Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You may find wind affected snow on a variety of aspects that could produce human triggered avalanches. Watch for simple clues like drifts behind objects, and changes in how the snow feels to highlight where wind slabs may exist. If you suspect wind loading, go around and seek out less wind affected terrain.

Avalanche problems

  • Wind Slabs

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

    At mid and upper elevations, new snow combined with moderate winds should easily form new and potentially reactive wind slabs. These thin drifts may overly older and deeper slabs formed over the past few days. On Sunday a skier triggered a wind slab on an NE aspect near Snow Lake Divide. Due to changing wind directions, you could find wind loaded snow on any aspect. Keep your eyes open for subtle signs that the wind transported snow onto a slope. Changes in the texture of the snow surface, how it feels under your foot, or small drifts behind objects could all clue you into where wind slabs may exist. Steer around wind-loaded features where you suspect the wind drifted snow. 

    In some locations, these wind slabs could overly older weak snow grains above a prominent crust. In these areas, you could produce larger and more surprising avalanches. Small facets may exist just above a thick crust layer formed in mid-January. You will likely need to dig with your hand or a shovel to check for these persistent grains. Plenty of uncertainty surrounds this persistent weak layer and may warrant an added degree of caution. 

    (1/31/2021) This slab was triggered by a skier in the Alpental Valley on Sunday 1/31.

Avalanche Discussion

While this recent weather pattern has not favored Snoqualmie Pass, each day we seem to add a couple of inches of snow to the upper snowpack. At this point, you may find more than a foot of snow above the very prominent crust (1/13). Several small storms and periods of dry weather created numerous weak layers and interfaces within this shallow upper snowpack. The layer of greatest concern sits just above the 1/13 crust. At this interface, you may find facets, surface hoar, and/or a thin melt-freeze crust. Nearby zones (East Central and West South) have experienced numerous avalanches on this weak layer over the past few days. If you plan to travel in the easter portion of the zone or into more remote areas consider reading these nearby forecasts. Snow profiles and snowpack tests can help you locate these weak grains, but they can not prove their absence. Ease into terrain and gather observations. If you see shooting cracks or feel collapsing, the scales may have finally tipped and avalanches could occur on this layer. Dial back your terrain choices and seek out lower angled slopes. 

Warmer temperatures and rain to mid-elevations on Monday moistened the snow surface at mid and lower elevations. This should help limit the avalanche danger below treeline as temperatures fall and the snow surface begins to freeze. Near and below Pass level you could encounter breakable crusts and “punch” travel conditions.

Regions covered