Bulletin d’avalanche

Togwotee Pass

Bridger-Teton Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
Sans niveau
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

It is possible to trigger an avalanche today due to weak layers of snow buried over the weekend and wind slabs that have developed since. If triggered, either type of avalanche could be large enough to bury a person. Choose terrain carefully and evaluate slopes for the existence of wind drifted snow or buried weak layers. When in doubt, seek out lower angled slopes that are sheltered from the wind.

A large avalanche triggered by several parties on Mt. Taylor three days ago illustrates this hazard. Skier-triggered avalanche on Mt. Taylor

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    Last weekend, a significant amount of snow  formed a  slab onto layers of weak snow on the surface as well at the base of the snowpack. Those weak layer is now buried one to three feet deep, deeper in wind loaded areas. Human-triggered avalanches, some of them triggered from a distance, have been reported recently. Triggering a slab avalanche 2-3 feet thick, possible thicker, on this layer remains possible, particularly in steep, rocky terrain. Dig, probe, and test the snowpack in safe location to determine if this layer if present before committing to consequential terrain.

    (1/30/2023)

    Natural avalanche on a E aspect around 10,000 feet at Togwotee Pass. 

    Photo: Antonioli

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Moderate to strong westerly winds have moved low density snow onto lee slopes since the storm cleared on Monday, with wind transported snow likely occurring just yesterday. Cold weather has, to some degree, preserved these slabs which may remain sensitive to human triggering today. These slabs may be hard and stubborn in some locations and softer and more sensitive in more sheltered areas. Look for cracking or hollow sounding hard slabs indicating soft and weak snow beneath.  Very steep, unsupported slopes or convex terrain are especially suspect. Be mindful of smaller terrain features like drainages where even small slabs can bury you.

    (1/28/2023)

    Small roadcut avalanches showing new snow sensitivity while grooming at Togwotee.

    Photo: Dawson Hatch

Avalanche Discussion

Today, you'll note that the danger ratings have dropped from 3 to 2 on a scale that goes, rarely, as high as 5. Last weekend, avalanche danger in the backcountry was rated 4, also known as High, and the danger was obvious. Record setting snowfall, some wind and an existing weak layer of snow on the surface created that level of danger. The danger was plainly obvious, and it was easy to understand the risks at hand, particularly given the evidence which included large natural avalanches. In the past few days, as skiers and riders have tested the snowpack, the feedback has been less clear, but it has been there; avalanches weren't occurring naturally but they could be triggered, though in fewer locations throughout the terrain. And lots of terrain, but not all, was ridden with no avalanches. The evidence for avalanche occurrences continues to taper today. Fewer signs of unstable snow will exist which is a good trend but this lack of obvious clues to unstable conditions could create a temptation to ramp up the risk taking. The bluebird conditions and warmer weather can play the siren song that lures the susceptible to go places they shouldn't go. Be sure to consider the recency of large avalanches, look for the buried weak layers and consider the consequences of being wrong, even if just a little bit wrong, before you commit to serious terrain.

Régions couvertes