Boletín de aludes

Mt Hood

Northwest Avalanche Center
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Peligro de aludes

Thu
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The risk of triggering an avalanche increases as more low-density snow arrives and redistributes with SW winds. Wind drifts on N-E aspects reside above a weak layer, which could create surprising and widely breaking avalanches. Choose ridges, windward, or sheltered terrain in favor of steep wind-loaded slopes.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–2.5

    An anticipated 3-6" storm plus low-density snow from Monday will be available for redistribution with moderate SW ridgeline winds.  Wind slabs will continue to be a slightly different flavor than we've seen much of the season. They may be subtle density changes that are easy to punch through with a pole, but in the most intensely wind-loaded areas, hard slabs that are more supportable aren't out of the question. They will be actively forming throughout the day, growing in size and distribution, mostly on wind loading N and E aspects. These same aspects feature a January drought crust that is thinner and more fragile. Any wind slab you trigger might step down to weak snow above or below that crust. If it does, expect the potential for a more widely breaking 1-3 ft slab that will be difficult to escape unscathed. These setups are difficult to analyze in the field. To deal with this uncertainty, the best strategy will be to avoid wind-loaded slopes over 30 degrees on N and E aspects.

    (12/16/2024)

    Example: Large wind-loaded aspects like this will be increasingly dangerous on Wednesday.

    Photo: Northwest Avalanche Center

  • Loose Dry

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1

    The low-density snow continues to stack up in the Mt Hood region. In wind-sheltered areas, dry, loose snow may run within the soft snow or where it bonds poorly to old crusts. Expect fan-shaped loose snow to move with you as you descend a slope approaching 40 degrees. You can deal with this problem with sluff management or by steering around steep rollovers, gully, and creek features where you might get into trouble. 

    One of the biggest points of uncertainty in tomorrow's forecast is whether there will be enough new snow to transition to storm slabs that can release on steep open slopes or rollovers in the terrain. Simple hand shears can help you identify the problem before you commit to a slope.

     

    Example: Small, natural dry loose avalanches over a terrain trap.

    Photo: Andrew Kiefer

Avalanche Discussion

With a more significant helping of snow and wind Tuesday night into Wednesday night, expect increasing avalanche danger throughout the day. Monitor the depth of the new snow and the degree of wind loading in your terrain as you gradually dial back your terrain selection and limit your exposure to building slab hazard. 

Mt. Hood Meadows weather station has picked up 18 inches and over 2 inches of snow water equivalent since the storm commenced, but the storm took a breather Monday night and Tuesday. The storm started warm and cooled as it piled up, making for blower powder riding in more sheltered terrain. 

On Wednesday, an observer traveling up the Palmer snowfield found plenty of relatively soft snow (4 finger hardness) still available to be transported once winds pick back up, even in upper-elevation terrain. 

While the snow remains exceptionally cold and lower density, it's not the typical snowpack that we've been dealing with this season. The January Drought Layer (JDL) is a crust with varying thicknesses that harbors a thick layer of facets just beneath and sometimes above. So far, observers have been finding this facet/crust combo to be most concerning on N-E aspects at middle elevations where the crust is thinner and more fragile. 

We haven’t observed any confirmed avalanches on this layer yet, but we have seen propagating test results  (observation/ observation) and whumping collapses on northerly aspects near Bennett Pass (observation). These types of observations hint at deeper instabilities and should help shape your terrain selection as you crest into more wind-loaded features on more shaded aspects. 

You can contribute to the avalanche forecast! Submit an observation here. 

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