Boletín de aludes

West Slopes South

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The day should start with generally safe avalanche conditions in all areas. However, as the storm starts to impact the region expect the danger to slowly increase. By the afternoon, you may find unstable pockets of wind-drifted snow at upper elevations.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1

    It will take a bit for new wind slabs to develop on Friday. You’re most likely to encounter them later in the day, at upper elevations, in places where new snow has already started to accumulate. Look for blowing snow and small drifts to help you understand local wind patterns and which aspects might hold newly forming slabs. If you see bright white pillow-like drifts of snow, you’ve found the problem. While these avalanches should stay relatively small, they could trigger very easily. Consider the consequences (presence of terrain traps) before committing to any wind-loaded features.

    (1/29/2023)

    Intense blowing snow along Hogback Ridge at White Pass with "fat" pillow-like drifts below.

    Photo: Dallas Glass

Avalanche Discussion

A storm will start to impact the West South zone during the day Friday. While not particularly impressive, it will (eventually) bring enough new snow to increase the avalanche danger. For most places, this won’t occur until Friday night or Saturday. However, for those locations that start to accumulate 2-3in of snow during the afternoon, you may see heightened avalanche conditions on a few wind-loaded terrain features. This is most likely at upper elevations near the volcanoes. For other areas of the zone that don’t accumulate much snow before sunset, expect generally Low danger. 

One of the things you’ll likely notice Friday will be the winds. While there isn’t much soft snow left to blow around, you will see some blowing snow and drifting near ridge crest. As the snow starts to fly, this will only add to the wind transport and loading. 

A lower elevation's rain could cause a few very small loose wet slides or rollerballs, but they should be so small to be inconsequential. 

A big question heading into this storm revolves around the old surfaces where the snow will accumulate. On southerly aspects firm melt-freeze crusts formed over the past few days. However, on slopes that don’t receive direct sunshine, you may find weak facets (sugar) or surface hoar (feathers) along with crusts, scoured ice, and lingering powder. You can help by submitting an observation of what you find on the surface Friday morning and/or if you see these weak layers getting buried during the day. While this may not be much of an issue on Friday, as snow accumulates we could encounter avalanches that fail easily over these persistent grains or icy crusts. 

Our attention is primarily on the new/old snow interface heading into this storm. However, we have been monitoring a number of layers in the upper snowpack above the very prominent MLK crust. We don’t think you’ll see avalanches on any of these layers Friday. However, if you dig, keep an eye out for weak sugary grains developing on or near the lingering crusts in the upper ~2ft of the snowpack.

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