Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

Wind drifted snow will build unstable slabs near and above treeline.  Steer around wind loaded terrain where you find 6" or more of new snow, shooting cracks, or signs of extensive wind transport like fresh cornices or deep drifts. Expect slightly higher danger from wet avalanches if the sun makes it out midday.

 

Avalanche problems

  • Wind Slabs

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

    With only a few inches of new snow but winds gusting to 50mph, backcountry travelers in West North found plenty of easy to trigger wind slabs that developed between large areas of wind scoured terrain. Sunday should bring similar conditions to West Central. Winds will blow strong from the south and there is a chance of getting a decent shot of new snow overnight. New wind slabs will form and might connect across greater stretches of terrain instead of being separated by old surface crusts. Additional loading could also wake up a layer of facets that have been found in some areas. 

    With strong winds, you might find wind slabs farther downslope and on cross-loaded features in addition to just below ridgeline. Poor visibility or a layer of new snow could make wind slabs harder to pick out in the terrain around you. Monitor new snow depth you as gain elevation and change aspects. Don’t ignore obvious signs of instability like shooting cracks or even subtler clues like a change in snow depth or texture. Evaluate each slope on a case by case basis and travel on lower angle or wind scoured terrain to reduce the likelihood of triggering an avalanche.

    (3/12/2022)

    Shallow skier triggered wind slab avalanche on a west aspect of Table Mt. at ~5000'.

    Photo: Pete Durr

Avalanche Discussion

Partly sunny skies midday and above freezing temperatures could create a round of loose wet avalanches Sunday. Consider moving off and away from sun-exposed terrain where you see increasing signs of instability like rollerballs, pinwheels, and small avalanches. Also, realize that wind slabs and other new snow layers that seemed unreactive earlier in the day could wake up with a little warming and be more sensitive to human triggers.

A dozen or more wind slab avalanches to D1.5 were reported from West North in the past two days. On Friday two incidents occurred in which those who triggered avalanches were caught and carried a short distance. Most wind slab avalanches looked to be around 4-8” deep and either released on a firm crust or within layers of wind loaded snow. Some wind loaded features were observed to be more reactive mid-morning Saturday with warming. The wind loading pattern varied widely across terrain with areas of wind slab separated by frozen crust or wind hardened snow, oftentimes with old tracks visible. Unfortunately, the best skiing and riding was also in the terrain where you were most likely to trigger an avalanche. On the other hand, the new wind slabs were at least easy to identify.

Other areas adjacent to West Central have experienced more benign, spring-like weather and snowpack with little in the way of reported avalanche activity other than loose wet avalanches. If you are traveling near Stevens or Snoqualmie Passes check out forecasts for those zones as a comparison.

New snow and wind slab layers are building on a variety of surface layers including sun crust, dry and weak snow in shady, wind sheltered terrain, old wind slabs, and wind scoured surfaces. Weak, faceted snow continues to be found around the Cascades around the old snow surface buried on March 8th. In some regions, they were found above crust layers from the most recent atmospheric river event in early March. They are more commonly found in shaded terrain but have been observed on most aspects farther south in the Cascades. Besides the snow surface and new wind slab layers, the upper snowpack is generally strong with no current layers of concern. Human triggered avalanches on the Valentine’s Day crust and the late January crust-facet layers continue to be an issue in adjacent regions (East North and the South Coast and Sea-to-Sky zones in Canada). There were no reported avalanches in West North or Central associated with deeper layers since the natural avalanche cycle in late February/early March.

Regions covered