Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 7 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

It remains possible to trigger very large, 3-5 foot thick slab avalanches. Buried weak layers underneath these slabs continue to show evidence of instability. Numerous very large and destructive avalanches failed naturally on these weak layers during the recent storm. Sticking to lower angled terrain and avoiding shallow areas in the snowpack are the best ways to reduce your risk.

Avalanche problems

  • Persistent Slabs

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

    The snowpack in this area increased significantly in the past two weeks and is now much deeper than in our southern areas. Similar layers of weak snow exist here, but they are buried considerably further down in the snowpack. This is a bit of a double-edged sword. While you may be a bit less likely to trigger one of these deeper slabs, the consequences of being caught in one would be catastrophically high.

    Dealing with deeply buried persistent weak layers challenges even the most experienced backcountry users. The snowpack won’t provide you with any signs of instability before it fails. One minute you are riding powder and the next minute the entire season’s snowpack is cascading down the slope.

    Avoiding this problem means avoiding the terrain that this problem exists in. You’re most likely to trigger one of these avalanches in terrain where there are shallow, rocky areas that allow you to impact the weak layer. Areas where the wind created slabs and added weight to this weak snow will also be more sensitive to human-triggering.

    ADDITIONAL DISCUSSIONAging wind slabs in exposed upper elevation terrain are becoming less reactive as time passes. However, if you do trigger one of these smaller slabs it may be capable of triggering a more sizable slab as it travels downhill. Local professionals observed this exact phenomenon yesterday (photo here).

Avalanche Discussion

If you are getting tired of reading about and dealing with persistent weak layers, you might want to think about relocating to an area with a different snow climate. Long-lived layers of weak snow are the name of the game around here and this season is no different.

Avalanches are more likely to occur when there is something to trigger them. This trigger can take many forms  — a falling cornice, a wayward herd of elk, and most importantly, you. Yesterday, multiple avalanches that failed within the past 24 hours were observed. These avalanches failed naturally, in the absence of any obvious trigger. These natural avalanches are a clear sign that the snowpack continues to be unstable. If it’s true that time heals all wounds, our snowpack is clearly in need of some more time.

Details from Wednesday's Avalanche Accident in Baker Creek:On Wednesday, January 15th, 2020, a snowmobiler was caught and killed in an avalanche in the Baker Creek drainage, approximately a half-mile northeast of Baker Lake. We visited the site Thursday to collect data on the avalanche. This video contains preliminary information collected during the site investigation; a full accident report will be published soon.

The avalanche released at an elevation of 9200 feet on a south-facing, wind-loaded slope. The slab broke 2-3 feet deep, 250-300 feet wide, and ran just over 600 vertical feet. The slope angle of the start zone was around 33 degrees, but the slope steepened significantly below the fracture line. The avalanche was triggered from lower on the slope, well below the crown line of the avalanche, and released on a persistent weak layer of faceted snow in the middle to lower snowpack. The avalanche debris range from 3-8 feet deep.

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