Avalanche forecast

Snake River Range

Bridger-Teton Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 6 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche hazard will increase throughout the day as new snow and wind make human triggered avalanches possible on steep, wind-loaded slopes at the middle and upper elevations. Hazard is also heightened on very steep, north facing slopes above 8,000’ where riders may be able to trigger a large slab avalanche that fails on buried weak layers. Give steep, wind-loaded slopes and suspect north facing terrain a wide margin today.

Avalanche problems

  • Wind Slabs

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

    Six to ten inches of new snow could accumulate by evening. Moderate winds out of the west, switching to the northwest by the afternoon will redistribute the new snow and form soft slabs in wind-loaded upper elevation terrain. Slab depths and sensitivity will increase throughout the day as new snow accumulates. Human triggered avalanches around a foot deep may become possible by the afternoon in very steep and wind-loaded terrain. While mostly on the smaller side, these slabs have the potential to catch and carry riders. Wind slabs will mostly be found in the upper elevations today, but may form on isolated terrain features below 8,500’.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    Weak layers of snow including surface hoar and facets are buried 2-4 feet below the surface on shaded slopes. While the sensitivity of this layer is decreasing, riders may still be able to trigger a large, hard slab avalanche in very steep terrain over 35 degrees. Northerly aspects above 8,000’ are where this layer is weakest and where the majority of recent persistent slab activity has been observed. Signs of instability including fresh avalanches and collapses in the snowpack may not be present before triggering. Giving very steep, north facing slopes a wide margin is the best way to manage hazard right now due to the difficult to predict nature of this problem, and the high consequence of triggering an avalanche of this size.

    A large natural persistent slab avalanche that happened around the last storm 2/25.

     

Avalanche Discussion

A Pacific storm is bringing snowfall and stronger winds to the region today. There is some uncertainty with regard to how much it will actually snow today as forecast models have been inconsistent. As of this morning, several inches of new snow has fallen in the higher terrain, with another 4-8 possible throughout the day. Keep an eye on conditions as they change today. Be ready to adjust your travel plans if the strom produces and you see evidence of wind-loading or signs of instability in the new snow.

Deeper in the snowpack, persistent weak layers that formed in January/February remain a concern on north facing slopes above 8,000’. These weak layers are slowly gaining strength, but have not changed as quickly as the weather. Large avalanches involving weak snow from January were reported last week. The snow from our February storms has settled and become strong, making it difficult to impact the weak snow underneath. Despite this, there are still thin spots in the overlying slab where a rider may be able to trigger an avalanche. Very steep, north facing slopes are the bullseye for instability. Use caution and build some margin into your travel plans around these terrain features for the time being. 

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