Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 7 years ago.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

Highlights

Human-triggered avalanches remain likely in areas of recently wind-hardened and drifted snow. Look for obvious signs of unstable snow, like cracks shooting from your boards or sled. Avalanches may be triggered remotely — from gentle terrain above, below, and to the sides of steeper slopes.

Avalanche problems

  • Persistent Slabs

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

    You’re most likely to trigger a persistent slab avalanche where recently wind-drifted snow sits atop one of the buried persistent weak layers that plague the majority of the forecast area. These layers are most prevalent at upper elevations and on shadier middle elevation slopes.

    Although obvious signs of instability are becoming less common, this problem isn’t going away any time soon. When dealing with persistent weak layers there are a couple of things to keep in mind: 

    1. Triggering avalanches remotely — from above, below, and to the sides of slopes, is a real possibility. 
    2. Persistent slabs can fail in surprising ways, break wider than expected, and span multiple terrain features that may otherwise contain storm slabs or wind slabs. 

    A small storm will impact the area this evening. While snowfall and wind are forecast to be minimal, it likely won't take a large load to awaken these layers. Keep this in mind this afternoon if you find yourself in a location where snowfall is piling up or you’re in an area with active wind-loading.

Avalanche Discussion

The primary weak layers in our snowpack are easy to see, but obvious signs of instability are getting harder to come by. Triggering avalanches, cascading whumpfs and zippering shooting cracks can really drive home the message that the snowpack is unstable and dangerous. Even as these warning signs decrease, there are two primary weak layers warrant your respect and attention:

  1. We buried a widespread layer of surface hoar in early December. We’ve found these weak, feathery crystals from Banner Summit, down through the Sawtooths and western Smokys, across the valley into the White Clouds, south to Galena Pass, further south into the Boulders, and in the mountains east of Ketchum and Hailey. In short, we’ve found it almost everywhere we’ve been.
  2. In areas that harbor lingering snow from September and October, large, sugary depth hoar sits at the base of the snowpack. This layer is more common in the Sawtooths, Western Smokys, White Clouds, northern Boulders, and Banner Summit area.

Last night, we (the forecasters) had a meeting to discuss current conditions. We talked at length about the subtle differences in weak layers with changing aspect, elevation, and location. We also discussed the uncertainty of dealing with a widespread surface hoar problem – something that is rare in this area. Personally, I deal with complexity and uncertainty by dialing back the consequence of the terrain I choose to ride. Complex problems warrant simple terrain.

Regions covered