Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dangerous avalanche conditions exist on leeward terrain from snowfall and wind loading.  Avalanches in sheltered terrain are possible where you find 8 inches or more of new snow.  It remains possible for you to trigger an avalanche that breaks deeper in the snowpack well beneath the storm snow.  Use caution if you are traveling in terrain with a snow depth less than 5 feet or highly variable in depth from previous winds or avalanche activity as these shallower spots allow your weight to affect deeper weak layers.  You can reduce your risk of triggering an avalanche by avoiding drifted terrain and choosing slopes with a deeper and uniform snowpack or simply defer to slopes around 30 degrees or less if you are in doubt.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    In the Southeast Mountains, faceted weak layers are buried 2 to 6 feet deep and are becoming more difficult to trigger as layers adjust to the last month of active loading.  Slabs are most easily triggered where they are thinner, which is most common in shallow areas near Crested Butte and CB South, or in wind-affected terrain.   Be cautious of windward terrain features with variable depths, rock bands, and slopes where slabs are only a few feet thick.   The safest riding is where the snowpack is uniform and consistently deeper than about 5 feet (150 cm).  

     

    This large persistent avalanche was explosively triggered on Mt. Crested Butte on 1/17.  It exemplifies the destructive size, and one example of the type of terrain that is troublesome.

  • Wind Slabs

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

    Up to 10 inches of new snow yesterday and more snowfall today coupled with westerly winds has formed another round of sensitive Wind Slabs on leeward terrain.  Terrain with 10 inches or more of new/wind drifted snow will help clue you into the increasing hazard.  Avoid leeward terrain where you see blowing snow, feel stiffer surface snow from drifting, or experience cracking in the snow.  Avalanches may release naturally while being loaded from snowfall and/or wind.

    1/26:  A trio of recent Wind Slabs on the easterly alpine terrain of Hunter Hill.  The lookers right avalanche is large enough to bury, injure, or kill a person.

Avalanche Discussion

Mother nature delivered yesterday and deposited more than a foot in the Northwest Mountains, 9 inches at CBMR, and lesser amounts to the east.  Southwest-to-west winds have blown the new snow to leeward terrain features.  With additional snow and wind today, expect problems with the storm snow to increase throughout the day if the weather forecast verifies or is exceeded.  Drifted terrain is the most likely place for you to trigger an avalanche today and some avalanches may run naturally.  In sheltered areas, you can expect steep terrain to produce Loose Dry avalanches and there is the possibility for some Storm Slab activity if the new snow bonds poorly to the old surfaces.

There is a greater hazard where you find more snow which makes conditions worse in the Northwest Mountains, but areas in the Southeast Mountains that border the Northwest Mountains, you may find just as dangerous conditions,  For example, the swath of terrain from Mount Emmons to Anthracite Mesa to Gothic  Mountain received similar amounts to the Northwest Mountains.

Triggering an avalanche deeper in the snowpack (Deep Persistent Slab problem) remains an unlikely problem in the Northwest Mountains, but is a worthwhile consideration in your terrain selection.  Given the issues with storm snow, your safest bet is to stick to sheltered terrain with a deep uniform snowpack and this will help reduce the risk of avalanches in the storm snow and on deep weak layers.

Avalanches breaking deeper in the snowpack (Persistent Slab problem) is possible in the Southeast Mountains.  This storm is not expected to significantly worsen Persistent Slab concerns, but the potential remains for areas with a shallower snowpack, less than 5 feet, to produce a deeper failing avalanche.  Keep in mind that some slopes may be shallower due to previous avalanche activity.  This observation from lower Wolverine Basin on Mount Emmons is a good example of the weak snowpack you can find on some slopes that previously avalanched.  If you are uncertain about triggering an avalanche deep in the snowpack simply choose terrain 30 degrees or less that isn't connected or below steeper terrain.

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