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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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

A significant amount of new snow over the last week has created dangerous avalanche conditions. Triggering avalanches 2-4’ deep is likely in steep upper elevation terrain. Conservative decision making and patience will be critical in avoiding avalanches today.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Significant snowfall over the last week has built a slab 2-4 feet thick on a variety of surfaces.  Avalanche activity seems to have spiked 2 days ago, with reports of large avalanches occurring naturally in north facing upper elevation terrain. The potential for triggering avalanches at this interface is on a downward trend.  Despite this fact, triggering is still in the possible to likely range. Given the potential size of avalanches on this layer, it remains critical to treat upper elevation steep terrain with a high level of suspicion. Wind loaded starting zones will be the most likely terrain to initiate an avalanche today. New snow in the forecast will add a minor amount of additional stress to the Feb 2 interface. Keep slope angles on the low side today and give this slab/weak layer combo time to adjust.

    Large remotely triggered avalanche on Four Pines just outside the JHMR boundary highlighting the poor new to old snow interface. 

    Photo: Josh Pope

  • Deep Persistent Slabs

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

    Weak snow that formed during a prolonged dry spell in December remains a lingering threat. Reactivity on this layer is slowly approaching a dormant phase but is not there yet. Waking up this beast remains possible and is more likely to occur as the result of a large avalanche involving the newer snow stepping down to this interface.  Avalanches in this category fall into the 3-5 foot depth range and would be unsurvivable if one were to get caught, carried and buried.

    (2/3/2024)

    Crown visible through the trees. 1.5-2ft.  This avalanche occured on Feb 3 on a north aspect at 8700'

Avalanche Discussion

A significant warm and dry period occurred between Jan 29 and Feb 2. This resulted in melting of snow surfaces and crust formation on all aspects in the mid and low elevations as well as upper elevation terrain on the south half of the compass. Upper elevation terrain on the north half of the compass was left with facets, some surface hoar and generally weak snow. Snowfall that began on Feb 3rd and will taper off today built slabs ranging from 2-4 feet thick. Snow water equivalent of this slab is 2.5-4”. This is a significant load over a short period of time. Bonding at the Feb 2 interface ranges from good to poor.  As a result there has been a natural avalanche cycle that likely peaked 2 days ago. While observations have been limited by low visibility, the information that has been gathered points to a fairly widespread cycle in the Tetons.

Deeper instability on the Jan 4th interface remains on the radar as the Feb 2nd interface takes time to adjust. The last known activity on this layer occurred south of Teton Pass on Feb 3rd. It is possible that some of the more recent avalanche activity stepped down to this interface, but there is uncertainty around this fact. While reactivity is trending towards dormancy on this layer, there is enough uncertainty to warrant a conservative approach. Low likelihood/high consequence situations such as this require patience and vigilance in how we travel through avalanche terrain.

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