Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

There’s a lot of new snow and a lot of uncertainty. Slides could break within or at the base of the storm snow. Figuring out how any particular slope will respond could be incredibly challenging. Keep it reined in and stay off of open slopes greater than 30 degrees.

Problemi valanghivi

  • Storm Slabs

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

    Even though this storm is ending cold, heavy precipitation rates, strong winds, and fluctuating snow levels likely built slabs that now hide underneath the fluffy powder. Some slides may fail on inter-storm layers, while others release on the 2/24 interface involving all the storm snow (2+ft). In some places, the new snow probably glued onto the old surface; in others, surface hoar, facets, or firm crusts could allow slides to trigger very easily. In these spots, avalanches may break widely or release on slightly lower angled slopes than normal. 

    The tricky thing is it will be nearly impossible to tell. Prior to this storm, the surface was incredibly variable. Even if you dig in one spot, it could be very different than the next slope you touch. Unfortunately, where the snow is deeper, small slopes and uptrack tests may not help you fully assess all the new snow and could lead to a false sense of security. In general, weaker snow was present on shaded aspects above 4500ft. Since it’s hard to tell if a slope is safe, choose lower-angled and treed terrain to help reduce your risk. 

    Below 4500 ft, warmer temperatures during the storm should help the snow stick to the old surface. You’ll likely need a much steeper slope or unsupported feature to encounter a slab avalanche.

    (1/17/2024)

    Example: Storm slabs like this can fail in small openings in the trees on Monday. 

    Photo: Dallas Glass

Avalanche Discussion

This winter storm will continue to bring significant snow to the Pass Sunday night. As a result, you’ll probably see the greatest avalanche danger first thing in the morning. As precipitation eases, the snowpack should slowly heal. This could take some time, given the colder temperatures and potential for persistent snow grains. 

A significant cooling trend should allow much of the storm snow to be right-side-up. This could result in small loose dry avalanches in steep terrain. You can see these sluffs even in treed areas. 

As the storm tapers throughout the day, there’s a slight chance of sun breaks. The cold temperatures will help limit any warming, but if the sun comes out, you may see a few loose slides releasing from rocky terrain. 

Below the new snow, several small storms and periods of clearing left potential weak layers in the upper snowpack. Strong wind events made these layers more variable. While we don’t expect slides to fail into older snow, it’s not out of the question. In higher elevation shaded terrain, an isolated avalanche could step down into deeper layers and produce a very large slide. Take this into consideration if you’re route leaves you exposed to these paths for a significant time.

Regioni coperte