Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

If plenty of soft snow is your idea of a Christmas Miracle, then you better start believing. You better watch out on slopes over 35 degrees, especially as you ascend in elevation or in wind-prone areas. Keep your partner in sight in case they fall into the deep snow and aren’t able to get up. 

Problemi valanghivi

  • Wind Slabs

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

    Wind-affected terrain will remain the most likely location for you to trigger large slab avalanches throughout the West South. Look for these slabs on the lee side of ridges, near the base of cliffs, or in gullies and chutes. Freshly formed slabs may be easier to identify by looking for textured surfaces or actively blowing snow. Where the challenge lies is in looking for the Wind Slabs that are now hidden below a few inches of freshly fallen snow. Feel for a change in snow depth or firmer snow below the surface as an indication that you are in wind-loaded terrain. Identifying the predominant wind direction by looking for freshly formed cornices or drifting behind natural features can give you clues as to the aspects where you need to take extra care. If you suspect a slope to be wind-loaded, best to give it a wide berth and choose an alternate path.

    (12/23/2021)

    Intense blowing snow was encountered Thursday (12/23) on the Paradise parking lot. When you see wind transported snow, anticipate wind slabs in near by terrain. 

    Photo: Mt Rainier Rangers

  • Storm Slabs

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

    Shallow soft slabs were reported by professionals in the West South zone on Friday. These slabs only propagated a short distance, but many have been able to entrain additional soft snow as they descended. You could find that these avalanches have similar characteristics to Loose Dry avalanches, and in some cases are difficult to decipher between the two. Regardless of what you want to call them, the end result is the same. As the snow continues to pile up, so will the size of these avalanches that are breaking in the new snow. These slides will be more likely on slopes over 35 degrees and you can use test slopes as a good indicator of how they could break due to your weight.

    (12/23/2021)

    Uptrack tests and small slope can help you see how the new snow reacts under your weight. 

    Photo: Shane Robinson

Avalanche Discussion

If you are recreating in the southern half of the zone, such as on Mount St. Helens or Mt. Adams, you may want to reference the Mt. Hood forecast for additional information. Sensitive slabs were reported at Mt. Hood on Friday and precipitation totals should continue to favor the south throughout the weekend. We have limited observations from the southern end of our zone, so if you are out in these areas, we’d love to hear from you. Take a minute and submit a public observation.

NWAC forecasters in the White Pass area reported 15-18” of generally light and right-side up snow above the Solstice Crust on Friday afternoon. Although reports indicate that the recent storm snow is generally well bonded to this crust, you will need to keep checking for slab development and potential weak layers as the snow piles up. We anticipate most avalanche activity to occur above the Solstice Crust. The storm track will continue to favor the West South over the next few days and with this much soft snow, even falling and not being able to get up can present a hazard. Keep your partners in sight and read up on snow immersion hazards here.

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