Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Avalanche conditions are dangerous.  Around 2 feet of snow fell recently with more forecasted today.  You can trigger an avalanche in the storm snow and on deeper weak layers; avalanches breaking on weak layers near the bottom of the snowpack are deadly.  Drifted terrain is the most concerning as southwest and south winds will load leeward terrain during the day.  You can reduce your risk of triggering an avalanche by avoiding drifted slopes, utilizing caution in sheltered areas, or simply deferring to slopes less than 30 degrees without overhead hazards.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    Slabs ranging from 3 to 6 feet thick have formed around much of the compass and at all elevations over faceted weak layers in the lower snowpack. These weak layers have adjusted to their current load and were slowly becoming more difficult to trigger. However, the variability in the slab depth, especially at near and above treeline elevations, is creating more locations for lighter loads, such as the weight of a human, to affect those weak layers and release the avalanche problem. These persistent slab avalanches can propagate widely through the terrain, or be remotely triggered from low-angle slopes connected to steeper slopes. You can reduce your risk by traveling on slopes with a deep, uniform snowpack. While you can further avoid the problem by traveling on slope angles that are consistently less than 30 degrees and not connected to steeper terrain above. 

     

    1/4:  A destructive natural avalanche in Red Lady Bowl broke full-width last week.  This avalanche would be hard to survive.

  • Wind Slabs

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

    Southwest winds overnight will transition to the south during the day.  Ample low-density snow is available for transport to leeward terrain.  Expect to find sensitive drifts where the winds deposit the recent snow.  Avalanches starting in the storm snow have the potential to "step-down" and release a larger avalanche deeper in the snowpack.  Even if avalanches in the storm snow do not "step-down", they will still be large enough to cause harm.  

    Example of an old wind slab that failed on a cross-loaded terrain feature. 

Avalanche Discussion

The storminess continues with another round of moisture overnight and continued accumulations during daylight hours on Tuesday.  Total snowfall is nearly 3 feet for areas around Irwin to Schofield Pass with 2 inches of Snow Water Equivalent.  Closer to Crested Butte and east of town, snow totals are less than 2 feet with around 1 inch of Snow Water Equivalent.  Winds overnight from the southwest will slowly shift to the south changing the loading patterns throughout the day.  Some natural avalanche activity is possible today on drifted terrain.

In the Northwest Mountains, the primary concern lies with the storm snow and avalanches in the upper snowpack.  Soft slabs around 2 feet thick exist this morning and will grow throughout the day as mother nature continues to pile up the snow.  Use caution while managing the storm snow as it can become increasingly sensitive during loading periods.  Reports for yesterday indicated generally well-behaved storm snow but no real loading occurred due to very light snowfall.  Expect an increased chance for sensitive Storm Slabs today during periods of stronger snowfall and on drifted terrain features.  Yesterday one observer was able to find an area in the Anthracites with buried Surface Hoar which created sensitive avalanche conditions and produced easy propagating test results; it can be nearly impossible to predict where areas of buried Surface Hoar exist.  Exercise caution as the Storm Slab problem grows in sheltered terrain and drifter features today; conservative terrain choices are your best defense.

Smaller storm totals and a generally shallower snowpack in the Southeast Mountains forecast zone make for a different terrain management plan.  It is possible to trigger avalanches in the storm snow in places where you find 12 inches of new or wind-blown snow.  The trickier part of the equation is weak layers deeper in the snowpack becoming more sensitive due to the loading event.  As snowfall accumulates the balance continues to slowly move towards more dangerous conditions and an increased likelihood of deeper failing avalanches.  Drifted terrain is the most dangerous due to the increased burden from wind-loading and greater variation in snowpack depth.  If you are uncertain about avalanches failing deeper in the snowpack, simply defer to terrain 30 degrees or less and avoid exposing your group to overhead hazards. 

Regions covered