Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Avoid traveling on big steep slopes that could produce large avalanches, as weak layers exist beneath the 3 or so feet of new storm snow that still can't be trusted. Exposed terrain at any elevation could produce an avalanche in slightly heavier, wind-affected snow, which would probably be smaller but still not to be taken lightly. Steer around wind-drifted slopes, as triggering an avalanche there might step down and produce an even larger avalanche than expected. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–2.5

    Large and unusual avalanches, signs of instability, and a poor snowpack structure are all indicators of a persistent slab avalanche problem. Weak upper layers developed during the January drought and are now coated with 2-4 feet of snow. The snowpack has had a couple days to adjust since the storm ended, when we saw multiple human-triggered and natural avalanches in neighboring zones, and now it's just waiting for the added weight of a human to stress the weak layer enough to avalanche. 

    It's hard to identify where exactly you might find this weakness, due to the unusual patchwork of layers that formed during the January drought. Structures vary across the zone, and even across the same slope. If you trigger an avalanche, it could propagate widely, release in adjacent terrain, from the middle, or maybe even from below a slope.

    Don't ignore signs of instability. But, don't expect to experience any signs of instability before you trigger one of these avalanches- the usual indicators like whumphing or shooting cracks may not happen. Snow pits likely don't paint the whole picture, as the weakness is very inconsistent even on a small scale. 

    You might be able to get away with stepping out onto steep slopes without result, but maybe the next slope over is where you might trigger an avalanche that could kill you. It's hard to tell exactly where an avalanche could happen. If you don't want to risk being caught in one of these avalanches, avoid traveling on large, steep slopes. If in doubt, avoid terrain beneath large steep slopes as well. 

    (2/3/2025)

    A skier triggered persistent slab avalanche in the West South zone This slide released over a 100ft wide and 2-3ft deep. WNW, 5600ft SS-ASu-D2-R2-O

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    You may be able to trigger an avalanche on recently wind-drifted snow. Low-density snow doesn't require much wind to redistribute, and the slabs could be very soft. Even if you trigger a smaller avalanche that doesn't seem like a big deal, it may be the additional weight needed to overload the underlying weak layer and produce a larger avalanche. 

    Wind will probably be light, but search for actively blowing snow and identify where it lands. Textured or scoured snow surfaces and cornices will point towards slopes holding freshly drifted snow. You might be avoiding big, steep open slopes due to danger from larger avalanches, but smaller terrain could have a wind slabs ripe for you to trigger an avalanche on as well. 

    (12/30/2024)

    Example photo: Obvious wind-sculpted features are good indicators that a wind slab sits nearby. 

    Photo: Irene Henninger

Avalanche Discussion

Snow totals for the storm that ended on Monday are 2-4 feet above 4000ft for most of the West Central zone. The bottom half of the lower elevation band still doesn't have enough snow to produce avalanches, although the top couple hundred feet may behave more similarly to the mid elevation band. 

If you decide to step out into steeper terrain, increase your survival chances by having a partner, only exposing one person at a time to the slope, and be equipped with a transceiver, shovel and probe. Know how to use your rescue gear and practice regularly so that you can quickly dig your friend out before they die of asphyxia if they didn't die from trauma first. 

 

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