Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

Another snowy and windy April storm should increase avalanche hazard in the West South throughout the day on Monday. Look for dangerous conditions to develop by day’s end on the volcanoes or areas near the crest where strong winds persist. If you see actively blowing snow or shooting cracks, avoid nearby slopes over 35 degrees. 

Problemi valanghivi

  • Wind Slabs

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

    Monday will be a return to snowy and windy conditions and you could see some freshly built Wind Slabs by day’s end. As the snow starts to pile up and the winds continue to blow, look for these unstable pockets of snow to develop on the leeward side of ridgelines, convex features, or in rocky terrain such as the base of cliffs and confined chutes. These slabs should be larger and possibly more reactive as you ascend in elevation or in areas that receive more significant snow totals. Regardless of your location, you could encounter some unusual loading patterns with slabs forming on aspects you’re not used to or more cross-loading than usual. Since they will be forming during the storm, you can look for actively blowing snow or fresh drifts to help you identify wind-loaded slopes that should be avoided.

    (4/17/2022)

    Blocks of snow failing in wind-loaded terrain near Crystal Mountain on 4/17.

    Photo: Andy Harrington

  • Loose Wet

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

    We expect this round of precipitation to be a little warmer than what we’ve experienced the past few weeks, with a slow warming trend throughout the day. This could result in lower elevations seeing some rain or a rain/snow mix. If you find that rain is falling on cold dry snow, the potential for Wet Loose avalanches may be increasing. The question could be how much cold dry snow is left at these elevations after our sunny Sunday. The most likely location to find some should be on shady slopes or sun-protected slopes where a surface crust doesn't exist. If you notice new fan-shaped avalanche debris or fresh rollerballs, head for slopes under 35 degrees.

    (4/17/2022)

    Rollerballs and pinwheels such as this one in the Tatoosh Range on 4/17 are a good indicator that the surface snow is getting heavy and wet and capable of producing wet avalanches.

    Photo: Dallas Glass

Avalanche Discussion

Our bout of nice weather was short-lived and the next winter-like storm is on our doorstep in the West South. On Sunday, NWAC forecasters near Crystal and in the Tatoosh Range of Mount Rainier National Park both reported areas of wind-drifting, sunny skies, and increasingly heavy/wet snow. By mid-afternoon, fresh rollerballs and a few Wet Loose avalanches were found in sunnier terrain. A possible difference between the areas was the thickness of the crust on sunny slopes. 

As we look ahead to Monday’s storm, avalanche hazard should increase throughout the day and into the evening hours. On the volcanoes and some areas closer to the crest, winds are expected to become strong in the afternoon. New snow will be falling and drifting onto a variety of surfaces across the zone including cold dry snow on shady slopes, melt-freeze crusts on those sunny slopes, and wind-stiffened snow in some locations. The surface the new snow is overlaying could help drive the size and likelihood of you triggering a slide. Take a moment to check the bonding of the storm snow to the old surface before committing to a slope. We anticipate most avalanches to be isolated to the new accumulation, but on those shadier slopes we could see some break into older layers. There is currently 2-3 feet of snow sitting above the 4/8 interface and we are not concerned about anything below this interface at the moment.

We have extended our forecasting due to the stormy weather to help you out. That means we still need you to share information with us by submitting public observations about what you're seeing out there. Help us build a better product for you.

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