Bulletin d’avalanche

Central Cascades

Central Oregon Avalanche Center
Voir sur la carte

Danger d’avalanche

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

Points saillants

More snow is coming in and wind will continue to move it around. Triggering avalanches in wind deposited snow will be likely and avalanches can be large. Triggering avalanches in the new storm snow will  be possible in areas where the wind has not scoured it away. Use terrain to your advantage, if you have uncertainty in the stability of the snowpack stick to slopes less than 30 degrees steep. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1.5–2.5

    On Thursday, the forecasted wind speeds did not match up to what I was seeing in the field. However, we must be vigilant. The current forecast calls for wind speeds in the 30 to 40 mph range overnight and during the day. Those wind speeds can move a lot of snow. The bulk of the wind slab problem will be above treeline and near treeline but continue to look for signs of blowing snow and wind slabs below treeline, especially in clearings and areas with dead trees.  Wind slabs typically form below ridges and high points. The wind wrapping around north and south aspects can cause cross loading. Strong winds can cause wind slabs to show up in unsual places and further down slopes than what we normally see. 

    Use visual clues such as wavy surface texture and pillowy drifits as an indicator of where this problem is present. Previous avalanches and cracking in wind deposited snow are indicators that wind slab avalanches can occur. 

    Wind can pile up snow many times deeper than the snow dropped by the storm. As wind slabs become deeper, avalanches can become larger.

     

    (2/29/2024)

    Cracking in wind deposited snow on a small test slope. This was in an area of sparse trees below treeline with minimal wind blowing snow. The slab was shallow, but a good indicator that wind slabs are out there especially in more wind exposed areas.

    Photo: Aaron Hartz

  • Storm Slabs

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

    As the temperature cools, the incoming snow will be weak on the surface and small dry loose avalanches will be possible in steep terrain. However, I am keeping storm slab on the list because of a mid storm instability I was finding on Thursday. The incoming snow will be above this and may add to the slab potential. Use small test slopes to check out this problem. Cracking and slabs releasing on small convex rolls can tell you a lot about the sensitivity of the storm slabs. In areas where the wind has moved snow away, storm slabs will be less of a problem. 

    (2/29/2024)

    On Thursday I found a mid storm instability down about 4" below the surface. I found cracking in storm slabs on small test slopes and triggered small (D1) avalanches on this layer. 

    Photo: Aaron Hartz

Avalanche Discussion

Cornices at ridge tops will continue to build. They are fragile when they are fresh. Be cautious when approaching ridges. Stepping out onto a cornice could result in an unintended air drop onto the slope below.

Earlier this week, patchy buried surface was observed on some protected north facing slopes. This will now be 25 - 40 inches below the surface. Before committing to steep north facing terrain, it is a good idea to find a safe spot to dig and check for the presence of buried surface hoar. 

Régions couvertes