Bulletin d’avalanche

Central Cascades

Central Oregon Avalanche Center
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Danger d’avalanche

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

Points saillants

Triggering avalanches in previously wind drifted snow above treeline and near treeline will be possible on Sunday. Minimize exposure to these avalanches by avoiding areas with pillowy drifts and sticking to wind sheltered areas. Triggering large avalanches that fail on a layer of old snow are possible in isolated terrain near treeline and below treeline on west, north, and east facing slopes; steep, convex, and rocky areas are likely trigger points for these avalanches. When you have uncertainty about the stability of the snowpack, choose to travel on lower angle slopes less than 30 degrees steep. 

Problèmes avalancheux

  • Wind Slabs

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

    Previously formed wind slabs will be trending toward stubborn to trigger, but it will still be possible. On Saturday, I snowmobiled up to the Moon Mt. area and I could see blowing snow but not much else in the whiteout. Wind slabs were probably forming on lee north - east - south features on Saturday. With no real snow accumulation expected  overnight and on Sunday, combined with light wind speeds, new wind slab formation will be minimal. However, keep wind slabs in mind if you venture into the mid and upper elevations on Sunday. Utilize small safe test slopes to check for reactivity of wind slabs before committing to lee terrain. Cracking in the slab and recent avalanches are good indicators you can trigger an avalanche, but keep in mind we do not always get that feedback. 

    Archive Photo: Elliott Reed

    Example of cracking in wind slab

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–2.5

    Despite the cold temperatures we have been experiencing in the mountains, this persistent weak layer seems to be gaining strength. On Saturday, in snowpits on east and north facing slopes around 6800', I found the facets to be rounding but this is still a weak layer in the pack. Triggering an avalanche on the Jan. 31 layer will become harder to do, but there are still some terrain features to be cautious around. Namely steep and convex slopes, and around shallow rocky areas where the weak layer can be closer to the surface. We may not get much feedback in the way of collapses and whumphs. Hedge your bets by sticking to more planar slopes and steer away from steep rocky areas. Although the likelihood of triggering a persistent slab avalanche is trending down, it is still possible and would result in a large avalanche. 

    (2/8/2025)

    The January 31 buried facet layer is easy to find in the snowpack under the recent snow (down 32 - 35"). On Saturday, I found it to be gaining strength but it is still weak compared to the surrounding snow above and below it. 

    Photo: Aaron Hartz

Régions couvertes