Observation: Hatcher Pass

Location: Archangel Valley (Crown Profile)

Route & General Observations

Traveled up Archangel Valley on Sleds just beyond our forecast zone to investigate a large avalanche that was triggered by a snowmachiner on 2/25/2024. This is a follow up observation and crown profile associated with a previous observation entitled Archangel Valley- up past Fairangel (out of forecast zone).

Avalanche Details
If this is an avalanche observation, click yes below and fill in the form as best as you can. If people were involved, please provide details.
Avalanche Details

While ascending this steep slope a snowmachiner triggered a large hard slab avalanche that stepped-down into old weak layers of the snowpack near the ground. This avalanche occurred on a northwest aspect at 3900 feet with a slope angle of 41 degrees. The crown was at most 7 feet deep and 175 feet wide and ran 350 feet downslope. As the rider climbed and traversed across the slope they impacted an area where the snowpack was shallower and weak persistent grains existed more near the surface. In this location we found the lower 2/3 of the snowpack to consist of faceted grains which were transitioning from a rounded moist facet back to a dry weaker solid facet particle. This cross-loaded slope has a concavity where old wind blown snow had drifted forming the thick dense layer which released. Luckily the rider was in the right trajectory which enabled them to escape the avalanche and retreat to more stable snow. Previous tracks were in the vicinity but none had been placed on this slope and this area had not previously avalanched. We did observe other avalanches in this area that were of similar aspect and characteristic, some being higher in elevation and further up valley.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?Yes
Collapsing (Whumphing)?No
Cracking (Shooting cracks)?Yes
Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.

Sunny and clear with calm winds

Snow surface

Loose dry soft snow


Firm layer of wind drifted snow above weak faceted snow grains. Weakest snow(near surface facets) was found below the upper layer of firm consolidated snow. Basal facets were moist and could make solid snowballs, but just above that was weaker and drier faceted snow.

Photos & Video
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