Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

The snowpack struggles to adjust to a week-long loading event.  Snowfall has ended but westerly winds continue to drift snow keeping some leeward slopes near natural release.  Wind-loaded terrain can produce destructive long-running avalanches like the one observed yesterday in Red Lady Bowl.  Dangerous avalanche conditions exist on all aspects and elevations.  Give a wide margin to steep terrain to protect your group from remotely triggering an avalanche from below.  The safest option is lower-angled terrain that is free from steep overhead slopes. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3.5

    Persistent weak layers in the middle and bottom of the snowpack were overloaded by 3 to 6 feet of new snow in the past week. Destructive avalanches have released around the compass and at all elevations over the past few days, and plenty of other slopes are hanging in the balance waiting for a human trigger.  Persistent slab avalanches can propagate widely through the terrain, or be remotely triggered from low-angle slopes connected to steeper slopes. Leeward start zones at higher elevations could release naturally today with additional wind loading, with the potential for very large natural avalanches (up to D3+).  At lower elevations, persistent slabs are sensitive to triggers on some slopes and are more commonly large (D2) in size.   You can avoid the problem by traveling on slope angles that are consistently less than 30 degrees without overhead hazards. Give yourself a wide margin for error given how consequential the problem is right now.  

    1/3:  This large persistent slab was remotely triggered from where this skier is standing, almost 300 feet away.  Persistent slabs can be triggered from adjacent to steep slopes or propagate widely across terrain features.    

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2

    Up to 20 inches of new snow and increasing west to northwest winds are forming sensitive drifts on leeward slopes at higher elevations.  These drifts could pose a hazard themselves or step down and trigger a much larger persistent slab.  Avoid travel on or below recently drifted slopes.  Though less likely, the new snow could also be reactive as a storm slab on steep, wind-sheltered terrain.  

    1/3:  A pair of soft slabs involving the new snow, skier triggered on a drifted rollover.  

Avalanche Discussion

The snowmachine has finally turned off for the Crested Butte area after 7 or 8 days of relentless loading.  Unfortunately, westerly winds will blow around 20mph with higher gusts today.  This means that some leeward start zones may continue to hover near natural failure due to wind loading.  Yesterday's avalanche in Red Lady Bowl is a good example of this potential.  Other observers reported very recent destructive avalanches from Climax Chutes that reached the valley bottom and slides off Schuylkill Ridge the hit the Slate River Road near Pittsburg.  Or consider these natural and explosive triggered avalanches reported from near treeline terrain by Irwin Guides.  Spending time underneath slopes with active wind loading is a deadly proposition today.

At lower elevations and on sheltered terrain, human triggering is our primary concern.  Slabs over buried facets, depth hoar, and surface hoar span the entire compass, several feet thick.  A number of large remotely triggered avalanches on Tuesday (Snodgrass, Cement Creek) highlight how tender the snowpack is right now.  Slabs are most sensitive to triggers in the shallower parts of our forecast area near and east of town: they are the ideal thickness for triggering and buried facet/depth hoar layers are more fragile, in general.  In deeper parts of the forecast area, persistent slabs are becoming more stubborn to human triggers, though the consequences are more serious due to the increased avalanche size.  Signs of instability like rumbling collapses may decrease in frequency but do not let this lull you into complacency.  Regardless of where you are traveling, bring a very conservative mindset and carefully assess the snowpack before considering slopes steeper than about 30 degrees. 

Regions covered