Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Mild weather and a lack of recent loading slowly reduce the likelihood of human-triggered slab avalanches but a poor snowpack structure remains.   A close call near Snowmass on Monday illustrates the potential for dangerous human-triggered avalanches.  Use caution on the north half of the compass with a snowpack depth of around 3 to 5 feet, on rocky slopes, and terrain with a variable depth.  You can find safer conditions where the snowpack depth is consistently 6 feet deep or more.  Warming temperatures and sunshine likely create wet snow avalanche problems on sunbaked slopes at lower elevations.  Rocky areas and terrain with dust at the surface could produce larger loose avalanches as the snowpack wets by the afternoon.

Avalanche problems

  • Persistent Slabs

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

    In the Southeast Mountains, high-consequence slabs breaking on older weak layers are becoming more difficult to trigger but remain a concern on the north half of the compass, or potentially on a few southerly slopes above treeline.  The most prominent weak layers are surface hoar buried a couple of feet deep and depth hoar near the ground.   Persistent slab avalanches can be remotely triggered from low-angle terrain and break deeper and wider than you might expect.   Triggered slab avalanches are unlikely on mid to low-elevation, southerly aspects, or areas where the snowpack is consistently deeper than 200 cm.  Slope angles consistently less than 30 degrees are a reliable way to avoid the problem.

    A large persistent slab on Mt. Crested Butte that ran on 3/16.  This slope is shallow, variable in depth, and on the north half of the compass: a combination of ingredients you want to avoid.  

  • Loose Wet

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

    Sunshine and warming temperatures will increase the threat of shallow wet avalanches involving surface snow.  Watch for rollerballs, pinwheels, or natural sluffs to indicate developing instabilities first on east, then south, then west aspects.  Natural and triggered sluffs are most likely to initiate from very steep or rocky slopes or places with a dirty snow surface.  Be careful in or above consequential terrain once the snow surface gets wet or sticky.  You can avoid triggering wet loose avalanches by riding on slope angles less than 35 degrees or moving to colder aspects.  

    (3/18/2024)

    Recent wet loose avalanches from easterly terrain on Whetstone.  This is a good representation of the potential size.

    Photo: Zach Guy

Avalanche Discussion

The Persistent Slab problem has become harder to trigger over the past week due to mild temperatures and a lack of recent loading yet the problem continues to linger.  Recent avalanche activity and observations suggest that shallower snowpacks on the north half of the compass represent the most likely place for you to trigger a dangerous slab avalanche.  A recent natural avalanche in Terminator Chutes on Saturday and a triggered avalanche resulting in a very close call near Snowmass on Monday highlight the issue.  An observer near Little Italian Pass (just a few miles northeast of Star Mountain and outside the CBAC forecast area) reported a rumbling collapse and shooting cracks on an alpine slope facing northwest.  Avalanches from early in the week and the rumbling collapse occurred in terrain with a seasonally shallow snowpack and/or wind erosion.  You can reduce your risk of triggering a slab avalanche by traveling where the snowpack is consistently deeper than 200cm (~ 6 feet) and by avoiding terrain with obvious trigger points.  The Persistent Slab problem is more concerning in the Southeast Mountains where the snowpack is shallower overall.

Wet snow concerns exist in both forecast zones due to seasonally warm temperatures and sunshine.  Wet avalanche problems are expected to remain small with this observation from Monday illustrating the current size and character.  Slopes with a dusty, brown surface or rocky terrain will warm faster and may produce larger wet loose avalanches due to increased melt.  Ideal conditions for riding have just enough softening for good turns, but the snowpack should remain supportive below.  If you find a punchy and mushy snowpack head to a cooler aspect or lower-angled terrain.  Conditions on the south half of the compass fit typical spring-time travel techniques.  By the early afternoon, you may want to shift to westerly terrain or head for cooler northerly slopes to avoid encountering Wet Loose avalanche conditions.

As meltwater infiltrates the snowpack, concerns for Wet Slab avalanches slightly increase.  An observation from near Snodgrass on Tuesday and Schuylkill Peak area on Wednesday suggests that easterly and westerly aspects below about 11,500 feet have meltwater draining into a winter-like snowpack.  Rocky, bushy, and/or dusty surfaced terrain often moves meltwater faster than open, white snow slopes.  Wet Slabs are difficult to predict and manage.  A good rule of thumb is to start your day early and move off slopes of concern before surfaces become mushy.  This isolated and unlikely threat will linger until cooler weather arrives this weekend and meltwater production ceases.

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