Bulletin d’avalanche

West Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You can trigger avalanches today in wind drifted pockets of snow. Look for smoothed or pillow-like firm surfaces and steer clear of them in areas steeper than 35 degrees. Sunny slopes may develop a wet snow avalanche hazard by midday.

Problèmes avalancheux

  • Loose Wet

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

    Intense winds likely hammered south slopes during the last storm, forming hard surfaces. These firm surfaces will require a lot of heating to get wet enough to avalanche, whereas lighter snow will avalanche relatively easily with Wednesday’s intense sun. You may see rollerballs on steep steep sunny slopes in the morning. Wet loose avalanches usually occur not long after.

    Rollerballs and small loose wet avalanche were triggered by travels during a period of warm sunny weather.

  • Wind Slabs

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

    It has been 24 hours since our last storm. Slabs linger in steep windloaded terrain.  The likelihood of triggering avalanches is dropping, but on Tuesday isolated pockets of wind slab were reactive to humans, and I expect this to continue through Wednesday. 

     Search for evidence of wind transport: cornices with drifts below, hard variable snow surfaces, and textured snow. Avoid steep wind loaded convexities, and other slopes greater than 35 degrees where you see any of these signs. Poor bonding exists on the interface between the new snow and the November 30 surface beneath. Take the time to test this layer before committing to consequential slopes.

    Small wind slab avalanche on steep rollover.

Avalanche Discussion

High pressure has arrived after our blast of early season storms.  This might be great for getting backcountry missions in, but it is also good at forming weak layers on and near the snow surface.  Watch for surface hoar growth on top of the snow in the next few days.  Surface hoar may be harmless and beautiful now but is a very dangerous weak layer if buried under snow in subsequent days. 

Overall, we have a substantial early season base of 40-65 inches. Avalanches have been limited to the upper layers, making for a good start to the year’s snowpack.  Snow lines in the West Central zone are averaging 2500 - 3000ft.  Remember that it is still early season and there are plenty of obstacles such as hidden logs, rocks, streams, and variable snow conditions at lower elevations to stay alert for.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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