Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Avalanche potential will increase as you ascend toward snowier and windier elevations. Uncertainty surrounds the bond between the new snow and the underlying crust, so collect plenty of information by using small test slopes and hand pits. Be suspect of most slopes over 35 degrees, particularly if they're wind-loaded.

Avalanche problems

  • Wind Slabs

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

    It's been gusty and will continue to be on Saturday. Larger drifts likely formed on leeward slopes near ridgelines, convexities, or rocky features such as the base of cliffs and sides of gullies. While a poor bond at the new/old interface could result in avalanches on any slope over 35 degrees, focus on wind-loaded areas where slabs should be larger and more consequential. Take the time to use plenty of small slopes to gauge how the new snow reacts to your weight. Quick hand pits or more formalized tests can help identify a poor bond and thus, avalanche likelihood. Shooting cracks or new avalanches are red flags that the snowpack is unhappy and needs time to adjust.

    (12/12/2024)

    Use lots of small features to test the snow for slab potential before you commit to a slope. You may be surprised at what you find.

    Photo: Andy Harrington

Avalanche Discussion

Friday's storm came in a bit warmer than expected, resulting in rain at lower elevations before changing to a mix and finally snow. NWAC forecasters in the Alpental Valley found that the transition to something resembling snow started around 3700'. By the time they reached 4000', you could call it mostly snow. Initial impressions are that a moderate to poor bond exists with the underlying crust. The Summit at Snoqualmie Pro Patrol agreed with that assessment based on their observations from the top of Alpental. They also noted a few pockets of natural activity in wind-loaded terrain near the base of cliffs.

Snow showers should slowly diminish on Saturday, but we'll likely squeeze out another handful of inches at upper elevations, accompanied by wind. All eyes should be on the bond to the underlying crust. Weak snow such as surface hoar and near surface facets existed on top of this crust before the storm. Our hunch is that you'll easily trigger avalanches on steep, unsupported, or wind-loaded slopes. Their size will depend on the amount of new snow at your elevation and exposure to wind. They could be loose or slabs and their moisture content will likely change with elevation. If those weak grains come into play, avalanches could break widely or wrap terrain features.

Prior to this storm, travel conditions were very challenging due to breakable crust, icy slopes, frozen tree bombs, and piles of avalanche debris. NWAC forecasters noted that conditions improved greatly on Friday morning, but many of these hazards are now only a few inches below the surface, making them more difficult to spot.

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