Avalanche forecast

Gunnison

Crested Butte Avalanche Center
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Avalanche danger

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

Recent wind loading has caused dangerous conditions at higher elevations, evidenced by a pattern of large to very large persistent slab avalanches breaking on leeward slopes near and above treeline.  Choose simpler, more conservative terrain as you gain elevation.  Slab instabilities are typically thinner and less common in wind-sheltered terrain below treeline.   Wind-protected terrain on the southern half of the compass offers the safest travel.  

Avalanche problems

  • Persistent Slabs

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

    In the past several days, we've observed large slab avalanches breaking on weak layers in the upper snowpack and near the ground near and above treeline.  Feedback on the problem will be variable and infrequent. These issues are most concerning on windloaded terrain on colder, shadier aspects highlighted by the persistent slab rose.  Avoid wind-loaded slopes and terrain with thin, variable snow depths to reduce your risk.   Persistent slab instabilities are more isolated below treeline, but can exist on the northern half of the compass. Southerly aspects typically lack the problem.  

  • Wind Slabs

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

    Today's increasing southwest to west winds could re-ignite wind drifting to form shallow slabs of drifted snow at higher elevations.   Watch for blowing snow or fresh wind drifts forming below corniced ridges or in cross-loaded terrain features to warn you of the problem.   Older, thicker wind slabs formed from Tuesday's strong winds.  Although these are mostly healed up now, stay alert for isolated exceptions.  You can avoid wind slabs by traveling in wind-sheltered terrain.  

    A shallow Wind Slab from earlier this week below a leeward ridgeline.  

Avalanche Discussion

The snowpack is still recovering from Tuesday's dramatic wind-drifting event, which stressed weak layers in the upper snowpack and near the ground.  Our forecaster videos of remotely triggered avalanches on Schuylkill Ridge yesterday and Elkton Knob on Sunday demonstrate the upper snowpack's weak layer of concern: a layer of small-grained facets buried a week ago.  In the past week, this layer has been most active on the northeast quadrant of the compass, especially near treeline.  Those slopes held the right combination of a better-developed and preserved weak layer stressed by more snow and recent wind-loading.  The layer has produced avalanches below treeline, as recently as last Saturday in Elk Creek.  Many wind-sheltered slopes in the Southeast Mountains lack sufficient snowfall to form a slab over the layer. In the Northwest Mountains, slabs exist above the layer but have shown improved results in stability tests in the past few days.   Because this layer is relatively small-grained, it will continue to adjust to recent loading and gain strength faster than our usual weak basal layers. Thus, the likelihood of triggering an avalanche on this layer will decrease through the rest of the work week unless we see more productive wind loading today than expected.  Most avalanches breaking on this layer have been D2 to D2.5 in size - demanding extra caution and a more conservative mindset as you gain elevation.  

The large avalanches on Axtell and Scarp Ridge likely broke on deep weak layers near the ground, similar to this very large avalanche off Schuylkill Ridge last weekend.   These avalanches share some characteristics:  steep, windloaded, shady terrain that has previously avalanched multiple times this season, thus holding a shallower and weaker snowpack.  Triggering an avalanche like this is a lower-likelihood, high-consequence concern on the north half of the compass.  Slopes with snowpacks that vary from thin to thick are most suspect for human triggering, and these ingredients are most common near and above treeline in wind-affected or rocky terrain.  

Events:  CBAC is teaming up with CBSAR, Snotrackers, and the USFS for our next trailhead day this Sunday at Kebler TH.  Snotrackers will be grillin' glizzies.  🌭

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