Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

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

Warming temperatures, rain, snow, and winds will create dangerous avalanche conditions. You could easily trigger large avalanches in the new snow, particularly where the wind drifts snow deeper near ridgelines. Make conservative travel plans and stick to low-angle terrain while the storm runs its course.

Problèmes avalancheux

  • Storm Slabs

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

    A warming storm will deposit heavier snow over the recent light dry powder we enjoyed recently, and storm slab avalanches will likely become easy to trigger on slopes above 35°. Avoid common trigger spots such as steeper, unsupported convexities even in lower angle slopes. While we expect avalanches only to involve the new snow, the potential exists for avalanches to break on older buried crust layers. It will be a great day to stick to low-angle terrain and look for signs of instability, such as recent avalanches or shooting cracks. Using simple hand pits and test slopes, you can quickly assess how the new snow is reacting. If the new snow slides easily, you could trigger an avalanche on a steep slope. As you would expect, moderate winds will accompany the storm. Wind slabs will form overnight and continue to build during the day on Monday. Look for actively blowing snow and drifts behind rocks and trees to identify the wind direction and avoid steep wind-loaded slopes.

    (12/20/2022)

    An example of a small storm slab. Test slopes like this are great ways to look for unstable new snow. 

    Photo: Public Observation

  • Loose Wet

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

    It's been a while since our last Cascade rain event, and while this storm isn't exceptionally warm, we will likely see rain below 4500ft. Previous sun and warm temperatures may have formed crusts that will hold off wet avalanches initially. Still, you can expect wet loose avalanches as the rain saturates the snow at lower elevations. These avalanches may start naturally with trees or cliffs shedding snow onto steep slopes, but you can also trigger these avalanches while skiing. Pay attention to overhead hazards and avoid getting caught in your sluff in steep consequential terrain.

    (1/14/2023)

    Low elevations may see wet loose avalanches like this on Monday.

    Photo: Dallas Glass

Avalanche Discussion

We received a brief break in precipitation and enjoyed some sun on Saturday after Thursday night's storm brought a healthy 10-12 inches of new snow to favored areas in the southern portion of the zone. Areas further north received 4-6 inches of snow. Joe Dellaporta was out near the western edge of the zone on Sunday and found a generally strong, deep snowpack. Southern slopes had a sun crust to around 4800ft, and northerly aspects held soft dry snow at mid-elevations. The storm was beginning to impact the area, and 5-6 inches of heavy wet snow had already accumulated by the afternoon. The previously strong winds built large sensitive cornices. Steer clear of these behemoths. They are hazards on their own but could also trigger an avalanche on the slope below.  In neighboring East Central, as the skies cleared on Saturday, observers saw some very large crowns from natural avalanches above 7000ft on northern aspects in alpine terrain. We are uncertain about the layer these slides ran on. However, they appear to be primarily in wind-loaded, high-elevation, exposed terrain. Older crust layers may be the culprit, so consider the consequences of a very large avalanche and avoid steep wind-loaded terrain at these higher elevations. 

Régions couvertes