Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Human-triggered avalanches are possible at middle and upper elevations where new snow and wind have formed fresh slabs up to 1 foot thick. Older wind slabs up to 3 feet thick will be difficult to trigger but still linger in very steep, heavily wind-loaded terrain. Evaluate steep terrain carefully, especially near wind-loaded features. Seek terrain sheltered from the wind to reduce your risk. 

Avalanche problems

  • Wind Slabs

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

    New snow and strong west/southwest winds have formed fresh wind slabs up to 1 foot deep above 8500'. Given the high wind speeds, expect slabs to have variable depth and to have formed further down and across the slope than usual. Pillows, fresh cornices, and stiffened surfaces are all indicators that winds have recently loaded slopes. Shallower slabs may be sensitive to the weight of a rider and could step down to deeper layers in very steep terrain. Stay alert for signs of instability such as recent avalanches and shooting cracks near exposed ridgelines and cross-loaded terrain features. 

    Older wind slabs formed earlier this week still linger on all aspects in middle and upper elevation bands. These slabs are becoming more difficult to trigger, but are sitting on weak interfaces and could break up to 3 feet deep. Triggering a fresh wind slab could step down to these deeper layers and there have been multiple large human-triggered avalanches reported over the past several days. Keep in mind that fresh snow has hidden signs of older slabs and visible warning signs may not be present. Carefully evaluate the snowpack for still underlying slabs on wind-loaded terrain directly off ridgelines or around rocky, wind-affected slopes where you are more likely to encounter these avalanches.

     

    The 18-24 inch crown of an avalanche in wind-loaded terrain that caught and carried a skier yesterday on the West side of the Tetons.

    Thanks for sharing this observation!

Avalanche Discussion

The Tetons received over 50 inches of snow and about 5 inches of water this week, combined with temperature fluctuations and lots of wind from the southwest, west, and northwest. This combination created several poor interfaces that remain reactive, with much higher consequences in wind-loaded areas where recent avalanches have been large enough to bury riders.  In heavily wind-loaded areas at upper elevations, the crust that was buried on 3/13 is up to 3 feet deep with a stiffening slab on top. This crust interface, as well as shallower storm density breaks, have continued to produce avalanches. The good news is that the poor interfaces are likely gaining strength, aided by settlement, but this process takes time. 

Managing this windslab problem will require identifying where the wind has deposited snow this week and considering that slab depths in some areas may not be conducive to your typical wind slab mitigation techniques. These slabs may or may not break at your ski tips and may not show warning signs beforehand. Investigating these interfaces before committing would be prudent. Entering this specific terrain (upper elevation, wind loaded) with a more conservative mindset and considering consequences might also be a good approach while we give the snowpack a little more time to adjust.

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