Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Traveling in avalanche terrain will require managing new snow avalanche problems. Storm slabs will be possible to human trigger on steep slopes around the compass. These slabs will be the largest in size and potentially more reactive at upper elevations. Small, steep, test slopes will offer a great area to start evaluating the avalanche problem before moving into bigger terrain. If you see the March sun coming out this afternoon, be aware that conditions will begin to change and the avalanche problem may become more reactive in areas that are rapidly warming. 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Storm slabs can be expected to be about 5 to 12" thick. They will be possible to human trigger on steep slopes, typically in the upper 30-degree range and steeper. At upper elevations, these slabs will be thicker due to westerly winds creating periods of additional loading. Look for cracking and signs of instability on small/steep test slopes before moving into bigger terrain. If we see a few hours of strong solar input this afternoon, be aware that storm slabs may begin to transition into small loose wet avalanches on steep southerly facing slopes. 

    Example of a small test slope that produced results yesterday. 

Avalanche Discussion

We are expecting a straightforward day of new snow management. Some east, southeast, and west-facing slopes had a very thin layer of facets develop above Tuesday's crust. It will be interesting to see if those aspects are any more reactive today than other aspects. The 12,000ft weather station on Scarps Ridge recorded southwesterly winds averaging in the teens to twenties yesterday. Those winds have died down early this morning, but we may see a period of similar wind speeds from the Northwest today. Those winds will have created deeper slabs on the lee sides of ridgelines and cross-loaded terrain features. Wind-loaded terrain will be most common at above-treeline locations and this is one reason the avalanche danger is higher for that elevation band. The storm slab avalanche problem will be more sensitive to triggering in areas where there is additional wind loading.

The cloud cover looks to decrease to a partly cloudy sky by this afternoon. If we do see some clearing keep an eye out for rapid warming and if the snow surface is becoming wet. We are now well into March and following each spring snowstorm, we will have to go through some form of wet avalanche cycle as we move back into clear and sunny weather. 

The primary difference in the SE Mountain forecast area is the additional concerns for avalanches to break on deeper weak layers. During last weekend's storm, we saw several large to very large avalanches break on old weak layers. We are most concerned about human triggering in terrain that holds unusually shallow snow depths or drifted slopes with variable snow depths. The warm, sunny weather over the last two days formed thick crusts on the southern quadrant which has strengthened the upper snowpack and reduced the threat of triggering a deeper avalanche on those aspects.  

Events:  The Al Johnson race is Sunday, March 19. Information and registration are here.  Day of race registration and bib pick up 9-11 a.m. at the Adventure Center in Mountaineer Square. Proceeds go to the CBAC.

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