Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

Similar conditions have existed for days now, but the same story continues: people are triggering small and large avalanches in predominantly in wind-drifted snow at upper elevations. This is not just in the West North zone but throughout all of the Cascades. To avoid triggering and getting caught in an avalanche, steer clear of steep, wind-loaded slopes, especially at upper elevations. 

Problemi valanghivi

  • Wind Slabs

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

    A lot of people have been getting surprised by triggering avalanches, when in most cases they've recognized that they're in wind-drifted terrain (observation, observation, observation). We thank these folks immensely for sharing, and are so glad they're not injured. At some point, this probably could have happened to any of us who are out there in the backcountry steeps. Check out these observations, as there's probably something we can all learn from in them. 

    Travel advice is simple: avoid slopes greater than 35° in areas where you're encountering wind slabs. All the signs might not be obvious- you might not see red flags like shooting cracks. The slabs might be hidden and subtle. You might be able to get away with it on one slope, but not the one next door. This isn't the time to push your luck. 

    Wind is continuing on Tuesday, and we might pick up an inch of snow. The wind direction is shifting subtly, to SW. This means that there may be low-density snow that this wind from a different direction could transport into freshly formed slabs, that are possibly more reactive. Many of the older slabs are probably becoming more stubborn. Most of the reported avalanches are a few days old. But conditions haven't changed much since then, and we still believe it's possible you could trigger an avalanche on those higher elevation wind loaded slopes. 

    (2/12/2024) A small slab avalanche on a subtly wind-affected slope which occurred a week ago now in the West North zone. Snowmobile triggered. Something like this might still happen in the zone. 

Avalanche Discussion

There's a small chance we could get more than the inch or so of snow we're forecasted to get by the end of the day Tuesday in some areas of the zone. If we get a couple inches or more, expect higher danger, as newly formed slabs will be larger and more reactive. 

We continue to hear about and find weaknesses above the Early February Crust (EFC) 1-2ft beneath the snow surface. There are also potentially other weaknesses midway down the newer snow layer above the EFC. In many circumstances, a slab larger than what we're seeing right now might be required to trigger an avalanche on one of these layers. That missing ingredient right now may be additional windloading. If this is the case, you've got one more reason to avoid steep, wind-loaded slopes. 

Steep, south-facing aspects are predominantly crusty, many surfaces are variably wind-affected, and lower elevations have a shallow, extremely variable snowpack with an abundance of bare patches and holes. Meanwhile, there are still sheltered slopes that are holding onto light, dry snow. Small dry loose avalanches may be triggered in these areas. Snow at the lower and mid elevations might get moist or sticky on Tuesday, but probably not enough that you'll see avalanche activity. 

Please submit an observation if you make it into the backcountry on Tuesday to let us know how conditions were. Even if you didn't see any avalanches, observations are still useful. 

 

Regioni coperte