Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
View on map

Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

While the Pass should receive several inches of new snow, it’s the wind-loaded areas where you may trigger an avalanche. Look for smooth pillow-like drifts along ridges and exposed features to indicate the potentially hazardous pockets you want to avoid.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Moderate winds should easily transport the few inches of new snow into slightly firmer and thicker slabs on the lee sides of ridges, near exposed features, and in rock-walled gullies. We don’t expect these fresh slabs to be widespread, so you’ll want to watch for wind-loaded pockets of snow and simply steer around them. Visual clues like blowing snow, sharp cornices, and drifts behind trees all point towards possibly loaded aspects. On these steep slopes, located the smooth pillow-like drifts and avoid them by using lower angled or less wind-affected terrain. Since these new wind slabs are so fresh, they may trigger easily, especially if the new snow doesn’t bond well to the old surface.

    (12/3/2022)

    Example: A small smooth pillow-like wind slab from earlier this winter. 

    Photo: Andy Harrington

Avalanche Discussion

This isn’t a particularly big storm for the Pass, but with such cold temperatures, we could see 4-6in of snow by the end of the day Sunday. Outside of wind-affected areas, you may encounter a few small sluffs (loose dry avalanches). However, they shouldn’t pose much of a hazard. This new snow will fall on a variety of old surfaces, which could make it react differently from one location to the next. On steep sunny aspects, a breakable sun crust formed this week and could be capped by small facets in some places. The new snow could struggle to stick to this layer and may slide very easily over the crust. In other areas, surface hoar and sugary facets were widely observed Saturday prior to the storm. This little round of snow probably won’t be enough to create an issue over these persistent grains, but it’s worth watching as storm totals start to stack up. 

We expect avalanche concerns to remain at or above the new/old snow interface. Observations over the last several days found a generally strong and right-side-up snowpack. While we were able to still locate the 12/8 buried surface hoar layer in some snow profiles, many avalanche professionals reported no significant results. At this point, any avalanche failing deeper in the snowpack would be a very isolated event.

Regions covered