Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

You're most likely to trigger an avalanche on steep, wind-loaded slopes near and above treeline on Wednesday. Search for clues like heavier snow, textured surfaces, shooting cracks, or recent avalanches as indicators to steer around nearby steep slopes. In non wind-loaded areas, you could also encounter and trigger loose snow avalanches in steep terrain running dry, or wet if the sun shines intensely on southerly slopes.  

Lawinenprobleme

  • Wind Slabs

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

    Steep, wind-loaded terrain is where you're most likely to get into trouble on Tuesday. Conditions got a little spicy on Tuesday when about four times more snow than was forecasted arrived by the early morning. Snowfall and moderate wind continued throughout the day. Small natural slab avalanches were reported, and several small human-triggered slab avalanches were reported as well. Most of these were around 6 inches deep.  We also received one report of a human-triggered avalanche which failed on a south-facing slope, 50cm down, on a temperature crust from 2/24. Most of the avalanches occurred in wind-loaded areas. Many slopes near and above treeline have now become wind affected. 

    An overnight lull in precipitation and a decrease in winds will help to heal new snow instabilities, but we still expect human-triggered avalanches to be possible on steep, wind-loaded locations on Wednesday.  Feel for an "upside down" snow structure, with heavier snow sitting on top of lighter snow as you travel. You might also be able to visually identify wind-affected snow, by noting textured surfaces. It may be the case that an inch or two of low-density snow is masking underlying slabs.  Pay attention to obvious clues like cracking or recent avalanches. If you notice any of these characteristics, steer clear of nearby slopes steeper than 35 degrees. Wind is expected to increase throughout the day, so you may also see active loading indicating areas to avoid, which could mean that slopes you were on earlier may produce an avalanche later in the day. 

    (2/28/2023)

    This was a wind-loaded, steep, south-facing slope with a human triggered avalanche failing 50cm deep on a temperature crust from 2/24. Boulderfield, Baker backcountry.

    Photo: Robert Hahn

  • Loose Dry

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    An overarching loose snow avalanche problem of dry or wet may be more applicable for Wednesday. An abundance of cold, dry snow has fallen in the last few days- there's about 2 feet of it at mid to upper elevations, which is ripe to sluff off steep slopes, especially if you step out onto them. This will happen in non wind-affected areas. Snow in the top couple inches may slide, but it could entrain snow a little deeper, and run faster and farther than usual. Make sure to stay alert to this if you enter steep terrain, and have an exit strategy off to the side of a slope if a sluff is flowing rapidly downhill with you. 

    We may see enough sun that it could moisten any low-density snow on steep, sunny slopes, causing wet loose avalanches. This could start on easterly slopes in the morning before shifting southerly and then west facing in the afternoon. There's about a 50/50 chance we'll be seeing enough sunlight for this to be a problem, so keep it on your mind during your outing. If you start noticing rollerballs or small wet loose avalanches, steer clear of steep slopes on similar aspects. 

    Dry loose avalanches may still be running faster and farther than usual in steep areas where non wind-affected snow still exists. 

    Photo: Dallas Glass

Avalanche Discussion

Conditions have been a bit of a rollercoaster since Sunday, as we've received extremely variable amounts of snow throughout the zone, probably ranging from 1-3 feet. Winds were also remarkably different in the last few days, depending on location as well. This is a day similar to others, where there's a lot of variability within the zone and from slope to slope. What you see in one location might vary quite a bit from other areas. Use this forecast as a starting point to further evaluate slopes during your day's outing. If you travel anywhere in this zone, whether you see any avalanches or not, please send in an OBSERVATION so that we know more about the conditions in the area. 

Wednesday is a brief lull before another system enters the area Wednesday night.

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