Bulletin d’avalanche

Togwotee Pass

Bridger-Teton Avalanche Center
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Danger d’avalanche

Sat
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

The combination of recent snow, wind, and buried weak layers make human triggered avalanches possible today. Heightened avalanche conditions exist where wind affected snow lies on top of slick crusts in steep terrain, especially on the southern half of the compass. Monitor the effects of the wind and the sun today, and pay attention to signs of instability such as cracking within the snow surface or audible collapsing of the snowpack.

Problèmes avalancheux

  • Persistent Slabs

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

    The snow that fell between the 26th and 28th of January has settled into a 1-2 foot soft slab. This snow lies on top of weak snow and slick crusts that formed prior to the major storm event. Multiple human-triggered avalanches, some of them triggered from a distance, have been reported on this weak layer. This January 26 layer is especially pronounced on west to south to southeast facing slopes, but could be present elsewhere. Pockets of surface hoar 1-3 feet deep could be encountered on protected slopes on the northern half of the compass. 

    Your best line of defense against a persistent slab avalanche within the top 2-3 feet of the snow surface is probably to dig a pit and perform an extended column test. Monitor the effects of the sun today on the snow surface. 

    Deep Persistent Slab: A weak basal structure is present on most aspects. This layer is 50 to 120 cm down from the surface in areas that correspond to the highest likelihood of human triggering but appears to be dormant at this time. While finding the trigger point is unlikely, the resulting avalanche will be very large.

  • 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. Cold weather after the storm has helped to preserve these slabs which may remain sensitive to human triggering today. Slabs that are 1-2 feet thick 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 features are especially suspect.

    Monitor the wind direction and look for signs of instability such as cracking within wind drifted snow. Moniter the effects of the sun today on the snow surface. 

Avalanche Discussion

Western Wyoming is currently under a ridge a high pressure with prevalent temperature inversions. A shortwave trough passes through Friday night/Saturday morning. A bigger trough shows up on the morning of the 5th. 

Recent avalanches have involved persistent weak layers at the upper elevations (Jan 26 layer) and wind slabs in the alpine. 

Current snow surfaces are composed of wind affected snow at the upper elevations, sun crusts on southerly aspects, and surface hoar and near surface facets on protected northerly aspects. Current snow depths are around 46-56 inches at upper elevation sites at Togwotee. Snotel sites range from 91-143% median snow water equivalent. 

Régions couvertes