Avalanche forecast

Snake River Range

Bridger-Teton Avalanche Center
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Avalanche danger

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

Dense new snow and strong winds have made triggering an avalanche 1-2 feet deep likely in steep, wind loaded terrain at the mid and upper elevations. These slides could be large enough to bury or injure a person. Larger avalanches involving weak snow buried 2-3 feet deep are less likely, but possible today with the rapid new load. Wet snow avalanches are possible in very steep low elevation terrain where rain has fallen on dry snow.

 

Avalanche problems

  • Wind Slabs

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

    The Snake has received 7-10 inches of dense new snow above 7,500’ since noon yesterday with several more inches expected today. During that period, moderate to strong winds out of the southwest have redistributed that snow and formed slabs 1-2 feet deep in leeward terrain. Wind slabs will be reactive to the weight of a rider in steep terrain and could be large enough to bury or injure a person. These slabs may break above you and farther across slopes than expected making escape difficult. While less likely, natural avalanches may occur in very steep and heavily loaded terrain above 9,000’. Because of this, It will be important to avoid traveling under very steep wind loaded terrain today.

    Careful and conservative route finding will be necessary in and around avalanche terrain today. Be on the lookout for signs of instability in wind drifted snow such as cracking, collapsing, and recent avalanches. Move to sheltered, low angle terrain if these signs are present.

  • Persistent Slabs

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

    Triggering a large avalanche that involves weak layers of snow buried 2-4 feet deep is possible in very steep (>35°), rocky, and unsupported terrain. Signs of instability such as cracking or collapsing may not be present before triggering. The heavy new snow received overnight is stressing these layers and could make triggering more likely today than it was yesterday. Therefore, it is worth keeping this problem on the radar in suspect terrain (see photo) given the consequences of being involved in avalanches of these sizes. Practicing safe travel habits such as skiing one at a time, stopping in islands of safety, and communicating with partners are ways to increase safety margins in avalanche terrain.

    A significant natural avalanche cycle involving these layers occurred five days ago (2/19). Avalanches involving these layers were observed on a variety of aspects at all elevation bands.

    A large avalanche in the southern Tetons that likely occurred around 2/19. This terrain is very steep, cliffy,  and has produced multiple avalanches in the past 10 days.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Rain is falling at the lowest elevations and can quickly destabilize snow surfaces. Watch out for wet loose avalanches in very steep low elevation terrain today. While these slides are likely to be small, they could catch you off guard in steep features such as road cuts.

Avalanche Discussion

A warm and powerful storm just delivered 10” of snow and over an inch of Snow Water Equivalent (SWE) to the Snake in the past 18 hours. Winds have been strong, averaging in the mid 20s (mph) out of the southwest. Temperatures are in the upper 20s at 10,000’ and above freezing in the canyon. This combination of strong winds and warm temperatures will create slabs that are harder than your average “soft slab”. This makes stability assessments more difficult because wind slabs may not release under your ski and instead break above you. Very steep, wind loaded terrain should be given a wide berth today as the snowpack adjusts to the rapid load. Down low, rain has fallen on dry snow and saturated the surface. Wet loose avalanches will be a concern in very steep low elevation terrain. Today is a good day to seek out sheltered, low angle powder and give the snowpack time to adjust.

While new snow avalanches will be the primary concern today, weak layers buried 2-4 feet deep are being stressed by the rapid load and liquid water. Large wind slab avalanches could be enough of a trigger to impact these deeper layers in isolated, very steep terrain. Above freezing temperatures and liquid water in the snowpack will not promote stability. It is worth keeping the potential for deeper avalanches in mind today given the current weather conditions.

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