Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

You could trigger avalanches in areas with recently wind-drifted snow. These areas are most widespread in alpine and upper elevation terrain. Some drifts formed above slick surfaces, crusts, and weak snow so any avalanches you trigger could be wider and larger than expected.  Natural and human-triggered wet snow avalanches are possible in very steep terrain receiving direct sun. 

Avalanche problems

  • Wind Slabs

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

    Look for drifts of windblown snow near ridgelines and on the sides of cross-loaded gullies and chutes. These will be most common at upper elevations but you may find some slabs at middle elevations as well. Wind-affected slopes may be hard to identify today. Multiple rounds of snow—some with wind and some without—created slabs on some slopes and not on others. The slabs that formed during Sunday's storm are now obscured by Tuesday and Wednesday's storm.

    It doesn't take much wind to stiffen snow into a slab. Some slabs formed on slick, icy crusts and small facets. This means they may be easy to trigger, break above you or wider than expected, and could pick up speed quickly as they travel downslope. This slab avalanche (observation) was triggered by a skier yesterday in the W. Smokys. Read more about the weak snow buried in the snowpack in the Forecast Discussion below.

    If you find the snow depth is quickly increasing or the surface is becoming stiffer, you've found a wind slab. Cracks shooting out in front of you are an obvious sign of instability. Some of the new slabs will be on the smaller side, but some are large enough to bury people. Think about where even a small avalanche would carry you before committing to riding or skiing any recently wind-loaded slopes. 

    (3/16/2022) Small cracks in older wind slab that likely formed following the small storm on Sunday (3/13). Snow since Tuesday morning (3/15) was obscuring the older, touchier slab.

  • Loose Wet

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

    Natural and human-triggered avalanches are most likely on very steep slopes that face the sun. These slides commonly initiate near warm rocks, fanning out and collecting snow as they go. They can travel quickly on the slick surfaces beneath them. Pay attention to the terrain above you. Large slopes can produce slides big enough to knock you off of your feet and carry you places you don't want to go. Pay attention to how sticky the new snow is becoming. If you can easily make a snowball, minimize the time spent below large, steep slopes.

Avalanche Discussion

UNCERTAINTY 

Yesterday, a skier triggered a small slab avalanche near the head of Smiley Ck in the W. Smoky Mountains. The slide failed on a thin layer of facets that formed above a stout rain crust (see pit photo here). The avalanche broke 150' wide and 6-10" deep, piling debris against a line of trees near a creek bottom (see observation and photo here). 

Multiple layers of facets exist in the upper 1-3' of the snowpack. You may find facets (shady aspects), crusts (sunny aspects and some rain crusts on all aspects), crusts + facets (mixed sunny/shady aspects), and possibly surface hoar. The complex nature of where these layers exist (or don't) makes it hard to pin down a large-scale pattern on which slopes or layers are most worrisome. 

It's unclear if yesterday's avalanche was an indication of a larger pattern, or simply an example of a "sweet spot" where a particularly touchy weak layer and subtly wind-affected slab overlapped. With better visibility this morning, we hope to get some answers to this question. Regardless, it's a perfect example of the type of complexity we're dealing with out there. 

While somewhat unsatisfying, the best way to face uncertainty is to scale back our terrain choices. Slides involving these layers are most likely on recently wind-loaded slopes that are over about 35 degrees. Remember that even light wind can be enough to tie together a slab. Cornices and stiff drifts are great indicators, but clues can be more subtle too. Look for shallow "dunes" and ripples in the snow surface or dig a quick hole with your hand to see if the slab stiffens quickly under the new-fallen snow.  

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