Avalanche forecast

Togwotee Pass

Bridger-Teton Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
No rating
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Highlights

Avalanche conditions will become increasingly hazardous throughout the day. This morning, your primary concern will be avalanches failing on weak layers 2+ feet deep in addition to isolated pockets of 6-10 inch wind slabs in steep terrain. As the day heats up, the likelihood of natural and human-triggered wet snow avalanches will increase significantly. Don't linger below large avalanche paths and avoid areas with wet, soggy snow.

Avalanche problems

  • Persistent Slabs

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

    We are in the midst of the first major warm-up of the season, and the wise move is to stand back and watch the show instead of trying to outsmart exactly where the persistent layers are most likely to fail. You're more likely to trigger persistent slab avalanches in areas where the wind has stiffened the snow surface or formed drifts, but they are possible in sheltered terrain as well. Activity in the past seven days indicates that though persistent problems will trend more and more unlikely with more warm-up and overnight refreeze, we are not out of the woods yet. March 20 and March 29 exist 1-3 feet in depth, and remain in the top meter of the snowpack. Currently, I'm avoiding terrain where both of these layers exist out of uncertainty, particularly where they exist as a crust/facet combination, while slopes are seeing direct solar input and while water is moving in the snowpack in the heat of the day. Deeper weak layers formed earlier in the season composed of crusts, facets, and depth hoar remain a concern of highlight here. Triggering wet snow movement or a wind slab here could step down to these layers resulting in a large to very large avalanche.

    ADDITIONAL DISCUSSION

    It is worth noting here that as we venture into terrain above 9,000 feet, a slightly different snowpack exists. Upper-elevation terrain was still seeing some dry snow transport up until yesterday, and even small wind slabs in the consequential terrain can prove incredibly hazardous. Yesterday in the Greys Zone, I found small pockets of stubborn 6-8 inch slab that will remain more sensitive today. Regardless of the terrain you enter today, the snowpack is reaching a peak throe of transition over the next 48 hours. It is also worth noting that as we progress more days into the freeze-thaw cycle so late in the spring, we may also see icy conditions set up on SW-S-SE aspects in the alpine quicker than we expect.  

     

    (4/6/2023)

    Cornice-triggered avalanche in the Greys Zone on an east aspect ~9,500'.

  • Loose Wet

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

    Yesterday I observed a handful of wet loose avalanches in the Snake River Canyon. For the most part, these avalanches involved thin layers of wet snow near the surface. With intense sunshine and even warmer temperatures today and tomorrow, I expect wet avalanche activity to continue. The size and destructive potential of these slides may increase as meltwater pushes even deeper into the snowpack. In favorable terrain (long, steep, and rocky slopes) these avalanches may become large enough to bury you today. I will be avoiding avalanche terrain later this afternoon as things trend more unstable.

    This problem is most likely:

    1. On steep upper-elevation slopes that directly face the sun
    2. On slopes sheltered from the wind 
    3. On lower and middle elevation slopes that still have a foot or more of snow, regardless of the direction they face.

    The snowpack was able to weakly freeze last night, but it won't take long for the surficial crust on top to break down. You'll be most likely to encounter natural and human-triggered wet loose avalanches on steep slopes receiving direct sunshine. Avalanches will also become problematic on steep, shaded slopes at lower and middle elevations as the day heats up.  As more snow is warmed, more material is available to move downslope.  

    (4/8/2023)

    Wet-loose avalanches on an east aspect of Ferry Peak: These surface avalanches will become deeper and more numerous as we progress through multiple days of direct sun, warm temperatures, and lighter refreezing of the snowpack at night.

    Photo: Antonioli

Avalanche Discussion

W.U.T.A.N.G. Season

That's right, another handy snow acronym to add to the list you might be familiar with. Though created jokingly, it's pretty applicable. W.U.T.A.N.G. stands for Wet, Unconsolidated, Terrain, Aspect, Non-refrozen, and Glide. Over the next two days when you encounter wet, mushy snow, particularly on solar aspects in terrain capable of producing an avalanche, or if glide avalanches are occurring, you've got at least one wet snow problem. 

Intense warming can have unpredictable effects on rapidly settling and deforming slab + weak layer combos. The upper 1-3 feet of snow that fell during a relatively cold and stormy month of March is undergoing rapid change. Today you'll be able to find anything from dry, cold powder to straight-up wet glop—likely all in one run. Although dry snow surfaces are harder to find, they're still out there, and this will be the spot you're most likely to encounter any remaining surface wind slabs, and probably a questionable persistent layer or two. Slab avalanches will be possible today and tomorrow. Cornices (while not entirely wet) will sag in ever-intensifying heat. It's important to give these huge hunks of snow some respect as a hazard in their own right, but also know that they have the potential to trigger larger slab avalanches as they tumble downslope. Warm temperatures today and tomorrow will send meltwater deeper into the snowpack, which leaves the potential for any snow movement to entrain more volume. More volume of loose snow will equal farther travel distances.  

The snow conditions today will be dynamic and your travel plans should be too. Not all of these problems will give you fair warning before they occur and I'm choosing to travel conservatively by building in a wide safety margin to help deal with my uncertainty. 

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