Lawinenlagebericht

Mt Hood

Northwest Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Rainfall on a mostly dry snowpack adds risk and uncertainty. The best way to mitigate the problem is to avoid the types of steep or poorly supported open slopes wet snow can gain momentum.  At upper elevations, steer around rapidly building wind slabs later in the day.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    We expect 3-6" of dry snow to destabilize on N and NE mid-elevation shaded slopes. The uncertainty in this forecast is whether the rain will impact any deeper in the snowpack. Natural or human-triggered point releases will entrain snow as they descend slopes steeper than 35 degrees and could become large.

    Travel conservatively and stick to supported slopes less than 35 degrees to avoid difficult to manage wet problems. If you do engage with steeper slopes, limit the slope size and ensure you don't sink into saturated snow past your ankles.

    (3/24/2024)

    Example: Wet loose avalanches with fan shaped debris like you might encounter on Saturday.

    Photo: Joe Dellaporta

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    We're expecting rain to above NWAC forecast zones to start the day, but by late morning, snow levels will descend into the upper elevation band with slabs building throughout the day. We generally expect a good bond with the refreezing upper snowpack but pay particular attention under fresh, sharp cornices and in areas where the snow is actively depositing. These areas could become reactive with 6" of drifting on slopes steeper than 35 degrees. 

    Note that if snow stacks up faster than we expect, this problem may become widespread and dangerous. 4" of average snow depth can produce widespread hazard on wind-loaded slopes given the sustained winds.

    (1/22/2024)

    Example: heavy drifitng along Pea Gravel Ridge

    Photo: Joe Dellaporta

Avalanche Discussion

We're expecting very active weather to start before dawn on Saturday with the potential for isolated natural avalanches. Travel conservatively and don't take unnecessary risks around large open slopes, above terrain traps, or near snow bridges that may fail as creeks swell. Better times are ahead later in the weekend as temperatures cool.

The extended stretch of high pressure left its mark across the Mt Hood zone. All but mid-elevation N and NE slopes have moist snow or crusts on the surface prior to the storm. Snowpack depths have settled a bit, but we’re still sitting well over 100% as of December first. You can check out the snow depth climatology data here. While freezing levels have been quite high, backcountry travelers and avalanche professionals continue to report cold, weakening surfaces along N-E aspects, particularly at the middle elevations. Once you move over to S-W aspects, you’ll start seeing the effects of recent warming in the form of a surface crust or wet snow during the afternoon hours. Above 7000 ft, expect to find a mixed bag variety of scoured surfaces and firm pockets of chalky, wind-drifted snow (see photos in the gallery). 

While surfaces are weak on many shaded slopes, the big question will be if these grains survive the incoming warm start to the storm. With snow levels soaring above 8000 ft at the start of the storm, we suspect this should help flush these weak grains away, but it will be worth tracking regardless. If you do say any signs of extensive wind slab propagation, it could be a sign that weak snow grains underly these slabs. In this case, take a step back and really limit yourself to simple terrain and low angle slopes. 

Early Season hazards are still abundant and will easily worsen the consequence of any avalanche. Lower elevations have plenty of rocks, creeks, and downed trees to navigate. Upper elevations have crevasses and bergschrunds that are thinly bridged or still fully open. Give yourself extra time to navigate these hazards. 

Remember that small avalanches or long, sliding fall can produce big consequences in the wrong terrain. Before committing to skiing or riding that steep terrain think about where an avalanche or fall could carry you. Could you get pushed over cliffs, through trees, or into creeks or gullies? In "high stakes" terrain, consider the risk versus the reward.

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