Bulletin d’avalanche

West Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

We’ve picked up a couple feet of new snow over the last three days and you will be able to trigger avalanches on steep, wind drifted alpine slopes. Stick to less steep terrain, or places where the snow isn’t wind affected. Although lower elevations are less dangerous, use caution in steeper, obviously wind-drifted areas.  Observations from this zone are limited - check the forecasts from West North and Stevens Pass for more information. 

Problèmes avalancheux

  • Wind Slabs

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

    Several feet of new snow and moderate to strong winds have created a patchwork of drifting patterns and shallow instabilities. We have limited observations in this zone, but the following information from the Baker backcountry may apply: 

    There was a natural avalanche cycle late Sunday night or early Monday morning, and on Tuesday we received several reports of smaller natural and human triggered avalanches in wind affected snow.  These more recent wind slabs were soft, 6-10 inches deep, and in the D1-D2 range. Some were ‘stubborn', or hard to trigger, and some were fairly ‘touchy’, or easy to trigger. Almost all of the reports are from lower and mid elevations (probably because conditions are keeping people out of the upper elevations) and it's likely that upper elevation slabs are larger, more unpredictable, and more dangerous. 

    So far we have no reports of larger avalanches in the storm snow, but take that for what it is worth – visibility was mostly poor over the last two days. 

    There is some uncertainty around the distribution, sensitivity, and size of wind slabs in this zone. It's a good idea to avoid steep, wind loaded terrain – especially if the runout is consequential. 

    (1/4/2022)

    Small avalanche in wind affected snow. Observers report easy triggering of 8-15 inch soft slabs in steep areas near and below treeline.  

    Photo: Zack Mcgill

Avalanche Discussion

A very large avalanche was observed on Mt Mastiff around December 26th and several very large avalanches occurred in the West North zone (since Christmas) on a deeply buried layer of surface hoar. There is a lot of uncertainty around the presence of deeper instabilities in the West Central zone, If they exist they are between 2.5 and 5 feet deep.  

The take-home is that an even small possibility of very large avalanches triggered deep in the snowpack is another reason to steer clear of large, wind-loaded slopes and their run-out zones.

Régions couvertes