Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

New snow and violent winds are creating dangerous avalanche conditions on wind-loaded slopes.  In leeward terrain, natural and triggered avalanches involving today's drifted snow will be common, and there is potential for avalanches to step down and produce a much larger avalanche.   Carefully assess the snowpack before riding in steep, wind-protected terrain, where the danger is lower but buried weak layers are also being stressed.  

Avalanche problems

  • Wind Slabs

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

    Strong southwest winds are drifting the new snow into sensitive slabs at all elevations.  They'll be largest and most widespread near and above treeline.  Avoid steep terrain where you find more than about 10" of dense, drifted snow.  Wind slabs will be most common below leeward ridgelines, in gullies, and behind rollovers, although they may form in unusual locations today.  Cracking underfoot or blowing snow signals potential danger. 

    Example of a triggered wind slab from last week's windy storm.  

  • Persistent Slabs

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

    Over the past few weeks, we have observed an infrequent but continuous pattern of large avalanches or collapses failing on weak, faceted layers deeper in the snowpack.  These have been most common during loading events like today's. Persistent slab activity has been most problematic on wind-loaded terrain this month, though issues are developing in some areas below treeline.  Carefully assess the snowpack structure and give yourself a margin for error in handling this problem because there is a high degree of variability across the region and on different aspects.  Some recent examples include naturals on Express Creek and Carbonate Hill, and a remotely triggered avalanche on Mt. Emmons. 

    2/23:  A large collapse and shooting cracks failed on weak, faceted snow about 3 feet deep on Mount Emmons.  Don't expect to get feedback like this before triggering an avalanche, but it's a clear sign of danger if you do.  

Avalanche Discussion

The first in a series of storms is slamming into the Elks this morning and the avalanche danger will rise through the day and into tomorrow.  Today's issues are most commonly driven by intense wind loading. Wind speeds nearly passed the 100mph mark this morning on Scarp Ridge, and they are certainly mixing into all elevations today drifting the new and recent snow.  Expect easily triggered and natural wind slabs today to be larger and more widespread as you gain elevation. 

Unfortunately, today's travel advice isn't as simple as "avoid wind loaded slopes".  Persistent weak layers in the upper and lower snowpack have been getting stressed during the active weather in the past few weeks.  The persistent slab problem has recently produced avalanches and obvious signs of instability on both wind-loaded and wind-protected terrain of the Southeast Mountains. One layer of concern is a layer of facets or faceted crusts up to a few feet deep, which has produced collapses and avalanche activity on Mount Emmons (Example A, Example B).  We have yet to observe collapses or avalanches on these layers in the deeper snowpack of the Northwest Mountains.  However, we have found a few concerning pit results in recent weeks, such as this propagating test yesterday in the Anthracite Range.  Given the significant loading this week, we recommend carefully assessing the snowpack and/or choosing more conservative terrain to manage for potential surprises of avalanches breaking deeper than expected, similar to this close call during last week's storm.  In the shallower parts of the Southeast Mountains, there is also the isolated threat of avalanches breaking on weak layers near the ground, exemplified by this unstable test result near Mt. Whetstone.  

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