Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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2 · Moderato
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2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Rain/snow and wind could create unstable snow over the course of the day, with the most dangerous conditions developing on and near Mt Rainier. Be leery of high-consequence terrain where one of these small avalanches could take you for a nasty ride.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Wind should increase on Sunday and could drift the few inches of new snow into a fresh batch of wind slabs. This problem will be most prevalent on the volcanoes and the higher exposed ridges closer to the Cascade Crest. Blowing snow should easily show you local wind patterns and highlight potentially loaded slopes. Textured surfaces and sharp dirifts will also point toward pillow-like slabs. Even if these slides should be small, they could knock you over a cliff or push you into rocks. 

    On more shaded slopes the new snow may sit on surface hoar, facets, or fluffy powder. If the storm brings more than 4 inches of snow, you may start to see cracking even in non-wind affected terrain. If you notice cracks in sheltered areas, expect wind slabs to trigger very easily on this weak interface.

    (12/8/2023)

    Example: Snow blown out of the windward side of trees and sharp drifts are great ways to anticipate wind-loaded slopes. 

    Photo: Dallas Glass

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    At lower elevations rain will produce piles of roller balls and maybe a few small wet loose slides. These will be most prevalent on shaded aspects where the snow surface remained cold and dry prior to the storm. On more sunny slopes, a new crust could limit wet avalanche issues. These slides should be very small, and not amount to much. However, don’t let one flush you into a creek or gully.

    (1/19/2024)

    Example: Rollerballs like this show the surface snow becoming wet, sticky, and potentially unstable. 

    Photo: Andy Harrington

Avalanche Discussion

The forecast on Sunday looks remarkably similar to Saturday, but for a totally different reason. This time a small storm will bring rain/snow and wind to the West South and cause the avalanche danger to slowly increase. This isn’t a very big storm, and it really favors Mt Rainier. You may see lower hazard in places that receive less precipitation. 

Saturday’s weather will probably impact how certain aspects react to the new snow. Sunshine across the zone created an aspect-dependent snowpack. On more southerly slopes, a new surface crust will likely form. As mentioned, it should limit wet avalanche concerns, but it could also make a slick surface of wind slabs. On more northerly aspects, expected winds didn’t materialize and cold dry snow survived. This might include weak grains like surface hoar and facets. 

Avalanche activity on Saturday was limited to a number of wet loose slides around the zone. Most of these avalanches were small (D1-1.5) but a few may have been slightly larger (D2). 

Over all 6-12in (15–30cm) of recent snow sits on the stout and slick Early February Crust (EFC). In non-sun affected areas, this snow is cold, unconsolidated, and right-side-up. 

Travel issues continue to be a concern. Thin coverage at lower elevations, open creeks, holes, and piles of avalanche debris make some travel routes quite challenging.

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