Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

New snow and recent strong winds will maintain the threat of large avalanches that could bury or kill you on Tuesday. Avoid steep leeward features if you notice blowing snow, sharp cornices, or textured slabs. Look for weakening snow surfaces on steep solar slopes as the day progresses. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–3

    Wind slabs were reactive to human triggering on Monday. Some slabs even broke several feet deep and widely across terrain features in heavily loaded alpine terrain. On Tuesday, more low-density new snow and moderate winds will maintain reactive slabs in exposed areas. The west winds have been cranking, so you'll typically find these slabs on leeward aspects (NE-E-SE). Look for variations in snow appearance, texture, and stiffness to determine which slopes are most likely to hold a wind slab. They'll often form under cornices, beneath rock and cliff bands, and near the break-over of chutes and unsupported features. Stomping on small test slopes can help you determine the reactivity of these deposits. When in doubt, use a lower-angled line or scoured surfaces to navigate around wind-loaded slopes.

    Improved visibility has allowed for a look around the mountains in the past few days, and the results have been impressive. Deep, wide crowns from artillery-triggered avalanches (and some natural) released during the storm in heavily loaded alpine terrain above 7000 ft. Layers of weak faceted snow that failed under extreme loading during the latest storm are the likely culprit. No human-triggered avalanches related to faceted snow or crust-facet combinations have been reported. Now buried 6-8 ft, it's unlikely - but not impossible. The best chance would be at upper elevations, and where the snowpack is also shallower over the weak snow near crusts from Mid February. 

    (3/4/2024)

    Wind-loaded pockets were touchy on Monday. Using test slopes like this can give you valuable information.

    Photo: Joe Dellaporta

  • Loose Wet

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

    If the sun pokes out, be ready for rollerballs or even small wet loose avalanches on steep, sunny aspects. The snow is really dry, so it won’t take much time for it to react to solar input. Rollerballs are often precursors to larger wet loose avalanches. Once you start seeing rollerballs, pinwheels, or gloppy surfaces default to shadier slopes.

    Loose Dry Avalanches

    In more sheltered, steep terrain dry loose avalanches could still run. These likely will be less of an issue on Tuesday, but it is worth considering if you plan to ski or climb in steep terrain on shaded northerly aspects. 

    (12/28/2023)

    An example of rollerballs. 

    Photo: Matt Primomo

Avalanche Discussion

On Monday, the Mt Hood zone received another 12-14 inches of low density new snow. This brings the storm total to over 7 ft of new snow in the last week. NWAC forecasters found wind slabs failing easily on Monday morning. These wind slabs ranged from 1-2 ft on test slopes. The Mt Hood Meadows Pro Patrol also reported reactive wind loaded pockets and triggered one very large avalanche (D3) with 10 ft crown depths on a ENE aspect at 7300 ft during the morning artillery mission. You can check out the photo in the gallery. 

Tuesday is shaping up to be a pleasant day in the mountains as our active weather is coming to a close. If we're lucky may squeeze out another 2-6 inches of new snow by Tuesday morning with a little less than .25 inch of water in the forecast. This freshen-up will likely keep wind slabs reactive to your weight in exposed areas, especially in the morning. 

Deep snow immersion/tree wells (SIS) remain a significant concern in sheltered terrain. Ride with a partner and keep one another within sight. A SIS resulted in a fatality on Friday in the Cascades, which serves as a strong reminder of this hazard. 

Regioni coperte