Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

A natural avalanche cycle is expected Saturday night into early Sunday morning. Heavy snow and rain will overload a snowpack with prominent weak layers. Very large wet avalanches may occur and run down to lower elevation areas. Travel conservatively, sticking to lower angled terrain and well away from steep slopes to avoid getting caught. 

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    Heavy rain overnight Saturday into Sunday morning will saturate a previously dry snowpack and cause natural avalanches. Although Sunday may be a lull in the precipitation, there is uncertainty whether avalanches will continue during the day. Signs of instability to key into are whumphing collapses, or wet, deep and punchy snow. These wet slab avalanches will be an unmanageable problem, as they could be very large. These could be 1.5-3ft deep, running on the prominent December 9th crust. With all of this uncertainty, keep it simple by staying off of, and out from underneath steep open slopes. 

    On Saturday observers noted a cycle of natural slab avalanches in the zone up to D2.5 (big enough to injure, bury or kill a person). Some of these had widely propagating crowns, and are suspected to have run on the prominent 12/9 crust. Above the rain line, the slab on top of our layers of concern has been gradually getting thicker. Seasoned backcountry travelers have been surprised when they triggered very wide avalanches from a distance or from below. If you manage to make it to the upper elevations where the snowpack remains dry, be advised that any avalanche that releases could be deadly. 

    (12/18/2020) Part of a persistent slab avalanche (D2) that was ~500ft wide and 15"-20" deep. Similar avalanches could happen with wet snow on Sunday.

  • Loose Wet

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

    Loose wet avalanches could be triggered or run spontaneously during the day. These could be large, and may gouge down to the early December crust. You will probably see evidence of recent activity if you look around at steep hillsides, as many naturals may run overnight Saturday into Sunday morning. Signs of loose wet instability are rollerballs, and wet sticky snow that entrains as it moves downhill. 

    The best way to manage large loose wet avalanches is to avoid being underneath very steep slopes, even in forested terrain if the trees are spaced out. 

    Example of a large loose wet avalanche.

Avalanche Discussion

A strong storm arrived Saturday afternoon, bringing heavy snowfall with warming temperatures.  A natural avalanche cycle is expected to occur overnight, likely tapering off by Sunday morning. There is uncertainty with how fast naturally activity will subside early Sunday. In any case, water is expected to soak through the snowpack below around 5,500ft. Above that, the snowpack may stay dry. Roughly 1.5 to 2.5ft of snow are likely to be resting over the prominent 12/09 melt freeze crust. Above 5,000ft folks have remotely triggered wide avalanches in some drainages, but not in others. 

Areas of thin coverage, open creeks, and shallowly buried obstacles still require your attention to navigate safely. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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