Bollettino valanghe

Southeast Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Human triggering a slab avalanche that releases deeply near the ground is unlikely. However, the consequence of a triggered avalanche remains severe. So here we are in our low likelihood but high consequence dilemma. The primary avalanche problem will not give you early warning signs or show obvious signs of instability. So take the time to evaluate avalanche terrain carefully and look for ways to further reduce your chance of triggering an avalanche. Such as avoiding trigger points and areas that the snowpack transitions from a deep area to a shallow area, or choosing to travel on southerly facing slopes. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    Persistent slabs are becoming a low likelihood but high consequence concern on the northern half of the compass, where faceted weak layers lurk near the ground.   You are most likely to impact these layers and trigger a dangerous avalanche where slabs are thinner.  Choose terrain with a deep, uniform snowpack to reduce your risk.  Be cautious near rock bands and in alpine terrain where winds have created variable snow depths.  Slopes that avalanched early in the holiday cycle or slopes in the shallowest parts of the Southeast Mountains also have thinner slabs that could be more easily triggered.  

     

    A persistent slab avalanche on an east aspect of Hunter Hill. This avalanche released at the start of the new year.

Avalanche Discussion

Since around the start of the new year and the end of the holiday natural avalanche cycle, we have observed a few explosively triggered avalanches releases near the ground, but no other natural or human triggered avalanches release near the ground. While the known snowpack structure and stability tests this past week, inform us that we can't completely rule out the potential of hard slabs releasing near the ground. The likelihood of triggering this avalanche problem fits closer to a level 1 danger rating, while the expected avalanche size and travel advice fit a level 2 avalanche danger rating. For the most part, we have MODERATE avalanche danger across the board and are still a couple or a few days away from seeing the overall avalanche danger rating further drop. 

Yesterday in the northern San Juans, a backcountry skier remotely triggered a large slab avalanche that broke an estimated 4 feet deep on old snow near the ground. This particular avalanche looks very similar to the current situation we are in. When you look at the terrain it looks like the snowpack coverage is fairly deep and somewhat consistent across the terrain. However, those skiers managed to find just the right trigger point. I suspect they found that trigger point near the ridge where the snowpack quickly transitions from deep to shallow. Looking at the observation it's difficult to tell whether there was a shallow wind slab that further stepped down or if the avalanche initially broke deeply. 

The last couple of days we have seen moderate winds transporting snow in the high peaks. There isn't an expected widespread wind slab avalanche problem. However, if you are riding extreme terrain at upper elevations, keep in mind there could be isolated areas where you could trigger a shallow hard slab that may be enough to knock you off your feet and send you somewhere you didn't want to go. 

Regioni coperte