Bulletin d’avalanche

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Danger d’avalanche

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

Points saillants

Triggering an avalanche in wind-drifted snow is possible today at upper elevations. Watch for pillows, drifts, and stiffened surfaces around exposed terrain. These avalanches can step down into buried weak layers - especially where the snowpack is thinner. Intense sunshine today will make it possible to trigger small wet avalanches on southerly slopes particularly near exposed rock. 

Problèmes avalancheux

  • Wind Slabs

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

    Heavy snowfall and strong winds from early March have built wind slabs and cornices on upper elevations. Wind slabs could be 1-2 feet and possibly 3-4 feet thick in isolated areas. Watch for signs of wind-affected snow such as pillows, drifting, and stiffened surfaces. You are most likely to encounter wind slabs around ridgelines, rocky areas, and cross-loaded terrain (gullies and roadcuts). Signs of instability - such as cracking and collapsing - could be less obvious than in previous days due to 3-4" of snow from two nights ago. Assess steep terrain thoroughly for reactive slabs. Travel in sheltered terrain to steer clear of this problem.  

    (2/29/2024)

    Active wind transport seen off ridgelines in the upper elevations. Old avalanche from the wind event on 2/26-2/27 seen lookers right on photo. 

    Photo: Alex Drinkard

  • Persistent Slabs

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

    Clear skies yesterday revealed multiple avalanches that potentially failed on buried weak layers.  Large loading events and large triggers, such as cornice falls, have been able to produce very large avalanches on weak snow buried in January. It is unlikely a rider could trigger one of these layers, however, a wind slab avalanche or cornice fall will make it possible to trigger one of these very large avalanches. Very steep slopes, hanging snowfields above cliffs, and rocky or notably shallow slopes are where you're most likely to find this problem. Weak snow formed in January currently sits 3-5+ feet beneath a firm slab at middle and upper elevations in the Salt and Snake River ranges. In drier parts of the forecast zone and lower elevations, the weak snow is closer to the surface. Travel on lower-angle slopes to steer clear of this problem entirely. 

    (3/7/2024)

    Large D2.5 persistent slab avalanche at 9500' NE aspect in the Snake River Range that likely failed 3/2 during rapid loading. 

    Photo: Alex Drinkard

  • Loose Wet

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

    Yesterday's sun and low winds allowed surface snow to start heating on southern aspects. Cold temperatures overnight refroze any wet snow, but with another day of intense sunshine and calm wind expect snow surfaces to warm by afternoon. Triggering one of these slides is most likely on steep rocky terrain directly facing the sun. Monitor the snow surface as you travel - look for roller balls, pinwheels, and wet snow (easy to make a snowball). While these avalanches will be small, they easily can push you off your feet making them dangerous in consequential terrain. The onset of wet avalanche activity can be sudden. Pay attention to signs of warming and minimize time spent lingering on or under steep, sunny slopes. 

    Small point release of wet snow from cliffs bands on an easterly aspect at 7600'.

    Photo: Cameron Galt

Avalanche Discussion

In December we asked ourselves "Where is all the snow?". Well, all that snow arrived fashionably late in February and early March. Our snowpack has made a significant transition to a more typical mid-winter status where new snow problems are the primary avalanche problem. As more storms roll through the forecast zones, persistent weak layers are buried deeper and deeper making it difficult for riders to trigger directly. The persistent weak layers can be triggered through other means. Significant loading events, cornice falls, and smaller slab avalanches all can impact buried weak layers. As we move into a short period of stable weather, reactivity will decrease but uncertainty will increase. It's easy to say avalanches will happen when lots of slopes are avalanching. The days following a storm, when activity decreases, is when it becomes more challenging. Continue to monitor the snowpack and watch for signs of instability. Use extra caution in traveling into more extreme terrain. With clear skies and lots of snow, riding conditions will be excellent. It will be a good weekend to get outside and enjoy our mountains. 

Régions couvertes