Avalanche forecast

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Recent snow and moderate winds will create new slabs of snow that will be most reactive below ridgelines and leeward sides of cross loaded slopes. Some of these slabs were formed during the last storm, while others will slowly evolve as winds progress today. One thing is certain, there are a number of interfaces in the upper snowpack that seem vulnerable to failure with either more drifting or influence from a person or machine. Indicators of drifted slabs are new cornice growth, cracking in the surface, and sculpted surfaces. Back away from slopes if you encounter these clues and seek lower angle or protected terrain features.

Avalanche problems

  • Wind Slabs

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

    Winds increase today as the next storm system moves in, and the existing snow that was delivered in the last storm cycle will get transported and form new compact slabs. These fresh slabs will be most reactive directly below ridgelines, and on the leeward facing side of steep terrain features that have been exposed to cross loading. Away from wind exposed areas, the upper 2-3 feet of snow consists of a variety of storm interfaces that may still be reactive to a skier or rider and need some more time to settle out. When travelling in the mountains, clueing in to the feedback the snow surface is presenting with will be essential. Observing cracking, density changes, and drifted or textured surfaces indicate that instabilities are present and it’s a good idea to scope out lower angle terrain. 

    On March 16th, a skier triggered a large and dangerous avalanche that failed in the storm snow. This avalanche was large enough to bury, injure, or kill an individual. Luckily, the skier was able to ride out of the slide and was unharmed. This close call is a reminder to carefully evaluate the snowpack and terrain before committing to any large and open slopes, and to ski and ride with a partner.  

    Below the large cornice on the leeward facing side of the ridgeline, a wind slab was triggered remotely with a crown that was approximately 8"-12" deep. Cracking extended across the slope beyond where the avalanche failed.  

    Photo: Mikey Church

Avalanche Discussion

The month of March consisted of an active weather period that delivered generous amounts of snow across the forecast area. On March 9th, light and low-density snow fell on top of a stout melt-freeze crust, that was quickly buried by heavier snowfall. This combination created a reactive and inverted slab that is 2-3 feet thick. The sensitivity of this slab was tested when a skier triggered a large avalanche with a crown height of approximately 2 feet that propagated 300 feet across the slope. Now, as we move further away from the initial storm, all the ingredients for a skier or rider to trigger a large avalanche still remains. Winds increase Wednesday afternoon and Thursday as the next round of storms come knocking on the door, which will only increase the size of existing slabs and add new weight to an already fairly complex upper snowpack. Taking a moment to dig in the snow to investigate these interfaces is a good starting point before thinking of committing to any large open slopes.

During the day on Wednesday, intermittent sunshine will make an appearance. As the sun peaks through a partly cloudy sky, mild temperatures and solar radiation will influence the snow surface. How quickly and to what extent the snow surface changes will be determined by how much sustained sunshine manifests and how much the temperatures are able to climb. If you find that the snow is becoming sticky to your climbing skins or see evidence of rollerballs gaining in size, keep an eye out for fan shaped point release avalanches failing around cliff bands or steep terrain. This problem will be less likely as you gain elevation and temperatures cool down a bit.

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