Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

You could find small wind slabs that could react to a human trigger in the morning before snowfall intensifies and winds increase in the afternoon, making slabs larger and more reactive. Pay attention to wind actively loading snow onto slopes, and feel for thicker drifts, avoiding these locations on steep slopes. A lot of variability in snowfall amounts is expected throughout the zone so adjust your travels based on how much new snow and wind activity you're encountering. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    The previous few days, small human triggered wind slab avalanches occurred on steep slopes. Sunday may start like this, but by midday the storm's grips will be upon us and you can expect to trigger larger avalanches in more locations as we progress through the day. You're likely to encounter active wind loading, with snow blowing across slopes and depositing into thick drifts. These are obvious locations to avoid, if they are on steep slopes.

    Use bullseye clues, or red flags as indicators throughout your travels. In the afternoon we expect at least two of the red flags will already be present - heavy snowfall (at least an inch an hour), and wind. Identifying other clues such as long shooting cracks, whumphing, or recent avalanches are just icing on the cake, all pointing to steering clear of wind loaded slopes greater than 35 degrees.

    Depending on the wind and snowfall amounts, some locations by the end of the day, wind loaded or not, could hold enough snow that you could trigger a slab avalanche on steep slopes. This is an important day to evaluate the snow conditions and terrain before you get out on it, determining how much new snow and wind redistribution there's been, before travelig in steep terrain. When in doubt, stick to lower angle slopes. 

Avalanche Discussion

You could trigger small dry loose snow avalanches on less wind-affected steep slopes on Sunday. Sluffs shouldn't grow too large - but keep an eye on how much snow is moving around or behind you if venturing into steeper terrain.

Throughout the zone half and inch to an inch of water may fall by Sunday evening, before it really intensifies overnight. Wind will continue to increase through the night as well. Avalanche danger will rapidly increase moving into Monday, where storm totals could reach almost 3 inches of water, or 3 feet of snow, by the end of the day. 

It's been over a week since the last large human triggered avalanche. Four different D2 avalanches (three on Feb 8th and one on Feb 11th) are suspected of failing in a layer of weak facets or graupel buried on Feb 3rd. Two of these avalanches were either triggered from low on the slope or remotely. Given the time for layer interfaces to bond and the lack of recent avalanche activity , it’s unlikely - but not impossible - similar avalanches failing at the same interface will occur. The big load from heavy snowfall which we're seeing in the next few days may reignite this weak layer. 

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