Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Keep an eye out for pockets of wind-loaded snow as you ascend in elevation on Saturday. Piles of snow behind trees or rocks along with textured snow surfaces can help you key you into where these pockets may exist.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Continued snowfall combined with moderate winds may form shallow Wind Slabs on the lee side of ridgelines or other exposed features on Saturday. As you ascend in elevation, keep an eye out for blowing snow, small drifts, fresh cornices, or textured snow surfaces to help clue you in to the existence of nearby Wind Slabs. You’re most likely to trigger one of these slabs near the base of cliffs or on rocky slopes such as confined gullies. While we expect these slabs to result in fairly small avalanches, don’t let them catch you off guard and sweep you off your feet in consequential terrain.

    (3/19/2021) Textured snow surfaces, drifts behind trees or rocks, and cornices are good visual clues you can use to help key you in to the possible existence of Wind Slabs. These were observed on North facing slopes on Friday (3/19) on Mt. Snoqualmie. [Photo: Robin Pendry]

Avalanche Discussion

The pass picked up a few inches of snow on Thursday night at upper elevations and more snow is on the way. By the end of the day on Saturday, we could be looking at close to a foot of snow since these storm waves began, especially if a convergence zone sets up. With springtime forecasting and poorly developed storm systems, forecasted precipitation amounts come with even more uncertainty than usual. That said, it’s been well documented that there is a generally strong snowpack around Snoqualmie Pass, and avalanche hazard will be driven by new inputs from snow, rain, or wind. We're hedging our bets that the weather forecast on Saturday produces enough snow and wind during the day that you will be able to trigger small avalanches at middle and upper elevations. Regardless of the amount of new snow received, it will be falling on a variety of surfaces. These surfaces vary based largely on aspect or elevation and include firm melt-freeze crusts, wind-stiffened snow, breakable crust, or potentially faceted snow. Take the time to investigate the bond between any new snow and the old surface by using test slopes and hand pits as you travel. Depending on what surface the snow falls on, it could behave differently given a human trigger, including running far and fast on slopes that contain a firm crust for a bedsurface.  We'd love to hear what you're finding out there, so let us know by submitting a public observation.

Continue to stay vigilant with your route planning this spring, avoiding overhead hazards such as cornices and glide slopes as much as possible. Although these avalanches are more likely during periods of warmer weather, they are unpredictable and could fail due to a variety of reasons.

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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