Boletín de aludes

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Peligro de aludes

Wed
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Isolated wind drifts exist on upper elevation slopes, where triggering a 1+ foot thick avalanche in steep terrain is possible today. A steady stream of new and windblown snow is creating slabs that will likely be small in size but will remain sensitive today. And while unlikely, it remains possible to trigger a large, 4-5 foot thick avalanche—especially on steep, rocky, wind-affected slopes. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Yesterday's moderate to strong winds blowing out of the west and northwest will transport new snowfall, as well as snow that has remained dry over the past week, and build slabs and drifts in exposed, upper-elevation terrain. I expect them to remain isolated to ridgelines and exposed terrain features and be anywhere from 6 inches to 1 foot in depth. While small, these slabs may be able to pick up steam as they travel downslope. Even small slides can have high consequences if they carry you through rocky, treed terrain or push you down into a terrain trap like a gully or a creek bed.

    Additionally, upper-elevation terrain features like narrow features with side flanks and the aprons of steeper areas may experience cross-loading or crafting of a slab from sluffing plus wind. 

    Digging a pit in the Palisades to assess the trend in weak snow and how reactive it is remaining on certain aspects.

    Photo: Drinkard

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–3

    The snowpack at middle and upper elevations this season has been plagued by a number of persistent weak layers. The layers most likely to produce large avalanches in this zone are found in the top 2-5' of the snowpack (dependent on aspect due to variability in snow depths), and consist of well-developed facets near the ground and crust+facet sandwiches. These prominent early-season facet layers are buried deeply, making it much more difficult, but not impossible, to trigger. Loading from snowfall (though very light) and wind over the past week are likely not giving these weak layers any relief.

    You are more likely to trigger an avalanche on upper elevation, "prime-time" slopes steeper than about 35 degrees. Most upper-elevation slopes have received additional loading due to wind over the past few weeks. While triggering a wind slab (Problem #1 above) is more likely, a wind slab avalanche could step down into these persistent weak layers resulting in a much larger avalanche.

    Long story short, you can greatly reduce your risk of triggering an avalanche of any variety by sticking to wind-sheltered, mid-elevation slopes.

    (1/23/2023)

    This wind slab avalanche in Crooked Thumb Basin in the Tetons entrained a larger amount of new snow and traveled over consequential terrain. Though not in the Greys River, this illustrates the importance of choosing terrain wisely with both wind slab and persistent problems. 

Avalanche Discussion

Adopting the pace of nature is easier said than done. Patience is one of the best tools I know of to deal with uncertainty. It's a way to purposefully slow down in the name of better comprehension and consciously add time to a process. One of the primary tests of patience is dealing with a persistent or deep persistent slab problem. When weather enters a holding pattern, more people enter higher in the alpine, less untouched snow is available, and I suddenly find myself with less of this magical quality. 

This is particularly true when assessing slopes that may or may not harbor a persistent problem type and subsequently, more risk. Feedback is poor with these avalanche problem types (i.e. not many human or natural avalanches, hard to tease out trends, and spatially variable). So try utilizing time as a decision management tool. We can utilize it to create more options, reduce uncertainty, and optimize timing. If I notice my risk tolerance shifting with timing, I know it's time to take a step back. Comprehension does not always follow perception immediately, or at all; i.e. just because I see or know the problem is there, doesn't mean I fully get it. Utilizing time can help shift perception to better comprehension and knowledge. 

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