Bulletin d’avalanche

Northwest Mountains

Crested Butte Avalanche Center
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Danger d’avalanche

Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Périmé — ce bulletin a expiré 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Persistent weak layers that were created during the early January dry spell, have now been loaded by the recent storm Friday into Saturday. The most dangerous avalanche conditions exist where SW winds have further drifted that snow onto the lee sides of terrain features at near and above treeline elevations, and where the recent snow is settling into a slab on the general northern and eastern half of the compass. Conservative decision making is essential for the most dangerous areas. Take the time this morning to make a well thought out plan, so you can find the best riding conditions in the least dangerous areas. 

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2

    There are two persistent weak layers of concern buried in the snowpack. The first is buried in the upper snowpack about 14 to 18" (35-45cm) deep at all elevations, and considerably deeper on wind-loaded terrain. The 2nd persistent weak layer was buried in early December and located near the bottom of the snowpack. This December weak layer could produce hard slab avalanches at near and above treeline elevations that would instantly become large and destructive. 

    A persistent slab avalanche problem may give you obvious signs of instability such as large collapses, or it may give no warning signs at all. These avalanches could propagate widely across the terrain, or be triggered remotely, such as from a lower angled slope connected to a steeper slope. 

    Example of a large natural avalanche that released deeply into the snowpack earlier this winter.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    This soft slab avalanche problem will require management, or evaluation, around the compass and at all elevations. Yesterday we saw fewer than expected results from this avalanche problem. Areas that lacked a slab yesterday, may have seen settlement in the recent storm snow and have formed a slab for today. This avalanche problem would release in the upper 1 to 2 feet of the snowpack. A resulting avalanche could further grow in size on large terrain features where they could entrain additional snow. This avalanche problem will be most suspect on cross-loaded terrain features and slope angles nearing 35 degrees or steeper. 

    Storm slab avalanche reported 1/23 out Kebler Pass in the Anthracites.

Avalanche Discussion

The last storm was the first real test on a variety of nasty persistent weak layers formed in early January. We are calling this layer of concern the 1/19 interface. Since 1/19, we saw steady accumulating snow in the NW Mountains, and dribs and drabs for the SE Mountains. Then last Friday the main event began. Storm totals since Friday are a little over an 1" of SWE for the NW Mountains, and under an 1" of SWE for the majority of the SE Mountains. All that snow and water weight came in with a strong southwest wind event. Intense wind-loading was observed throughout Saturday, and some upper elevation slopes were likely teetering on the edge for natural avalanche activity. With another round of snow today, natural avalanches again remain possible, primarily for near and above treeline elevations.

If you scroll through the observations tab, you will see a few avalanche results from yesterday. Saturday was surprisingly quiet for such a good loading event on an absolutely junky and weak snowpack. I have no trust in this current snowpack and will again enjoy the fresh snow with a conservative mindset today. If you don't find signs of instability, don't let yourself get sucked into bigger terrain. Give the snowpack time to adjust to the new load, don't trust those persistent weak layers. If you keep that mental game strong, you can have a really fun day out in the backcountry and enjoying the new snow.

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