Bulletin d’avalanche

Bulletin d’avalanche

Payette Avalanche Center
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Danger d’avalanche

Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The avalanche danger will rise to Moderate today. Small wet-loose natural and human-triggered avalanches will become more possible on steep solar aspects as the sun heats up the new snow surface.  Solar aspects have a surface crust but are wet to the ground. Gusty winds formed shallow wind slabs yesterday.

Problèmes avalancheux

  • Loose Wet

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

    2 inches of new snow yesterday saw some sun and warmth but the winds helped keep things a little cooler. Today, full sun is going to be heating up solar aspects that are saturated to the ground below the 2 inches of new snow and the frozen surface crust that was semi-supportable yesterday. We will see some natural wet-loose avalanches that are probably going to be small but could grow larger as they entrain more of the wet snowpack. Northern aspects are only saturated in the upper inch of the old snow. During the afternoon, Solar aspects that are steeper than 30 degrees are going to be most dangerous. Choose cooler aspects that face away from the sun. If you are sinking past your ankles it's time to move to a cooler, northern facing aspect.

    (4/5/2021) SE aspect of Sgts: saturated snow all the way to the ground from the heat wave this past weekend.

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1

    Winds were tough enough yesterday to move snow, and make you want to move to another protected aspect. I witnessed a lot of wind transporting snow on the ridges of sgts, North of Brundage Mountain Resort, that was forming small wind slabs on slick frozen crusts. Steep, upper elevation terrain near cornices have the potential to have 4-6 inch deep sensitive wind slabs that more than likely will only be a problem in exposed, steep, complex, leeward terrain. Watch for signs of drifting, and red flags like cracking, and choose another route.

    (4/5/2021) Strong winds were transporting snow off of the frozen old snow surface creating 4-inch soft slabs.

Avalanche Discussion

Our snowpack is very different right now on solar aspects as opposed to shady aspects. The solar aspects are wet below the frozen surface, all the way to the ground. The northern aspects had only a little bit (1") of saturation just below the new snow and the crust that formed on the old snow surface. This wet/dry interface was failing easily.  Winds were moving the 2 inches of new snow around and forming 20-foot plumes into the leeward sides of the ridges yesterday. The wet snowpack may take a few days to re-freeze, but afternoon temps and sun are going to soften the snowpack each day enough to add concern on steep solar aspects. We did not see any signs of wet-slab avalanches from the last heat up, but I would not totally rule them out given that most of our snowpack is wet.