Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

It probably won’t be that dangerous first thing in the morning, but a strong winter storm will cause the avalanche hazard to rise throughout the day. It may be easy to trigger slides in wind-loaded terrain and in the afternoon. Once you find more than 6-8 inches of new snow, start dialing it back and seek out lower-angled slopes.

Problemi valanghivi

  • Storm Slabs

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

    Right out of the gate in the morning you may find a few shallow wind-loaded pockets along ridges and on exposed features. However, once the storm shifts its focus to the West South, heavy precipitation rates will cause slabs to build quickly. 

    The new snow will fall on a variety of surfaces, including surface hoar, facets, wind-scoured slopes, firm crusts, and textured snow. This variability may make it incredibly difficult to assess how any one slope will reach. Hand pits, uptrack tests, and small slopes can give you an idea, but they might be different than the next slope you touch. Since some of these slabs may fail on persistent grains, avalanches could break widely and even wrap around features. Instead of trying to thread this needle, you can just dial it back and stay off of steep open slopes. 

    While you could trigger a slide in any steep area, expect avalanches to be deeper and more dangerous in wind-loaded terrain.

    (1/6/2024)

    Example: Small slopes like this could start to produce avalanches in the afternoon. 

    Photo: Andy Harrington

Avalanche Discussion

The West South zone will be a little late to this winter storm party but don’t worry. The storm should turn its firehose toward the south on Sunday afternoon and evening. Avalanche danger should rise and peak during the overnight hours with very strong winds and high precipitation rates. Some locations could see widespread natural avalanches. 

Since the storm won’t impact all areas equal Sunday, you could see slightly higher avalanche danger on Mt Rainier and less near Crystal Mt, Mt St Helens, and Mt Adams. The amount of new snow and how fast it falls will have a big impact on the hazard. 

To make things more complicated, the upper snowpack is variable and, in some places, contains various layers of weak snow. This could lead to very irregular avalanche patterns even within a local area.  In general, the snowpack is weaker and more layered on shaded aspects. We don’t expect avalanches to break into older weak layers on Sunday, but as more snow stresses the snowpack, that’s certainly not out of the question. 

At and near the rain-snow line, you might see a few wet loose slides. However, the thinner snowpack at these lower elevations should limit the wet hazard. Be leery of punchy snow on any steep slope. 

A few limited observations on Saturday suggest that surface hoar survived on some shaded aspects at middle elevations. Southerly slopes once again warmed and will thicken an already existing crust.

Regioni coperte