Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

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

Numerous avalanches were reported yesterday providing a clear indication that recent snow is unstable on steep slopes. Triggering an avalanche will be likely again today, as avalanches will be small in the middle elevations and larger the higher you travel in elevation. Avoid steep slopes on consequential terrain, especially in the upper elevations. Seek lower angle terrain and assess recent snow instability above 7500’.

Avalanche problems

  • Wind Slabs

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

    Recent snow combined with gusty SW wind around 20 mph formed reactive slabs 1-2 feet deep. Slabs could be up to 3 feet deep in isolated areas in the upper elevations. Several poor interfaces exist near the top of the snowpack resulting in unstable recent snow, as seen yesterday with numerous avalanches above 7500’ primarily on steep northerly aspects. Expect to see similar reactivity today and keep in mind that avalanches will be larger or more dangerous in the upper elevations due to higher amounts of recent snow and stronger wind. Avoid wind loaded terrain where you encounter obvious signs of wind drifted snow including cracking or stiffened surfaces and large pillows. Look for wind drifted snow on leeward slopes off ridgelines and cross loaded slopes adjacent to large wind funnels such as large creeks and canyons. Confined features such as couloirs can also entrain more snow even if small avalanches are triggered. In addition, watch for increased activity on slopes facing the sun due to solar influence by the afternoon if skies clear.

    See recent observations of avalanche activity here. 

    (3/28/2024) 

    Avalanche in Granite Canyon outside of the JHMR boundary large enough to bury a person. 

  • Deep Persistent Slabs

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

    Hard slabs 3-5 feet thick overlay weak snow that formed earlier in the season. Shallow, rocky, and unsupported terrain on the north half of the compass is where this problem has been most active. Thin areas in the snowpack can act as trigger points and are most common in these locations. It is currently unlikely that a human would trigger one of these slabs. Larger triggers, like cornice fall or surface snow avalanches, still have the potential to impact weak layers buried deeply in the snowpack and initiate a much larger avalanche.

    The last reported avalanche on these persistent weak layers occured on 3/19 (Bernie's Bowl) in the form of a wet slab during a week of warm weather and strong solar influence. The last dry avalanche occured on 3/5 after a large and rapid loading event. 

    (3/5/2024)

    A very large persistent slab avalanche failed during the early March storm cycle. This terrain characterizes where this problem is most active: very steep, unsupported slopes near cliffs.

    Photo: Dan Hayes

Avalanche Discussion

Yesterday we saw an increase in avalanche activity due to rapid loading of new snow with rates of an inch per hour with around 5” of new snow in the last 24 hours in the middle and upper elevations of the Tetons. This rapid loading was combined with sustained W/SW wind around 20 mph and gusts above 40 mph. Multiple poor interfaces exist in the top portion of the snowpack including facet and crust combinations buried 3/21 and 3/23. Most of the avalanches appeared to be failing on the upper interface on northerly aspects. Due to the uncertainty in the poor interfaces, expect to see similar avalanche conditions today. We will continue to track these interfaces. Performing quick hand shear tests and assessing the recent snow instability on these interfaces will be critical before committing to a slope. Remember that avalanche danger will increase the higher you travel in elevation. Most avalanches reported yesterday were D1 or less. These small avalanches can knock you off your feet or machine and result in serious consequences. Avalanches in the upper elevations will be large enough to bury a person and have more severe consequences. Slopes above 35° will be most dangerous today. Don’t let the clear skies and good visibility lure you into more complex or challenging terrain. Enjoy the fresh powder and play it safe out there. 

Thank you to everyone that submitted observations and avalanches yesterday. Submitting these observations greatly benefits the entire community so we can all make more informed decisions in the backcountry.

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