Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Sat
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Rapid loading of snow with strong wind the last two days and continuing today will create dangerous avalanche conditions. Avoid upper elevations below steep complex terrain where natural avalanche danger will be high. Assess the new snow instability carefully across all elevations and choose lower angle slopes to avoid triggering a large avalanche.

Avalanche problems

  • Persistent Slabs

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

    Recent snow will add stress to weak layers buried Feb 2nd overlying hard slabs 3-4 feet deep. Sensitivity of these weak layers has been most reactive on N to E aspects in the upper elevations as seen by avalanches prior to this storm. Avoid these areas in steep terrain as the snowpack is rapidly loaded today. Use caution in the highlighted areas of the compass rose above due to uncertainty in the distribution and reactivity of these weak layers.

    A skier triggered avalanche that occurred two days ago (2/10) on the west side of the Tetons.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Weak snow formed during an atypically long dry period in December is buried more than 4 feet deep below a hard slab. Triggering an avalanche on these layers is unlikely as reactivity is approaching a dormant phase. Large avalanches involving new snow and persistent weak layers could step down to these deeper layers in steep and sustained terrain. This was seen on Feb 10th on Rendezvous Mtn as a result of a very large trigger from an avalanche above a cliff feature.

    An avalanche on the north side of Rendezvous that stepped down to the 1/4 layer.

  • Wind Slabs

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

    Another 12 inches of snow fell overnight accompanied by W/SW winds 20-30mph. Triggering 2-3 foot soft storm/wind slab avalanches today will be likely both in sheltered and wind affected terrain across all elevations. Human triggered avalanches are more likely in upper to middle elevations near ridgelines and open/exposed terrain where wind is rapidly loading new snow. Avoid upper elevation runout zones below steep and complex terrain. Look for obvious signs of instability such as cracking snow surfaces.

    (2/12/2024)

    Cracking in upper-elevation, wind-loaded terrain, a clear sign of unstable snow conditions. 

Avalanche Discussion

Don't get caught off guard, conditions are touchy.

The Tetons have received 22-36” of snow with 1.7-2.9” of snow water equivalent over the last two days. Another 6-10" is forecasted today. The characteristics each day have been significantly different. Low density snow around 5% accompanied the first pulse. Then temperatures and wind increased creating dense, firmer snow. And today you’ll find new snow slightly less dense (hopefully) due to lower wind speeds. There is a lot of uncertainty in trying to predict how exactly all these interfaces between storms will behave. The bottom line is we’re getting a lot of snow rapidly. A serious red flag. Especially in combination with consistently strong winds. Avoid runout zones beneath steep terrain in the alpine due to natural avalanche potential. Assess the new snow very thoroughly or simply stick to lower angle slopes to stay safe in the backcountry today. Managing the wind and storm slab instability by choosing lower angle terrain will also help manage the uncertainty of the persistent slab problems. 

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