Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

The warmest storm of the season will deliver rain, high elevation snow, and strong winds to Snoqualmie Pass on Tuesday. Stay conservative with your terrain choices and consider avoiding large avalanche paths for the duration of the storm. Unusual weather often leads to unusual avalanches and we have had a lot of those recently. 

Avalanche problems

  • Storm Slabs

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

    Storm Slabs should develop above the rain/snow line on Tuesday as precipitation and strong winds load slopes. This storm is warm and should be delivering thick heavy snow on top of weaker surface snow, resulting in an excellent recipe for slab avalanches. These slabs should be thicker in wind-loaded terrain on the lee sides of ridgelines or near rocky features such as gullies and the base of cliffs. Digging in the snow with your hand or shovel can give you an indication of how the new snow is bonding to the old surface. If you find heavy snow over weak snow or that blocks are failing easily in your tests, avoid slopes over 35 degrees.

    Recent very large avalanches in the zone are at the forefront of our minds heading into this storm. You can read more about these slides in the discussion and may want to consider limiting your exposure to large avalanche paths for the duration of this storm event.

    (1/10/2022)

    A deep crown from the January 5-7 cycle on the north side of Chair Peak

    Photo: Jonathan Spitzer

  • Loose Wet

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

    Below the rain/snow line, we’ll be dealing with wet avalanche problems on Tuesday. Recent snow at lower elevations has already been rained on and could be well suited to handle more. But rising freezing levels throughout the day means that some elevations will be seeing rain on the recent storm snow for the first time. Therefore we expect larger and potentially more widespread wet problems as you ascend in elevation. Regardless of aspect or elevation, anywhere you find rain falling on dry snow you should have these slides on your mind for slopes over 35 degrees. Wet Loose avalanches often start at a point and can entrain significant snow or even trigger slabs as they fan out and descend downhill.  With rain and wet snow comes a multitude of other issues such as Glide and Cornice collapses. Your best bet to avoid all these wet hazards will be to head for low-angled slopes away from overhead hazards such as open avalanche paths or hanging blocks of snow and ice. 

    (1/9/2022)

    A natural Glide avalanche occurred within the Alpental Ski Resort on the night of 1/7. This slide contained the entire season's snowpack as evident by the exposed rock.

    Photo: Alpental Pro Patrol

Avalanche Discussion

The snowpack around Snoqualmie Pass has hardly had a chance to adjust to the load of the last big storm and now we are heading into a multi-day warm storm. We still do not have a lot of information about conditions after last week’s storm, but we did catch just a glimpse of the carnage that was caused by multiple very large avalanches. On Monday, we received a report of a very large D3 avalanche that had occurred on the north side of Chair Peak. Add this one to the list of D3 and D4 avalanches reported throughout the cycle by WSDOT, Alpental Patrol, and avalanche professionals. We do not have enough information about what these slides may have failed on or how widespread the issue is to label this a deep slab avalanche problem at this time. That said, you should consider shaping your travel plans with the assumption that there is a deep slab problem. Think about not lingering in large open avalanche paths or in areas below them. The same could be said for big alpine terrain where a lot of these slides have failed. The Kendall avalanche (D4) hit the PCT in 3 different locations and ran near its historical maximum, meaning you need to be aware of what kind of terrain is above you, even in the forest. On the same mountain, a more prominent slide path only produced D2 slides during the cycle. Could that slope now reach its tipping point during this warm spell and fail more deeply? Or will it simply produce another D2 avalanche?

Warming temperatures and rain could trigger Glide avalanches or cause freshly built cornices to sag and fall. These are dangerous avalanches in their own right, but could also be the large trigger needed to cause deeper layers in the snowpack to fail. The same phenomenon can be extended to talking about tree bombs and structures such as roofs and signs. Give all of these overhead hazards a wide berth, especially if it's raining. We expect the height of hazard for this storm to be on Tuesday night as temperatures continue to rise and precipitation continues. That said, conditions could reach High avalanche danger by the end of the day on Tuesday if temperatures warm faster or precipitation rates are heavier than forecast. Make your own observations and be prepared to retreat to low-angle terrain.

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