Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

You will likely trigger an avalanche on most slopes facing west through north through east.  Each day for nearly two weeks, we have documented human-triggered avalanches, with two close calls on Mount Axtel and along Kebler Pass earlier this week.  The frequency of collapsing/cracking in low-angled terrain has lessened recently, so don't rely on these signs of instability to alert you to the dangerous snowpack on nearby steep slopes.  You can reduce your chance of an avalanche accident by selecting terrain with slope angles less than 30 degrees on suspect aspects or by choosing wind-sheltered southerly slopes.

Avalanche problems

  • Persistent Slabs

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

    Slabs averaging 1 to 3 feet thick in sheltered terrain and larger in wind-loaded terrain will be most sensitive to triggers where they formed over fragile facets and collapsible crusts on west, north, east, and high southeast aspects.  Slab behavior is becoming more challenging as slabs stiffen and thicken, with dozens of recent remote triggers and slabs propagating wider across terrain features.  You may not see obvious warning signs, such as collapses or cracking, before triggering an avalanche. You can reliably avoid the problem on slope angles less than 30 degrees without steeper slopes above you.    

  • Wind Slabs

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

    Strong northerly winds developed on Wednesday night and will likely last through Thursday.  Previous winds hardened snow surfaces on many alpine terrain features, but soft snow is available for transport at mid and lower elevations.  The distribution rose above reflects where you are most likely to encounter a fresh Wind Slab based on snow available for transport.  Carefully read the snow surface for previous and ongoing drifting and avoid those terrain features.  These may form below ridgelines, in concave gullies, or behind abrupt changes in terrain shape.

    An example of terrain where you may find a freshly formed Wind  Slab tucked below a near treeline ridge.

Avalanche Discussion

Two weeks of dangerous conditions are unusual even by 'Colorado' snowpack standards.  I struggle to remember a season in my 20 winters around Crested Butte when dangerous conditions persisted for so long.  This is certainly a unique event by any measure.  Several more avalanches were remotely triggered on Wednesday, which extends the human-triggered avalanche streak to 13 consecutive days.  Conditions remain primed for an accident in our area, and sadly, a fatal avalanche accident occurred in the northern San Juan mountains on Tuesday.

The current conditions are a product of a prolonged dry spell during December.  This dry spell caused the snowpack to facet and form well-developed weak layers on west through north through east slopes.  Adding to the problem was the extensive natural avalanche cycle around Thanksgiving.  This natural avalanche cycle left many steep slopes very shallow and allowed for even worse facet development during the dry spell.  The dangerous conditions started around Christmas once stormy weather formed slabs above the well-developed weak layer.  

The snowpack has shown very little improvement recently, hence the continued human-triggered avalanches.  The trickiest part of our current predicament is that signs of instability have diminished in some areas, but certainly not all, as observers reported rampant collapsing in the Copper Creek and Cement Creek drainages.  Fewer signs of instability may result from a deeper snowpack in non-avalanche terrain, folks following well-established skin tracks where collapsing occurred from earlier groups, and skin tracks through a densely forested snowpack that is often less troublesome than nearby open slopes.  Don't take the lack of cracking and collapsing as a sign to step out into steeper terrain on suspect aspects. 

Patience and a disciplined approach to terrain selection will reduce your risk of an avalanche.  Playing on steep avalanche terrain highlighted by the Persistent Slab rose is a deadly game of chance, and unfortunately, the 'snowpack' deck is heavily stacked against you.  If you want to ride on steeper terrain, you can find a less problematic snowpack on sheltered, southerly slopes; as a bonus, many sunny slopes out of the wind offer nice riding conditions.

 

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