Lawinenlagebericht

Northwest Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Kernpunkte

A break in wind-loading and snowfall over the last couple of days has allowed the avalanche danger to drop again. While many areas have a low likelihood of triggering a slab avalanche, if you push into steep and/or extreme terrain you could still trigger an avalanche. Last Wednesday skiers triggered a small slab on a steep east-facing slope of Mt Axtell. That small avalanche further ran for 1,200 feet through continued extreme terrain and accumulated mass on its descent. Riders yesterday observed small wind slabs producing some cracks. Today your travel advice will require assessment for shallow slabs on steep slopes, and regrouping areas clear of the very unlikely potential for avalanches releasing deeper in the snowpack. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1

    Tuesday Night into Wednesday, southwesterly winds were gusting into the 80's at 12,000ft, and averaging 10-20mph at 11,000ft. These winds combined with about 4 to 7" of fresh snow to form wind slabs on the lee sides of ridgelines and cross-loaded terrain features. Most of these slabs are small, while drifts up to around a foot deep have been measured. This avalanche problem has become stubborn to human triggering and is becoming more isolated in the terrain. Some of these slabs formed over persistent weak layers and could still be triggered on steep slopes. Steep slope angles could loosely be defined as upper 30 degrees and steeper. 

    Example of a shallow wind slab from the archives.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–3

    Hard slabs that break 2 to 6 feet deep on weak layers near the ground remain a low likelihood concern.  The problem has become increasingly stubborn and isolated, and it has been several weeks since we have observed a persistent slab avalanche.  There is lingering uncertainty that skiers or riders can trigger a large avalanche from the margins of the slab where it thins out,  especially at higher elevations.   Cornice falls can also trigger large avalanches.  You can reduce your risk by traveling where the snowpack is deeper and more uniform.  Regroup in safe zones that are clear of unusually wide and long-running avalanches.  

    An example of a thick, hard persistent slab that released naturally in mid-February.

Avalanche Discussion

Earlier this week we expected to see some accumulating snow through each 12hr period heading into today. Unfortunately, that continued light snowfall didn't happen. Given the lack of new snow and the recent calm winds, the avalanche danger has been on the decrease. Each time we make the drop to LOW avalanche danger, forecasters worry that people will forget that they can still trigger avalanches. In the big picture, those avalanches are unlikely to trigger. However as riders push into more aggressive terrain, they will be testing the waters for where you could still trigger a slab avalanche. Riding steep or previously wind-loaded terrain will still require assessment, and if you travel blindly, or make no assessment, you could get yourself into trouble. 

Heading into the weekend the avalanche danger will be back on the rise. There are several persistent weak layers near the snow surface that will become concerning with more snow. If we see enough snow by Sunday or the end of the weekend, avalanches breaking deeper into the snowpack may also become more concerning. This recent video highlights these topics. Keep your eye on the avalanche bulletin as we continue to assess just how this weekend's storm is going to impact our area. 

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