Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

The avalanche danger is slowly decreasing in the wake of last week's major storm, but conditions remain unusually challenging and winter-like for late March.  Numerous large avalanches have been remotely triggered in the past few days.  Ongoing wind transport will keep concerns for natural activity going at higher elevations.  The safest riding is on slopes less than 35 degrees protected from wind-loading.   Terrain that recently avalanched or small terrain features with clean runouts offer lower risk options for riding in steeper terrain.

Avalanche problems

  • Wind Slabs

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

    A few inches of new snow and increasing west-northwest winds today will form shallow, sensitive wind drifts at higher elevations. These slabs overlap with thicker, more stubborn drifts that formed earlier this week.  An avalanche in recently drifted terrain could step down and trigger a much thicker and wider persistent slab.  You can avoid the problem by traveling where the snow is protected or eroded by winds. Cracking in the snow or blowing snow are signs of instability.  

    A recent slab avalanche on a leeward slope.  

  • Persistent Slabs

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

    Last week's storm formed slabs up to several feet thick over faceted weak layers.  Remote triggers and natural avalanches failing on these persistent weak layers have been gradually diminishing since widespread activity peaked last Wednesday.  The greatest number of avalanches have occurred on easterly-facing slopes where a collapsible crust exists. Similar structures are also found on westerly-facing slopes. On northerly-facing slopes, these slabs formed over a layer of near-surface facets.  Slabs are larger and may be more sensitive at higher elevations due to ongoing wind transport.  In a few cases, avalanches have stepped down into older weak layers much deeper in the snowpack, causing destructive avalanches.  

    Early warning signs for this avalanche problem are rare and feedback is infrequent. You can reduce your chance of triggering this avalanche problem by avoiding wind-loaded terrain and limiting slope angles to less than 35 degrees, without steeper slopes above. 

    3:23 A pile of large natural avalanches ran on easterly aspects of Purple Ridge last week. 

Avalanche Discussion

The avalanche danger has been slowly trending down through the weekend as we distance ourselves from the last atmospheric river event that culminated on Wednesday with widespread avalanche activity on our faceted storm interface (3/20 layer).  Slabs breaking on this interface are becoming increasingly stubborn as the snowpack consolidates and settles.  The most concerning slopes are those with a collapsible crust at the storm interface; crusts often delay bonding and form a hardness change in the snowpack that causes wider and more unusual propagation.  Apart from shallow drifts that are forming today, the sensitivity of problems fits best with Moderate danger.  However, the potential size, and lingering concerns for isolated natural activity due to today's wind drifting is dictating our Considerable travel advice at higher elevations.  This very large natural (D3) that ran over the weekend near Marble exemplifies the impressive propagation that is possible in some terrain.   A single collapse on Saturday triggered three adjacent paths in the Anthracite Range (D3s).   Similar but smaller avalanches (D1 to D2) have been remotely triggered on below treeline slopes over the past few days (Example A, Example B, Example C, Example D).  Last week's storm also produced a few avalanches that broke into older weak layers, such as this one in Barcelona Bowl. We have a more complicated snowpack right now than we've seen since mid-January, with persistent slab issues around the compass across our entire forecast area.  It's a good time to target fun powder laps in simpler terrain and save those bigger spring objectives for once the snowpack recovers from the major loading events we've seen this month.  Consider snowpack structure, terrain consequences, and recent avalanche activity if you are seeking out more challenging terrain.  

Tomorrow, we'll see the late March sun out in full force for the first time since last week's storm ended.  We're expecting the danger to rise as the snow surface warms, producing shallow wet loose avalanches which could also act as triggers for warming persistent slabs.  

Regions covered