Lawinenlagebericht

Togwotee Pass

Bridger-Teton Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
Keine Stufe
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Kernpunkte

You're most likely to trigger a slide breaking on deeper, weak snow on slopes with wind drifts or stiffer snow at or near the surface. Wet snow avalanches are also possible on very steep slopes facing the sun. Pay attention to the surface conditions—avoid slopes where you're either sinking into a wet, mushy snowpack or encountering stiff drifts and cracking, and avoid being under large avalanche paths if you encounter these conditions. Middle and upper-elevation features near or under cornices should be given a wide buffer. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    Triggering an avalanche remains possible on weak snow buried within the snowpack's top 2-4 feet. Togwotee's snowpack is characterized by a thick layer of weak, sugary snow buried near the base of the snowpack on all aspects and elevations. This problem is most sensitive on steep, rocky, and wind-affected slopes on the north half of the compass. Watch for thin spots in the snowpack where weak layers are easier to impact, and trench your sled track into the snow or probe to identify these areas. Multiple tracks  on a slope are not an indicator of stability with this avalanche problem, particularly as we see more warming and sunshine each day. Use caution in steep terrain and give yourself a wide margin for error on slopes with high consequences or around terrain traps. 

    (3/8/2024)

    Persistent Slab avalanche that covered the 'K' trail at Togwotee. This avalanche occurred on an east aspect around 7600'. 

    Photo: Cameron Galt

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

     As the day heats up, more slopes will become unstable. Yesterday, wet loose avalanches were reported on very steep sunny slopes. These avalanches are possible again today. Wet loose avalanches begin at a "point", usually the base of a warm rock or tree, and fan out to collect snow as they move. They are most problematic in confined terrain or on large slopes where they gather a lot of snow. Rollerballs, or small snowballs peeling off steep terrain, can be a helpful clue that the snow's surface is weakening and wet loose slides may occur. 

    Give yourself options, including a safer, low-angled exit not threatened from above by features such as cornices. Most natural wet avalanches have been relatively small lately. While we haven't quite reached the warming threshold for more activity, each day ticks closer. The cumulative effects of the prolonged warming can lead to an uptick in the size and frequency of avalanches. While wet slide conditions are fairly predictable, avalanches' expected nature (type, frequency, and size) can be hard to pin down. The forecast discussion below provides more information about wet snow. 

    Pinwheel formation off of south facing cliff bands.

    Photo: Noah McCorkel

Avalanche Discussion

With a warm weekend ahead, it's time to remind ourselves about W.U.T.A.N.G. snow conditions. What are these conditions, you ask? What was meant as a silly acronym two fellow forecasters and I made up for forecasting wet avalanche conditions actually rings quite true. It stands for Wet, Unconsolidated (re: mush), Terrain (capable of producing an avalanche), Aspect (solar), Non-refrozen, and Glide (not really an issue here, but a few pockets hang out in select terrain). It's easy to remember; these are all things to keep on your radar this weekend. Forecasting the transition from a dry to a wet snowpack is fascinating and unpredictable. Adding liquid water to a snowpack takes the complexity to the next level, as water is the only material on earth that can exist in all three phases (liquid, solid, and vapor). 

The sun adds energy to the snowpack surface, which melts the surface to produce water. This water can melt the bonds holding snow grains together and weaken the snow. If melt continues, particularly if the snowpack does not refreeze overnight (the N in WUTANG), things become saturated. Rocks, being darker in color, can absorb more solar energy and transfer that to the surrounding snowpack more rapidly. This is also why ridgelines and outcrops can be initiation points for wet loose and wet slab avalanches.

All in all, warming can do unpredictable things to a snowpack, even on shady aspects. Today, expect to find some wind slabs still sensitive to your weight in upper-elevation terrain. And for all their complexity, wet snow avalanches often be easier to manage.  Plan your days early and retreat from being on or under steep slopes as the sun rises in the sky and things warm throughout the day. 

 

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