Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Small amounts of incoming snow will continue, and although the bulk of the storm has passed, the snowpack is complicated and so is the avalanche problem. It's likely that you can trigger a large avalanche on steep slopes, so avoid all steep terrain, and when in doubt, avoid traveling on lower angle slopes where avalanches run and stop as well. The snowpack is complicated and inconsistent, so even if you don't trigger an avalanche in one spot, a few feet over you might trigger a large one that could kill you. 

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    Small and large natural, human-triggered, and remote avalanches occurred over the last few days, including a partial burial in the Baker backcountry on Friday. The snowpack is complicated right now, and what we're looking at is not your average storm slab problem that goes away in a day or two. You might get away with being on a steep slope, but you're taking a gamble if you're doing that, and just because you didn't trigger a deadly avalanche on one doesn't mean you won't on another slope. 

    Many avalanches are failing within the new snow 6-16 inches deep, some occurred at the new/old snow interface, but we've had a couple reports that human-triggered avalanches stepped down to the 1/10 crust and surrounding facet (weak) layers. We've got an irregular patchwork of layers beneath the new 2-3+ft of snow. That weakness is about a foot beneath the new snow layer, resulting in larger avalanches that could propagate further than what you'd expect. This is very alarming, and warrants treating the backcountry with extreme caution. 

    The issue is the spread of the weak layers, which one individual described as "consistently inconsistent." You may find the weakness and potential resulting avalanches in one spot but not a few feet away, so trying to outsmart this problem is not the right way to manage it- your best option is to avoid all steep terrain and let it rest. If you see natural avalanches, experience large whumphs or shooting cracks, or remotely trigger an avalanche, take a step back and avoid traveling beneath large paths as well. You can still have a good day in the backcountry- just stick to lower-angle terrain.

    It's been windy, and slabs are thicker and deeper in wind-loaded spots. Triggering an avalanche in one of these spots will probably be easier, and could provide more weight to impact a deeper layer. 

    Example photo: Shallower and deeper avalanches, both of which are ones that you could trigger on Sunday. 

    Photo: Jason Speer

Avalanche Discussion

Our current avalanche concerns are something we don't normally have to deal with here on the west slopes of the Cascades. But it's also very uncommon to have a long, cold dry spell in January like the one that produced these weak layers. We need to behave with more of a Colorado mindset right now.  As the hours and days continue, it may get harder to trigger these shallower storm slab avalanches, and you might start gaining confidence and stepping out a little more because you aren't seeing as many avalanches. But there might still be that underlying problem that could really ruin your day if you hit the right spot. 

This storm produced at least 2 inches of water, or 2+ feet of snow, but maybe closer to 3 inches by Sunday. In steep areas that aren't wind-affected, loose dry snow can run fast and far. The Cascade Mountain Ascents team found holes from spots such as creeks beneath the new snow layer as major hazards that you might fall into, given all the new snow. 

If you must travel in avalanche terrain, be sure to have a partner and expose only one of you to avalanche terrain at a time, including the runout at the bottom. Carry a transceiver, shovel, and probe, and be super dialed in with partner rescue so you can get your partner out alive if there aren't other complications that have already killed them. This strategy, however, is not recommended. 

Regioni coperte