Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Westerly wind gusts peaked at 109mph yesterday at the 12,000ft Scarps Ridge Weather Station, while valley winds were gusting into the 40's. Dangerous avalanche conditions exist on recently wind-loaded terrain and the general northern half of the compass where slabs are resting on weak snow from earlier this season. The safest riding today is either on low slope angles free from overhead hazards or on southerly aspects where the new snow is either sheltered from or being eroded by winds. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    Persistent slabs up to several feet thick are becoming more stubborn to human trigger and they may not alert you to their presence with obvious signs of instability. The problem is on the north half of the compass, where the foundation to our thickening snowpack is weak and faceted. In steep terrain, the distribution of these slabs is variable because of a widespread cycle that occurred last week.  Persistent avalanches can be remotely triggered from flat terrain below a steep slope, and avalanches might propagate much wider than you expect. Collapsing snow and shooting cracks are warning signs telling you to stay away from steep terrain or move to a southerly aspect where the snowpack structure is lacking weak layers.  

    This widely propagating persistent slab ran naturally during last week's storm on Mt. Axtell. 

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    The recent extreme winds will have greatly altered the snowpack. Some slopes will be wind-eroded, and others will have thick wind slabs that can be human triggered. This avalanche problem will be most problematic at near and above treeline elevations, but they can also be found on cross-loaded slopes at below treeline elevations. Given the extreme wind event, expect unusual drifting patterns. Many of these slabs will be hard, and may not show immediate signs of instability until you find the right trigger point. Wind slabs releasing in the upper snowpack could also step down and trigger a much larger persistent slab on shady aspects.  

    This is an example of several wind slabs that failed during the last storm.  

Avalanche Discussion

New snow totals from yesterday's storm are looking to average 4 to 7 inches in the Northwest Mountains, and 2 to 4 inches in the Southeast Mountains. However the new snow isn't the headline, it's the extreme wind event that accompanied the storm. Those winds will have altered the distribution of snow at all elevations. A cautions mindset will be key today, as you step out and assess how conditions have changed. Fresh avalanche activity will be an obvious red flag, but other signs of instability such as shooting cracks and a collapsing snowpack may not be very prevalent. If you are not observing signs of instability today, be cautious of becoming overconfident. 

The avalanche danger was dropped to MODERATE at below treeline elevations. This is primarily due to the persistent slab avalanche problem becoming more stubborn to human triggering, and many slopes having previously avalanched during last week's avalanche cycle. As we look ahead, conditions at all elevations are expected to mostly stay the same through Friday thanks to more wind and snow forecasted for Thursday night. Then with dry weather arriving on the weekend, we can expect the avalanche danger to decrease.

Regions covered