Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Slab Avalanches remain reactive to human triggering. More natural avalanche activity is also possible Friday, primarily during the morning on wind-loaded slopes at mid and upper elevations. Cautious route-finding and conservative decision-making are key for backcountry recreation. Many slopes have already avalanched and cleaned out the current slab avalanche problem, while many others are prime for human triggering. It will be difficult to see this difference from one slope to the next, so expect conditions could change quickly. While planning for the day here are some good terrain characteristics to look for: Slope angles near or below 30 degrees while keeping an eye on overhead Hazzard. Or recreation on southerly facing slopes that have enough snow to ride. As of Sunrise, about 6" of new snow has accumulated in the NW Mountains overnight. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    On steep slopes that haven't already avalanched, you can easily trigger persistent slabs over buried facets and faceted crusts.  Evidence of the problem is clear:  there has been an ongoing parade of natural and human triggered avalanches reported from all but the sunniest aspects all week.  Be wary of traveling below steep, connected slopes: many of these avalanches were triggered remotely from low angle terrain and we continue to observe natural releases from wind loading.   While slabs are generally soft and 1 to 2 feet thick below treeline,  they will be thicker and denser in wind drifted terrain at higher elevations.  

Avalanche Discussion

At 6am, it looks like the NW Mountains have accumulated about 6" of new snow. The western edge of the SE Mountain forecast area also looks in the 6" range at CBMR. The next weather station to the east in the SE mountains is all the way out in Taylor Park and that one is only showing a couple of inches of new snow. All this new snow is looking low-density, with fairly lower water content. Winds at 12,000ft have been SW averaging 20mph and gusting around 40mph. Those winds are becoming west at sunrise and will finish the day out of the north. 

New snow and wind are continuing to load our well-touted, exceptionally weak snowpack. There has been a lot of avalanche activity over the last week. Both natural and human triggered avalanches. This is going to make for a potentially variable snowpack from one slope to the next, depending on where, or if, that slope previously avalanched. If that slope avalanched last weekend, it may have refilled with a slab on the remaining facets. If it avalanched recently it may not have developed a new slab yet. If that slope hasn't yet avalanched, it's likely prime for human triggering on the aspects highlighted by the problem rose. Looking at a slope and understanding its history will not be an easy task. It's best to understand this potential variability and understand that you could move from an unreactive to a reactive snowpack, with little or no warning. 

The Persistent Slab Avalanche problem remains the primary concern. Fresh Windslabs are also forming at upper elevations this morning. The only areas that you may find yourself managing for wind slabs, and not the more significant Persistent Slabs, is on upper elevations southerly facing slopes. 

Heading into the weekend, the primary driver for the avalanche danger is expected to be the wind. The wind forecast is expected to increase late Saturday. That associated wind loading is expected to keep upper elevation at CONSIDERABLE. While some mid and lower elevations have a trend to MODERATE danger. 

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