Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Fri
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Northerly winds will begin forming new wind slabs later this afternoon, while the storm and wind slab avalanche problems that formed earlier this week have become stubborn to human triggering and may not show obvious warning signs such as shooting cracks. Slab avalanches breaking 1 to 3 feet deep will be most suspect on steep and/or unsupported slopes, and on previously wind-loaded terrain. This will be a beautiful day in the mountains with excellent riding on all aspects. Use your eyes to see what you can learn from any past natural avalanche activity that occurred earlier this week, and continue to discuss with your group how you can manage or reduce the chance of triggering an avalanche in the terrain you are traveling through. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Earlier this week, a strong to extreme southwest wind event combined with about a foot of new snow to create reactive storm and wind slab avalanche problems. Those winds have since calmed down and avalanche problems have become less reactive and more stubborn to human triggers. A few inches of snow has since accumulated without much wind and is now hiding those previous wind-loading patterns. You may not see obvious signs to instability today, so don't forget that it still remains possible to trigger a slab avalanche 1 to 3 feet deep. The most suspect areas would be on steep unsupported slopes, and on previously wind-loaded slopes near ridgelines and cross-loaded terrain features.

    With good visibility, today, have a look around and see what you can learn from any avalanche activity that occurred in recent days. Later this afternoon northerly winds will begin increasing and they will start forming a new wind slab avalanche problem on the southern half of the compass. 

    2/28:   A shooting crack in a wind drifted slope.  This is an obvious sign of unstable snow.  

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–2.5

    There are several layers of small-grained facets in the upper few feet of the snowpack that were getting stressed by the storms earlier this week.  We have yet to observe any avalanches breaking on these layers in the Northwest Mountains and in the big picture this avalanche problem is unlikely. The layers appear to be most problematic on easterly or westerly facing slopes where they are associated with crusts, or in unusually shallow or rocky areas on northerly aspects.  Stability tests can be helpful for identifying this problem, or you can choose more conservative terrain when in doubt.

    2/27: A stability test in the Anthracite Range that failed on a faceted weak layer a couple feet deep.  

Avalanche Discussion

After the strong to extreme wind event earlier this week. The wind remained light for much of Wednesday, other than a 4 to 5-hour period early yesterday evening where the Scarps Ridge weather station recorded SW winds in the 20mph range with gusts into the 30's and 40's. The wind has since calmed down during the AM hours on Thursday. These lighter winds and breaks in the loading periods have allowed the avalanche danger to drop to MODERATE as the storm and wind slab avalanche problems have become more stubborn to triggering. 

Riding conditions are generally excellent, thanks to the soft snow surfaces out there in many places. However, that also translates to a lot of snow available for transport during the next periods of increased winds. Northerly winds will begin to increase this afternoon and we'd expect to see snow plumes off the peaks and a new round of wind slabs forming. As we head into the weekend we'll continue to assess how much snow is available for transport as the wind looks to be the main player in the weather outlook. 

The persistent slab avalanche activity over the last month has been well-documented in the SE Mountain FX area. There hasn't been much change there, other than forecasters keeping an eye on how this avalanche problem is developing in some below-treeline areas. The NW Mountains haven't seen any notable persistent slab avalanche activity. Today is the first clear day to look around the range after this past week's weather events. So we'll be taking a good look across the area and updating the observations tab with the observed avalanche activity. 

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