Boletín de aludes

Mt Hood

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Despite modest amounts of recent snow, strong winds formed potentially large slabs sitting on a poorly bonded crust. You can trigger them on steep, upper-elevation slopes, particularly on shaded aspects. It's the first day of spring, so expect the sun to destabilize less consolidated snow on steep slopes and they may be above you.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Strong winds Sunday night and Monday transported 4-5" of fresh snow. Snowfall and wind transport should ease Monday night. Mt Hood Meadows Patrol found reactive 4-10" slabs that ran efficiently on a firm 3/19 crust (on all aspects). Slabs will be most reactive in the morning hours and on colder, shaded aspects, upper elevation slopes where the bond to the 3/19 crust may remain poor and worth evaluating. While most slabs will be less than 1 ft deep (up to size 1.5), expect 2-3 ft large slabs to lurk above treeline. Note that wind slabs were reported in exposed areas below treeline, but we think that it is unlikely you will trigger them at these elevations on Tuesday. Ascend to higher elevations with increased caution, utilizing small test slopes to gauge slab reactivity and noting the transition to more widespread wind-textured snow. Avoid all steep, wind-loaded slopes at upper elevations and utilize extra caution to steer around steep wind-loaded features near treeline. Anticipate that you might find slabs below fresh, sensitive cornices and that you are most likely to trigger a slab on an unsupported slope.

    Example: Large wind slabs may be triggered in above treeline start zones.

    Photo: Ben Ticknor

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Tuesday is the first day of spring and the sun has noticeably more impact. Expect increasing sunshine throughout the day with light winds and temperatures rising above freezing during the mid-day hours. Expect surface snow layers to destabilize within 10-20 minutes of receiving direct sunshine in less wind-affected areas. Pay attention to steep slopes above you that may destabilize to produce small natural wet avalanches that entrain the recent snow above the crust and gain steam quickly. Rollerballs are your best clue to seek cooler shaded slopes before you get caught in a compromised situation (such as above a cliff or terrain trap).

    Example: Expect brief clearings to easily produced small wet loose avalanches on steep rocky slopes facing the sun.

    Photo: Andrew Kiefer

Avalanche Discussion

Mt. Hood Meadows Patrol reported dangerous avalanche conditions near and above treeline with very sensitive wind slabs and cornices on Monday. In some cases, fresh cornices released upon approach and triggered wind slabs spanning across the scale of the terrain feature on the slope below. With time, the bond to the 3/19 crust will improve and wind-affected layers will gain strength. Cornices will become less sensitive, but could fail naturally in isolated locations on Tuesday as the sun comes out. Given this possibility, it's a good idea to limit your exposure to cornices on the slopes above and to remember that cornices may break farther back on the ridgeline than you anticipate.

As we transition from winter to spring, it's fitting that we have to deal with overlapping cold snow (slab problems) at upper elevations and warm snow (wet loose) problems. In reality, the wind slab problem occurs in wind-affected terrain and the wet loose occurs in unconsolidated snow. Sunshine and mild temperatures may begin to limit slab reactivity on more sun-impacted aspects by the afternoon.

On Friday, forecaster Joe Dellaporta found widespread firm, wind-textured snow (chalky snow, sastrugi) above treeline on the south side of the mountain (shown in the image gallery).

If you get out let us know what you see by submitting an observation!

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