Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

The storm track is back and avalanche danger is on the rise!  It will be easy to trigger slab avalanches in wind-loaded terrain, and some avalanches could run naturally.   In wind-sheltered terrain, use sluff management techniques where the upper snowpack is weak and cohesionless: some could grow larger than expected.  Stay alert for cracking in the snow to warn you of slab instabilities or changing conditions.  Avalanche conditions will become increasingly dangerous overnight and into this weekend with much more snow on tap.  

Avalanche problems

  • Wind Slabs

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

    Fresh snow is adding fuel for continued wind transport at higher elevations.   Winds have shifted from the north to west and are forming wind slabs on the lee sides of ridgelines and cross-loaded terrain features. In some areas, wind slabs are forming over a notably weak interface and will be easy to trigger or could entrain additional loose snow as they run downslope.  Most slabs are relatively small; slopes with large fetches or in long-running terrain could be large.  Look for evidence of recent drifting to identify the problem.  Wind slabs will feel thicker and denser and have a smooth, rounded appearance.  You can avoid the problem by traveling in wind-protected or wind-eroded terrain.  

    Natural wind slab avalanches on a cross drifted slope in Redwell Basin that ran around 1/7.  More snow and more wind today means more avalanches like this.  

  • Loose Dry

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

    New snow is adding volume to facet sluffs that have been ongoing for the past week or so, and in a few wind-sheltered areas, soft slabs may be starting to form.  In most wind-sheltered terrain, the new snow will break as a point-release avalanche that is small and relatively easy to manage. Where the snowpack is unusually weak or shallow, new snow instabilities can entrain most of the snowpack and become large and difficult to manage.  If your skis or sled are sinking deep into a cohesionless, sugary snowpack, you've found deeper gouging issues. Dry loose avalanches are most common and larger in wind-protected terrain on the north half of the compass.  You can manage the problem by riding off the fall line or pulling out of the way to let your sluffs go past you. You can avoid the problem by riding on lower slope angles less than about 35 degrees. 

    Dry Loose avalanches start from a point, before growing in size. Don't be that tree and move to the side. In sustained steep terrain, this problem may grow large and become difficult to manage, especially where sluffs start gouging deep into the snowpack.   

Avalanche Discussion

"To slab or not to slab, that is the question," asked by a modern-day Hamlet looking to make steep turns in Crested Butte.   Our New Year started with an atypically shallow, weak, and sluffy snowpack, eager to bring future slabs of new and drifted snow down the mountainside with it.  This week, slab avalanches have been confined to wind-drifted slopes, while wind-protected slopes continue to produce sluffing in our faceted snowpack.  Our avalanche visualizations page shows the uptick in wind slab activity associated with Sunday's northerly wind event.  We expect activity to increase again today with a change in wind direction (from the west now) and with an additional 4 to 8" of new snow for transport. Given the small amounts of snow available for transport this week, most wind slabs have been relatively small, with a few thicker slabs in heavily drifted slopes, and a few larger avalanches in longer-running terrain.  

Will today's new snow be enough to form slabs in wind-protected terrain?  Most likely not, with some uncertainty in areas that pick up 6" or more.  Minor loading in the past week along with cold temperatures are generally keeping slab formation at bay below treeline and in wind-sheltered near treeline slopes.  That will start to change soon; perhaps on a few slopes today, but more likely, on numerous slopes by tomorrow and in most terrain by the end of the weekend.   This video demonstrates how newly forming slabs have the potential to grow larger than expected once they start moving downslope and entraining old snow.  This avalanche in the Terminator Chutes is a great example of how either a shallow wind slab or sluff grew to a dangerous size as it entrained old weak snow running down sustained steep terrain.   Newly forming slabs are fairly easy to recognize right now: look for cracking in the snow and monitor the snow surface for signs of freshly drifted and denser-feeling snow.  Even if you don't find a slab, ride cautiously and defensively in steep terrain because a facet sluff might be on your tail, growing larger as it gouges through our junky snowpack. 

Although dangerous conditions are developing on wind-loaded slopes today, there are still plenty of options to choose avalanche terrain with small and manageable hazards.  Options for safe travel will continue to diminish in the coming days as more snow starts to pile up and slabs become larger and more widespread.  If weather forecasts verify, we are expecting dangerous conditions at all elevations tomorrow and a widespread natural avalanche cycle to ensue this weekend.   Hamlet sums it up well: "If it be not now, yet it will come: the readiness is all."

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