Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You’ll need to navigate around wind-loaded pockets on a variety of aspects Monday. While actively blowing snow will make some of these slopes obvious, others could hide in more windward areas. Avoid steep slopes where you find slightly firmer and deeper slabs of snow.

Problèmes avalancheux

  • Loose Dry

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    While we’re most worried about wind-affected areas, even in sheltered terrain you could still trigger avalanches. These would likely be smaller loose dry sluffs or very soft shallow slabs. The reason we’re talking about these slides is they could fail very easily, run quickly, and even travel far downslope over a firm bed surface. Don’t let one of these small avalanches take you for a ride in high consequence terrain.

    (2/5/2023)

    Example: Natural slab and loose avalanches on Edith's Knob near Paradise. [SE 5800ft]

    Photo: Dallas Glass

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Monday could be the tale of two wind slabs. Increasing E-SE winds during the day may form fresh drifts in some odd locations. Some of these new slabs may trigger easily and run quickly over a firm old surface. Fortunately, this newer version of the wind slabs will be pretty easy to spot and avoid. Blowing snow will be your best clue to figure out where these pockets of wind-loaded snow are forming. 

    The trickier problem to avoid could be older slabs formed during the storm on Sunday. They could sit on currently windward slopes. So, you’ll need to look closely and even feel for this older version of the wind slabs. Larger cornices, textured surfaces, and deeper pockets of snow can help you anticipate steep slopes you may want to avoid. While these older slabs might be harder to trigger, they also could produce larger avalanches that may even break above you.

Avalanche Discussion

Sunday’s storm came up a bit short on the snow totals, but the West South zone still received 4-12 in (and counting) as of 4 pm 2/26. The forecast calls for another 3-8 in by sunset Monday. As the snow continues to pile up, it could slowly increase the avalanche danger. We expect the danger to peak Monday afternoon along with the easterly winds.

Storm weather limited observations on Sunday. However, we did hear of a few natural wind slab avalanches in the Gunsight Chutes near White Pass ski area (NE, 6200ft). These shallow (6in deep) slides ran on a firm bed surface below. 

Prior to the storm variable snow surface conditions were reported. This included very firm crusts, soft powder, wind-textured snow, and weak sugary grains (facets). This could cause the snow to react differently from one slope to the next. We expect any avalanche activity to remain at or above the new/old interface. 

Régions couvertes