Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Kernpunkte

Weeks of dry weather and recent wind erosion have eliminated the threat of avalanches on most slopes.  Isolated exceptions exist: they're most commonly easy to identify as smooth, thin hard slabs in concave features or behind abrupt transitions in the terrain.  Stay alert and steer around these features in high-consequence terrain.  You'll find safer, higher-quality riding on soft snow surfaces from wind protection or wind erosion.      

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1–1.5

    Strong to extreme northerly winds last week formed thin, hard slabs on features that collected drifting snow. The wind event mixed down to mid and low elevations, cross-drifting relatively small slabs onto weak, faceted snow surfaces - most commonly on the shady side of the compass where there was more snow available for transport and on higher southerly aspects.  These slabs will stand out as smooth, hard, lens-shaped snow formations, next to wind-eroded areas or softer, wind-rippled snow surfaces.  Although these slabs are typically stubborn to trigger now, skirt around these harder drifts in consequential terrain to avoid the threat of getting pushed into trees, rocks, or gullies.  

    An example of a wind-loaded feature that is best avoided in consequential terrain.   Look for the smooth, rounded, firm surfaces to identify the problem.  

  • Persistent Slabs

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

    Instabilities involving old slabs breaking on old weak layers are rare due to slab faceting and wind erosion.  There is still a lingering threat of triggering a slab that fails 1.5 to 3 feet deep on depth hoar, facets, and faceted crusts without obvious warning signs.  In the Southeast Mountains, slabs are most likely to be triggered in terrain where slabs are more cohesive from previous windloading. The most reliable way to manage this problem is by choosing slope angles less than 30 degrees.  Wind-eroded and wind-protected terrain offers a safer snowpack where slabs are typically lacking.  

    A large persistent slab on a wind-loaded slope near Crystal Peak that likely ran around January 10th during a previous wind event. 

Avalanche Discussion

We continue to assess the aftermath of last week's wind events, which brought strong to extreme northeast-to-northwest winds for several days, peaking on Saturday.  As is typically the case with extreme wind events, we observed extensive wind erosion in some areas, while wind loading appears to be rather limited: thin, hard wind slabs are scattered around various aspects and often collected at lower elevations where wind speeds were lower.  Keep your eyes open for the obvious smooth hard lenses of drifted snow that stand out amongst erosional textures.  Some of these will be thin wind crusts that aren't a concern, while others will be stubborn drifts that might knock you off your feet if you get one to pop.  This video of a skier getting caught in a wind slab in the San Juans over the weekend is a great example of what that looks like. 

Persistent slabs breaking in old December and November weak layers have become unlikely.  The combination of nearly two weeks of dry weather, along with more recent wind erosion events, has made the issue increasingly isolated and stubborn.  I'll borrow an analogy that the Utah Avalanche Center used yesterday: Imagine squeezing a spring between your fingers. As you apply force, the spring compresses and stores energy. Loading the snowpack with new snow or wind-drifted snow does the same thing—it compresses the system and increases stored stress. When you slowly ease your fingers apart, the spring relaxes and releases that energy gradually. Similarly, when there’s a prolonged break in loading, the snowpack begins to creep, adjust, and settle. As the system adjusts, the likelihood of a sudden failure—like a slab avalanche—decreases, though it doesn’t disappear entirely.

The thinner snowpack in the Southeast Mountains is more prone to losing slabs from both faceting and wind erosion, and our confidence is higher that the danger has finally subsided to Low there.  This video demonstrates the typical situation.  The Northwest Mountains may be there as well, or trailing close behind.  The larger slabs and very large natural that ran last week give us more uncertainty; we're looking for a bit more time and field data before we go there.  

Upcoming Outreach Events:  

Fireside Chat:  Jan 23, Dave Scheefer "Historical avalanches in Gunnison County."  Mallardi Theatre 5-7 pm.

Trailhead Day: Jan 24, Slate River, 10 am-2 pm.

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