Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

You can easily trigger a large and sensitive slab, particularly at upper elevations where you should avoid all wind-loaded slopes steeper than 35 degrees. Wind-sheltered slopes receiving even 10 minutes of direct sunshine may produce small wet loose avalanches.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Strong ridgeline winds at times will blow fresh and recent snow into deep drifts in avalanche start zones.  We expect a sharp elevational dependency to the instability with slabs becoming markedly more reactive above treeline due to stronger winds and consistently colder temperatures enabling more wind transport. Mt Hood Meadows Patrol found that upper elevation NE slopes were sensitive and produced a handful of avalanches, including several large ones on Wednesday. With further loading these aspects will remain unstable, while an easterly low-level component to the southerly winds should extend the sensitive slabs throughout the northern half of the compass by Thursday. Ascend with caution into near treeline bands, steering around wind-affected slopes steeper than 35 degrees. As you move into fully wind-exposed upper elevation terrain, note active blowing snow and signs of recent transport such as sharp fresh cornices to determine which sides of ridges have been wind-loaded. Avoid all wind-loaded slopes steeper than 35 dgrees above treeline.

    Example: Cracking and drifted snow can help you identify and avoid wind slabs in your terrain.

    Photo: Paige Baugher

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    We're expecting 6-10" of snowfall within the past 24 hours by Thursday morning. If the sun comes out, loose wet avalanches will be quick to follow. Pay attention as the clouds start to thin or the sun makes a full appearance. While winds may reduce the impacts to upper elevation slopes, sheltered near and below treeline slopes receiving sunshine will be quick to shed the recent snow. Navigate around steep slopes or similar slopes above you that may be impacted by sunshine.  On a larger slope, a loose avalanche could be sizeable enough to bury you in a terrain trap. If you find yourself below the rain/snow line, keep in mind that you can trigger an avalanche in wet, slushy snow even in a forest.

    (4/13/2022)

    An example of loose wet avalanches from last week.

    Photo: Andrew Kiefer

Avalanche Discussion

Mt. Hood has picked up 80-100" of snow since April 8th, with 1-1.5 ft falling in the last 36 hours. This most recent snowfall has elevated the avalanche hazard at Mt. Hood. You'll find a significant elevational dependency to the avalanche danger. On Wednesday, slabs were sensitive primarily in the uppermost avalanche terrain at Mt. Hood Meadows. Milder temperatures changed snow to rain below 5000 ft by the afternoon and likely reduced the potential for wind transport. As temperatures cool Wednesday night into Thursday, expect slightly drier snow and more wind transport into the near treeline band, but these slabs will be smaller and less reactive. Keep in mind that the bands of moisture rotating into the region will come with breaks. You could experience rain at lowest elevations, snow (heavy for brief periods) above 4000 ft, strong winds transporting snow, and intense April sunshine. During and after periods of rapidly changing weather, assess the impact of these rapid changes on the snowpack. Simple hand shears and small test slopes can help you identify slab formation, while rollerballs and snow shedding off rocks or cliffs can help you identify the effects of sunshine.

NWAC is aware of a possible avalanche fatality at Mt. Hood Meadows on 4/5. We are actively working with local authorities to gather more information about the incident. This incident involved a solo snowboarder and a multi-day SAR effort. You can read our initial statement here. We will update the statement the week of April 18th. 

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