Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

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

Lo esencial

Avalanche conditions are no joke today. Natural avalanche activity remains possible in areas with active wind loading. The avalanche size is large and potentially deadly if you were caught. Some avalanches can further be remotely triggered from low-angled terrain connected to steeper terrain. There are areas to enjoy the new snow today, but high confidence in identifying those areas will be required. Otherwise, let these avalanche problems settle out and avoid avalanche terrain. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–3

    Large and dangerous avalanches breaking into old weak layers are a real concern for both human triggering and natural avalanche activity today. Any natural avalanche activity is expected to be confined to terrain with active wind-loading, while this avalanche problem will be the most sensitive to human triggering on northerly to easterly facing slopes. Slabs are typically 2 to 3 feet thick below treeline and grow larger and even more dangerous in wind-loaded terrain; a few could be up to D3 in size. These avalanches have the potential to break wider than you expect, they can be triggered from flat slopes below steep terrain, and avalanches could further run well into low-angled runout zones. 

    This is a 2.5-foot thick slab that was remotely triggered yesterday in Washington Gulch.

  • Storm Slabs

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

    Storm totals are approaching three feet in the Northwest Mountains. Avalanches breaking within the storm snow will be the most sensitive to triggering near wind-loaded terrain features. This avalanche problem will be less reactive in wind-sheltered areas. Where this avalanche problem overlaps with the persistent slab avalanche, a triggered storm slab could further release a larger persistent slab avalanche such as this observation from yesterday. 

    A storm slab was triggered on Saturday, below treeline, in the Slate River drainage. 

Avalanche Discussion

Welcome back winter! December has arrived with the winter storm we really needed to get things going. Let's look at snow totals and then see how things are shaping up. Last night's snow totals were only an inch or a couple, but the weekend's snow totals are impressive. Since 11/30, the NW Mountains have picked up 2 to 3 feet of snow while the SE Mountains picked up 1 to 2 feet of snow on average. As for total water, Schofield Pass is showing 1.7" SWE, and Butte Snotel is 1.4" SWE. We are looking at SWE increases of around 30%. 

A notable natural avalanche cycle is expected to have occurred over the weekend. Poor visibility yesterday only allowed for a few avalanche observations to come in. We expect many more avalanche observations to come in today with the clearing weather. A break in the loading occurred overnight and this has allowed the avalanche danger to drop slightly, and end the more widespread natural avalanche cycle that is expected to have occurred. Any natural avalanche activity today will be more specific to areas with active wind loading. Wind speeds are forecasted to increase slightly this afternoon and the potential for more natural avalanches will be a real threat to watch out for. 

Obvious signs of instability will also have decreased today. Shooting cracks and a collapsing snowpack help keep our decision-making and terrain selection in check. In some areas, the slabs have become thick, and they may be scary quiet when it comes to the obvious signs of instability. If you experience these conditions today, don't let the lack of those warning signs lure you into more aggressive terrain choices. Instead, look big picture, and give the avalanche problems more time to settle out. 

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