Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Strong sun and warming temperatures will create small loose wet avalanches on slopes that receive direct sun during the day. Start early, and plan to move off of steep slopes once you find signs of warming snow surfaces, such as rollerballs and fresh, loose avalanches. At upper elevations you could trigger large wind slabs, so be ready to navigate around wind-affected snow on steeper slopes. 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    Although the day will start cold, we can expect the strong mid-April sun to quickly warm snow surfaces, and set off a round of wet loose avalanches. The size of these slides will be related to the amount of new snow, and the size of the terrain feature. In general these should be small on Sunday, but slides could be large if you find more than 8" of new snow on a large terrain feature. Look for these to occur first on east-facing slopes, but then will begin happening on south and west-facing slopes by mid-day. Plan your day to start and end early, and have a contingency plan in place if these begin happening sooner than you anticipate. Feel for moistening snow surfaces, and watch for indicators of warming snow surfaces, such as rollerballs. Be ready to move to shadier slopes, lower angled terrain and avoid going into areas with steeper slopes above you. 

    (4/9/2021) Example small wet loose avalanches from near Stevens Pass.

  • Wind Slabs

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

    Although slabs may become more stubborn to trigger on Sunday, you could still trigger one. Wind slabs could break at the new snow/old snow interface, but in prime loading locations they could step down to older layers around 1.5ft deep. Expect thicker slabs at upper elevations and on leeward slopes (north to east to south). You are most likely to find these below ridgelines, in gullies, and on open slopes or beneath rock bands. Feel for stiffer snow and look for wind-textured surfaces or pillows. Warming snow surfaces may make for more easily triggered slabs during the day on slopes that receive direct sun. If you notice shooting cracks or strong over weak layering, navigate around slopes steeper than 35 degrees nearby. 

    (3/20/2021) Example: Using visual clues is a great way to help identify the potential for Wind Slabs.

Avalanche Discussion

A cold spring storm with very strong winds left around 3-5" at Washington Pass on Saturday. The new snow adds to the 3-6" of new snow that fell over the 4/7 interface. On sunny aspects, a firm crust marks that layer. In shadier terrain, you may find a variety of surfaces at the same depth. The cold temperatures will help limit, but won't eliminate the potential for cornice and glide avalanches. These difficult to predict spring events can still fail even during a colder spell. Choose routes that help you limit the amount of time you need to spend below looming cornices and crevasse-like glide cracks. The lower snowpack is generally strong and well settled.

If you're out this weekend, help us and the rest of the backcountry community keep up with the quickly changing spring conditions by submitting an observation here. 

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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