Bulletin d’avalanche

Northwest Mountains

Crested Butte Avalanche Center
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Danger d’avalanche

Mon
Alpin
1 · Faible
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 8 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche problems have become isolated in distribution, and normal caution has established across the forecast area. Continue using good travel techniques in avalanche terrain, such as limiting exposure to one person at a time. You can further reduce your risk by avoiding steep slopes that hold old hard slabs formed by recent wind events. Wind-sheltered terrain offers both lower avalanche hazard and better riding conditions.

Problèmes avalancheux

  • Persistent Slabs

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

    An extreme wind event occurred last Wednesday night. These winds did more wind erosion than wind loading, but they will have left behind a few thin, hard slabs, or windboard. If you are traveling in avalanche terrain, it will be wise to keep an eye out for these thin slabs. The perfect setup would still be stubborn to human-triggering and isolated in distribution, creating a less likely scenario. 

    Snowfall and wind drifting in early December formed slabs up to a few feet thick over facets near the ground.  These weak layers are most widespread on the northern half of the compass. Mild weather through the middle of December has helped the snowpack adjust to its current load, or in some cases, the shallow snowpack has seen slabs completely facet away. The last documented avalanche on these old, weak layers occurred on 12/14. 

    An example of a thin, hard slab over sugary facets. The resulting avalanche would be small in size, but the hard snow surface could easily pull you off your feet or push you into a tree. 

Avalanche Discussion

Following the extreme wind event, snow surfaces are highly variable. Those winds were to strong to effectively load terrain features, and there wasn't much snow available to transport. The most likely of the unlikely avalanche scenarios has become thin hard slabs created by that wind event. The perfect setup would most likely be found near treeline or in open areas below treeline, where one of these slabs formed over soft facets. The older generation of persistent slabs created during the first quarter of the month have been worked over by the windy and warm weather. In our shallow continental snowpack that has plenty of weak snow, you can completely rule out an old slab avalanche. Still, the perfect setup that could be human-triggered will be both difficult to trigger and very isolated in distribution. 

The forecasted warm temperatures in the coming day will help soften snow surfaces and hopefully create more areas with decent riding. Otherwise, our attention has turned to tracking the current snow surfaces before the next loading event. The weather pattern starts to get interesting again around December 24th and 25th. 

Régions couvertes