Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Warmer overnight temperatures will allow snow surfaces to soften earlier today. On southerly-facing slopes, watch for developing wet avalanche concerns. If you find a few inches of wet snow in steep terrain, small wet loose avalanches will be possible. Or, if you find conditions where your boots sink deeply into wet snow, you've found an isolated area that could potentially produce a wet slab avalanche. 

On the north half of the compass, heightened avalanche conditions remain due to a lower-likelihood but high-consequence persistent slab problem. Choosing terrain with a deeper, more uniform snowpack and fewer thin spots will help reduce the chance of triggering one of these old slabs. The recent avalanche on Mt. Whetstone is an example of terrain to avoid, where a thick slab transitions to thinner trigger points near its edges.

Avalanche problems

  • Wet Slabs

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

    There is an isolated chance for wet slab avalanche conditions later today. The most concerning terrain for wet slabs is on slopes where persistent slabs were active in recent weeks, and are now producing meltwater: east, west, and higher southeast aspects, especially in steeper, rockier terrain. You'll find safer travel conditions while the upper snowpack is mostly frozen and supports your weight.  If your boots sink deeply into wet snow, it's a sign you have overstayed your welcome and should move to lower-angle or colder terrain. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    Old, hard slabs 1.5 to 3+ feet thick overlie buried weak layers and are typically difficult to trigger. Without obvious warning signs, avalanches are most likely triggered where the slab is thinner and easier to impact the weak layer below. The most fragile layers are buried in the middle and lower portions of the snowpack on the north side of the compass. Persistent slab avalanches are dangerous in size; they can propagate widely and be remotely triggered from adjacent low-angle terrain.  The most reliable way to manage this problem is to choose conservative slope angles or travel on southerly aspects, where the snowpack structure has become stronger and more spring-like. On northerly aspects, avoid steep terrain with a thin or variable snowpack, such as rocky areas, rollovers, or places where winds have created uneven slab thickness.

    This recent avalanche on Mt Whetstone is an example of terrain to avoid, with a thick slab transitioning to thin trigger points around its boundaries. Photo: Kelly Jensen

  • Loose Wet

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

    In steep terrain, keep an eye on the snow surface as it warms through the day. If you find a few inches of wet snow, you could trigger a small wet loose avalanche. These conditions will be more likely in rocky terrain, where the snow will heat up faster. Easterly facing slopes will warm up first this morning, followed by southerly facing slopes and eventually westerly facing slopes as the sun tracks across the sky. Westerly winds may keep the snow surface more frozen on some wind-exposed terrain features. 

    An example of a wet loose avalanche that ran out of steep rocky terrain earlier this week. Photo: Travis Guy

Avalanche Discussion

A weather station in Crested Butte at 8,923ft stayed above freezing last night, with a low temperature of around 35 degrees. Weather stations closer to 11,000ft, like Elkton and Schofield, recorded low temperatures in the 28 to 30 degree range. Those temperatures were higher than previously expected, so more attention was put on potential wet avalanche problems today. The snow surface has gone through numerous freeze-thaw cycles, and this has helped the loose wet avalanche problem become more resistant. The snow surface will need to become wet and start losing cohesion before that avalanche problem potentially develops later today. 

Regarding wet slabs, water is moving through the snowpack slowly. With a weaker freeze, we can't rule out the potential of this problem developing on some terrain today. The east and west sholder aspects have seen a hybrid of persistent slabs vs wet slabs, as the warming temperatures make slabs softer so that the weight of a human can more easily affect buried weak layers, and those weak layers are becoming moist to wet on some slopes, decreasing the strength of the weak layer. 

An extreme wind event passed through the mountains on Tuesday night and into Wednesday Morning. During that event, the wind direction was initially out of the west-southwest, before backing to the west and eventually northwest. Those winds, unfortunately, destroyed much of the soft snow on northerly-facing slopes. They also created a few hard wind slabs. One of those small slabs was human-triggered in steep, northerly-facing terrain near Ohio Pass. While more notably, this large persistent slab avalanche on Mt Whetstone may have run during that wind event.

The recent Whetstone avalanche is the first persistent slab avalanche that we have documented in the forecast area, since a small slab was human-triggered on Snodgrass Mountain on March 4th, or other large avalanches occurred in late February. Outside of our forecast area, there were several destructive avalanches that ran above Conundrum Creek during last Friday's storm.   Closer to home, we continue to find the most concerning snowpack structures along the eastern side of the forecast area. Brush and Cement Creek areas, which typically had the weakest layers going into the February storms, now have thinner slabs that remain more susceptible to human triggers and thinner rain crusts in the upper snowpack. Despite the lack of persistent slab avalanche activity in our Northwest Mountain forecast area, land mines do exist across our entire forecast zone. Careful terrain selection remains essential for managing the persistent slab avalanche problem.

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