Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
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Out of date — this forecast expired 6 years ago.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

Dangerous avalanche conditions exist. Triggering an avalanche that fails on weak snow buried 3+' deep remains possible on most slopes—especially in wind-drifted terrain. Avalanches may be triggered remotely—from below, above, and to the sides of steep slopes. 

Avalanche problems

  • Deep Persistent Slabs

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

    The same layer of weak snow that exists in our other zones also exists in the Banner Summit Area. The big difference here is that this snow is buried beneath a dense, 3+' thick slab of snow. This slab of snow is "protecting" the weak layer, making it more difficult to trigger an avalanche on it. However, if you are unlucky enough to trigger a slide it is going to be large enough to snap trees and leave piles of debris many, many feet deep. If you're anything like me, that doesn't sound like something you want to encounter. 

    Deep slabs behave unpredictably, often failing after many riders have already traveled on a slope. Tracks on a slope are not an indication of stability. You are most likely to trigger one of these monsters in steep, rocky terrain. In these areas, the weak layer is closer to the surface. The best—and often only—way to manage a deep persistent slab problem is by sticking to lower-angled terrain. Given the possibility of remote-triggering, you'll also want to avoid being below steep slopes. 

    WIND SLABS: Periods of strong to extreme winds have been the theme for the past week. Yesterday brought more of the same. Although wind slabs are becoming less reactive to the weight of a skier or rider, these slabs are adding stress to the buried weak layer of snow underneath. If you do trigger a wind slab, it could "step down", failing on layers deeper in the snowpack and becoming much larger than the initial avalanche. 

    (1/14/2021) Avalanche that released south of Copper Mountain. This slope avalanched during the Solstice storm. E, 8700'

Avalanche Discussion

The snowpack is relatively simple in our region this season, but it sure isn't what we'd hoped for. I say that it is simple because it can be easily summed up in a sentence or two. A thick layer of weak snow that was buried in December forms the base of the snowpack. Snowfall over the past month gradually buried this weak snow, and it now sits beneath a 1-4' thick slab of snow. See, simple. 

The travel advice is also pretty simple right now. Avoid steep slopes where this weak snow exists, and lower-angle terrain threatened by avalanche hazard from steeper slopes above. Unfortunately, this weak snow exists on all slopes that haven't been melting back to dirt. See, also simple. And quite unsatisfying.

So what can we do? I'd challenge you to consider this a learning opportunity. Use it to learn about snow and the mountains where you live. There is an abundance of low angle terrain in our neck of the woods, something that can't be said in many places. Find a new spot to explore in the region and see for yourself. And while you are out there dig a snowpit and interact with the snow, you might learn a thing or two! 

Be sure to check out Ethan's Weekend Update from Friday. Spoiler alert—it was another wild week in our mountains!

Regions covered