Bulletin d’avalanche

Tetons

Bridger-Teton Avalanche Center
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Danger d’avalanche

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

Points saillants

Dense new snow and strong winds have made triggering an avalanche 1-2 feet deep likely in steep, wind loaded terrain at the mid and upper elevations. These slides could be large enough to bury or injure a person. Natural avalanches are possible in very steep and heavily wind loaded terrain above 9,000’. Wet snow avalanches are possible in steep low elevation terrain where rain has fallen on dry snow.

Problèmes avalancheux

  • Wind Slabs

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

    The Tetons have received 7-10 inches of dense new snow above 8,000’ since noon yesterday with several more inches expected today. During that period, strong winds out of the southwest have redistributed that snow and formed slabs 1-2 feet deep in leeward terrain. Wind slabs will be reactive to the weight of a rider in steep terrain and could be large enough to bury or injure a person. These slabs may break above you and farther across slopes than expected making escape difficult. While less likely, natural avalanches may occur in very steep and heavily loaded terrain in the upper elevations. Because of this, It will be important to avoid traveling under very steep and wind loaded terrain today.

    Careful and conservative route finding will be necessary in and around avalanche terrain today. Be on the lookout for signs of instability in wind drifted snow such as cracking, collapsing, and recent avalanches. Move to sheltered, low angle terrain if these signs are present.

  • Loose Wet

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

    Rain is falling at the lowest elevations and can quickly destabilize snow surfaces. Watch out for wet loose avalanches in very steep low elevation terrain today. While these slides are likely to be small, they could catch you off guard in steep features such as road cuts and gullies.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1.5–2.5

    Triggering a large avalanche that involves weak layers of snow buried 2.5-4 feet deep is currently unlikely and limited to isolated pieces of very steep terrain (>35°). The rapid new load has added stress to these layers making the likelihood of these events slightly higher than it was yesterday, though still on the low end of the scale. A notable natural avalanche cycle involving these layers occurred five days ago (2/19). Avalanches involving these layers were observed on a variety of aspects at all elevation bands. Despite the likelihood of triggering being on the low end of the scale, it is worth keeping this problem on the radar in suspect terrain (see photo) given the consequences of being involved in avalanches of these sizes. Practicing safe travel habits such as skiing one at a time, stopping in islands of safety, and communicating with partners are ways to increase safety margins in avalanche terrain.

    A large avalanche on the Pyramid that likely occurred around 2/19. This terrain is very steep, cliffy, and has produced multiple avalanches involving mid-snowpack weak layers  in the past two weeks.

Avalanche Discussion

A warm and powerful storm just delivered 10” of snow and over an inch of Snow Water Equivalent (SWE) to the Tetons in the past 18 hours. Winds have been strong, averaging in the upper 20s (mph) out of the southwest. Temperatures are in the upper 20s at 10,000’ and above freezing in the valley. This combination of strong winds and warm temperatures will create slabs that are harder than your average “soft slab”. This makes stability assessments more difficult because wind slabs may not release under your ski and instead break above you. Very steep, wind loaded terrain should be given a wide berth today as the snowpack adjusts to the rapid load. It is worth noting that natural avalanches were reported on Teton Pass this morning and affected travel on the road. Down low, rain has fallen on dry snow and saturated the surface. Wet loose avalanches will be a concern in very steep low elevation terrain. Today is a good day to seek out sheltered, low angle powder and give the snowpack time to adjust.

Régions couvertes