Bulletin d’avalanche

Togwotee Pass

Bridger-Teton Avalanche Center
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Danger d’avalanche

Thu
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
Sans niveau
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche conditions remain dangerous. Make your terrain selection accordingly and be alert to the consequences of being caught in a slide where you are traveling. The recent storm formed sensitive wind drifts and added weight to weak layers buried in the snowpack. Reduce your risk by sticking to gentler slopes sheltered from the wind.  

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Yesterday brought a buffet of wind in the upper elevations from multiple directions. Fresh wind slabs will continue to form with moderate winds from the south/southeast at ridgetops, shifting to the northwest into the tail end of today. Yesterday we found sensitive wind slabs and upside-down snow (harder snow on lighter snow). Folks riding more sheltered terrain on found protected conditions and right-side-up snow (lighter snow on harder snow). The middle elevations were definitely touched by winds yesterday, and though speeds will taper today, the primary problem will remain the movement of recent and continued storm snow.

    As new snow settles or is worked further by the wind, slabs can become stiffer and sometimes the above problem can be worse days after a storm. This is worth bearing in mind as the weather clears briefly tomorrow. Slab depths will range 1+ feet in depth, and may break on mid-storm interfaces but also hold a higher possibility of breaking on layers deeper in the snowpack.  

     

     

     

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–3

    Weather conditions are rapidly changing, and subsequently, as are the avalanche problems dictated by them. The persistent slab problem here is tricky. 

    What you shouldn't do: attempt to overthink/outsmart this problem. Some of the new weak layers have already produced avalanches, but others have yet to show their hand. 

    What you should do: take a step back and take a more holistic view. Recent loading due to new snow and wind? Check. Weak layers in the snowpack? Check. Recent avalanches? Check. When you look at it that way, the situation becomes more clear. Keep terrain selections simple whenever conditions are changing. Triggering an avalanche will be most likely on upper-elevation slopes steeper than about 35 degrees. Excellent skiing and riding conditions exist, and you can enjoy the new snow in a relatively safe manner on moderate slope angles on mid-elevation slopes sheltered from the wind. 

    (2/28/2023)

    This avalanche was triggered by a rider in northwest-facing terrain near the Cliffs area of Togwotee Pass. 

    Photo: D. Hatch

Avalanche Discussion

Remember back to the first half of the winter when we had one primary facet layer, and we knew that each loading event would likely produce large avalanches and dangerous conditions? Sigh...those were the days: dangerous, but simple and predictable. But the times are a-changin'.  Our snowpack isn't as hair-trigger, and unfortunately, has become more complex and a much less predictable animal. Even though we've seen a very snowy February, brief intervals earlier in the month between storms crafted some new weak layers. The higher sun angle of late winter has easily formed crusts, brief periods of clear and cold weather have created near-surface facets, and we've even had a few high-elevation rain events in the northern portion of the Greys River.

As we move towards spring, these fast-forming weak layers usually heal quickly.  But this steady trickle of light to moderate loading continues to keep some weak layers on edge, and we appear to be heading towards a colder and snowier spring. There have been enough natural and triggered avalanches to know that several weak layers remain in play. Realizing that snowpack conditions are exceedingly complex can be relieving in a way. It requires a shift in our approach to the problem—we can simplify the situation by going back to the basics. New snow + wind + weak layers + recent avalanches = dangerous conditions. Luckily we also have plenty of tools at our disposal to combat the aforementioned hazard equation. We can read a forecast and hopefully gather some useful information, look for evidence of the problems in the field, assess and reassess as winds or weather change, and ride plenty of fun snow this week. 

Régions couvertes