Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You may trigger large avalanches at upper elevations in wind-drifted snow near ridges. Loose avalanches may run fast and far at lower elevations in sheltered areas. Travel carefully and assess snowpack conditions as you move through terrain.

Problèmes avalancheux

  • Wind Slabs

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

    Snowfall and steady, moderate winds have been the ongoing weather trend. This cold, low-density snow can easily be transported by light to moderate winds, developing large wind slabs on lee aspects. If traveling above treeline, use caution near ridges and look for blowing snow building fresh wind slabs. These wind slabs are likely to be found in alpine terrain near ridges, rocky outcrops, and wind-exposed slopes.

    As wind and snow taper off, these lingering and freshly formed slabs may be difficult to identify by visual clues in the surface texture of the snow. Instead, it may be best to identify wind-loaded terrain by using your probe, ski pole, or hand to dig down and feel for stiffer snow overlying softer snow. If you find hollow-sounding snow, experience shooting cracks, or collapsing avoid traveling on steep slopes. 

    With new snow depths tapering from west to east from the Cascade Crest, expect that larger and more sensitive wind slabs may exist closer to the crest and as you increase in elevation. 

    Example of a shooting crack in wind-loaded terrain. 

  • Loose Dry

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

    Cold temperatures and continued low-density snow accumulations have resulted in a deep and relatively cohesionless upper snowpack. This lack of cohesion can cause the new snow to run fast on steep slopes and entrain additional snow as it moves downhill. Look for signs of fan-shaped avalanches, or point releases, that typically start from a single location and spread out as the travel downslope. They can run naturally, or you can trigger them as you move through steep terrain. 

    Travel carefully and know your partner's location. Stay out from under others in steep or consequential terrain and be wary of terrain traps such as creeks, trees, or cliffs that you could be carried into or over. 

    Example of a small Dry Loose avalanche in steep terrain. 

Avalanche Discussion

While the winter started off to a slow start, stormy weather with significant snowfall has been the norm since early December, and total snow depths are steadily increasing. The most recent storm cycle began on the Winter Solstice with significant snowfall and strong winds. Areas near the crest may have picked up 35" while Blewett Pass and Mission Ridge may only have around 8". New snow is resting on a melt-freeze crust from December 21st, and avalanches on this layer may run farther and faster than expected. Steady cold temperatures and light to moderate snowfall continue through the weekend.

The snowpack is generally strong and gaining depth near the crest but shallow and weaker in the Wenatchee Mountains near Mission Ridge. There may be a layer of buried surface hoar on a melt-freeze crust (from 12/21) near Lake Clara/Mission Ridge. This layer may not be very widespread, but it's something to check for with quick pits if you head out to that area. In these easternmost areas of the zone, basal facets (weaker snow) may exist near the ground. This weaker structure may become problematic in the future with new snow and wind loading.

Bitterly cold temperatures are in the forecast for tomorrow and early next week. Expect single digits and below zero temperatures. Cold injuries to fingers, toes, and noses are common at these frigid temperatures. So it will be worth it to bring some extra layers, extra warm gloves, hand warmers, and a thermos with a hot drink.

With significant snowfall totals in many areas of the zone, make sure to keep partners in sight and give tree-wells extra space.

Régions couvertes