Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

You may encounter the greatest avalanche danger at mid and even lower elevations where soft snow could quickly become wet and unstable. If the warm temperatures and sunshine cause the snow to shed from trees and rocks, anticipate natural loose avalanches on similar aspects.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    The strong March sun and very warm temperatures will rapidly go to work on the snow surface Wednesday causing it to become wet and unstable on some slopes. In locations where the surface remains relatively soft and non-wind-affected, this process will occur quicker. You’re most likely to find softer snow at mid and lower elevations and in sheltered areas. These are the same spots you’ll see the warmest temperatures. As a result, you could encounter more avalanches near and below treeline. Even so, with freezing levels soaring to near 8000’, only the highest shaded slopes will escape Wednesday’s warm-up. 

    No matter where you travel, simple observations can help you determine when the snow surface has become unstable. Watch for the snow shedding from rocks/trees, new rollerballs, and wet “punchy” snow to indicate loose wet avalanches could occur. When you see these clues steer around similar slopes. Make sure to pay attention to the terrain above during this period of warm weather. It may bask in the sun, even while you travel in the shade.

    (3/23/2021) Example: Natural loose wet avalanches on Snow Lake Divide.

Avalanche Discussion

Snoqualmie Pass received 8-15” of snow during Sunday/Monday’s storm accompanied by very strong winds. At upper elevations and on exposed slopes this resulted in scoured surfaces, deep drifts, and wind-packed snow. On many aspects the recent snow sits over a firm crust (3/28). This smooth surface could allow avalanches to run far and fast. 

Below the surface, recent weather with periods of warm sunny days interrupted by winter-like storms created a highly variable and somewhat aspect dependent snowpack. Despite the spring-like weather, the snow has not undergone its full transition. On more southerly aspects, thick and well-developed layers from several melt-freeze cycles create a strong upper snowpack. On more shaded aspects, cold, dry, layered snow still exists. You may find different conditions from one slope to the next even though they appear similar. Continue to make observations as you travel to highlight when conditions may have changed. 

Large cornices developed along many ridgelines during this stormy winter. Periods of warmer weather often cause some of these waves of snow to collapse. With hot temperatures in store Wednesday, choose routes that limit the amount of time you spend below this looming hazard. You could see natural loose and cornices avalanches trigger large slabs on slopes below. This is most likely on heavily wind-loaded or steep rocky slopes. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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