Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

The snowpack remains on the edge of failure and only needs a trigger to release.  Expect to easily trigger a dangerous avalanche on any slope with weak snow near the ground.  You can release an avalanche from a surprisingly long distance and from below.  Some avalanches could be unsurvivable due to their very large size.  You can greatly reduce your risk by choosing low-angle terrain that is completely free from steep slopes above. 

Avalanche problems

  • Persistent Slabs

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

    Days of snowfall and wind-drifted snow have the snowpack near collapse.  There's a widespread weak layer of facets and faceted crusts buried by 2 to 4-foot slabs on west to north to southeast aspects. The slabs are largest in leeward terrain at higher elevations.  The problem is less common, but still possible, on windward terrain or south-facing slopes that hold old snow layers near the ground.  Choose routes that keep you off and out from under steep terrain that holds old snow below our recent storms.  Collapses and shooting cracks are clear signs of danger warning you to stay on slope angles that are consistently less than 30 degrees.  Avalanches on drifted terrain could reach very large sizes in the Northwest Mountains. 

    A deep and broad natural avalanche from West Beckwith.  This represents the dangerous scale of avalanche size in the Northwest Mountains.

  • Storm Slabs

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

    Up to 24 inches of snow fell in the past few days, with moderate westerly winds on Thursday.  The more recent storm snow rests above a layer of graupel from a week ago and has produced some propagating test results.  You are most likely to trigger an avalanche in storm snow where winds have stiffened the recent snow.  Cracking in the upper snowpack is a clear sign you have found sensitive conditions in the recent storm snow.  Relatively shallow releases in the storm snow are likely to step down and trigger a larger persistent slab avalanche where the two problems overlap.

Avalanche Discussion

Snowfall and wind drifting since Tuesday have kept the snowpack teetering near the edge of failure.  Simply look through the media gallery below and scroll through the observations page to view the stream of recent natural and human-triggered avalanches.  Make no mistake, avalanche conditions remain dangerous.  Even though the loading period has largely ended, there's a chance for natural avalanches if you observed continued wind-loading today, and human-triggered avalanches remain likely.  Slopes facing west through north through southeast are the most dangerous due to the well-documented persistent weak layer.

Slabs have gained strength over the past few days and this increase in strength only serves to drive propagation further and create bigger avalanches.  Thoughtfully consider your exposure to overhead hazards as you make a plan for today.  Choosing low-angled terrain, 30 degrees or less, that is not beneath steeper terrain is the best defense against the current Persistent Slab problem.

The snowpack isn't nearly as dangerous on slopes that were bare dirt prior to our recent storms.  These two observations from the Northwest Mountains and Southeast Mountains document the distribution of our problematic weak layer that formed during November's dry spell.  In terrain that's lacking the troublesome old snow layer, you'll need to manage storm instabilities that developed over the past few days of snowfall and wind.  Even steep terrain without old snow near the ground requires thoughtful assessment and terrain selection as an avalanche just in recent snow can be large enough to cause harm.  

Regions covered