Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sun
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 9 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Heavy snowfall and strong winds are creating very dangerous avalanche conditions at upper elevations.  Expect large, natural and easily triggered slab avalanches in steep, wind-loaded terrain.  Instabilities are smaller and less common in wind-protected areas below treeline.  Consider overhead hazards and closely monitor for signs of instability, such as shooting cracks, below treeline. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2

    Snowfall from the past week has accumulated on weak faceted layers near the ground—most prevalent on the north half of the compass and some higher-elevation southeast aspects. Sensitive persistent slabs exist where favored snowfall or wind loading overlaps with these weak layers, most commonly near and above treeline. The problem is possible below treeline on the north half of the compass.  Shooting cracks and collapses are clear warnings to stick to slopes under 30 degrees.  Be cautious of overhead terrain, as both remote triggering and natural avalanches are on the menu today.  You can avoid persistent slabs by traveling on slopes that were bare ground through November.  

    A trio of natural avalanches that likely failed on weak layers near the ground. Purple Ridge. 12/4 

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Strong west to northwest winds are drifting new and recent snow into reactive slabs on leeward features. Fresh wind slabs are forming below alpine ridgelines, in cross-loaded gullies, and behind abrupt terrain breaks; they could also form in exposed low elevations as winds blow down valley.  Avoid steep slopes where you find thicker, stiffer drifts of snow. Blowing snow and shooting cracks are clear warning signs. Look for wind-eroded or wind-sheltered terrain to avoid the problem.

    Shooting cracks above a windloaded east facing slope of Purple Ridge. 12/5

Avalanche Discussion

If you're just getting caught up on our snowpack setup, check out our weekly snowpack summaries published every Friday. 

When combining both snowfall and windloading, today’s storm is the biggest thump our snowpack has taken since the 11/30 facet layer was buried last Sunday. Each of last week’s modest storms produced natural avalanches on this November drought layer, and with stronger winds and more load today, we expect that pattern to continue.  Avalanche activity is expected to increase in both size and frequency compared to earlier this week.  

The higher danger rating in the Northwest Mountains reflects more continuous existing slabs, along with heavier snowfall today, creating broader potential for large persistent slab avalanches. In both forecast zones, wind-loaded slopes will be the most dangerous, while sheltered terrain will hold fewer and smaller slabs. However, the switch could flip in sheltered terrain today: watch for the soft, incohesive snow of earlier this week quickly transitioning into tender slabs—something we highlighted in our recent field video.  If you’re hunting for steep powder turns out of the wind, monitor for changing conditions as the snow stacks up. Look for signs of instability and seek feedback from steep but low-consequence test features.  When in doubt, head to those wind-protected slopes that were grassy and bare of old, weak snow at the end of November, or move to mellow slope angles.  

Upcoming Events: 

  • Avalanche Awareness Night: Saturday, December 6th at the Center for the Arts. Doors at 5, show at 6:30.
  • Beacon Brush-Up: Sunday, December 7th, 9 am - 2 pm at the Community School

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