Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The storm totals around the West South zone continue to grow during this cold and snowy pattern. Don’t let powder fever get the better of you. Give the snow time to heal by staying off of large steep open slopes.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Despite the date on the calendar, the mountains and snowpack sure look and feel a lot like mid-winter. These storms have been very good to the West South zone with plenty of cold deep powder. However, with so much new snow and cold temperatures, it will likely take a bit longer for the upper snowpack to gain strength. Several storm layers have been observed in the recent snow and any one of them could produce an avalanche in the right terrain. Steer around large steep open slopes and rocky complex areas to give the snowpack time to heal. Given the volume of new snow, simple small slope and uptrack tests likely won’t give you all the information you need. Instead, you’ll want to dig with your hand or shovel. Look for strong over weak snow and layers that fail easily to highlight the storm slab issue. With plenty of snow to entrain, any avalanche could quickly grow large enough to bury you, especially on long sustained slopes. 

    You may find that avalanches trigger more easily and are deeper in wind-loaded terrain. Over the course of these storms, the wind blew from nearly every direction. Unless you’re standing on an icy scoured crust, anticipate slab avalanches. Because of these widely varying winds, expect drifts in some strange spots, and occasionally both sides of the same ridge.

    (4/10/2022)

    A mid-storm density break near White Pass was highlighted by snowpack tests on 4/10.

    Photo: Dallas Glass

Avalanche Discussion

The winter weather continues for the West South zone. Snow totals on Tuesday ranged widely from 4-6” near the crest to 12-18” on the volcanoes. This brings storm totals to 30-50” for the zone since April 8th! Needless to say, conditions are DEEP. Some locations could receive an additional 3-6” by Wednesday afternoon. Given the showery nature of the precipitation, you could encounter periods of intense snowfall, while nearby drainages see very little. All this new snow accumulated over the easy to find 4/8 crust. You can use this marker to indicate how deep you may want to dig. It can also help you locate deeper, wind-loaded, and shallower, wind-stripped areas. Some snowpack tests have failed easily at the interface of the new snow and the 4/8 crust over the past few days. So far, we are not aware of any avalanches breaking at this layer, but it could be worth keeping an eye on. For the moment, we aren’t concerned about any deeper weak layers in the snowpack. 

The biggest source of uncertainty continues to be the sky. Given the time of year, it won’t take much for the sun to trigger natural loose avalanches. We expect mostly cloudy skies, cool temperatures, and a stiff easterly breeze will offset the impacts of any short sunbreaks. However, if you start to see snow shedding from trees, rollerballs, and/or teardrop-shaped slides, the danger may be changing. These avalanches will be most likely on steep sunny slopes. If you think these conditions are developing it's time to head for shadier terrain away from these features.

Régions couvertes