Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Monday will be a bit of a transition day as temperatures and sunshine peak before we head into a multi-day wind event. As the weather changes, so should your avalanche problem focus. Most slides are expected to be small, but don’t let them catch you off guard near terrain traps or other consequential slopes.

Avalanche problems

  • Wind Slabs

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

    There’s an east wind event coming our way. With cold dry snow already in place, increasing winds throughout the day should grow strong enough to easily transport it into shallow Wind Slabs on lee slopes. Due to the atypical wind direction, these slabs may form on aspects where you’re not used to seeing them. East wind events also often result in more mid-slope loading. Look for actively blowing snow as your easiest indication of aspects where slabs may be building. They’ll be more likely on convex rollovers and near rocky features such as the base of cliffs or confined chutes. If you suspect a slope is wind-loaded, simply avoid it by choosing another path.

    (3/25/2023)

    This slab was triggered by a skier in a confined chute in what was likely wind-loaded terrain.  {Kendall Adventure Zone N 5300']

    Photo: Public Observation

  • Loose Wet

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

    The slow uptick in sunshine and temperatures will continue into Monday, maintaining the possibility of Wet Loose avalanches. It will be a race to see if there is enough sunshine to destabilize the surface before the easterly winds kick in and limit this avalanche problem. Further away from the Pass proper or in areas where the easterlies have less influence, you could see more widespread wet avalanche activity. Keep an eye on how the snow surface is changing throughout the day due to solar input. If the snow is getting wet and sticky and you see new rollerballs or fan-shaped avalanche debris, head for shadier slopes. Be sure to stay aware of hanging blocks of snow such as cornices or glide cracks above you.

    (3/18/2023)

    Wet Loose avalanches on Kendall Peak occurred due to solar input on 3/18. Most originated near rocky terrain.

    Photo: Rachel Gronvold

Avalanche Discussion

It seems like springtime will have to wait at Snoqualmie Pass. After a weekend of hoping for nice spring weather, full sunshine eluded us and temperatures were a bit chillier than one would hope for this time of year. That helped the new 8-18 inches of snow that fell at the end of last week stay cold in many locations. Spring is trying to break through, however. And it was able to pop up here and there to moisten the surface at lower elevations and on some slopes that see direct sunshine. You’ll likely encounter a new surface crust in these areas on Monday morning.

Last week’s snowfall is overlaying a melt-freeze crust on most aspects except high-elevation northerly slopes (3/22 interface). Multiple shallow (3-10”) soft slab avalanches were human-triggered over the weekend, failing within or at the base of the recent storm snow. Most of these slides appeared to be on steep convex slopes or near rocky terrain such as rocky chutes or the base of rocks. Pockets of weak snow have been identified by avalanche professionals and NWAC forecasters, with a few whumpfing collapses experienced on west aspects at mid to upper elevations. 

We had some concerns about weak snow being buried during this storm. If it survived, the distribution is spotty at best but could explain some of the whumpfs or a few of the triggered slabs. We are continuing to gather more information about this potentially weak point in the snowpack. Be sure to check the bond at the 3/22 and the snow above it as you travel on Monday. All avalanche activity is expected to occur at or above this interface.

Regions covered