Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 5 years ago.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

Highlights

As the weather continues to heat up, the snowpack may begin to reach its breaking point Thursday. You could encounter large natural wet avalanches especially at mid and lower elevations where water will continue to weaken the snowpack. Plan your day by choosing routes that limit the amount of time you spend in larger avalanche paths and reduces your overhead hazard.

Avalanche problems

  • Loose Wet

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

    Another night with the potential for a poor or shallow freeze will allow conditions to change rapidly on Thursday. Warm temperatures and a strong April sun should quickly weaken the surface and increase the potential for wet avalanches. You’ll need to think about the terrain around and above you to anticipate which slopes could become dangerous during what part of the day. The snow you are standing on may not accurately reflect the wet and hazardous conditions developing on rocky slopes basking in the sunshine. Watch for snow shedding off of rocks/trees as an early clue. You may also notice small rollerballs falling down steep slopes. If you see these signs, limit the amount of time you spend under similar terrain. You’re likely to see these conditions on easterly aspects in the morning at mid and lower elevations. The wet snow will spread to other aspects and possibly into the alpine as the day progresses. At upper elevations, a colder snowpack and breezing conditions may help limit the potential size of any natural avalanche. 

    If you begin to find yourself sinking into the snow past your ankle, you may also trigger loose wet slides on slopes greater than 35 degrees. While loose wet avalanches can seem easy to predict, observe, and manage they often hurt travelers when they carry them down very long slopes, over cliffs, or into gullies. The consequential terrain you crossed safely in the morning may react very differently later in the day.

    (4/11/2021) Wet Loose avalanches were observed in the Alpental Valley on Sunday 4/11 as sunshine destabilized recent storm snow and it started to shed from trees and rocks around noon. Skiers for scale.

  • Glide Cracks

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    After several days of warm sunny weather, water is again moving through the snowpack. In some locations, it may reach the ground and cause glide avalanches. These incredibly difficult to predict avalanches can occur without warning and at any time of day. They are one of our classic low-likelihood/high-consequence avalanches problems. Limit the amount of time you spend underneath any terrain where you see crevasse-like glide cracks. On Wednesday, a glide avalanche occurred at Stevens Pass. This may be a good indication that similar events could return to the Snoqualmie area as temperatures begin to climb.

    (4/11/2021) Glide cracks are still prevalent around Snoqualmie Pass and multiple large Glide avalanches occurred during the last warm-up. Some of these slopes now contain up to two feet of recent snow and may fail a second time.

Avalanche Discussion

The further we move into this prolonged warm period the more uncertainty that arises. After the third night of relatively warm temperatures and a potentially poor freeze, we’re worried the snowpack may pass its breaking point. Predicting the timing of these spring cycles is incredibly challenging, but Thursday could be the day. This lengthy period of high freezing levels allows water to travel within the snowpack, reach deeper layers, and in some cases, affect the ground. You could see wet slabs, glides, cornice, and/or “shedding” avalanches during these events. As the upper snowpack accumulates more water, slides could entrain wet snow or even gouge into older snow layers at mid and lower elevation. Choose routes that help reduce the amount of time you spend under rocky slopes, hanging cornices, and other overhead springtime hazards. 

On more shaded aspects and at higher elevations, cold and dry snow may still exist in the upper snowpack. Warmer temperatures and lighter winds should help wet snow begin to reach around to the north side of the compass dial. As it does so, it’s hard to say how the snow will respond to the abrupt transition. As a result, you could encounter wet avalanche concerns on a variety of aspects and elevations by the end of the day. 

Daily avalanche forecasts will end on Sunday, April 18th.

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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