Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

You could trigger an avalanche on a steep, wind-loaded slope on Wednesday. Avalanches could be triggered in shallower drifts which will likely be forming throughout the day, or in older drifts, around a foot deep and may be a bit harder to trigger. Steer around steep slopes where you identify thicker wind loaded deposits of snow. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    On Monday I traveled to 5000ft in the West Central zone and experienced active wind loading forming reactive wind slabs. They were mainly about 6 inches deep where I saw them on small slopes. We've since received a few more inches of snow at upper elevations, and these slab avalanches are probably becoming more difficult to trigger. It might be tougher than in previous days to find clues indicating a slope is unstable, but we don't expect that the avalanche problem will have fully gone away overnight.

    Steep, wind-loaded locations below ridgelines, around rock outcroppings, in gullies, and on convex slopes are where you're most likely to find these slabs. They may be hidden under a smooth coating of snow that hasn't been wind affected. In addition to the older slabs, which may be a foot or so deep, wind could build shallower new slabs during the day Wednesday. These newer slabs will likely be more reactive. You may see active wind drifting occurring, which is a handy clue to use in deciding what areas you want to avoid. If you trigger a smaller, shallower slab, it could have enough weight to step down and trigger a deeper slab avalanche. Steer clear of steep, wind-loaded terrain on Wednesday. 

    (1/9/2023)

    Tiny slab avalanches failed on steep, convex rollovers, or test slopes, for me on Monday. These small test slopes are good indicators to check for reactive shallow wind slabs which may be a problem on a larger slope as well. 

    Photo: Irene Henninger

Avalanche Discussion

The sun expectedly came out in full force on Tuesday, and wet loose avalanches became a problem. Expect steep, south-facing slopes to have a crust early in the day. We don't think wet loose avalanches will be as much of a concern today, as we've already seen one day of warming, and incoming clouds will likely dissipate the sun's intensity as the day progresses. 

Temperatures have been relatively warm, so lower elevation areas have seen rain. This low elevation snow has mainly firmed up and transformed through several melt freeze cycles and rain events. There was a solid crust on the snow surface where I traveled on Monday, up to 4000ft. Higher up, wind slabs have been our major concern this week.  Although the signs may be more subtle, continue to investigate and use caution when approaching steep terrain on Wednesday. 

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