Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

Wed
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Out of date — this forecast expired 7 years ago.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

Triggering avalanches on shallow and deeply buried weak layers continues to be a possibility. 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

    In this zone there are two separate persistent slab problems to think about:

    1. Recent natural avalanche activity indicates that a recently buried interface in the upper portion of the snowpack continues to be capable of producing avalanches. I observed one such slide yesterday in the Frenchman’s drainage near the headwaters of the Salmon River (photo). The slide appeared to have failed on Sunday.
    2. Weak snow exists near the base of the snowpack. This snow was the culprit layer in a widespread avalanche cycle that took place during last week’s storms. Chris reported that this was one of the most extensive deep slab avalanche cycles in recent memory. Avalanches failing thousands of feet wide were observed in many cirques.

    You are more likely to encounter the first of these problems. The shallow weak layer is much closer to the surface and your chances of triggering an avalanche involving it are greater. However, if you are trying to avoid exposure to avalanche hazard entirely, you have to be mindful of the monster lurking in the basement. 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. Triggering an avalanche on a near-surface weak layer may result in a much larger, deeper avalanche as it moves downhill.

    ADDITIONAL DISCUSSIONPrecipitation starts again this afternoon. Wind speed will increase a bit late in the day and overnight as the storm exits our area, shifting from SW to NW. Fresh wind slabs will be small, but may be touchy. More importantly, these slabs will add stress to the weak snow underneath. Also, one of these much smaller, fresh slabs may be able to trigger a larger, deeper slab as it travels downslope.

Avalanche Discussion

With each passing day without additional loading we are trending towards the dreaded “scary moderate” stability rating. Avalanche hazard is the likelihood of an avalanche impacting something of value — for our purposes, that thing is you. As the likelihood of an avalanche occurring decreases, the avalanche danger also decreases. But it gets tricky: as the likelihood of triggering a slide decreases, the consequences of such a slide remain constant. 

This scenario is commonly referred to as “low probability, high consequence,” or LPHC for short. LPHC events are very tricky to deal with, in the backcountry and in life in general. Each individual has to decide what threshold of risk is acceptable for them. Most people have decided that flying in an airplane is an acceptable risk. The odds of an airplane crashing is commonly cited as 1 in about 5 million. How much higher would these odds need to be before you decided you wouldn’t fly anymore? 1 in 1 million? 1 in 100,000? 

When dealing with persistent weak layers, even subtle changes in the snowpack can impact stability and keep the snowpack on edge. Put simply, our snowpack doesn’t need a quick trip to the spa, it needs an extended cruise in the Caribbean. Over the past few days the snowpack has been agitated by prolonged exposure to air temperatures near freezing. A quick shot of snow tonight will continue to irritate our weak layers. As you travel through the backcountry today, recognize that you are dealing with a LPHC problem who’s odds are impossible to know with certainty and are continually changing. The best way to reduce your risk is to build in wide safety margins into your travel decisions. Be aware of the terrain that you are traveling through and underneath and be alert of the consequences of being caught in a slide in that terrain.

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.

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