Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Avalanche danger is abruptly increasing this weekend with around a foot of snow and strong winds forecasted for Friday night. It is likely that you could trigger large avalanches in the storm snow layer, which will grow in size and become more reactive with additional wind influences as you gain elevation. Pay attention to the terrain you're moving through and avoid traveling onto steep slopes during your outing on Saturday. 

Problemi valanghivi

  • Storm Slabs

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

    Avalanche danger will rise to Considerable with over an inch of water overnight and strong wind. Any steep locations with thick storm slabs could avalanche with a human trigger. Storm slabs will probably be deep and heavy enough to avalanche in non wind-affected areas. If you travel above treeline, you can expect that most areas will be wind-affected, and thicker slabs of wind-drifted snow will likely be even easier to trigger.  A few inches of snow will continue to fall throughout the day, with less wind. Thicker wind slabs could subtly be hidden beneath non wind-affected snow, making choosing a safe line more complicated. This and other factors could play into a more complex day on Saturday, with avalanches surprising you in areas you may not expect to trigger them. 

    Long, shooting cracks traveling out from your feet or sled, whumphs, and recent avalanches are some of your best indicators to stick to lower-angle terrain. Small test slopes are good locations to check for instabilities in the top foot or two of snow, like what we'll be seeing on Saturday. Hand pits could also help you identify if the new slab slides easily on the old snow surface. Even if you're checking the snow with these tests, Saturday is probably a day to avoid heading out onto steep slopes, and sticking to terrain less than 30 degrees. 

    (2/3/2023)

    Cracking and small pockets failing beneath newly formed wind slabs occurred in the Baker backcountry during the day on Friday. This is with very little new snow and strong winds. An abundance of new snow Friday night will exacerbate this problem on Saturday.  

    Photo: Matt Lubar - Cascade Mtn Ascents

  • Loose Wet

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

    A freezing level rising to 4500ft in the afternoon means we could see some small wet loose avalanches at lower elevations. Activity could just be rollerballs, or enough snow could get entrained to produce small avalanches. Snowline for the majority of the storm is resting at about 3500ft before freezing levels start increasing. Wet avalanche activity will likely remain limited to the newly fallen snow. If you notice rollerballs or small wet loose slides coming down, give nearby steep locations a wide berth. 

    (1/13/2023)

    Rollerballs and small wet loose avalanches, like you may see on Saturday. Steer around the terrain beneath steep slopes if you notice wet avalanche activity coming from the steeps. 

    Photo: Trevor Kostanich

Avalanche Discussion

The current storm started out with intense wind and a thick layer of graupel, which you can read about in THIS observation. The graupel could be a weak interface for avalanches to fail on in some locations. Cold temperatures last weekend led to a weakening snow surface. Since then, we've had scattered light snowfall and plenty of wind to shift low density snow around. Small wind slab avalanches have continued to plague us, and avalanche danger was never quite low for the entire zone. Some of the recent small avalanches may have failed on the weaker old snow surface,  and this weak interface may continue to be a concern as more weight is added with Friday night's storm. Thicker, older slabs have a very small chance of avalanching with a new load on top as well. We're not quite sure exactly how reactive this new, larger addition of snow will be, but it's a good idea to start your day conservatively before even considering stepping out into steeper areas.  

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