Bulletin d’avalanche

Bridgeport Avalanche Center

Bridgeport Avalanche Center
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Danger d’avalanche

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

Points saillants

Strong snow on top of weak snow remains a concern in the snowpack and allows for the possibility of triggering an avalanche in the backcountry today. Slabs of snow can be more destructive and travel farther than anticipated. Consider alternative terrain options if you encounter this snow and are uncertain about traveling in it. 

Problèmes avalancheux

  • Persistent Slabs

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

    Persistent slabs are a tricky avalanche problem to deal with. Unless a backcountry traveler digs down and confirms the snowpack structure in the terrain they look to engage with, there will be a degree of uncertainty about its presence and sensitivity to triggering.  The likelihood is low, yet the consequence is high. While many areas on the compass rose above do not have this problem, some of the most desirable snow for backcountry travelers exists on north-facing terrain in and above the treeline on NW-N-NE aspects.  High pressure and little avalanche activity since the storm on 12/16 can push users to explore more consequential terrain. Consider digging into the snow to confirm or deny the presence of faceted snow underneath the slab at the top of the snowpack. This faceted snow has been gaining strength however, snowpack tests still show propagation on this layer. 

    (12/19/2024)

    Strong snow on top of weak snow produced propagating results in our snow pit tests on northerly aspects in treeline terrain.

    Photo: Julian Hanna

Avalanche Discussion

Signs of recent wind slab activity was visible in the BWRA around Leavitt and Koenig Lakes this week. The most recent loading event on Monday brought rain and freezing levels up to 8300 feet. It also brought in fresh snow with lots of wind, creating wind slabs in Treeline and Alpine terrain.  A natural cycle ran its course, followed by several days of high pressure, inverted temperatures, and light winds. 

During the week, we found facets below the wind slab which created a Persistent Slab problem. This can be a source of confusion as the slab was formed by the wind (Wind Slab) yet what the slab has been breaking on is the faceted angular snow grains that formed during the dry spell over Thanksgiving to the 2nd week of December (12/12) These facets have been rounding out and gaining strength, yet snow pit tests are still producing unstable results. 

Most of the below treeline slopes did not have a slab of snow on top of faceted grains which allowed for a low danger rating.  We also found this elevation band in the BWRA to be sparsely covered in snow and hard to navigate as early-season conditions remain the primary hazard below the treeline. 

As always, make your own terrain assessments and snowpack checks and please let the BAC know how your day was through an observation. Today will be the last calm weather day before a big shift in the weather starts this weekend. 

Régions couvertes