Aspen
AvalancheDylan Craaybeek, Griffin Mueller · Feb 20, 2024 · Aspen
Weather
Low 40s (Fahrenheit) in Marble this morning with snow starting around 10:00. On and off S-1 to S2 snow continued throughout the day with generally warm temperatures and a light to moderate southwest breeze picking up in the afternoon. Warm, wet snow back at the trailhead around 16:00 and raining on the other side of Marble around 7800 feet. Some light snow transport through the afternoon loading northeast slopes.
Snowpack
Close to 10 snowpits on all aspects mostly below and near treeline helped confirm the current distribution of the Persistent Slab avalanche problem is accurate. On south, southwest, and west-facing slopes there is still a well-developed layer of moist depth hoar near the ground but one to three thick (4-6cm), and hard (K hard on the hand hardness scale) are insulating the weak layer from any backcountry travelers and disturbing the overlying slab. One notable collapse on a shady west-facing slope below treeline where the crust was notably thinner than surrounding west-facing slopes. The early January layer of well-developed near surface facets (FCsf) is buried well over a meter deep on all northerly and easterly aspects and too deep for any backcountry traveler to easily impact. The primary persistent weak layer of concern is the buried surface hoar around a meter deep. Extended column tests showed no fractures occurring until additional loading steps showed a propagating failure every time. Propagation saw tests would consistently fail after cutting around 30-40% of the column. These snowpack tests highlight that this weak layer is becoming harder to trigger but is still capable of propagating if a failure in the weak layer is initiated. The surface hoar is showing clear evidence of rounding but is large and buried fully intact so this may take some time still. No signs of the buried surface hoar were observed on a northeast-facing, open slope near the treeline likely from the wind. Here the early February weak layer was still noticeable with some poorly developed near-surface facets but showed non-propagating failures in extended column tests.
Avalanche
Low visibility, did not observe any avalanches.