Bulletin d’avalanche

Northwest Mountains

Crested Butte Avalanche Center
Voir sur la carte

Danger d’avalanche

Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré 6 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The avalanche danger will be increasing throughout the day as new snow accumulates. Wind slabs will first develop on the lee sides of ridgelines and cross-loaded terrain features. New snow will also add volume to triggered dry loose avalanches in areas with a very weak snowpack. By the time ~6 inches of new snow accumulates, the possibility of triggering soft slabs will become more widespread. Keep an eye out for changing conditions today and the developing heightened avalanche conditions. 

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    The warm new snow will form soft slabs in areas with a faceted, weak snowpack. These areas will be the same location where you could trigger dry loose sluffs in the last week. Most commonly, where the total snowpack has a below-average depth. Keep an eye out for the previous dry loose avalanche problem transitioning into a storm slab avalanche problem. A triggered sluff will entrain additional volume with the new snow, or new soft slabs will become reactive on those same weak layers. 

    An example of dry loose avalanches above Peanut Lake RD.  These same areas will be transitioning to a storm slab avalanche problem as snow accumulates today. 

  • Wind Slabs

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

    Southwest to west winds will first form a new slab avalanche problem on the lee sides of ridgelines and cross-loaded terrain features. Keep an eye out for this developing avalanche problem and expect changing conditions through the day. In some locations, these slabs will form over persistent weak layers, leading to the potential of an avalanche propagating wider than expected later in the day. 

    A small wind slab that was human-triggered earlier this winter on a cross-loaded terrain feature. 

Avalanche Discussion

New snow is bringing changing avalanche conditions. The first changes to occur will be the developing wind slab avalanche problem, and the dry loose avalanche problem transitioning into a thin storm slab avalanche problem. With the warm temperatures today, I suspect thin storm slabs will form over the weak facets on some northerly-facing slopes. On those northerly-facing slopes, the weakest snowpack is in the SE Mountain forecast area. While over in the NW Mountain forecast area, the snow surface was not as weak, except for very steep slopes and old bed surfaces, where the total snowpack depth was below average. This will be an interesting hybrid avalanche problem to watch. 

East, south, and west aspects have surface crusts that formed over the last 2 weeks of dry and hot weather. Avalanche problems will be slower to develop in these areas until we see enough load to overload and collapse those crusts. Avalanche problems will begin expanding around the compass tonight and into tomorrow, depending on how much snow accumulates. 

There is a chance that HIGH avalanche danger (level 4 of 5) could develop in the NW Mountain forecast areas early tomorrow morning. This morning, high-resolution weather models began to back off on their total precipitation forecasts, raising doubts about whether we will see HIGH avalanche danger develop. We do have a favorable southwest-to-west wind direction and a plume of moisture impacting the area. So let's hope we see the high end of snow forecasts going into tomorrow. If that's the case, we will see HIGH avalanche danger issued in the northwest mountain forecast areas tomorrow. 

Régions couvertes