3/28/2024 Field Report - Aspen

Investigated an avalanche incident that occurred on March 27, 2024 (see avalanche section for narrative). There is around 30-50cm of new snow since March 23. This new snow rests on top of a layer of well-developed near-surface facets and spatially variable, small surface hoar on northerly slopes above 11,000 feet. On most slopes, the new snow is soft and cohesionless but on wind-loaded slopes, the new snow forms a cohesive slab on top of a weak layer. Where there is a cohesive slab on northerly slopes it is easy to trigger small avalanches and snowpack tests show unstable results. Several small to large natural Wind Slabs failed today both within the new snow and on the March 23 interface.

This is one of several incidents this season highlighting the importance of effective companion rescue. Skier 2 followed the transceiver signal, slowed down as he got closer, and was looking around and listening to more than just his transceiver. The group commented how the couloir seemed relatively low-angle it is less steep and wider than surrounding couloirs. Estimating how steep one slope is relative to nearby slopes is unimportant if all the slopes are steep enough to avalanche. It is more beneficial to measure the angles of the slope where you plan to travel.

Ashcroft

Main road to Lindley Hut then up dense trees above Cooper Creek to Star Bowl just north of Star Peak and west of Tayor Peak. Back down and out the same way.

Two skiers, out of a group of four, were caught and carried in an avalanche and one of them was fully buried on March 27, 2024. This group of skiers was on a multi-day hut trip at the Lindley Hut near Ashcroft with a larger group. This smaller group of four decided to ascend and ski a couloir locally known as "Dr. Evil" north of Star Peak. While ascending the couloir two skiers stayed near the base of the couloir behind a rock outcrop and transitioned to descend as they did not want to continue farther up the couloir. The other two skiers continued ascending the couloir via steep switchback with skins on their skis. One of them waited at a switchback about halfway up while the other neared the top of their ascent. About 20 feet from the ridgeline Skier 1 heard a muffled collapse and noticed the slope drop a couple inches. It took several seconds before he realized the slope had avalanched and he was being taken for a ride. Meanwhile, one of the skiers near the bottom of the slope that transitioned skied out a short distance beyond the rock outcrop and was looking down at the run when he was struck in the back by the avalanche and immediately knocked over and carried down the slope. When the avalanche came to a stop the lower skier was on the surface and the group quickly realized one member was missing, the skier that triggered the avalanche near the top of the couloir. The skier halfway up the couloir watched this happen, hit the SOS button on his InReach, and began a transceiver search of the debris pile. As the numbers on his transceiver got below 10 meters he took his skis off and as the numbers got under 2.5m and he was beginning his fine search he heard muffled yells underneath the snow. He immediately took his shovel out and began digging where he heard noise. He cleared the buried skier's airway in less than 10 minutes from the start of the avalanche. The skiers spent several hours looking through the debris pile for lost gear after ensuring everyone was okay and then returned to the hut shortly after 6:00 P.M.

The March 23 layer is the main layer of concern coming into another stormy period. Several pits near and above treeline on northerly aspects show consistent 1-2mm near-surface facets (FCsf) with some buried surface hoar existing at this interface near treeline. The buried surface hoar was not found about 11,800 feet. Long column snowpack tests show mostly non-propagating failures along the March 23 layer but on wind-loaded slopes or slopes where the slab was about 4F hard extended column tests consistently got propagating failures in less than 10 taps and propagation saw tests showed propagating failures after cutting around 30% of the column. This was highlighted while traveling across the terrain as we did not observe any shooting cracks or collapses until we traveled on wind-loaded slopes steeper than 35 degrees and triggered shooting cracks traveling dozens of feet around us.

Windy with very effective snow transport above treeline. Scattered clouds and cold morning warming up but staying cold at higher elevations throughout the afternoon.