Avalanche forecast

East Slopes North

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

With warming temperatures that lead to moistening snow surfaces, loose avalanches may run on steep slopes in the sun. You could still trigger a wide persistent slab avalanche 2-3ft deep at mid and upper elevations.  Consider using simpler, less steep and more supported terrain while these dragons linger on the slopes. 

Avalanche problems

  • Persistent Slabs

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

    Over the weekend, observers reported numerous large and very large avalanches that failed and ran on deeply buried weak layers. Put a larger buffer of terrain between your group and large start zones or complex avalanche paths above 6,500ft. Choose smaller, well-supported slopes and stay well out from under larger features. Signs of instability can be inconsistent, creating a tricky problem that is essentially 'unmanageable'. You might not receive signs of instability before the whole slope fails. It could be the 2nd, 3rd, or 8th person on the slope that triggers it. There are two problematic weak layers that you could find 1-2.5ft down and 2-4ft down respectively. A layer of surface hoar and facets were buried on 2/24, as was faceted snow over a strong crust from late January. These rest under a hefty new snow load, and have been the culprit of numerous close calls and one fatality in the eastern Cascades.  

    A very large avalanche was triggered by skiers on 3/2 on Kangaroo Ridge. This broke very widely and ran almost the entire length of the path. 

    Pk 8183, WNW, 7,600ft

    (3/2/2024) Photo: Willie Webster

  • Loose Wet

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

    Direct sun and slightly warmer temperatures may create wet loose instability on steep slopes. You can anticipate this problem by considering your aspect vs. timing of when you might be on any given slope. Look for signs of instability, like small rollers falling out of trees or small fan shaped slides. Feel for moistening snow surfaces on slopes in the sun. You can use test slopes to check and see how any given area might react. These slides should remain small, but may be able to entrain more than you'd think, especially in larger terrain features. 

    Example medium sized wet loose avalanche.

    Photo: Matt Primomo

Avalanche Discussion

Tuesday should be a beautiful, sunny day in the mountains. Temperatures should rise a notch from the cold temperatures on Monday. The strengthening March sun may begin to have more of an affect on snow surfaces, especially those steep slopes that face SE-SW. Continue to keep your slope angles mellow while the persistent slab adjusts over time. 

Signs of instability have been abundant in the past week and dramatically so on Saturday. Multiple close calls and numerous snowpack observations in the Highway 20 corridor point to a couple of buried weak layers (2/25 and 1/31) in the top 2-4 feet of the snowpack. On Saturday, an NWAC observer witnessed a group trigger a widely breaking, very large avalanche on Kangaroo Ridge. It ran almost the entire length of the avalanche path. This likely ran on one of the persistent weak layers. More details on the Kangaroo Ridge avalanche can be found in the photo caption below and in this observation. In a sepereate event on the southeast sholder of Cutthroat Peak (6,400ft, SE) a party remotely triggered avalanches that propagated to either side of them 800-1000ft after leaving a profile site that they dug on the slope. A number of other very large natural avalanches have been reported, mostly from upper elevations, and appear to involve deeper weak layers.

Snowpack information is limited outside of the Highway 20 corridor and Harts Pass. Let us know what you find if you get out into the backcountry!

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