Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Triggering an avalanche breaking 1-2 feet thick remains possible. Avoiding steep slopes—especially those exposed to the wind—will help you stay out of trouble. While unlikely, we can't rule out triggering a very large, 4-5 foot thick avalanche—especially on very steep, rocky, wind-affected slopes.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    The snowpack is deepest in this zone, but the two problematic layers that exist elsewhere are also concerning here:

    1. Surface hoar and facets buried 2' down: The train of storms that brought significant snowfall across our region buried a weak layer that has produced avalanche activity in all of our zones. In the Banner Summit area, most of the activity that we have observed failed on a layer of surface hoar at this interface (photo at right/above). I went looking for this layer in the northern portion of this zone yesterday (observation here). In places I found surface hoar here and in others I found facets on top of a crust. These layers were stubborn in my snowpack tests, but I still let the presence of these layers drive my terrain selection. Human-triggered slides on these layers are possible again today. You are most likely to trigger one in "prime time" avalanche terrain that has been loaded by the wind.
    2. December facets buried 4-5' down: This layer is deeply buried in this zone but has been slow to gain strength. Because the slab over this weak snow is so thick and dense, it is difficult for us to impact the weak snow underneath, but the bad structure (strong snow over weak snow) isn't improving.  It would take a dose of bad luck to trigger a deep slab, but it could happen in very steep, rocky, wind-affected terrain where more "trigger points" exist.

    We are in the midst of a multi-day wind event that is producing strong W to NW winds. These winds are loading many slopes at middle and upper elevations, keeping these weak layers on edge. Avoiding steeper slopes (those over about 35 degrees) and those that have been affected by the wind will greatly reduce your chances of triggering a persistent slab avalanche.

    (2/4/2021) This avalanche failed 2' deep on buried surface hoar. This weak layer has presented itself as surface hoar in some areas and small facets in others. NE, 8400', Copper Mtn.

  • Wind Slabs

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

    Because of the weather patterns and terrain characteristics of this zone we don't often see widespread wind slab problems here. I went out to look for wind slab problems in the northern portion of this zone yesterday. I found plenty of wind and saw lots of snow being transported by the wind, but found that the slabs that were building seemed to be bonding well with the snow underneath. However, recent observations of touchy wind slabs in our other zones make it difficult to ignore these slabs altogether.

    From an avalanche danger perspective, the larger concern is the ongoing loading on the persistent weak layers described above. Even small wind slabs can be great triggers for more deeply buried weak layers. Any avalanche that steps down to these persistent weak layers will be large and destructive.

    ADDITIONAL DISCUSSION: The ongoing wind event is moving plenty of snow, and even though the slabs we've observed in this zone aren't particularly touchy, there has been some significant cornice formation in the past few days. Yesterday, I found large, fresh cornices that were easy to trigger, often toppling off the ridge with a single kick (from a safe distance, of course). As the wind continues, these cornices will be failing naturally, tumbling down the slopes below. These dense blocks can penetrate deeply into the snow as the cartwheel downslope, providing a great trigger for both shallow and deeply buried weak layers.

Avalanche Discussion

Since January 30th, 15 people have lost their lives in avalanche accidents in the U.S. This has been the deadliest avalanche week in our country in over 100 years. While that is a terrifying, heart-wrenching statistic, the people who lost their lives aren't statistics. They are brothers and sisters, sons and daughters, each with countless loved ones that will never get to see them again. Don't just gloss over this, take a minute to let it sink in.

When we enter avalanche terrain in the backcountry we are playing a dangerous game, one with high stakes and small margins for error. Faced with the harsh realities of the backcountry environment it is easy for us to find ways to explain away these dangers. We do this without even thinking about it, it is a defense mechanism that our brain employs to help us feel comfortable with our choices. But pretending that the beast isn't real doesn't make the beast go away. If you have been backcountry riding or skiing for long I can guarantee that you have made some bad choices in the mountains. I know that I sure have. If you don't think you have, I suggest you spend some time reflecting on the complexity of backcountry travel and your past experiences.

This isn't an indictment of you or me, it is an opportunity for us to reflect on our good luck and to learn from it. We don't learn much when we think we already know everything. The backcountry environment is a feedback-poor one. Oftentimes when we make bad decisions we don't get any negative feedback from them, just good powder skiing and riding. But that isn't a sustainable way to travel through the mountains. I've spent much of this season worried about my close friends and the people I love who spend lots of time in the backcountry. I've spent much of the season worried about you all as well.

I feel incredibly fortunate that we haven't had any serious accidents in our area this season and I hope that trend continues for us. I know that part of the reason for that is because you have been making good decisions and part of it is because we get lucky sometimes. Waiting out bad persistent weak layers, and sticking to mellow terrain during prolonged instability, requires discipline and patience. Stay the course my friends, there will be times with good stability and steep powder but we aren't there yet. Thanks for your good travel decisions, lets keep it up.

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