Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 7 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

We are now at 9 days since our last refresh of new snow. Northwesterly winds have since redistributed that snow into stiff drifts on the lee sides of terrain features. Heightened avalanche conditions exist on these specific terrain features at mid and upper elevations. On Saturday, a couple of slab avalanches were human-triggered in Upper Cement Creek and one to the north of our area near Aspen. On northerly-facing wind-sheltered slopes, there is still some nice soft powder to ride. In those wind-sheltered areas, your primary avalanche problem is small, dry loose avalanches on steep terrain. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    Persistent slab avalanche concerns mostly involve slabs of drifted snow that formed over the facets and faceted crusts from the January drought.  These slabs, typically 1 to 3 feet thick, are hard and stubborn to trigger. Requiring heavier loads, or light loads in just the right location to trigger. There is isolated potential for a slab failing in the upper snowpack to step down and trigger a deeper, harder avalanche near the ground. Searching for wind-eroded and soft wind-dappled snow will help reduce your exposure to this avalanche problem, while the best way to avoid it is by riding in wind-sheltered areas. 

    An example of some hard wind-drifted slabs on the eastern side of Cinnimon Mountain. 

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Dry Loose avalanches have developed where the snowpack is below average in depth, typically on the bed surfaces of old avalanches. While the average snowpack in the NW Mountain forecast area is still strong enough to prevent these sluffs from occurring. A triggered sluff will be relatively harmless, but where they run through sustained steep terrain, they can become larger in size and push you into more hazardous terrain features, such as trees, or pile deeply in terrain traps.

    A long-running sluff that was skier-triggered on an old avalanche bed surface. Birthday Bowl, Schuylkill Ridge. Photo: Miles Morris

Avalanche Discussion

The best riding and softest powder can be found on northerly facing wind-sheltered terrain. Given the reduced avalanche hazard here, this is a good time to get out and enjoy the backcountry in those areas. Small dry loose avalanches are starting to creep into the problem list as the snowpack loses strength in these wind-sheltered areas. These sluffs are the most common in the SE Mountain forecast area, where the snowpack is thinner. In the NW Mountain forecast area, the upper snowpack is still holding some cohesion, helping to hold back these sluffs. Exceptions exist in the NW Mountain forecast where the snowpack is below average in depth, like on an old avalanche bed surface. There, small sluffs will be more common, and conditions will be similar to the SE Mountain forecast area.

The persistent slab avalanche problem was primarily formed during a northwesterly wind event on Sunday, 1/25. The sensitivity of this avalanche problem has greatly decreased since. New sun crusts are forming on top of the snowpack in some of the most suspect terrain for this avalanche problem. As those crusts grow, they will further decrease the chance for a triggered avalanche. The persistent slab avalanche distribution rose was trimmed to the few remaining aspects where the avalanche problem is most commonly encountered. Cross-loaded drifts on west-to-north-facing slopes are very isolated and rare. Those windward aspects typically have hard wind crusts or wind boards, with only a few wind-exposed areas still holding onto soft wind-dappled power.

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