Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Although conditions are gradually improving after our recent spell of mild weather, the Southeast Mountains have been the problem child in recent weeks for triggering dangerous avalanches that break several feet thick or more.  Recent human-triggered avalanches and continued signs of instability highlight our concerns.   Choose less consequential terrain and lower slope angles on the north half of the compass to manage the problem.  You can find safer riding on southerly aspects where you find a few inches of new snow over thick crusts.

Avalanche problems

  • Persistent Slabs

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

    In the Southeast Mountains, slabs breaking on older weak layers are becoming more difficult to trigger but remain a concern on many slopes.  The most prominent and active weak layers are surface hoar and facets buried a couple feet deep on the north half of the compass. There is also smaller potential for avalanches to break on faceted crust layers on some higher, southerly aspects or depth hoar layers near the ground.  Persistent slab avalanches can be remotely triggered from low-angle terrain and break deeper and wider than you might expect.  Avalanches breaking into old weak layers are unlikely on mid to low elevation, southerly aspects.  Slope angles consistently less than 30 degrees are a reliable way to avoid the problem.

    This large avalanche was remotely triggered in West Brush Creek on March 8.  

     

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Up to 6" of new snow overnight and westerly winds at high elevations formed shallow soft slabs in a few leeward terrain features.  Fresh wind slabs will be sensitive to triggers: stay alert and ride defensively anywhere that you can't afford to get knocked off your feet such as above cliffs or in gullies.  You can avoid the problem by traveling in sheltered areas where the snow is fluffy and unaffected by winds.  Fresh drifts will look and feel thicker than wind-sheltered snow.  

Avalanche Discussion

3" to 6" of low-density snow overnight provides a nice surface refresh that won't significantly change conditions:  Watch for minor sluffing in favored areas and thin wind slabs in alpine terrain where the new snow is getting blown around.  

We've lowered the likelihood of triggering a persistent slab to "unlikely" in the Northwest Mountains and "possible" in the Southeast Mountains.  The chances of triggering a persistent slab are decreasing after nearly a week of mild, dry weather.  This has given weak layers a chance to adjust to the last significant loading event. Furthermore, surface crusts formed on sunnier aspects, which adds some strength to the snowpack.  The thicker the crust, the more of a stabilizing effect it has.  We've trimmed back the distribution of the persistent slab rose to reflect the aspects and elevations that saw the most significant upper snowpack strengthening.  

The pattern of triggered and natural persistent slab avalanches over the past 2 weeks clearly points to areas with shallower snowpacks being the most problematic.  Most of the avalanche activity has been in the shallower part of our forecast area (the Southeast Mountains), and the few persistent slabs in the deeper zone occurred on windward slopes or on slopes that have repeatedly avalanched this season keeping the snowdepth unusually shallow.  It's an appropriate time to step out if you are choosing slopes with consistently deep snowpacks (>200cm), or choosing southerly aspects with strong crusts near the snow surface.  

CBAC Event:  Don't forget the 50th Al Johnson Race is this Saturday, March 17th.  Registration and information can be found at cbavalanchecenter.org.  All proceeds to benefit the CBAC.

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