Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

You can trigger avalanches on slopes steeper than 35 degrees where the wind forms fresh drifts. Watch for signs of danger, like recent avalanches, blowing snow, and cracks shooting through the snow. Stay off of and out from under large, open slopes steeper than 35 degrees, especially where winds have formed deep drifts. Be prepared for deep snow and frigid temperatures!

Avalanche problems

  • Loose Dry

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

    With all the recent snow, you may still be able to trigger avalanches on steep, sheltered slopes. Use quick tests and small test slopes to check how easily the snow slides before committing to bigger terrain. Deep snow can be a hazard in itself. be aware of falling in creek holes and tree wells. Keep your riding partners in view, and consider using radios to maintain communication.

    On the 11th, observers reported easily triggering avalanches in very reactive storm snow. On the 12th the avalanches were more stubborn to trigger. Stevens Pass picked up 15" of very light snow on the 11th, with periods of snowfall nearing 6"/hour. Storm totals between the 8th and 11th were over 4 feet.

    (1/11/2024)

    Small storm slab that was easily triggered by approaching a steep convex roll. Lanham Lake.

    Photo: Matt Primomo

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    Avoid large, open, and steep slopes, especially where the wind forms thick drifts of snow. Avalanches will be easiest to trigger on leeward and cross-loaded slopes at mid and upper elevations. Watch for blowing snow to show you where wind slabs are forming. Steer around pillows and drifts of snow on slopes 35 degrees and steeper.

    Expect east winds to transport snow onto slopes that haven't been loaded since before the recent storms. Light surface snow will quickly form slabs. You can still find drifted slabs from northwest winds that formed as recently as the night of the 11th. If you see classic "red flag" signs of instability like whumphing collapses or recent large avalanches, stick to low-angle terrain. All the recent snow is resting on weak layers and crusts buried in late December. While triggering avalanches on persistent weak layers is unlikely, it's worth keeping in mind. 

    (1/10/2024)

    Stevens Pass patrol triggered a hard slab avalanche with explosives on a heavily wind-loaded slope.  Stevens Pass Resort, NE, 5,000ft. D2.5, 190cm deep

    Photo: Stevens Patrol

Avalanche Discussion

Until Friday, visibility was poor for most of the week. Most avalanches that occurred during the recent storms are likely long buried by more recent snow. Just from what we know, conditions were very active. Natural avalanches occurred on the 11th, possibly on the 9th, and a widespread natural cycle occurred on the night of the 8th. Stevens Pass Patrol and WSDOT reported many avalanches triggered by ski cuts and explosives. Most were size D1.5 or smaller, running within the recent storm snow. A few explosive-triggered slides were deeper and ran in layers of older snow (Solstice crust). On the 10th, ski patrol triggered a notably deep (190cm or 6 feet!) size D2.5 wind slab avalanche in heavily wind-loaded terrain. On the 6th, a skier was carried in an avalanche on Valhalla Peak that also ran on the December 30th crust. 

It's not been long since all of the new snow put a manor load on older weak layers, especially in the eastern part of the zone. On the 11th, NWAC forecasters went to the Lanham Creek area and found repeatable sudden test results 4 feet below the surface, within a sandwich of crusts and weak layers that formed around the Solstice. The East Central zone is more plagued by persistent slab avalanches on a similar but shallower snowpack structure to our east. On the 10th, a skier remotely triggered a persistent slab avalanche on Dirty Face Mountain, just over the border. In the Stevens Pass zone, the thin Solstice crust is now 4 feet below the surface. While these layers are deeper and harder for the weight of a backcountry traveler to impact, it's worth keeping them in mind. Snow profiles below show some of these deeper crusts and weak layers.

Forecast models are showing some of the coldest temperatures we've seen in many winters. Be prepared to stay warm and prevent frostbite and other cold weather injuries. With all the recent snow, deep snow immersion is a concern- beware of falling into tree-wells and open creeks!

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