Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Dangerous conditions exist because of the potential for triggering wind slabs near the surface, and deeper slabs on layers of buried crusts and facets. Loose dry avalanches may be easy to initiate on steep slopes, and could entrain lots of snow. It'll be best to let the deep snow settle before getting onto big terrain features. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Most places hold deep, cohesionless powder, but you may find some areas with stiffer snow. Look and feel for signs of drifting such as pillowed snow, cornices, and sculpted features near ridgelines, especially in exposed alpine terrain. Wind direction has been flip-flopping back and forth from east to west, and temperatures have been rising and cooling. You could find minor shallow storm slab instabilities due to the nature of the slight temperature swings. Use small, inconsequential test slopes and snowpack tests to determine if the new snow is cohesive and breaks as a slab.

    The potential for triggering deeper, surprising avalanches on older layers of crusts and facets is unlikely, but is not null. This 'sleeping dragon' may stay asleep for now, but it should be in the back of your mind before entering big terrain. Large, steep slopes above 5,000ft may be the most likely places to trigger this deeper weak layer. If triggered, the crown could be 2-5ft deep at this point and the resulting avalanche could be deadly. Gulp. 

    With all these, we're talking about slab avalanches. Heed signs of danger such as shooting cracks, loud audible Whumphs, and pay attention to signs of recent avalanches as you travel in this relatively young, weak, snowpack that is actively growing deeper by the day.

    Example deeper slab avalanche from the Salmon la Sac drainage in 2021. Photo: Matt Primomo

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Loose avalanches may be easy to trigger on very steep slopes, and could entrain a significant amount of snow on larger features. Stay alert in steep terrain and stop once in a while to let snow 'sluff' as needed. These avalanches could push you into dangerous areas like creek bottoms or other terrain traps if you're not paying attention. You could also be injured by getting pushed into shallowly buried logs and rocks. If you don't want to deal with managing these avalanches,  it may be best to avoid steep terrain. 

    (11/30/2022)

    Small soft slab triggered by a loose dry slide above in the Baker Backcountry on Wednesday.

    Photo: Lee Lazzara

Avalanche Discussion

Snowfall looks to become more scattered and showery during the day on Thursday, and visibility may improve in the afternoon. So far as of 5pm on the 30th, the Sasse Ridge Snotel site picked up about 2" of Snow Water Equivalent. It's likely that the upper Salmon la Sac, Teanaway and Stuart Range all received similar amounts. One important thing to note is that many areas likely DOUBLED their snowpack depth. Anytime that happens...well, there are usually avalanches. Expect chances for all of the types of avalanches mentioned above, especially in areas where the new snow is very very deep. Access at lower elevations could be challenging because of the deep snow, many snowmobile trails are not punched in or groomed yet, and we have limited information about the snowpack at upper elevations. Here's what we do know:

Layers of weak snow and slick crusts were buried by a series of storms in mid to late November. These have not been a problem for avalanches since their initial burial, but because of their persistent nature, professionals continue to monitor this layer as more and more piles onto it. Explosive testing at Stevens Pass on Wednesday produced minimal activity, but that doesn't mean we can 'ride it if it's white'. On Tuesday, observers within the boundaries of Stevens Pass resort found two northerly slopes that harbored weak, larger (1.5mm) facets near the ground. A couple profiles in different areas showed unstable test results. This is strong evidence that this layer is not ready to be trusted yet. This layer may be weaker, or more pronounced further east of the crest in the East Central Zone.

It's still early season, and the snowpack is relatively shallow and unconsolidated. With DEEP, unconsolidated snow out there, make sure to stay within earshot or visual of partners. Tree wells are getting deeper, and plentiful buried snags, creeks, and rocks exist. If you are out and about in the mountains, let us know what you find by submitting an observation.

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