Avalanche forecast

Northwest 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

Westerly winds increased overnight and continued to load the lee sides of terrain featuers. In the last couple of days, there have been a few human-triggered avalanches on both wind-loaded and wind-sheltered terrain. Slab avalanches remain possible today in the same areas. Loose-wet avalanche activity will increase through the day as the sun and rising temperatures begin to wet the snow surface. 

Avalanche problems

  • Storm Slabs

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

    Slab avalanche concerns primarily exist on wind-loaded terrain. However, we can't rule out lingering storm slab issues in wind-sheltered terrain as well, where snow accumulations earlier this week totaled a foot or more. A layer of small facets was buried last weekend, and this layer is responsible for the most avalanche activity in the last few days. These avalanches have released on both wind-loaded slopes and a few wind-sheltered slopes. Consider avoiding wind-loaded terrain today, and further look for small test slopes where you can look for obvious signs of instability such as shooting cracks. 

    This storm slab was human-triggered Wednesday near Purple Ridge. There is now another 6 to 12 inches of snow on top of this avalanche problem.

  • Loose Wet

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

    The new snow that accumulated earlier this week is transitioning into wet loose avalanches. This transition started yesterday and is expected to continue today. This avalanche activity will begin once the sun and rising temperatures have had a chance to wet the snow surface. This will occur first on easterly facing slopes, then move to southerly facing slopes and further onto westerly facing slopes. Some of these avalanches could become large in size. Watch for rollerballs, pinwheels, or natural sluffs to indicate developing instabilities, and move out of steep consequential terrain if the problem develops in your area. 

  • Persistent Slabs

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

    In the Northwest Mountains, high-consequence slabs breaking on older weak layers have become isolated and difficult to trigger. The last observed persistent slab avalanche occurred on March 8th in this forecast area. Any lingering persistent slabs would most likely be triggered from an unusually shallow or previously wind-eroded slope where the total snowpack height is below average.  Large cornice falls could act as triggers as well. Persistent slab avalanches can be remotely triggered from low-angle terrain and break deeper and wider than you might expect.  Slope angles consistently less than 30 degrees are a reliable way to avoid the problem when in doubt.  

    The crown of a very large persistent slab remotely triggered by snowmobiles on March 8.  This slope is west facing and eroded by seasonal winds, making for a shallower and more problematic snowpack than other slopes. 

Avalanche Discussion

We have seen some good snow totals adding up since last Saturday. The big winner was the Irwin area with a measured 34" of snow accumulating and 2.17" of SWE. Slightly less snow accumulated north of that area like the Slate River Drainage, and as another data point, Schofield Pass measured 1.4" of SWE for the same timeframe. Similar measurements were recorded in upper Brush Creek. With reports from the Friends hut totaling around 16 to 18" of settled snow and 1.8" SWE. CBMR is reporting 21" of snow. 

That snow has combined with a variable wind direction over the same period, Creating the largest loads on wind-loaded terrain. Most recently we have seen a wind direction from the west. Heading into this stormy period, we had a week of warm and dry weather. During the dry week, the snow surface on northerly facing slopes begins to facet. This observation is the best documentation of some of that weak snow. Now we are just starting to see a pattern of avalanches releasing on those buried facets. Such as this small avalanche in the Anthricites, these avalanches near Mt Axtell,  these couple of triggered avalanches near Purple Ridge, and a couple of triggered avalanches into Red Lady Bowl. These avalanches have all occurred on northerly-facing slopes. At the same time, there has been some steep skiing and riding on northerly facing terrain without resulting slab avalanche activity. So we don't have a widespread issue, but we certainly have enough documentation of a potential avalanche problem that warrants caution and consideration. 

All the snow reported above is also fueling our wet loose avalanche problem. This is a normal springtime avalanche problem, and we can expect that snow to continue transitioning from dry snow to wet snow while producing loose wet avalanches today. 

Regions covered