Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Continued snowfall and wind-drifting are creating dangerous avalanche conditions at upper elevations. Triggering a 1-2 foot thick avalanche is likely in steep, wind-loaded terrain—especially in the northern Sawtooths where more recent snow has fallen. While unlikely, we can't rule out the possibility of triggering a very large, 3-4 foot thick avalanche on very steep, rocky, wind-affected slopes. 

Avalanche problems

  • Wind Slabs

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

    Around 6-12" of snowfall that's accumulated over the past 48 hours and more is in the forecast today. This snowfall has been accompanied by periods of moderate westerly winds, and you're likely to find fresh wind drifts and slabs along upper elevation ridgelines. These will be larger and more dangerous as you head north into the Sawtooths where the most snow has fallen. An observer in the Sawtooths yesterday reported seeing a medium-sized debris pile, likely from a natural wind slab avalanche.

    These fresh wind slabs are likely to be soft, but still slightly denser than snow on more sheltered slopes. Watch for these fresh drifts in wind-exposed, upper elevation terrain. Owing to the craggy nature of the Sawtooths, snow trickling down cliff faces tends to accumulate on the aprons below, forming "spindrift slabs." Avoid steep and/or consequential slopes where you find evidence of wind drifted snow.

    The ongoing snowfall has been accompanied by periods of moderate westerly winds, and you're likely to find fresh wind drifts and slabs along upper elevation ridgelines.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    The more recent weak layer in the top 2' of the snowpack is showing signs of giving up the ghost. As a result, our attention returns to our old, familiar friend—the December facets near the base of the snowpack. This layer is buried beneath a very dense, 3-4'+ slab. A unique characteristic of this weak layer is that despite having a crushing amount of weight above, it is not getting "squashed" like a more normal layer of facets would.  When a layer is buried this deeply, stability tests are very time-consuming and really don't work that well—but don't worry, we did the work for you.

    It would take being in the wrong terrain, as well as a dose of bad luck, to trigger this layer. But if you did trigger a deep slab, you'd need all the luck in the world to survive it. So what's the wrong sort of terrain? Steep (over 35 degrees), rocky, wind-affected, "prime-time" terrain. You can avoid most risk of triggering a deep slab by sticking to sheltered, mid-elevation slopes where a more uniformly deep snowpack exists.

    (2/9/2021) A natural deep slab avalanche on McDonald Peak in the southern Sawtooths. It occurred last Sunday during the ongoing wind event.

Avalanche Discussion

The avalanche conditions are almost always a good news/bad news situation. First the good news: we're slowly emerging from the deep, dark forest of dangerous avalanche conditions we've been lost in almost the entire winter. And now for the bad news: snowpack stability had become extremely variable across the forecast area. What this means is that you'll need to do a bit more homework to fully understand the conditions in the area you plan to ride in. Here are some tips to help you know before you go:

  • Understand what zone you're heading to. If you don't know, our new Trip Planner tool can help you locate yourself within our forecast zones.
  • Read the forecast carefully, paying attention to clues indicating where you're more likely to trigger slides.
  • Form a guess as to the average depth of the snowpack where you're headed. Where the snowpack is deeper than about 4', you're likely to find more predictable conditions. Where the snowpack is shallower, expect to find more variation as you move from slope to slope—especially in those areas exposed to the wind.
  • Hot tip: skiing and riding on wind-sheltered, mid-elevation slopes is very good right now, especially further north where more new snow has piled up. By sticking to these sheltered slopes, you can avoid most of the risk of triggering a slide.

Be sure to catch up on the happenings this past week in Ethan's latest Weekend Update.

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