Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

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

Triggering an avalanche is most likely where the recent snowfall and wind have formed drifts. The avalanche danger may be greatest in the Soldier Mountains, where large triggered avalanches occurred yesterday and Thursday. Weak layers exist in the top several feet of the snowpack—while less likely, avalanches are also possible in areas sheltered from the wind. You may be able to trigger slides remotely: from flatter terrain above, below, or to the side of a steep slope. With warming temperatures today, wet sluffs will become possible—primarily at lower elevations.

If you're traveling in the upper reaches of the Warm Springs Ck drainage near Dollarhide Summit where more snow fell this week, refer to the Galena Summit & Eastern Mtns zone forecast. 

Avalanche problems

  • Persistent Slabs

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

    Weak layers of snow are buried 1.5-3 feet deep in this zone. In our other forecast areas, human-triggered avalanches were failing on this weak interface even before the new snow fell earlier this week (photo, photo). In the days since the storm, skiers and riders have triggered multiple slides that failed on this snow. On Thursday, Chris investigated an avalanche near Galena Summit that was remotely triggered by skiers from flatter terrain above. I'd recommend taking the time to watch the video he made, available at right/above.

    The culprit weak layers in all of these slides have been sugary facets that developed in March during clear and cold weather between storms. The distribution and sensitivity of these layers are somewhat irregular. They have proven to be reactive on some slopes and unreactive on others. You are most likely to find them on slopes that face E-NE-N-NW. On these aspects, it's best to assume these layers exist and choose lower angled terrain not threatened by steeper slopes above. These slabs are more likely to be reactive in areas where the wind has stiffened the snow surface and added more weight (see wind slab problem described below), but they are possible in sheltered terrain as well.

    Dealing with persistent weak layers is tricky business. Snowpack test results can be difficult to interpret and obvious signs of instability are often absent. The first clear sign of an unstable snowpack may occur when you trigger a large avalanche. 

    ADDITIONAL DISCUSSIONThe days since the recent storm have been much colder than average. Last night's temperatures were the warmest we've seen in a week. If the sun comes out for longer than expected today we may see some wet snow issues develop. Keep an eye on the condition of the snow surface. If it starts to get wet or you are seeing wet balls of snow forming and rolling downhill it is time to think about moving to an area where the snow surface is colder and drier. 

  • Wind Slabs

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

    On Thursday above the Soldier Mountain Ski Area, a snowmobiler triggered a large wind slab avalanche but fortunately was able to ride out of it (photo at right). The hard wind slab broke 2-3 feet thick and pulled into very gentle terrain at the ridge crest. It's possible this slide may have involved the persistent weak layers described above.

    Moderate to strong winds overnight and another inch of snow produced a round of thin wind drifts. Use snow surface textures (like ripples and dune-like drifts) to help you identify wind-affected areas from a distance. When you find a wind slab, expect the snow to be thicker and denser than snow that is unaffected by the wind. Cracks shooting out from your skis, board, or machine are a great sign that you've found a sensitive wind slab.

    ADDITIONAL DISCUSSIONThe days since the recent storm have been much colder than average. Last night's temperatures were the warmest we've seen in a week. If the sun comes out for longer than expected today we may see some wet snow issues develop. Keep an eye on the condition of the snow surface. If it starts to get wet or you are seeing wet balls of snow forming and rolling downhill it is time to think about moving to an area where the snow surface is colder and drier. 

Avalanche Discussion

Ahhhh, April. A time of good stability, right? Not this year, unfortunately. Skiers and riders have triggered slab avalanches on six out of the past eight days. For perspective, a total of 27 human-triggered avalanches have been reported to us throughout the entire season. Pause and let that sink in for a moment. Nearly one-quarter of the reported human-triggered avalanches occurred last week. 

These avalanches have occurred across much of our advisory area but the layers responsible have proven to be variably reactive. In some places we are seeing clear signs of instability (unstable snowpack test scores and both natural and human-triggered avalanches) while in others they appear to be somewhat inert. This irregular pattern of activity makes these layers even more challenging to deal with. But, with weak layers buried 1-3 feet deep, the consequences of being wrong in your stability assessment can be quite high.

Today, I'd strongly advise that you let the snowpack guide your terrain selection and not the calendar. We are dealing with a snowpack that is behaving more like it is February than April. Its easy to be lulled into the false sense of security at this time of year, particularly after the long periods of relatively good stability that we saw during February and March. But the snowpack doesn't care what the date is and you shouldn't either. In order to avoid the hazards posed by the type of avalanche problems that we are dealing with we need to travel accordingly. Be alert to the terrain you are in and the terrain you are below. Think about the consequences of triggering and being caught in a large avalanche. Your safety and that of your riding partners demands that you ignore the calendar and focus on the snowpack.

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