Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
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Pericolo valanghe

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Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Triggering a very large avalanche that involves the majority of the season's snowpack continues to be an unnerving possibility. The first sign of instability may be the unsurvivable avalanche you trigger. Smaller loose snow avalanches will be easy to trigger and may release naturally throughout the day as the sun warms the snow. These can become large in big terrain and can also trigger much larger slides on deeper weak layers as they travel downslope. 

Problemi valanghivi

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    A disconcerting weak layer lies buried beneath very dense, 2-4 foot thick slabs on most slopes in this zone. Beneath this meaty slab, you'll find thick facet stacks with or without surface hoar on shaded aspects, and crust with associated facets on sunny slopes. Storms in January produced many avalanches involving this weak snow in this zone. With a lighter load from February storms, triggering an avalanche involving this snow has become less likely than in our other zones. 

    Triggering an avalanche on deep weak layers isn't easy, but if you do find a trigger point you can expect the entire slope you are on to shatter, sending the majority of the season's snowfall on a fast track downhill. The thick slab acts as armor for these weak layers, making triggering a slide more difficult. Likely trigger points are in steep, rocky, wind-swept terrain where the overlying slab is thinner.

    The large avalanche you trigger may be the first obvious sign of instability you see today. Don't expect feedback from this layer, but know that it is down there. You may be able to trigger avalanches from flat or low-angle terrain long distances away from steep slopes.

    (1/22/2024) The debris of this slide ran into a creek, a lower and mid-elevation terrain trap that is characteristic of the Banner Summit Zone. Terrain features like these multiply the consequences of these slides.

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    Recent storms brought well over a foot of snow to this zone. Expect to encounter a range of smaller issues related to this new snow:

    Loose snow: Sluffs of new snow will be easy to trigger on steep slopes without crusts at the surface. Natural loose snow slides may occur on slopes that face the sun if the clouds allow more sun through than expected. If the snow you are traveling through is becoming moist and you are seeing balls of wet snow rolling downslope, these small slides may be releasing naturally.

    Wind slabs: Winds have been generally light in this zone and recent observations point to a lack of wind slab development. If you head to upper elevations,look for reactive slabs in places where the wind has been transporting snow and building drifts. Wind slabs that formed earlier in the storm when conditions were much breezier will be hard to identify visually, thanks to the low-density powder sitting on top. 

    Slabs at new/old interface: Snowpit observations and natural avalanches point to the potential for avalanches failing at the base of the new snow, even in terrain sheltered from the wind. We have not seen slab activity in this zone. Our observations are limited, and we can't yet say with confidence if this interface will be a longer-lived weak layer or just a flash-in-the-pan. Some of the observed avalanches that failed on this layer broke many hundreds of feet wide. 

    Even small slides can knock you off your feet and send you for a ride in ugly terrain. Surficial slides will travel fast and far on the stiff surfaces underneath. Remember that all of these smaller avalanches take place on the stage set by the Persistent Slab problem above. Smaller slides can be effective triggers for much larger Persistent Slab avalanches as they rocket downslope. 

Avalanche Discussion

How's It Going Now?

A very close friend of mine passed away this fall. Today is his birthday. Let me tell you a short story about him that might help you today and tomorrow. His name was Kyle, and he cared deeply about his friends. Each time you saw him, whether it had been just a day or a year, he would ask you, "How's it going now?". This wasn't a casual question. It was an in-depth inquiry into your life.

I ask you to carry that question and spirit with you into the backcountry today. Stay in touch with the snowpack and stay in touch with your partners. Spend the time to think about, and to care about the snow underneath your feet. Today you will be tasked with managing a dangerous snowpack and managing your own excitement and expectations. Head out into the mountains with a plan that takes the widespread layers of weak snow in our snowpack into account. Take the time to make sure that you are on the same page as your partners about the risks you are comfortable taking and the terrain that you are planning to avoid. Then, stick with that plan. 

Our snowpack is dangerous and difficult to predict. Ongoing natural and human-triggered avalanches point clearly to this danger. We are a long way from being out of the woods with our Persistent Slab problems. Move through the snowy world understanding the nature of these hazards and be honest with yourself about the risks you are taking.

As Kyle taught me and many others, it doesn't hurt to carry this approach into life more broadly. When you get home from the hills safely tonight, think about finding a friend, giving them a hug, and asking them, "How's it going now?". 

Regioni coperte