Aspen
AvalancheDylan Craaybeek · Mar 4, 2022 · Aspen
Weather
Warm morning, 37F at the trailhead at 9:30AM and Overcast sky with light westerly winds. Clouds cleared to Scattered and off and on Light snow starting around noon. A brief period of High winds and Moderate snowfall occurred around 1:30PM. Temperatures seemed to drop throughout the day at upper elevations but air temp. was 44F back at the trailhead at 4:15 P.M. Raining on the drive back to Carbondale
Snowpack
Below 9,000 ft. the snowpack was moist throughout on all aspects and saturated in the top 20-40cm. Here, localized collapses propagated 5 to 10 feet with almost every step on a new slope even in dense trees. The collapsing was occurring on the buried layer of near-surface facets (FCsf) that developed during the Jan-Feb. dry spell and the facets were moist. Between 9,500 and about 12,000 feet cracking and collapsing began to grow more widespread propagating hundreds of feet across entire slopes on all northerly aspects. Northeast and northwest-facing slopes had a moist slab but water was pooling at the bottom of the slab likely being prevented from percolating further into the snowpack via capillary forces from the slab. All the collapses on these slopes failed on the buried FCsf 30-50cm below the snow surface and the facets were dry at these elevations. A number of these collapses shook large trees 50 to 100 feet away from where they were triggered. Multiple northwest-facing slopes collapsed naturally and slide several inches within the past week on the same layer. One particular natural collapse on a northwest 28-34 degree slope around 10,700 feet propagated at least 800 feet through multiple dense tree islands, sparse trees, and multiple shoulders on the slope and slid 1 to 3 feet downslope. Numerous snowpack tests further confirmed the reactive nature of northerly slopes with propagating failure on extended column tests with less than 10 taps. (6x ECTP's <10 on NE, N, NW between 10,000 and 11,500 ft.) Southerly slopes had a melt-freeze crust (MFcr) that varied in thickness and strength dependent on aspect and slope angle, lower solar incidence angle thicker and more supportable crust. On one southeast-facing 33 degree slope I triggered a slope-scale collapse with shooting cracks traveling over 100 feet but no avalanche. On a 35 degree south-facing slope around 11,700 feet there was 0cm of ski penetration on the stout MFcr but I triggered a loud collapse and felt myself drop and inch or two with no shooting cracks or avalanches. After digging on the same slope to investigate the slab below the crust collapsed about 1-3cm and left a gap between the slab and the MFcr on the surface that stayed intact. Above the treeline no more collapses were triggered and snowpack tests showed mostly stable results (3x ECTx's and 2x ECTPH's on northerly slopes).
Avalanche
Numerous avalanche from the past week were observed and coded separately. D1 above Snowmass Creek Rd.: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70415 D2 Wet Slab: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70416 D2 Wet Slab (2): https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70417 D2 off Haystack: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70418 D2 near Haystack: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70419 D1 north of Garrett: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70420 Loose wet avalanches: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70421 Above Snowmass Creek: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70422 D1 near Willoughby: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70423 East of Daly: https://avalanche.state.co.us/caic/obs/obs_report.php?obs_id=70424