Bulletin d’avalanche

West Slopes Central

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The storm is winding down, but we have a complicated snowpack and avalanche problems that cannot be taken lightly. It's likely that you can trigger a large avalanche that can kill you on steep slopes, so avoid all steep terrain, and areas under steep slopes if you see natural avalanches, remotely trigger an avalanche or experience large whumphs. Expect unusual activity with inconsistent weaknesses - you may not trigger an avalanche in one spot, but a few feet over, you might trigger one. 

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1.5–2.5

    Natural, human-triggered, and remote avalanches were reported on Friday and Saturday in neighboring zones. This isn't your average storm slab problem which will dissipate very quickly like it often does here on the west slopes of the Cascades. You might get away with being on a steep slope, but you're taking a gamble if you do, and just because you didn't trigger a deadly avalanche on one doesn't mean you won't on another slope. 

    Avalanches could fail in the new snow possibly around a foot deep, some avalanches could occurr 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 of a large avalanche like one that you could trigger and get killed by on Sunday. 

    Photo: Jeremy Jouppe

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. 

The firehose really turned on Friday night on the north side of the Mountain Loop, which recorded over a foot of snow overnight. Most other spots in the zone only got a few inches of snow overnight. Storm totals in the zone are ranging from 2-3 inches of water, which equates to 2-3+ feet of snow at mid and upper elevations. 

 

Régions couvertes