Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

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

Expect another day of light snow accumulation and enough wind to transport existing snow at upper elevations. You may be able to trigger avalanches near and above treeline where the wind forms drifts of snow. Avalanches in deeply buried older layers are very difficult to trigger, but the weak structure remains.

Avalanche problems

  • Wind Slabs

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

    Use caution on leeward sides of ridges and terrain features. Look and feel in the snow for clues such as stiffer drifts, or sculpted snow surfaces. Steer around convex roll-overs and slopes 35 degrees and steeper where you see evidence of drifting. 

    Light snow accumulations and increasing wind will form slabs over older wind drifts. Existing soft snow could be transported and contribute to fresh wind slabs. On shaded, northerly aspects above treeline, you may still be able to trigger older wind slabs, formed on the 15th, where they rest on weak snow.

    (3/15/2022) A small (D1) slab avalanche, triggered on a leeward slope on the 3/14 interface. Crown: 14" deep x 25' wide. Kangaroo Ridge, WNW, 6850ft Photo: Josh Hirshberg

Avalanche Discussion

While triggering an avalanche on the late January facets is very unlikely, the consequences could be serious.  You can limit your exposure to shallow, rocky areas, and very steep and unsupported slopes. The layer can still be found about 3 feet deep, sandwiched between eroding crusts on NW-NE aspects near and above treeline, and has been particularly problematic in the Harts Pass area. From February into early March, the bulk of the avalanches on the weak layer were near Harts Pass. The most recent of these was triggered on March 9th in Allen Basin. After a widespread avalanche cycle on 2/28-3/1, observers reported a number of deep crowns and avalanches throughout the zone that likely ran on the weak layer. See the avalanche occurrence database for more details. 

Observers continue to report tests breaking on a mid-storm interface from March 15th and wind slab avalanches involving the storm snow. On Saturday, observers triggered loose snow avalanches and a small wind slab avalanche on a northeast aspect near Harts Pass. The storm of the 14-15th delivered over 1-2 feet and brought an active day of natural and triggered avalanches. The storm buried a variety of surfaces from moist melt forms at low elevation to crusts or old wind-pressed snow. On wind-sheltered NW-NE aspects near and above treeline, you can find a thin layer of near-surface facets 1-2 feet below the surface and often on a crust. This layer (similarly buried on March 8th in other zones) has been the source of impressively dangerous persistent slab avalanches near the Mount Baker ski area and in the West South zone. 

Regions covered