Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The likelihood of triggering a slab avalanche slowly decreases; however, if you do it could be very large (like these recent avalanches on Mount Baldy 1, 2).  You are most likely to release a slab where the snowpack thins to a below-average depth.  You can reduce your risk of avalanches by avoiding shallow areas like wind-eroded slopes, rocky terrain, or features with highly variable depths.  Favor terrain with a deep uniform snowpack.  By the afternoon, the March sun will wet snow surfaces and create a loose avalanche problem on steep southerlies.  There is a small chance that loose avalanches pry out a slab as they run.  Monitor surface wetness and move to a cooler snowpack if you find more than a couple inches of wet surface snow.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    As snow surfaces warm, expect the potential for wet avalanche activity to increase. This avalanche problem will be most likely on slopes holding dry snow this morning, that becomes wet for the first time today. Steep slopes with cliffs and rock outcross will produce the most avalanche activity as those rocks absorb more heat and transfer that heat into the snow. In most cases, this avalanche activity will be small, easy to identify and avoidable. In isolated areas, wet avalanche activity could produce a larger slab avalanche. Keep an eye out for wet avalanche activity today and consider moving to colder aspects as steep and sunny slopes heat up through the day. 

    A recent Wet Loose avalanche from Saturday.  Similar conditions will exist on Sunday.  Avalanche size may increase a small amount as temperatures climb a few degrees warmer.

    Photo: Evan Ross

  • Persistent Slabs

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

    In areas with a total snowpack height of over 2 meters, weak layers continue to slowly gain strength. In the NW Mountains, there has been a notable downturn in avalanche activity in March, compared to February. These two recent avalanches were triggered from areas with variable snow depths and highlight the potential size if you find the right trigger point (1 & 2). Since early February the weak layer that produced the most avalanches was a layer of buried surface hoar and small facets, several feet deep on the north half of the compass. There is also 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 still be triggered after multiple people have traveled across a slope and will be more likely to be released from a trigger point where the snowpack thins to a below-average depth. Avalanches breaking into old weak layers are unlikely on low elevation, southerly aspects. Slope angles consistently less than 30 degrees away from runout zones are a reliable way to avoid the problem. 

    Remotely triggered avalanche. West, 10,400ft. The snow height here is 115cm. 

    Photo: Evan Ross

Avalanche Discussion

A spring-like day creates both dry and wet avalanche concerns.  Temperatures are forecasted to rise several degrees warmer than Saturday and this expectation is reinforced by last night's lows running around 5 degrees warmer than the previous night.  Warming conditions are likely to cause a Wet Loose avalanche concern.  Avalanche size remains relatively small, but higher elevation east and west aspects may produce bigger loose avalanches as recently dry surface snow becomes wet.  Additionally, a chance exists for loose avalanches to release a deeper slab.  This less-likely scenario could occur on shoulder aspects where the Wet Loose problem overlaps with the Persistent Slab problem.  Keep tabs on the wetting surface snow throughout the day and remain cautious of triggering a Wet Loose avalanche on slopes with a Persistent Slab problem.

The Persistent Slab problem is the more dangerous issue on Sunday.  There is a notable difference in the likelihood of triggering a Persistent Slab between the Northwest and Southeast Mountains.  In the Northwest Mountains, the snowpack is commonly 2 meters or deeper.  It is harder to trigger an avalanche with a deep and uniform depth snowpack, but there are places where the snowpack thins and triggered avalanches become more concerning.  Wind-eroded, rocky terrain, or slopes that previously avalanched this winter will have shallower than normal snowpacks.  The perfect case and point is the avalanche activity from the west side of Mount Baldy on Friday.  Two dangerous avalanches failed in a generally shallow and variable snowpack (1,2). Take a moment to watch the video in this observation and consider the magnitude and dire consequence of releasing a Persistent Slab.  Steer clear of slopes where you expect to encounter a shallower snowpack and trigger points.  Warming temperatures may slightly increase the risk of natural cornice fall which could act as a trigger for a dangerous slab avalanche.

In the Southeast Mountains, the snowpack is generally shallower with depths commonly less than 2 meters.  A shallower snowpack increases the chance of you impacting weak layers and releasing a deadly avalanche.  Recent avalanche activity points to this increased risk with dangerous remotely triggered avalanches on Double Top, West Brush Creek, and an accident just outside the Southeast Mountains zone near Italian Mountain.  Take a look at this video from Double Top to get a better visual on the increased risk of riding steep terrain in areas with a shallower snowpack.  Take a cautious approach to your terrain selection in the Southeast Mountains particularly in areas with less than 2 meters total depth (this is much of the Southeast Mountains).  Don't expect warning signs before releasing a dangerous avalanche.

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