Avalanche forecast

Gunnison

Crested Butte Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You can trigger a large avalanche that breaks up to several feet thick in some steep terrain features. Carefully evaluate the snowpack for the presence/absence of a cohesive slab and visualize the terrain consequences before traveling in avalanche terrain.  Smaller, simpler terrain or riding on lower elevation southerly aspects is the most reliable strategy for managing persistent slab uncertainty.   Watch for shallow instabilities in the new and drifted snow today, with more entrainment potential on the north half of the compass.  

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Slabs up to several feet thick can be triggered where they formed over well-developed facets and collapsible crusts on west, north, and east aspects. Additionally, heavily wind-loaded slabs can be triggered above buried crusts on high-elevation, southerly aspects.  Slab behavior is challenging with variable and deceptive feedback, remote triggering potential, and wide propagation across terrain features.  Sheltered slopes with snow depths around 100 to 120 cm, and thin areas in previously windloaded terrain appear to be most problematic. You can reliably avoid the problem on slope angles less than 30 degrees without steeper slopes above you, and most mid to low-elevation southerly aspects lack the problem.  

    This avalanche was explosively triggered 1/13 on the Irwin West Wall. The avalanche debris was 10 to 15 feet deep! Photo: Jake Hutchinson

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Manage for shallow instabilities in the new snow.  These will most commonly be soft slabs of wind drifted snow at higher elevations and loose avalanches at lower elevations.  New snow instabilities can entrain older, weak snow below and grow in size on the north half of the compass.  Use small, steep test slopes to gather feedback on the problem.  Look for cracking, fresh drifts, or point-release avalanches to alert you to the problems.  

    The storm interface is weak and cohesionless, so any shallow storm instabilities will entrain more volume in sustained steep terrain on the northern half of the compass.  

Avalanche Discussion

Relatively quiet weather over the past week allowed the snowpack to make gradual adjustments, decreasing the likelihood of triggering a persistent slab.  New snow and windloading today will subtly reverse the downtrend. The potential size of persistent slab avalanches has not changed.  Recent improvements are attributed to incremental weak layer adjustments (most effectively in the deepest snowpacks greater than 150 cm) and slab decay (most effectively in the shallowest snowpacks less than 90 cm).   Because weak layer improvements are difficult to assess with our tricky snowpack (remember, low-angle terrain has a stronger snowpack than steep terrain due to our early season avalanche cycle), it's better to focus on more palpable variables: terrain consequences and presence/absence of slabs.

If you are traveling in avalanche terrain highlighted by the persistent slab rose, ask yourself and your partners these questions, and default to lower angle, simpler terrain when in doubt.  

  • What will happen if one of us gets caught in a 2 or 3-foot slab avalanche? Will we be pushed into trees, gullies, or a more survivable runout?
  • Is there a slab?  Or has the holiday slab been eroded by northerly winds, faceted into cohesionless snow, or avalanched away sometime in the past few weeks?

This video dives into these considerations, and our weekly summary provides more insight into our current snowpack conditions.   If you are traveling in steep terrain where the persistent slab problem has decayed or avalanched in the last few weeks, anticipate new snow instabilities gaining volume in the cohesionless snow below.  We'll most likely see a mix of wind slabs from shifting southwest to northwest winds and dry loose avalanches in sheltered terrain on the north half of the compass.  Given how fragile the snow surface is, a few thin storm slabs could release in sheltered terrain.  To keep it simple, we've bundled all of this into one storm snow problem that should be relatively small and easy to recognize/manage compared to our persistent slab issue.   

Regions covered