Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

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

Avalanche danger will increase Sunday as a storm deposits around a foot of snow Saturday night. It is likely that you could trigger an avalanche in deeper drifts of snow, especially if wind-loaded, and you may encounter signs of instability such as shooting cracks or whumphing collapses before an avalanche occurs, a good indicator to avoid nearby steep slopes. Travel carefully, as the snowpack is thin and many shallowly buried obstacles still exist, possibly buried under a thin coating of new snow. 

Avalanche problems

  • Storm Slabs

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

    You could trigger an avalanche in the storm snow that came in overnight Saturday and continues to deposit lighter amounts of snow throughout the day Sunday. An avalanche is most likely to occur in areas where wind deposited snow into thicker drifts, such as along ridgelines, around outcroppings, or in gullies. Strong winds are expected to redistribute snow during this storm, especially at higher elevations.  However there could be enough snow, even in non wind-loaded areas, that you could trigger an avalanche.

    Clues such as long, shooting cracks in the snow running from your feet or snowmobile are good indicators of an unstable snowpack. Hearing or feeling a whumph, or seeing large collapses not just underneath you but stretching several feet away from you are other indicators that an avalanche is likely to occur on slopes steeper than 35 degrees. Snow that feels stiffer, or upside-down (a harder surface and softer beneath), are signs that the snow may avalanche on a steep slope. If you find any of these signs, stick to lower-angle terrain. 

     

     Long, shooting cracks like these are good indicators that an avalanche could occur on a steep slope. 

    Photo: Ron Martin

Avalanche Discussion

Some isolated shady areas could still harbor weak snow from the long mid November dry spell. Be leery of these spots, especially if you hear whumphing collapses or punch through the surface into sugary snow. These locations are most likely to be in more easterly areas of the zone. It's easy to check for this layer with hand pits. If you find sugary, weak snow and a thick slab of snow on top, then avoid slopes steep enough to avalanche nearby.  Since Nov 23 we've seen a variety of snow conditions where the weakness was found in shady and sheltered areas, accompanied by whumphs, whereas other observers reported healing grains and no obvious signs of instability or avalanches. 

As a brief season history up to now, a couple feet of low density snow sat on the ground for a long period of high pressure Nov 8-21. North facing slopes became weak and faceted in the shade. Strong winds and days of sunshine created firm surfaces in many places in the alpine, and slopes exposed to direct sun. Warm temperatures and rain around thanksgiving may have healed some of the weak layers, but the jury's still out on how prevalent it still is. As there's a lot of uncertainty in the snowpack right now, please submit an observation if you get out on Sunday.

Despite this last storm,  it's still early season, and the snowpack is shallow. Expect to find around 3-4ft of snow in the deeper locations. Lots of early season hazards exist such as shallowly buried trees, rocks, and other obstacles. In terms of our snowpack, we're still gathering information about what's out there on the ground, so this forecast comes with a fair amount of uncertainty with limited information as a starting point.

 

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