Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Wed
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Limite del bosco
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In sintesi

On Tuesday, a bright and sun shiny day is in store for the West South. Solar input is expected to destabilize the surface, resulting in wet avalanche activity. If you see fan-shaped avalanche debris or new rollerballs, head for shaded slopes.

Problemi valanghivi

  • Loose Wet

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

    If the sun warms and destabilizes a dry snow surface on Tuesday, anticipate wet avalanche activity to follow. These slides often start at a point and fan out as they move downhill. They could entrain all of the snow above the Early February Crust and potentially grow large or trigger slabs as they descend. Rollerballs/pinwheels and snow shedding from rocks/trees are precursors to wet loose avalanches. If the snow surface is wet and sticky and you notice these signs or see fan-shaped avalanche debris, head for shaded slopes. The target zone for the highest hazard will be sun-exposed slopes with dry surface snow.

    (2/10/2024)

    Rollerballs and other wet loose activity was observed at Paradise on a sunny day this past weekend.

    Photo: CLusk

  • Wind Slabs

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

    On shaded slopes, you might encounter a lingering slab in Monday’s storm snow. Use quick hand pits, uptrack tests, and small test slopes to get an indication of how the snow over the Early February Crust is bonded and reacting to your weight. Most of these should be shallow wind slabs, but on the volcanoes, you could encounter slabs in wind-sheltered terrain. 

    Look for fresh cornices, textured surfaces, or new drifts to help identify wind-loaded slopes. If you see cracking of the surface or the snow failing easily in your tests, you should avoid convex, unsupported, or wind-loaded features over 35 degrees. 

    (2/12/2024)

    Fresh cornices and drifts help indicate that wind slabs may exist on leeward slopes.

    Photo: Dallas Glass

Avalanche Discussion

Since our last atmospheric river created the stout and easily identifiable Early February Crust (EFC), we have been in a similar pattern in the West South zone. Small storms have rolled through, dropping a few inches of snow, with higher totals on the volcanoes than near the crest. 

You can expect to find 1.5-2 feet of snow over the EFC near Paradise, with 8-12 inches closer to the crest. Depending on your aspect and elevation, the structure may look slightly different. Sun crusts on slopes that typically see direct sunshine have created crust sandwiches or may have melted into the EFC. Weak facets could be interspersed in the recent snow on shaded slopes, including right on top of the EFC.

The question mark on Tuesday is the extent and size of wet avalanches in the February sun. We often don’t expect significant wet activity this time of year, but this hasn’t been a typical year. Will the warmup on Saturday or the moist, wet snow on Sunday be enough to keep the bulk of wet avalanches in check? Will the snow start to “slab up” and stress weak layers above the EFC?

Travel conditions have improved significantly around the zone, but natural hazards such as open holes/creeks or exposed rocks/bushes still exist, particularly at lower elevations. 

Regioni coperte