Bulletin d’avalanche

Stevens Pass

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Updated 0800: Increased ATL and NTL avalanche danger to Considerable. New snow and strong westerly winds with cold temperatures are creating reactive windslabs. Slabs may be triggered at all elevations, and could be large and dangerous above 5,000ft. Use caution on steep slopes exposed to wind if you observe shooting cracks, thick and hollow slabs, or active wind transport. 

Problèmes avalancheux

  • Wind Slabs

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

    New snow is continuing to accumulate and winds have continued in the strong range. Combined with cold temperatures we expect wind slab hazards at all elevations. Slabs may be thickest and larger at upper elevations, but you may stumble upon a small isolated slab even in open areas below treeline. 

    Look for active wind transport and areas of drifted snow as you travel. You may be able to easily identify slabs with surface texture. If you observe shooting cracks in drifted snow, then be sure to avoid steeper or consequential slopes. Consider areas that get enhanced wind loading such as steep slopes near low points on ridgelines, and cross drifted raised features mid-slope. Cornices may be fragile from recent growth, and could break under the weight of a person. Make sure to stay well away from the edge of them.

    Example small wind slab. Photo: Lee Lazzara

Avalanche Discussion

We're back into a colder, and snowier pattern for the weekend, at least. The pass could see around 8" of new snow by Saturday afternoon, with blustery winds from the west. A front came through Friday morning and rain fell to high elevations before quickly transitioning to snow. Later in the afternoon, convective cells passed through with scattered snow showers. Some of the precipitation may have fallen as graupel, and could bounce and roll off of firm surfaces, collecting at the bottom of slopes and divets. On Saturday, the recently formed, and frozen crust may be at the surface in exposed, windward locations and may make for slick travel in those areas. There aren't any deeper layers of concern beneath this crust (for the time being), as much of the snowpack has been through numerous freeze/thaw cycles and has transitioned over to spring-like wet grains.

Wednesday and Thursday we saw a pronounced warming event, with a number of wet loose avalanches up to D2 observed on the pass. Most surfaces become moist or wet. A recent storm ending on March 5th dropped 2-3ft on Stevens Pass. On the 5th, a 3ft deep wind slab was triggered with control work that ran on the early April crust on a SE aspect. If you're in the mountains, submit an observation and let us know what you see, because springtime is a dynamic time for snow.

Régions couvertes