Bulletin d’avalanche

Northwest Mountains

Crested Butte Avalanche Center
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Danger d’avalanche

Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

On Monday night, accumulating snow combined with strong west-to-northwest winds to form fresh wind slabs on the lee sides of terrain features. Those wind slabs will remain possible to human trigger today. That new snow will also transition into wet loose avalanches on some steep slopes. This is a great time to be out in the mountains while keeping your eye out for lingering wind slabs and any developing wet avalanche concerns. 

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    As the new snow from earlier this week transitions from dry snow to wet snow, wet loose avalanches will become possible to human trigger or run naturally. Pay attention to the feel of the new storm snow.  If you notice it becoming thick, sticky, or moist then expect that you can trigger a loose avalanche. You can use sluff management techniques to handle loose avalanches or move to lower-angled terrain. 

    An example of moist and sticky storm snow becoming a loose snow problem.  Roller balls and pinwheels are clear evidence of the problem.

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    On Monday Night into Tuesday, moderate winds with strong gusts from the west and northwest have drifted the recent storm snow to leeward terrain features.  Easterly aspects are the most likely place to encounter a fresh drift.  Most old surfaces are comprised of slick crusts which may not bond well with the storm snow.  These wind slabs can be found below ridgetops, underneath cornices, and cross-loaded into gullies.  Shooting cracks are a clear sign of sensitive conditions.  Carefully read the terrain to identify drifted features and consider traveling around them to reduce your chance of triggering a Wind Slab.

    A wind slab from a few weeks ago.  Avalanches might grow larger than the one pictured here but expect to find them in similar types of terrain.

Avalanche Discussion

The Monday through Tuesday Storm totals vary across the forecast zone. Areas near the town of Crested Butte at valley bottom received just a few inches, but areas to the west and north of town recorded nearly a foot of snowfall. Today avalanche problems will be the most common in those areas that received the most snow, while the areas that only received a few inches of new snow will have more isolated avalanche problems. This recent snow had already started to transition from dry to wet on Tuesday afternoon, but the most notable transition will occur today as we can expect more sunshine and high temperatures today climbing another 10 degrees warmer than yesterday. 

These avalanche conditions are typical of spring weather following a winter storm. Keep an eye out for wind-loaded slopes and stay aware of developing wet avalanche concerns as the day heats up. The expected avalanche size is on the smaller end of the scale, but don't forget that even a small avalanche can push you into more hazardous terrain or accumulate additional volume while running down a big slope. 

The last persistent slab avalanche ran during warm weather on 4/14 near Avery Peak. Before that, on 4/3 there was a human-triggered persistent slab avalanche on Mount Whetstone. Last weekend's warmup further reduced concerns for this already isolated avalanche problem, and it has now been removed from the daily problem list. As is typical, if you are riding in extreme terrain, stay observant for any old slabs hanging out above unsupported slopes or where the snowpack is variable in depth through rocky terrain that could hold the potential for isolated slabs over weak faceted snow. 

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