Avalanche forecast

Southeast 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

New snow and wind drifting are increasing the avalanche hazard.  Make conservative decisions to manage instabilities in the new snow, especially at higher elevations where snow totals and drifting are greater. At lower elevations, watch for wet loose avalanches that can grow quickly in new snow and run far; with warming temperatures and sun this afternoon, these instabilities may spread to higher elevation solar slopes.

Avalanche problems

  • Wind Slabs

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

    Moderate southwest to west winds have been drifting the 17-22" of new snow, forming thicker and more cohesive slabs that are expected to be reactive today.  These avalanches are most likely found below leeward ridgelines or cross-loaded terrain features.  Watch for blowing snow, thicker-feeling drifts, or shooting cracks to warn you of the problem.  

    If you are riding steep slopes in wind-sheltered areas, continue to evaluate for new snow avalanche problems, such as loose snow avalanches and more stubborn storm slabs. 

    An example of a wind slab from the archives

  • Loose Wet

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

    Yesterday, observers reported easily triggered wet loose avalanches below treeline on northerly aspects, running on the storm interface where the old snowpack below the new snow was saturated due to fluctuating rain/snow lines and warm temperatures. These are most concerning in slopes with long runouts, where avalanches can grow to large sizes and entrain the entire snowpack. We expect loose avalanches to expand into higher-elevation solar aspects as clouds break and the sun comes out this afternoon, warming the new snow. Rollerballs or pinwheels are good indicators of this instability developing in terrain.

    A saturated, cohesionless snowpack exists beneath the new snow at lower elevations. If you are able to initiate a small instability at the snow surface, it could grow surprisingly large in the new snow or by gouging deeper into the wet snowpack. 

Avalanche Discussion

The April Fools storm has transported us back into winter, bringing with it new avalanche problems to manage. The current storm has produced 22-27” in the Northwest Mountains and 17-22” in the Southeast Mountains. Snow water equivalents for this storm are ~2.6” SWE at Schofield Pass, and 1.4” SWE at Butte. (The SWE sensors were fluctuating prior to the storm, so the starting points were estimated.) Snow rapidly accumulated and is very dense. 

Yesterday, observers reported easily triggered loose avalanches below treeline on north and northeast facing slopes (Climax Chutes, AMR) that became wet in character as they entrained the moist, dense new snow. These avalanches failed on the storm interface, but there is potential for this instability to gouge deep into the wet snowpack, typically at lower elevations. Even in the new snow, a wet loose avalanche can quickly gain mass and can become large in size. We expect wet loose avalanche activity to continue today, spreading into higher elevation solar aspects as clouds decrease and sun warms snow surfaces.

After our March Meltdown, the snowpack has largely become homogeneous, and the storm interface is a textured melt-freeze crust on most slopes, which is expected to bond favorably with the new snow. But density changes within the new snow can act as weak layers, formed by atmospheric changes as the snow is falling and wind drifting. As you gain elevation, expect higher snow totals and fresh wind slabs on leeward terrain features, resulting in increased avalanche danger. On wind protected slopes, assess how well the new snow is bonding with small test features. Snowfall favored the Northwest Mountains, so you can expect avalanches in the new snow to be larger and more hazardous as you move towards the Ruby Range. 

As seems to be the theme this winter, we find ourselves in somewhat uncharted territory, with greater uncertainty: a big loading event that began on a wet snowpack that hasn't seen a legitimate refreeze.  As you gain elevation, we can't completely rule out the possibility of a deeper wet slab that releases from loading during this storm, similar to this avalanche last season.  Water has drained through basal weak layers on most slopes by now, but a few might retain enough liquid content and grain weakness to cause a surprisingly large slab failure near the ground.   This seems like a very low-probability event, and one that would be quite difficult to assess.  

Events: Join us Friday, April 3, at the Talk of the Town from 5-8 p.m. for our Party for the People. We will have live music from CBAC house band Deep Slab Instability and beers are on us. It’s our way of saying thanks for all of the support again this year!

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