Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Mon
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Highlights

Slopes capable of producing avalanches are isolated across the landscape.  A small chance remains for you to trigger an avalanche near the previous storm interface.  If you choose to step into larger, steep terrain assess the upper snowpack prior.  You can reduce your risk by exposing only one person at a time to a hazard and consider the terrain consequences if you are wrong.  Increasing winds may form fresh drifts if the winds can find snow available for transport.

Avalanche problems

  • Persistent Slabs

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

    The Northwest Mountains picked up over 2 feet of snow accompanied by strong winds during the most recent storm that ended Monday.   The storm formed slabs up to several feet thick above small-grained facets that are prolonging instabilities on some slopes.  Be cautious of leeward terrain and southerly aspects, which have been most active this week.   Slabs are larger and more cohesive on wind-loaded slopes.  Slabs are smaller and less common in wind-sheltered terrain.  Use stability tests to assess instabilities in the upper snowpack.  You can generally avoid the problem on slopes less than about 35 degrees.

    1/31: A trio of natural avalanches on Schuylkill Ridge.  This image highlights the dangerous size potential of avalanches in leeward terrain.

Avalanche Discussion

The danger rating has dropped to LOW for the Northwest Mountains.  Over a week ago, a layer of facets and faceted crusts was buried 1 to 3 feet deep.  Some natural avalanche activity occurred on well-drifted slopes (natural activity after the storm cleared) and on sunny slopes.  A trickle of natural and human-triggered avalanches occurred Tuesday through Thursday primarily on sunny terrain when slabs were warming and settling (Red Lady, Snodgrass, Schuylkill Ridge, Evan's Basin).  The snowpack had an additional few days since this activity to adjust to the previous storm and modestly rising temperatures.  Triggering an avalanche in the upper snowpack is 'unlikely' but not impossible.  Take the time to assess the upper snowpack, particularly on sunny slopes that may become moist or wet at the surface with daytime heating, and bring a thoughtful mindset if you consider 'stepping out' into bigger and steeper terrain.  Today's LOW danger is not the same as a late spring LOW danger day. 

The avalanche danger remains MODERATE in the Southeast Mountains.  Two layers of concern exist across the terrain; one in the upper snowpack and in some areas deeper weak layers of concern.  The layer of facets buried 1 to 2 feet down and the potential for avalanches to break on deeper weak layers.  Travel advice for upper snowpack problems is similar for both forecast zones, but for some areas in the Southeast Mountains that are snow-deprived (less than 5 feet deep), you should consider the potential for a surprise avalanche that breaks deeply and propagates widely.  A recent example of this came from Park Cone on Wednesday which resides outside the CBAC forecast areas but has similar snowpack depths to some portions of the Southeast Mountains.  This forecaster follow-up has a lot of informative details about the close call.  An additional observation came in yesterday from above Copper Creek with unstable pit results on deeper weak layers on a slope that was around 5 feet deep.  That is why we are continuing to message the threat of avalanches breaking on deeply buried weak layers in our shallower zone.  A good rule of thumb would be to consider this threat in areas with less than 5 feet of total snowpack depth and change your travel habits by selecting lower-angle terrain when you are in doubt. 

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