Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

Dangerous avalanche conditions exist, especially on wind-loaded slopes. The wind has transported new snow into touchy drifts and slabs that will continue to grow in size and distribution today. You're likely to find these in upper-elevation, wind-exposed terrain. The snowfall is also adding weight to buried weak layers, and it remains possible to trigger a larger avalanche 2-4 feet deep—even on wind-sheltered slopes.  

 

Avalanche problems

  • Wind Slabs

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

    Observations yesterday have indicated that wind slabs are more of a concern than the persistent slab problem. Yesterday, I found both stiff and soft drifts of windblown snow starting to build, and these cracked easily under my weight. These slabs could be 1-2 feet thick today, but could also be loaded to variable or shallower depths where they are easier to trigger and well-connected. Though snowfall was not as heavy as forecasted throughout the day yesterday-a shift in temperature, additional snowfall throughout the course of the day today, and optimal wind speeds for transporting lower-density new snow will be the name of the game today. The added weight of windblown snow will also increase the probability of triggering a larger avalanche on a deeper layer. This is of note, particularly on southerly slopes or areas with shallower snowpacks. If you triggered a wind slab, it could "step down", failing on layers deeper in the snowpack and becoming much larger than the initial avalanche.  

    Additional note: New snowfall today may sluff easily on any crusted surface (i.e. steeper slopes in the low-elevations that warmed and refroze, or rain/sleet crust layers that will be beneath the newest snowfall up to the mid-elevations).  

    (12/27/2022)

    Winds slab just starting to gain sensitivity by the end of the day yesterday. These will grow in size today. 

  • Persistent Slabs

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

    The November facet layer is buried about 3+ feet deep on almost every slope, with another layer from early December atop that (~1-2 feet deep). While there have been early signs that these layers are starting to strengthen—we're definitely not out of the woods yet.  It's important to come back to the simple facts: today we will gain a hefty slab on most aspects and elevations, which will be overlying known weaker snow. The best—and often only—way to manage a persistent slab problem that hasn't quite shown its cards to us yet (particularly on shallower slopes facing south and east) is by sticking to lower-angled terrain.

     

    (12/23/2022)

    Olive Oyl Pit showing low-strength ECTN (non-propagating) scores that may shift to ECTP (propagating) scores with incoming heavy snowfall.

Avalanche Discussion

Snow is a sensitive register to the forces that mold it. In the long term: additional water and a slightly warmed snowpack that has refrozen could prove well. In the short term: variable snowfall, temperature swings, and shifting winds can equal weird avalanches. We are more prone to see what we know and overlook the unfamiliar, and even the most conspicuous snow features can be missed if we are not paying attention to visual and other sensory clues. This is easier said than done. As I was buffeted in the face with graupel yesterday, it was hard to notice anything else.

When conditions are changing (or weather doesn't pan out as forecasted), a wider circle of clues is needed to infer what will happen next. Continue to practice good habits and communicate with your partners, and other parties, if entering the backcountry today. Pay attention to changing conditions and be aware of the terrain you choose to enter and the consequences of an avalanche in that terrain.  

Of note, a recent accident:(Zero Space avalanche involving multiple parties outside JHMR boundary)

Regions covered