Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Mon
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Slopes on the north half of the compass and wind-drifted terrain, regardless of aspect, remain dangerous today.  Weak snow below the recent massive storm on northerly aspects continues to be very sensitive to the weight of a person and can be remotely triggered from below or from adjacent slopes.  Northwest to west winds drifted snow at upper elevations and created sensitive slabs on leeward features.  You can reduce your risk by choosing slopes less than 30 degrees on northerly-facing terrain and exercising caution around sunny drifted terrain.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–2.5

    2 to 4-foot slabs have formed over a very weak foundation. That weak foundation exists on slopes that face the north half of the compass. These avalanches could still run naturally where wind-loading occurs and will be sensitive to human triggers. You can also trigger this avalanche problem from low-angled slopes connected to steeper terrain.  Slabs continue to settle and stiffen which means you can remotely trigger an avalanche from a distance and avalanches may propagate much wider than you expect.

    This widely propagating persistent slab ran naturally during the recent storm on Purple Ridge

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Certain
    Tamaño
    1–2

    Recent northwest to west winds drifted snow to leeward terrain features with east and southeast slopes directly in the crosshairs.  You can find other areas of Wind Slab formation on cross-loaded terrain features like in windward gullies or behind breaks in terrain.  Use caution around upper elevation features where you identify wind deposited snow or feel stiff snow textures.  

    This photo shows several wind slabs that ran recently on Mt. Owen.  

Avalanche Discussion

Great visibility yesterday gave observers an opportunity to take stock of the natural avalanche cycle that transpired during the last storm.  Take a look through the observations page to get a clearer picture.  As expected, slopes on the north half of the compass at all elevations produced extensive avalanche activity on drifted and wind-sheltered terrain.  Some slopes ran very early in the storm with the evidence buffed out by later snowfall while others held on towards the end of the storm leaving stark crowns.  On sunny aspects, the avalanche activity pointed towards wind-loading as the critical factor hence the transition to the Wind Slab avalanche problem listed today on east and southeast terrain at upper elevations.

Continue to manage northerly-facing terrain very conservatively.  Choosing low-angled terrain that is not below, or connected to steeper northerly slopes will serve you well.  Anticipate that avalanche hazard to diminish at a very slow pace in the coming days due to the very weak nature of the old snow beneath the slab.  Avalanche conditions will improve at a quicker pace on drifted sunny slopes, but extensive drifting yesterday will keep upper elevation sunny slopes as suspect terrain for triggering an avalanche.  

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