Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You can trigger a large avalanche on slopes facing the north half of the compass.  Avalanches can fail several feet deep on a well-developed weak layer.  Signs of instability like cracking and collapsing have become less frequent so the snowpack may not warn you of the lurking danger.  Careful snowpack assessment is necessary if you intend to play on steep northerly and easterly terrain features.  You can choose lower angled slopes or head to southerly aspects to reduce your chances of triggering a large avalanche.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    On northerly and easterly aspects, you can trigger a dangerous slab avalanche that breaks up to several feet thick on weak faceted snow that was buried last month. Slabs can be triggered remotely from below or adjacent slopes. Collapsing and cracking are clear signs of instability, although direct feedback on this problem has become less frequent. The distribution of this avalanche problem is highly variable from one steep slope to the next due to past avalanche activity. In some cases, the slope may have avalanched in late February and has yet to fill back in with enough snow to form a new slab. In other cases, the slope may have filled back in with a new slab or it has yet to release to begin with. Where the avalanche problem exists, you may be able to decrease your chance of triggering by avoiding trigger points and areas where the slab thins. When en doubt, head for lower consequence terrain or slope angles in the lower 30-degree range and less. 

    3/12:  A large persistent slab that likely failed on last Friday night from wind loading.  

Avalanche Discussion

The Persistent Slab problem requires your full attention.  Avalanche conditions remain tricky on slopes facing the north half of the compass.  The February weak layer has been buried by 2 to 5 feet of snow over the past few weeks.  Slopes, where the slab is relatively thin, are more concerning than where the slab is thick and uniform.  In the Northwest Mountains (observation from the Ruby Range), it is more common to find a thicker slab and in the Southeast Mountains, you are more likely to find a thinner slab.  Even areas with a thicker slab could produce a dangerous avalanche, it is simply less likely.  The tricky part is that wind redistribution, previous avalanche activity, and variations in snowfall across the forecast zones will have an impact on slab thickness/weak layer characteristics and therefore the likelihood of you triggering an avalanche.  Safely recreating on steep slopes with a northerly or easterly component requires you to make careful assessments of the slab and weak layer.  Do NOT expect the snowpack to provide you with direct feedback, like cracking and collapsing, to alert you to the danger.  The simplest solution is to choose lower angled slopes or head to southerly aspects where the Persistent Slab problem is unlikely to be found.

The CBAC is saddened to share news of an avalanche fatality yesterday in the Northern San Juan Mountains.  You can read the preliminary report here.  Our sincere condolences go out to all those impacted by this accident.

And don’t forget, the 48th annual Al Johnson Memorial Telemark Ski Race is this Saturday, March 19 at Crested Butte Mountain Resort. A portion of the proceeds from the race will go to the Crested Butte Avalanche Center. Additional Information can be found here.

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