Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Update 0700: Well over a foot of new snow overnight, and more on the way has created dangerous conditions. Use a conservative approach to travel around avalanche terrain, as storm snow continues to pile up deeply. Loose avalanches may become large, run naturally and could be easily triggered in steep terrain and on slopes that receive sunshine. Winds have been transporting snow into very deep drifts at upper elevations, and it's possible to trigger slabs of various sizes on steeper slopes in these areas. 

Problèmes avalancheux

  • Loose Dry

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

    The light, dry snow has been sliding easily on very steep slopes, especially in areas where the sun warms the surface. Stay alert to changing conditions and slopes well over 35 degrees where the snow slides easily. Use small test slopes to check how the snow is behaving. Use extra caution near slopes with terrain traps like trees, gullies, or rocks. Be aware that large and/or complex terrain features could produce larger and more consequential slides.

    (2/21/2022) Loose avalanches earlier this season on Devore Peak Photo: NWAC public obs

  • Wind Slabs

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

    Wind slabs and storm slabs may form anew with a fresh round of snow and more wind into Thursday. Winds have been creating thick drifts with the low density new snow in many areas.  Most are likely to be small, but there's potential for some to become large avalanches if they fail on an old crust from early April. Slides could be well over 3ft deep if they did run on this layer. You can minimize your chances of triggering a slide by sticking to wind-sheltered areas and lower angled terrain.  If you see warning signs like fresh avalanches, shooting cracks or active wind transport, stick to slopes less than 35 degrees. 

    Recent winds have shifted directions and formed wind slabs on various aspects and sometimes in unusual locations. This has been a large storm for many areas in the East Central and we have minimal information from alpine terrain. Cautious and conservative travel are a great approach to use when heading into the mountains.

    (3/16/2022)

    Wind slab in high elevation terrain in the Icicle Creek drainage.

    Photo: Matt Primomo

Avalanche Discussion

Expect yet another round of overnight snowfall with upslope flow into Thursday morning. Although this round should be lighter than the past few days, there's uncertainty with the weather forecast. If you find that it is snowing heavily, expect instability to rise quickly, and make adjustments to your route to fit the observed danger. Skies should be mostly cloudy with the potential for more sun in the northern portion of the zone.The storm snow is up to about 3ft at upper elevations of Mission Ridge, with areas of drifts well over 6ft deep. I observed what appeared to be a small, natural wind slab from an exposed feature at 6,500ft near Mission Ridge on Wednesday. The storm snow appeared to be bonding fairly well with the older crust from early April, and lacked much cohesion for slabs. Exposed areas appeared thickly drifted, and I wasn't ready to trust steep, wind-loaded features. On Tuesday, observers in the Salmon la Sac area reported approximately 3 feet of snow on the ground resting over the Early April Crust. Northerly aspects had a favorable, right-side-up dry snowpack, while southerly aspects quickly became wet with widespread rollerballs, loose slides, and a thin crust.If you are out adventuring during the long days, keep your senses tuned into the snow and look for signs of deteriorating snow stability. Even brief sun breaks can quickly cause wet loose or dry loose avalanche problems. The dynamic spring weather and increased diurnal temperature fluctuations create more uncertainty about what avalanche problems you may encounter during the day. If you observe weather or snowpack conditions you did not anticipate, it may be best to simplify your terrain selection and choose lower angle slopes.

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