Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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

Snowy and windy conditions on Saturday night should result in dangerous avalanche conditions at Snoqualmie Pass on Sunday. You’re most likely to trigger an avalanche in wind-loaded terrain, with slabs becoming larger and possibly more reactive as you ascend in elevation. You should avoid any slope over 35 degrees if you notice signs of unstable snow or suspect it to be wind-loaded.

Avalanche problems

  • Wind Slabs

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

    While you may be able to trigger an avalanche on any steep slope over 35 degrees on Sunday, we’re most concerned about wind-loaded areas where thicker slabs may exist. You can look for textured surfaces, fresh drifts behind objects, or smooth pillow-like piles of snow to help you identify wind-loaded slopes. Larger slabs could be hanging below freshly built cornices near ridgelines or on convex features. Using small test slopes as you travel can help you get an idea of how the new snow is reacting to your weight, and small hand pits can give you an indication of how well it has bonded to the existing surface. If you have any doubt, default to slopes less than 35 degrees.

    (1/20/2023) A small skier triggered wind pocket on a convexity. Note the slightly textured surface. Photo: Andy Harrington

Avalanche Discussion

The storm arrived fashionably late to Snoqualmie Pass on Saturday, but it brought freshly fallen snow and strong winds as promised. Snowfall accompanied by gusty winds should continue throughout the evening into the morning hours on Sunday. Unless it decides to continue to be late, the storm should be wrapping up by the time most folks are thinking about heading into the mountains on Sunday morning. This is also the timeframe where you could find the most dangerous avalanche conditions as the snowpack adjusts to the recent load.

The new snow has been falling on a variety of surfaces and further increasing the depth over the prominent MLK crust. On Friday, NWAC forecasters and multiple avalanche professionals noted a sun crust on slopes that see direct sunshine and weaker surfaces on protected shady slopes. On Saturday, we received murky information about whether those weak surfaces survived the onset of the storm. If they did, you could see isolated avalanches breaking in some surprising ways such as spanning far distances or wrapping around terrain features. Make sure you take a minute to check the bonding of the new snow to the old surface to see if it is failing easily wherever you’re recreating. On slopes that contained the sun crust, a bed surface may now exist for avalanches to run far and fast, whether that’s in loose form or as a slab. Any avalanche should be confined to the snow above the MLK crust (about 1.5-2 feet below the surface) and the majority should revolve around the new storm snow.

Regions covered