Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

This might not be your normal storm day. Additional snow could test older weak layers in the snowpack and potentially create dangerous avalanche conditions. Keep it simple by using lower angle and lower consequence terrain. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    This storm adds another level of uncertainty to an already challenging avalanche problem. How will the persistent weak layers handle the additional load from precipitation while a potentially protective new crust forms? Hard to say. Ultimately, this isn’t an issue you can easily nail down or predict. The best thing we can do is give it space, especially during a storm. Snowpack tests can highlight the unstable snow, but they can’t prove its absence. A pile of avalanche and snowpack data from the zone over the past week has documented this issue quite well. Even if the likelihood of these avalanches may be decreasing, the consequences have remained the same. During this active storm, other small avalanches could trigger these deeper slides. You can avoid the problem by staying off larger steep slopes.

  • Wind Slabs

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

    Cooling temperatures, generally light precipitation rates, and mild temperatures should help the new snow to stick to the old surface and become mostly right-side-up. However, gusty winds could drift the snow into fresh slabs in higher elevation and exposed terrain. Some of these wind loaded slopes may trigger easily.Pay attention to the local wind patterns and blowing snow to anticipate potentially loaded slopes. It might be hard to assess these slabs during a storm. So, use lower angle, wind scoured, and more sheltered terrain to slip around this problem.

    (12/24/2025)

    Example: Blwoing snow is an easy way to determine local wind patterns and anticipate potentially loaded slopes. 

    Photo: Sam Clairmont

Avalanche Discussion

Cooling temperatures should help the snowline creep down the mountain side Wednesday! While not a huge storm, we’ll take what we can get. This should form a new crust below the new snow. Near the volcanoes, a foot or more of fresh snow may accumulate by the afternoon, creating larger and more dangerous avalanches. 

Near and below the rain-snow line, wet, heavy snow could result in small wet loose avalanches. At these lower elevations, there’s not much snow to slide, but there are plenty of obstacles to hit. So, while the avalanches aren’t that consequential, getting caught in one of these isolated dribblers sure is. 

The big question with this storm is how the persistent weak layers will respond. This might not be the wallup we’d like to really test the snowpack, but it's certainly a test nonetheless. These layers have been quiet the past several days in the West South zone, but the the snowpack structure remains. These layers are typically above about 5000-5500ft. 

  • 2/13: Surface Hoar/Facets: Shaded aspects. About 4-8 inches above the 2/7 crust. 
  • 2/7 Crust: Facets above and sometimes below this weak crust. All Apects. The first major crust in the upper snowpack. 

The recent weather has been much snowier than January, but conditions remain thin. Holes, creeks, logs, and bare ground make travel convoluted and time-consuming. 

Regioni coperte