Avalanche forecast

Northwest 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

Strong winds and snowfall raise the avalanche danger throughout the day.  Dangerous conditions exist on leeward terrain features, with natural avalanches possible.  As storm totals near or exceed 10 inches, avalanche concerns could spread into wind-protected slopes.  Avoid wind-loaded terrain features and carefully monitor the new snow for signs of instability in wind-sheltered areas.  Cracking in the snow is a clear sign you have found unstable conditions.  There is a chance for avalanches to break on older weak layers on heavily drifted alpine slopes facing northwest - north - northeast.

Avalanche problems

  • Storm Slabs

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

    New snow and wind will create dangerous avalanche conditions in the storm snow.  Avalanche problems will be larger and more sensitive on leeward terrain near and above treeline elevations as strong southwest-to-west winds deposit snow.  The powerful winds may drift snow in unusual places below treeline.  As snowfall accumulates throughout the day,  slab avalanche conditions may spread into wind-sheltered locations, particularly during periods of high-intensity snowfall.  Avoid travel in wind-loaded terrain and carefully assess sheltered areas before entering steep terrain.  Cracking or collapsing indicates unstable conditions within the storm snow.   

    Expect to trigger a similar avalanche on wind-drifted terrain today.

    Photo: Evan Ross

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    The distribution of the current persistent slab avalanche problem has narrowed after last week's heat wave.  Weak layers in the upper snowpack from early March or near the ground remain a lingering concern.  Don't expect to see any feedback or obvious red flags from this avalanche problem. The problem may become more sensitive due to wind loading from the current storm, especially on slopes with an unusually shallow snowpack from wind erosion or previous avalanche activity. Persistent slab instabilities are even more isolated below treeline, but you should still stay alert on very steep or unusually shallow slopes.   

    A large persistent slab on Gothic triggered by a shallower wet avalanche on 3/25.

Avalanche Discussion

Less snow accumulated overnight than expected, but a foot of snow may stack up throughout Tuesday.  However, the wind arrived in full force, with gusts hitting 96 miles per hour along Scarp Ridge.  The reduced snowfall leaves some uncertainty about the formation of slab avalanche problems in wind-sheltered terrain. Still, the wind definitively points to dangerous conditions on wind-loaded slopes.  Given the strength of the wind, you may encounter drifts in odd places at lower elevations in addition to the typical spots below cornices and ridgelines or pressed into gullies.  Heavily drifted slopes will have enough new snow to work with to produce large avalanches, particularly at upper elevations.

Older weak layers associated with the Persistent Slab problem could reawaken on isolated slopes with extensive drifting.  An avalanche in the drifted storm snow could 'step down' to deeper weak layers.  The most suspect slopes will be on terrain with highly variable depths or shallow snowpacks.  The persistent slab problem in the Southeast Mountains is more worrisome due to thinner slabs above the weak basal layers, but the problem can't be ruled out in the Northwest Mountains.  Today's wind-loading patterns will drift snow onto the most suspect slopes for the Persistent Slab problem, making it an easy call to simply avoid that terrain.  

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