Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 7 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

The danger slowly decreases during the current dry period; however, there is a lingering chance for you to trigger a slab avalanche on previously drifted terrain at upper elevations.  You can reduce the risk of a slab avalanche by steering around features that have been previously drifted or choosing wind-sheltered terrain.  Dry Loose avalanche conditions have developed on wind-protected northerly slopes steeper than about 38 degrees.  You can manage this problem by riding lower-angle slopes or using sluff management techniques.

Avalanche problems

  • Persistent Slabs

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

    Persistent slab avalanche concerns mostly involve slabs of drifted snow that formed over the facets and faceted crusts from the January drought.  These slabs, typically 1 to 3 feet thick, are hard and stubborn to trigger. Requiring heavier loads, or light loads in just the right location to trigger. There is isolated potential for a slab failing in the upper snowpack to step down and trigger a deeper, harder avalanche near the ground. Searching for wind-eroded and soft wind-dappled snow will help reduce your exposure to this avalanche problem, while the best way to avoid it is by riding in wind-sheltered areas. 

    An example of some hard wind-drifted slabs on the eastern side of Cinnimon Mountain. 

  • Loose Dry

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

    Dry Loose avalanches have developed where the snowpack is below average in depth, typically on the bed surfaces of old avalanches. While the average snowpack in the NW Mountain forecast area is still strong enough to prevent these sluffs from occurring. A triggered sluff will be relatively small, but where they run through sustained steep terrain, they can become larger in size and push you into more hazardous terrain features, such as trees, or pile deeply in terrain traps.  You can manage the problem through lower-angle terrain selection or sluff management techniques.

    A long-running sluff that was skier-triggered on an old avalanche bed surface. Birthday Bowl, Schuylkill Ridge. Photo: Miles Morris

Avalanche Discussion

Approximately 11 days have passed without notable loading, resulting in a gradual decline in avalanche hazard.  The avalanche danger remains MODERATE at upper elevations, with the travel advice being to steer around terrain features with evidence of previous drifting.  The likelihood of the Persistent Slab problem dropped to 'unlikely' given the time since the loading event.  There is some lingering concern that if you did find the wrong place on the wrong slope, the avalanche size could be large (D2).  You are most likely to encounter old drifts below ridgelines, in concave gullies, and cross-loaded behind ribs or tree fences.  Drifts often feel stiff and hollow, unlike the soft textures you find in other places.

The best riding conditions can be found on wind-sheltered northely slopes, but evidence is clear that you will need to manage Dry Loose conditions on steep slopes.  Although the size of this predictable problem is typically small, being pushed into rocks, trees, or terrain traps could be dangerous.  As we move deeper into this dry period, the snowpack continues to weaken, and the potential size of loose avalanches slowly increases.   It's fairly easy to predict where these will occur by simply investigating the snowpack.  These areas will typically have boot penetration to the ground and ski/board penetration roughly halfway through the snowpack.

A notable warming trend begins today with even warmer temperatures on Thursday and Friday.  Wet snow avalanche problems may develop on the southern half of the compass, particularly on Thursday and Friday.  Low-elevation sunny slopes went through a melt/freeze cycle last weekend, and upper-elevation sunny terrain is quite stiff and hard from previous winds.  These two factors may reduce the amount of wet avalanche activity.  A few wet avalanches were documented last weekend (Mount Owen, Mount Bellview), and it's probable that a few more fail in the coming days. 

 

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