Bollettino valanghe

Southeast Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Yesterday an observer reported remotely triggering a large persistent slab avalanche near the Friends Hut. Persistent slab avalanche activity has been the most problematic on wind-loaded terrain over the last several weeks. Northerly winds will begin increasing this afternoon and creating a new round of wind slabs near ridgelines and on cross-loaded terrain features. 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. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Over the past few weeks, we have observed an infrequent but continuous pattern of large avalanches or collapses failing on weak, faceted layers deeper in the snowpack.  Such as this remotely triggered avalanche that occurred near the Friends Hut yesterday. Persistent slab activity has been most problematic on wind-loaded terrain this month, though issues are developing in some areas below treeline.  Carefully assess the snowpack structure and give yourself a margin for error in handling this problem because there is a high degree of variability across the region and on different aspects.  Some recent examples of persistent slab activity include naturals on Express Creek and Carbonate Hill, and a remotely triggered avalanche on Mt. Emmons. 

    2/23:  A large collapse and shooting cracks failed on weak, faceted snow about 3 feet deep on Mount Emmons.  Don't expect to get feedback like this before triggering an avalanche, but it's a clear sign of danger if you do.  

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    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.  

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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