Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

8:00 PM update - Moderate danger extending into Near Treeline after late avalanche observation

Unusual avalanche activity in the last week is still giving us pause for traveling out onto steep, wind-loaded slopes near and above treeline. At the end of the day Saturday an avalanche was remotely triggered by a snowmobile, 2 feet deep, at Canyon Creek. Consider avoiding steep, wind-loaded slopes near and above treeline as this layer we saw avalanches on earlier in the week is still producing infrequent large avalanches. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Danger from wind slabs will come in two flavors this weekend. One type is deeper slabs in wind-loaded mid to upper elevation areas. An avalanche was reported late in the day on Saturday, and it occurred at 4pm in Canyon Creek, remotely triggered by a snowmobile. The large avalanche occurred on a 5400' north-facing slope, and was 2 feet deep. Most of the human-triggered large avalanches which have happened since the storm ended on 2/7 have occurred in Canyon Creek, a location where you may be more likely to find this layer. If you trigger one of these slabs it would likely ruin your day. These are not typical wind slabs although so far the common terrain characteristics for these avalanches are near and above treeline in wind-loaded terrain.

    Pits may or may not do much to help you gauge if the slope in front of you is good to go. If you do dig look for and test a layer of facets or graupel above a melt-freeze crust down anywhere from 1-4 feet. If you head into this sort of terrain you are just assuming more risk than usual.

    The variety of wind slabs that should be easier to anticipate is recently formed slabs from strong winds and 4-8" of snow early Friday morning. If you trigger one it would probably be on a convex rollover, gully wall, or around a cliff or rocky outcropping.

    Key into the pattern of wind loading by using scoured snow surfaces, cornice-like features, and changes in snow texture and depth to figure out where smaller slabs might lie in wait. A few inches of soft snow might hide signs of wind loading. These avalanches should be small but still have big consequences in terrain with cliffs, rocks, or other hazards in the runout. 

     

    (2/11/2023)

    A 2' deep slab avalanche was remotely triggered by a snowmobile in the Canyon Creek area at the end of the day on Saturday. 

Avalanche Discussion

Freezing levels will be slightly higher on Sunday than Saturday was. We don't expect to see much for wet loose avalanche activity, but as usual, pay attention to moistening snow under your feet and rollerballs running from nearby steep slopes, and if you encounter these conditions start thinking about avoiding steep slopes and the terrain beneath them. I went to the south side of Baker on Saturday to hang out with the Northwest Glacier Cruisers during their Youth Snowmobile Ride. We only encountered thick crusts where we were, up to about 4000ft. These thick crusts means we don't expect to see much avalanche activity at those elevations, including any wet loose activity, as the snow has already been so affected by warm temperatures. 

Several parties and a Rec Level 2 avalanche course on Saturday searched for underlying weaknesses where we saw several natural and human-triggered avalanches occurring on Wednesday. The parties found those layers, however pit tests didn't produce results that were concerning. We're not quite ready to put this concern to bed yet, especially at higher elevations where we've had less information and there is a higher likelihood of the presence of these layers of concern. There were also reports of large surface hoar feathers in the Baker backcountry, which may be our next problem once snow falls on it. 

By midday we may start seeing some precipitation. It probably will not be enough to form new reactive wind slabs by the end of the day, however as suggested in the last paragraph, always pay attention to changing conditions and consider making changes if it is warranted. 

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