Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

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

The mountains received a big inch of much-needed new snow overnight. That snow will help brighten those backcountry spirits while otherwise not changing current avalanche conditions. Stay cautious of those stubborn hard slabs that can be found below leeward ridgelines, rollovers, or in concave gullies. Last weekend, a triggered slide occurred on Mt. Emmons. The softest snow for skiing and riding can be found on sun and wind-sheltered slopes. In those areas, you may need to manage small, dry loose avalanches if you are riding sustained steep terrain. 

Lawinenprobleme

  • Persistent Slabs

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

    Since 12/9, several northwest-to-southwest wind events formed slabs around a foot thick or more in heavily wind-loaded terrain features. These wind-drifted slabs are most commonly found at higher elevations below leeward ridgelines and rollovers on east to northeast-facing terrain. They can also be found around the northern half of the compass in a few concave terrain features that collect drifting snow, such as gullies. These slabs are often hard and difficult to trigger, but some formed over weak, faceted snow that is slow to heal, making for variable feedback.  Assess recent wind-loading patterns and consider avoiding previously wind-loaded terrain features, especially in high-consequence terrain. 

    In very isolated areas, an avalanche could release a couple feet deep on weak layers near the ground. These areas would have needed to retain the full-season snowpack without that snowpack having been removed by the widespread avalanche cycle that occurred in late November. 

    This small hard slab was skier-triggered near Mt. Tilton on 12/20.  Note how the slab is in a concave, previously wind-loaded feature.

  • Loose Dry

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

    In terrain that has been protected from the sun and wind, most commonly on the north-to-east aspects, you can find a snowpack that is weak and cohesionless.  In these areas, you can trigger dry loose avalanches in terrain steeper than 35 degrees.  Point-release instabilities are relatively small and easy to recognize. Still, they can spell trouble by pushing you into trees, rocks, or gullies, especially in long, steep terrain where they will gouge to the ground and gain more volume.  Use sluff management techniques or move to less consequential, lower slope angles to manage the problem. 

Avalanche Discussion

The prolonged December drought has decreased the snow water equivalent in the Gunnison River Basin from ~150% of the median at the start of the month down to 95% of the median today. The driest December recorded in Gothic was 1976, with a total of 18cm of new snow. So far this December, Gothic has recorded ~9cm of new snow. This drought has allowed rampant weak layer growth in our snowpack and left it susceptible to increased avalanche activity from even small loading events. The last small loading event occurred a week and a half ago, on the weekend of 12/14. We are still dealing with the lingering hard slabs that were created around that timeframe. That avalanche problem is highlighted by the persistent slab avalanche problem in the avalanche bulletin.  As we look ahead through the coming holiday week, we finally have new snow in the forecast, and that snow will begin loading the weak snowpack again. Last night's inch of new snow, and the snow forecasted on Christmas Day, will first start to add a little bit of volume to the dry loose avalanche problem. Later in the week, we have a more notable storm and stronger winds on the horizon. So we can expect rising avalanche danger to return.  

The latest in our steady trickle of feedback from our persistent slab problem comes from Mt. Emmons on Sunday, right on the boundary between our two forecast zones.   The second rider to cross a wind-loaded feature on the far looker's left side of Red Lady Bowl popped a hard slab that broke 1 or 2 feet deep near the ground.  Although our slab issues are localized to previously wind-loaded terrain features, like a wind slab, we've been calling it a persistent slab due to its unusually prolonged period of instability. A hybrid problem, if you will. These slabs started forming earlier this month as multiple wind-drifting events over the very weak snowpack created by the December drought.  Other recent feedback includes booming collapses on Saturday below Schuylkill Peak (video) and a skier-triggered slab on Friday on Mt. Tilton.   

Where the snow surface is soft, sugary, and protected from wind effects (most commonly below 11,000' on the north half of the compass), the snowpack lacks any slab concerns as it continues to facet and weaken.  In both zones, observers report dry loose avalanches (aka facet sluffs) picking up momentum and gouging to the ground once they get moving (ex. Snodgrass, Schuylkill Ridge, Axtell, Emmons). Two people have been caught and carried in dry loose avalanches near Marble, one earlier this month and one on Friday.   Sluffs aren't a concern where the snow surface is stiff from wind (generally at higher, more exposed terrain) or sun crusts (south to west aspects) or on slope angles less than 35 degrees. 

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