Front Range

Avalanche

On 23-Mar-19 at approximately 8:30 am, one skier and one snowboarder were caught and carried in a wind slab avalanche (R2 D2) halfway up the Northeast Couloir of Hallett Peak (NNE aspect) while boot packing. The slab broke several feet above the leader when it failed. Both individuals were caught and carried in the avalanche (estimated 6-8" crown, not sure how wide). One rider was able to take a few steps to the left before getting carried 150 feet and coming to a stop on the left side of the couloir with no injuries or lost gear. The second rider was also caught, carried 300 feet, and lost two poles, an ice axe, and a snowboard during the slide. The second rider was carried off a small cliff at the top of the apron and sustained an injury from impact with a rock. The snowboard and one pole were recovered, and both partners were able to safely exit to the parking lot under their own power. Both individuals discussed the forecast the night before, stating that wind and new snow in the forecast were a potential concern. In the morning, it was verified that there were sustained winds through the night and in the parking lot, unsure of how much new snow was on hand, the team decided to head up Tyndall Gorge to see what conditions were like (and to keep options open), avoiding an ascent of Flattop Mountain due to high winds. Near the Bear Lake parking lot, there was 1-2" of new snow. Above Nymph Lake, there was 3-4" of new snow (likely wind deposited), and there were high winds on Dream Lake and above. As the team ascended toward the NE couloir, up the south edge of the Gorge, they skinned up a small slope where a small 4" pocket of wind deposited snow released on a hard windboard base. The team noted the event but continued on, aiming to examine conditions in their intended line. On the apron, a mix of windboard and shallow new snow was found (likely wind deposited). The team felt comfortable transitioning to boot pack near the top of the apron. They ascended the left side of the couloir, finding old edge-able/boot-able snow and a previously set boot pack with the steps slightly filled in with new snow. While boot packing above the apron, they noticed a couple of small sluffs coming down the couloir to their right. About one-quarter of the way up, the team switched places at a small rock band. After the rock band, the snow consistency changed (in hindsight, it was a newly deposited soft wind slab). The team was heading for a rock island in the middle of the couloir (at roughly 11,000 ft) to reassess conditions when the slab released below a small convexity on the left side of the slope. Both riders are trained to the level of AIARE 1 (one having taken a refresher in December), were carrying active avalanche rescue gear (beacon, shovel, probe), and consider themselves experienced in the backcountry and familiar with the terrain that was on hand. Warning signs: - Forecast new snow - Forecast winds - Verified winds in the parking lot - Increasing snow deposition with elevation - High winds on the ascent with lots of snow transport in the air! - Small test slope release - Medium hard base when booting with new snow deposition - Sluffing in the couloir - Boot pack steps filled in - Change in snow consistency to wind slab after switching leaders.