Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

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

Avalanche conditions are dangerous right now and another round of snow with increasing winds isn’t going to improve the situation. Don’t rely on snowpack tests or clear signs of instability to guide your decision making. Set yourself up for success by planning a route through lower-angled terrain or head for the forest where you will find excellent snow and safer avalanche conditions.

Lawinenprobleme

  • Persistent Slabs

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

    Since Saturday, we have received daily reports of natural and human-triggered avalanches from multiple locations in the West South. Some propagated widely and broke up to 3 feet deep on well-documented weak layers buried in January. Avalanches like these are often unsurvivable. This, by itself, should be enough to shape your travel plans, even in clear weather. Add more snow and wind on Wednesday and the tour plan should become pretty straightforward.

    Though the formation of these problems is complex, the strategy for staying safe is quite simple. Don’t try and outsmart this one. Tracks don’t mean a slope is safe, snowpack tests may not produce problematic results, and you probably won’t see clear signs of instability before a slope releases. Simplify the approach and avoid steep and open slopes that face west, north, or east.   

    (2/3/2025)

    A skier triggered persistent slab avalanche near White Pass on a WNW aspect at 5600ft. This slide released over a 100ft wide and 2-3ft deep. Getting caught in an avalanche like this could prove unsurvivable.

  • Storm Slabs

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

    Storm and wind slab avalanches are becoming more stubborn to trigger as we get further away from the heavier accumulations over the weekend. However, temperature changes early in the storm and periods of heavier snowfall left a few subtle inter-storm weak layers. What's more, new snow and increasing wind speeds could form stiffer and more reactive slabs on lee slopes below steep ridge lines, cornices, below cliffs, and at the tops of gullies and chutes. By avoiding the persistent slab problem, you will also avoid the brunt of any storm/wind slab instabilities. If you are traveling in steeper terrain on the southern half of the compass, feel for hard over soft snow and look for signs of wind-loading like blowing snow, textured surfaces, and lens-like deposits, and avoid slopes where you see those signs. 

    While these slabs themselves aren't the main hazard on Wednesday, triggering a storm or wind slab could step down into the older weak layers and cause a deeper and more dangerous avalanche. 

    (2/1/2025)

    An intentionally triggered small storm slab. 3-12" deep, and 20 feet wide. SS-ASc-D1-R2-S, NE, 6200ft

    Photo: Dallas Glass

Avalanche Discussion

We continue to receive reports of deep, wide, and scary persistent slab avalanches in the West South, including a 3 ft deep skier-triggered avalanche near White Pass on Monday that thankfully did not result in any injuries. Spotty and squally weather on Wednesday adds another layer of complexity and could actually increase the likelihood of avalanches, especially in parts of the zone that receive more snow than forecast (think St. Helens or Rainier), or in freshly wind-loaded start zones, regardless of how much new snow falls from the sky.  

With problems like these, structure trumps results. The snowpack may not talk to you right now and many (perhaps most) slopes will not avalanche, but the structure for this problem exists on many slopes and is dangerous. A 2-3.5 ft slab of snow has buried the weak January Drought Layer (JDL) comprised of facets, crusts, and surface hoar, depending on location. A bit below is the also suspect 1/10 crust complex complete with facets on top and within. We have seen avalanches, poor test results, and rumbling whumpfs (would-be avalanches in the flats) on these layers. While all notable results have been on the northern half of the dial, we don't yet have full confidence that you couldn't find this problem on an isolated south-facing slope, especially on slopes that are somewhat locally protected from direct sun. 

With a conservative tour plan that avoids steep open north-facing terrain, you don't need to dig a pit to stay safe and have a great day in the mountains. If you do decide to dig, the purpose should be to help build a dataset that shows trends over time, not to clear a slope as stable. When we all put our observations together, overtime, we may be able to further isolate this problem to specific aspects or elevations. But, at the individual level, a pit is highly variable, and test results should not be used to assess a specific slope as safe. Remember, we didn't get here overnight, and this problem won't magically go away overnight either. 

 Please help us hone in on this problem by submitting an observations. All obs are helpful, whether they involve a pit or not!

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