Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

If we don't get snowstorms in 2021, at least we got a sweet wind storm! Last night NW wind gusts hit 90mph at 12,000ft and 30mph in the valleys. Most of that blowing snow should have continued onto Kansas, but we can't rule out some form of recent wind-loaded at all elevations. The primary avalanche problem remains persistent slab avalanches where you find a cohesive slab resting above weak old snow. The most suspect areas for triggering this avalanche problem will be recently wind-loaded terrain. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    On or near steep, leeward terrain features, you can trigger persistent slabs 1 to 3 feet thick that fail on weak snow near the ground.  Persistent slabs often surprise even the most experienced travelers: They give irregular feedback, they can propagate unusually wide distances, and they can be remotely triggered from below or adjacent to the slope.  To avoid this problem,  choose routes that stay off of, and out from underneath, steep terrain holding dense slabs over sugary weak layers.  In the Southeast Mountains the thickest and most reactive slabs will be on previously wind loaded slopes that face north through southeast.  Slabs below treeline or on windward aspects are less common and smaller.     Shooting cracks and collapses are clear warning signs to stay on slope angles less than about 35 degrees, although their absence isn't a guarantee of safety. 

    Remotely triggered Persistent Slab avalanche above West Brush Creek on a drifted, easterly slope. 1/3.

Avalanche Discussion

Well, the recent wind storm is obviously the highlight or biggest change of recent. Given that we have only seen single-digit snow accumulations this January, there sure isn't much snow available for transport. I'm sure there were some facets blowing around, and those winds were strong enough to erode crusts or old hard snow surfaces. So, some form of loading must have occurred. This wind event has produced at least one large natural avalanche overnight, up in the I-70 corridor. Forecasters across Colorado have some uncertainty as to just how much loading actually occurred last night. Today, keeping a sharp eye out for freshly formed hard slabs, above old week facets, should be on your list. 

With 30 mph wind gusts down in the valleys, you can expect to find wind-loading even down in the valleys. Those winds will have flowed through the valleys and cross-loaded some terrain features. The below treeline danger rating in the SE Mountains was temperately raised to MODERATE to account for these newly formed slabs. 

Skier triggered facet sluffs, or small loose snow avalanches, have recently been reported. You could encounter this avalanche problem on steep terrain, facing W to N to E, primarily at lower elevations. This is due to the last week of cold temperatures and a shallow snowpack leading to faceting and decaying slabs. This recent video highlights some of those changes. This is basically the circle of life for the snowpack on a below-average snow year in our continental snowpack climate. During the dry periods, we watch the snowpack weaken and facet. With each loading period we see slabs build back over that week snow, a cycle of avalanche activity, then the whole thing starts to facet away again during the next dry period. 

Yesterday forecasters tried another form of video and attempted to highlight, decision making, while out on a fairly simple tour. It's a bit long, but for some user groups, it may offer some skills or lessens to be learned. 

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