The avalanche occurred on a South slope at 6,700 ft. The slope was open with clusters of trees. Many of the details are unknown because both skiers were buried and killed. They were found with their skins on, and it is suspected that they triggered the avalanche while skinning midway up the path.

The avalanche was a size 2 Storm Slab, which propagated surprisingly far given the nature of the weak layer (compression tests throughout the range, near the slide, and along the crown yielded mostly resistant planar results) which was a layer of mostly intact stellar dendrites buried beneath 40-55 cm. of more recent and harder storm snow. The bed surface was a melt-freeze crust which was very isolated throughout the range. Details of how the avalanche was triggered remain unknown, but clusters of trees throughout the slope and in the runout exacerbated the consequences of the avalanche.

The avalanche forecast for February 17, 2025 was Considerable (level 3 of 5) at all elevations. The primary problem was Wind Slabs, which were anticipated near and above treeline on all aspects except due West. The likelihood was likely and the size was small to D 2.5. The second problem was Storm Slabs which were forecast near and below treeline on all aspects. They were forecast as likely, and small to large (up to D2). The bottom line read: Avalanche danger will continue to rise overnight and on Monday as new snow piles up. Avalanches large enough to bury or injure a rider are possible throughout all elevations, and likely wherever the wind has blown in deeper deposits of snow. Monday will be a good day to start with conservative terrain choices, and only move to bigger or steeper slopes when/if you feel confident that it is safe to do so.

Early February provided wonderful riding with lots of cold, dry powder. From Sunday, February 9 – Wednesday, February 12 the mountains received no new snow. During that time, skies were increasingly clear and temperatures were very cold (on Wed. 2/12 the ODOT Weather Station on Century Drive at 6,424 ft. recorded a low temperature of -5.1 F). Snow began to fall overnight and then throughout the day Thursday. Temperatures were initially cold (low teens near treeline), but warmed throughout the storm to near freezing. Wind speeds on Thursday were Strong and Extreme. The snow continued to fall on Friday (2/14). After a break in the snowfall on Saturday, we received a second round of precipitation on Sunday and Monday. By midday on Monday (2/17) we had received 40-55cm. of new snow.

February began with lots of cold, dry snow. February 9-12 were dry and cold with clear skies. Observers didn’t find much in the way of faceting near the snow surface but the snow remained weak. A new storm began dropping snow on Wednesday night. This newest snow began to fall with cold temperatures, but temperatures warmed up on Thursday and the wind speed near treeline and above was Strong and Extreme. This provided classic Storm Slab conditions with harder, wind affected storm snow overlaying weaker precipitation particles. A second round of snow fell on Sunday (2/16) and Monday (2/17). Hard over weak layering was easy to observe on Monday with nearly every pole plant. We didn’t see much natural avalanche activity, and stability tests yielded Resistant Planar results. I never observed any faceting in these weak layers.

On the slope that avalanched we found a melt-freeze crust beneath Thursday’s (2/13) storm snow. This crust was very isolated in the terrain (it was hard to find anywhere else), and likely formed during the high pressure despite the very cold temperatures. Crown profiles revealed a weak layer of 2mm preserved stellar snow grains above the melt-freeze crust. The crown height was 45-55cm.

Many of the details leading up to the avalanche are unknown because both riders were killed in the avalanche. Neighbors report that the two riders left home in the early afternoon. They snowmobiled up to Happy Valley and parked along the snowmobile road directly beneath the slope that they were touring on. Based upon their tracks it is likely that they skinned directly uphill. Both riders were found with their skins on their skis; it is most likely given the slope configuration that they triggered the avalanche from mid-slope. The only tracks that were observed were the ones leading into the avalanche path.

On the evening of Monday February 17, neighbors and friends noted that the riders had not returned. These friends were able to get a rough location of the riders via Rider 1’s cell phone location (exact method is unknown). Three friends departed on snowmobiles and were able to locate the riders’ snowmobiles. After returning home to get touring gear, the friends followed the riders’ skin track and quickly came upon avalanche debris. Using beacons, probes, and shovels they were able to find the two riders and ascertain that they had not survived. The rescuers were able to find and uncover the riders between 11 and 12 pm. Given the size of debris, uncertainty about the snowpack, and exercising caution, these rescuers marked the burial locations and returned home.

Deschutes County Search and Rescue was initially contacted between 9 and 10 pm on Monday (2/17). They arrived on scene very early Tuesday morning and completed the recovery during the day on Tuesday (2/18).

All the fatal avalanche accidents we investigate are tragic events. 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 difficult to make much in the way of commentary with so little understanding about what occurred on February 17. The slope that the riders were skinning up was not particularly large, nor was it an obvious path, but it was steep, reaching 45 degrees at multiple spots. There were less steep and better supported skinning options nearby.

There was obvious hard over weak layering in the upper snowpack, but forecasters had not been observing natural avalanches or collapses in the snowpack, and test results were not raising “red flags”. Even in a relatively “simple” mountain range like the Oregon Cascades there is a lot of variation in the snowpack as was evidenced by the melt-freeze crust we had not seen elsewhere.

As in other avalanche accident scenes that I’ve been to, I was again impressed by how much even sparse or clustered trees increase the consequences of being caught in an avalanche.