Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

More new snow and wind will make for a dangerous Saturday. Steer around slopes that show signs of recent wind loading, especially on leeward sides of ridges at middle and upper elevations. As new snow starts piling up, consider steering around all slopes steeper than 35 degrees. 

Problèmes avalancheux

  • Wind Slabs

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

    More snow and consistent winds will renew the wind slab avalanche problem. The winds will change more easterly, so don't be surprised to find these slabs forming in unusual areas like west aspects or forming across terrain features (cross-loading). However, you'll still encounter the largest, deadliest wind slabs that could break 3-5 ft deep on east-facing aspects at middle and upper elevations. While less likely, some avalanches could grow very large if they fail on weak snow associated with a crust that now sits up to 6 ft below the snow surface. 

    Blowing snow and drifting should show exactly what aspects are loading up. As you move through the terrain, pay attention to changes like snow stiffness and texture. You can look for surface clues like sharp cornices, rippled snow, and pillow-like slabs to help you identify problematic slopes. Pull back and default to less steep slopes if you notice obvious signs of instability like shooting cracks or audible whumphing. The best practice will be to let the storm run its course before moving into wind-loaded terrain. 

    Let your eyes be your guide on Saturday. Look for and avoid slopes that appear textured like this. 

    Photo: Joe Dellaporta

  • Storm Slabs

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

    Strom slabs will increase in size and become more reactive throughout the day as new snow accumulates. These soft slabs will likely stay shallow but could pack a punch in the wrong terrain. You're more likely to trigger these soft slabs during periods of heavy snowfall. As precipitation intensifies, consider steering around convexities greater than 35 degrees. You can use quick hand pits or small test slopes to see how reactive the new storm snow is acting. 

     

Avalanche Discussion

Mt Hood will continue to get the lion's share of precipitation out of this storm track. So far, we're approaching 6-8ft of new snow since Junauary 5th. On Saturday, look for snowfall rates to pick up during the late morning hours. We may easily see another 6-12 inches by the end of the day. Temperatures will be quite cold, so be sure to bundle up if you head out. 

Friday was a pretty quiet day for observations, but the Meadows Pro Patrol reported triggering D1 soft slabs below treeline. In more exposed areas they observed stubborn slabs of drifted snow. The main story remains slow, laborious trail-breaking. The new snow is deep and still quite unconsolidated. So be sure to give treewells a wider margin than usual and keep your partners in close sight. 

All this new snow sits on a crust buried January 4th that did hold some weak snow on more shaded aspects above 6000 ft. This weak layer was likely responsible for the close call on Pea Gravel Ridge last week when backcountry skiers unintentionally triggered a D 2.5 hard slab (avalanche observation here). We have uncertainty regarding how these old, weak layers are adjusting to the new load. If you do venture to these elevations, make sure to dig down and complete your own assessment. At lower elevations, new snow basically fell on bareground.

If you get out, let us know what you see by submitting a public observation. 

 

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