Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Points saillants

Saturday should be similar to Friday in terms of weather and avalanche hazard. As you ascend in elevation, you could encounter wind-loaded features where you’re more likely to trigger an avalanche. Look for actively blowing snow and smooth pillow-like drifts to help you recognize areas to dodge.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    You may encounter shallow Wind Slabs as you ascend in elevation on Saturday. Slabs will likely be larger and more prevalent on the volcanoes where there is more snow available for transport. Look for actively blowing snow or new drifts to help distinguish aspects that may be getting wind-loaded. Once you have the direction figured out, you can start to locate specific features such as convex slopes or confined gullies that could be harboring Wind Slabs. Textured surfaces or snow that feels stiffer than the surrounding area and looks more “pillow-like” are visual clues you can use to help determine that a feature is indeed wind-loaded. Once you go through the steps and identify a potential Wind Slab, you’ll be able to easily avoid it. 

    (2/14/2023)

    A skier near White Pass triggered this Wind Slab in a steep gully near rocks on 2/15.

    Photo: Matt Slaney

Avalanche Discussion

The West South picked up a couple of inches of snow on Friday as a quick front moved through the region. Snow totals weren’t all that impressive for most of the zone, with the crest getting 1-2 inches and Paradise getting closer to 4 inches as of Friday afternoon. On Saturday, you can expect similar accumulations to those that we received on Friday, increasing the depth over the newly created 2/17 interface. The winds should be a notch stronger on Saturday than they were on Friday.

On slopes that see direct sunshine, the 2/17 contains a sun crust that may become a good sliding surface. On shadier slopes, cold dry snow was present prior to Friday’s snowfall. In some locations, it was capped by weak surface hoar. In the neighboring Snoqualmie Pass zone, NWAC forecasters found that these weak grains were buried by Friday’s snowfall, creating a poor initial bond. This could change with time as the load increases, but keep it in the back of your mind that some surprising avalanches could occur in our zone if these grains were buried intact.

No new avalanches were reported on Friday but we had some earlier this week. Human-triggered slab avalanches occurred at White Pass and on Mount St. Helens the day after Monday’s storm had wrapped up. The storm dropped 3-6 inches of snow near the crest and a foot or more on the volcanoes, creating the 2/13 interface. In the following days, smaller loose avalanches failed with the help of solar input. We suspect any avalanche on Saturday to occur above the 2/13 interface with the majority of those avalanches occurring above the 2/17.

Régions couvertes