted in the search said they wished they had practiced complex scenarios when doing rescue drills. Knowing how to use your rescue equipment in complex situations and practicing with it often increases the chance you will be about to use the equipment effectively in a real rescue.

Recent avalanche activity on similar slopes is a primary indication of unstable conditions. The triggered avalanches in Lift Gully and Nitro Chute occurred within a few hours and a few hundred feet of each other. The slopes are similar in elevation, aspect, and slope angle. Investigators do not know if the four family members saw the avalanche in Lift Gully. If they did, they did not recognize the implications of other avalanches in similar terrain features.