Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

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

A similar day is in store for Wednesday, with light snow, warm temperatures, and easterly winds. The snow is wet and heavy down low, but you could trigger small avalanches in wind-drifted snow at upper elevations. Avalanches are most likely in steep, confined, rocky terrain and unsupported slopes.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    In general, wind slabs are becoming stubborn and more difficult to trigger. However, since February 15th, there have been many recent close calls with people getting caught and carried in surprising avalanches throughout the Washington Cascades. Anytime we get this many reported avalanches, it usually means we are dealing with a tricky or unusual pattern. A few things could lead to the prolonged instability of wind slabs and a higher-than-normal number of incidents. Easterly winds created uncommon loading patterns, and wind-loaded features exist well below ridgelines and potentially on all aspects, even on the same ridgeline. There is also weak, faceted snow associated with the Early February Crust. This weak layer is highly variable, making it nearly impossible to tell exactly where it exists in the terrain, and adjacent slopes could have very different stability. Be suspicious of any firm slab in steep terrain. These slides might be more likely in cliffy or rocky areas where the snowpack is often thinner and may be unsupported.

    (2/19/2024)

    This graph shows the general locations of recent natural and human triggered wind slab avalanches since 2/15. 

    Photo: Northwest Avalanche Center

Avalanche Discussion

It feels like we're stuck on a merry-go-round of repeating weather patterns and avalanche concerns. Wednesday will bring another 1-3 inches of snow, low-elevation rain, and easterly winds. The snowpack has already seen warm temperatures, so we don't expect widespread wet loose avalanches. But you could see a few rollerballs throughout the terrain at mid and lower elevations or snow shedding off steep rocks.

On Tuesday, observers reported better travel conditions and up to 6" of fresh but heavy snow. Unfortunately, as the day continued to warm, misty rain made its way up to mid and upper elevations. So, there could be another new surface crust to contend with on Wednesday morning. 

The upper snowpack consists of various layers of settled snow, crusts, and facets over the prominent Early February Crust (EFC). The exact layers and depths depend on aspect and elevation. In general, about 18 inches of snow exist over the EFC. Snowpack tests this weekend highlighted several potential weak layers, though they were inconsistent. Travelers continue to report "better than expected" conditions. However, breakable crusts, frozen tree bombs, slick surfaces, holes, and open creeks are still common.

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