Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Early this week, a northwest wind event formed slabs of varying thickness in wind-affected terrain at higher elevations. These slabs have become stiff and stubborn to trigger. The specific terrain for this avalanche problem will be on the lee sides of ridgelines, below steep wind-loaded rolls in the terrain, and on cross-loaded gullies. Consider avoiding consequential slopes where you see or feel thicker deposits of windblown snow. 

Avalanche problems

  • Persistent Slabs

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

    During the first half of the week, a northwest wind event combined with an average of 4" to 12" of new snow, and created hard slabs on various wind-affected terrain features. On west to northerly-facing slopes, these slabs formed on a few cross-loaded terrain features. While on easterly to southerly facing slopes, these slabs are more commonly located below ridgelines and steep wind-effected rolls in the terrain. 

    In isolated areas, an avalanche could release several feet deep on weak layers near the ground. These areas would need to retain the full-season snowpack without that snowpack having been removed by the widespread avalanche cycle that occurred in late November. 

    This old wind slab ran off the Summit of Mt Owen. Similar avalanches could be triggered today, even on smaller wind-loaded features lower in the terrain. 

Avalanche Discussion

Wind slabs that formed earlier this week have now been added to a persistent slab avalanche problem. These hard slabs have already become difficult to trigger, but the potential threat will remain for an extended period where they formed over weak faceted snow. On southerly facing slopes, these slabs appear to be healing where they formed over sun crusts, but a little more time and targeted data are needed for verification. 

The old persistent slab avalanche problem that has been with us since Thanksgiving has become very isolated and unlikely to trigger. The last documented persistent slab avalanche to release below the Thanksgiving slab was 11/28 in the Northwest Mountains and 12/5 in the Southeast Mountains. The hard slabs that formed earlier this week are now taking the persistent slab spotlight as a comparatively more likely avalanche problem. In isolated areas where the snowpack is still retaining the Thanksgiving Slab, we can't complely rule out an avalanche releasing severl feet deep.

Looking ahead, we can expect a new round of wind slabs to begin forming on Friday afternoon with the arrival of our next small storm. As new wind slabs form, there will be the possibility of those slabs stepping down into the older generation of slabs that formed this week. In wind-sheltered areas, the newly accumulating snow will slowly starts to add volume for loose dry avalanches where the snowpack consists of all weak snow on many northerly-facing slopes. 

Regions covered