Avalanche forecast

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Dangerous avalanche conditions exist, and there are continued reports of large human-triggered and natural avalanches occurring nearly every day this week. Avalanches can be triggered remotely from a distance on adjacent slopes or from low-angle connected slopes below, and propagate widely across terrain features. Avoid travelling on, below, or near slopes over 30 degrees in steepness.

Avalanche problems

  • Persistent Slabs

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

    Slab depths have now reached 2 to 3 feet, large enough that an avalanche failing on any of the buried weak layers would be capable of burying, injuring, or killing a person. These cohesive storm slabs have developed from incremental snowfall since the end of January, with more consistent loading over the past seven days. They are resting on a complex stack of weaknesses: buried surface hoar from Valentine’s Day, another layer of surface hoar from late January buried deeper in the pack, and faceted snow sitting near crusts.

    As the slabs have grown thicker and more connected, we’ve observed an uptick in both natural and human-triggered avalanches, along with clear warning signs such as shooting cracks and collapsing. Persistent Slab avalanches are notorious for their unpredictable behavior. They can propagate widely across slopes, wrap around terrain features, and even be triggered remotely from a distance. Because of this, it’s not enough to simply avoid traveling on slopes steeper than 30 degrees. You must also avoid traveling below steep terrain where a remotely triggered slide could occur. Unlike storm slab problems, which often stabilize within a few days of a storm, persistent slab instabilities can linger for days or even weeks after the last significant loading event.

    On February 20, a large skier-triggered avalanche was spotted that consequently released other sympathetic slides on the same slope. 

    Photo courtesy of Essex Prescott and the Potato Boys.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    A week of incremental snowfall has added up, adding depth to storm slabs at all elevations. The middle and upper elevation bands have picked up significant totals over the past week, with slab depths averaging 1.5 to 3 feet deep. Lower elevations, below 5,500 feet, have also received enough new snow to increase the danger. While slabs here may be slightly thinner, they remain capable of producing dangerous avalanches, especially on slopes where weaker snow layers are preserved. In many areas, these cohesive slabs sit on top of a fragile layer of surface hoar that formed prior to Valentine’s Day, creating a classic setup for widespread instability. As you gain elevation, fresh slabs will become thicker, more connected, and in turn more reactive. Over the past week, we’ve received multiple reports of human-triggered avalanches across several forecast zones, and some failed naturally. There have also been incidents of riders who were caught, carried, and partially buried or skied out of an avalanche. Avalanches triggered in the storm snow have the potential to step down into deeper weak layers, resulting in a larger and more destructive avalanche. With such reactive storm slabs widespread across slopes, conservative decision-making is essential and avoid traveling on, below, or adjacent to steeper slopes.

    On February 17th, an IPAC field team easily triggered this large Storm Slab Avalanche while traveling along a gentle ridgeline. This soft slab was 18 inches thick, failed on a layer of buried surface hoar, and propagated 700 feet across the slope

    Photo: Jackson George

Avalanche Discussion

Avalanche conditions are dangerous right now. The structure is in place, and the only thing missing is a trigger. With slabs now 2 to 3 feet thick resting on fragile weak layers, the snowpack is primed for a skier or rider to tip it past its breaking point. Reports of natural avalanches and human triggered avalanches have increased over the past 3 days. We are beginning to see more avalanches and hear about more human involvement as continued snowfall and wind increase slab depth and stiffness.

Over the past seven days, storm totals have stacked up to 27 to 36 inches in the Selkirks, 25 to 37 inches in the Cabinets, and 16 to 31 inches across the Silver Valley–Bitterroots. This snow fell in incremental pulses, but each round added weight to an already weak foundation. As slabs thickened, we received multiple reports of both natural and human-triggered avalanches. In one incident, a skier was caught and partially buried. In another, a skier triggered a large avalanche on a 30-degree slope and was able to ski out.

Early in the storm cycle, a layer of surface hoar that formed around Valentine’s Day was buried and preserved. Snowpack tests show this layer becoming increasingly reactive, producing shooting cracks and audible collapses. It has been especially sensitive where wind has stiffened the slab above it, primarily on northerly aspects. Notably, these same areas also harbor a late January buried surface hoar layer deeper in the snowpack. This stacked weak-layer combination creates a dangerous scenario where an already large avalanche could step down and fail on deeper layers.

Persistent Slab avalanches can propagate surprisingly wide distances across terrain, connecting features you might not expect. Trying to outsmart this setup can quickly lead to trouble. Avoidance is your most reliable tool right now. It’s been a lean season for snowfall and powder days, and the excitement around fresh snow is real, but this is not the time to thread the needle or push onto slopes steeper than 30 degrees. The safest way to enjoy the new snow is to stick to low-angle meadows that are well away from steep overhead terrain and disconnected from adjacent avalanche paths.

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