Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

You can still trigger an avalanche in wind-drifted snow. Search out thicker and heavier slabs of wind-loaded snow and avoid them on steep slopes. We're through with the coldest of the temperatures, but it's not over yet- prepare for a cold day with extra layers, food, and warm drinks  and have a plan for what you might do if you get stuck in the backcountry, away from resources. 

Problemi valanghivi

  • Wind Slabs

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

    Strong winds subsided in many locations in the last day or two, but near mountain passes and further east, there may be more recent wind distribution of snow. Locations with newer slab development could have higher avalanche danger. However, places with less recent wind may have more stubborn and less reactive snow. There may be wind-sheltered areas where low-density powder exists, and avalanches are less likely to occur. 

    It's up to you to investigate wind slabs in the area you travel. Red flags, or bullseye clues, such as long shooting cracks from your steps or sled skis are indicators of a weak snowpack. If you see recent signs of avalanches, where crowns have not yet filled in, that's an indicator to avoid steep slopes. If it's still windy where you are, and you're watching the wind actively shifting snow, steer around steep patches of newly deposited snow. 

    Hand shears and small wind-loaded test slopes may give you a sense of slab reactivity. Remain alert if you head into more aggressive terrain, as initially you may find stable snow but a slight shift around a feature might transition you into a wind-loaded pocket you might trigger an avalanche in. When in doubt, avoid wind-loaded slopes greater than 35°.

    (1/12/2024)

    Fresh human-triggered wind slab on the southeast side of Herman. Wind slabs you could still trigger like this may still exist on Sunday. 

    Photo: Simon Trautman

Avalanche Discussion

A few human-triggered slab avalanches were reported around the West North zone on Friday. These were mainly freshly wind-loaded locations. Also, two large natural avalanches were reported on Goat Mountain at upper elevations on Friday. On Saturday, sledders on the south side of Baker reported calm conditions, and they didn't see or trigger any avalanches. The wind died down in the Baker backcountry as well. 

Although wind slabs are the type of avalanche you're most likely to encounter, there is a tiny chance that you trigger a very large avalanche on a deeply buried layer of weak snow, or facets. A few avalanches have likely occurred on this layer with explosives use at Mt Baker, and the Goat Mountain avalanches may have occurred on this layer as well. The weakness is most likely to exist at upper elevations, and sits just above the 12/30 crust. An avalanche, if it occurs, would probably fail 3-5ft deep, something that's fairly unlikely for a human to trigger unless you find a thin spot where the weak layer, just above that obvious crust, is less than 3ft from the surface. More weight, such as a snowmobile, might be the perfect ingredient for triggering one of these very large avalanches. This may happen on a wind-loaded slope, or it's more likely you could trigger one of these avalanches in an area stripped of new snow, hence shallower. 

With the large transition to winter we've seen in the last 10 days, make sure to approach big slopes carefully. Test smaller slopes first, and have an understanding of the snowpack structure and any concerning weak layers and recent avalanche activity before approaching more committing, complex terrain. If cold temperatures persist where you're traveling, be sure to prepare for them with extra layers, and emergency heat sources in case you get stuck in the backcountry. 

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