Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Expect a dangerous day in the mountains as heavy snowfall and strong winds provoke a big jump in avalanche danger. You can easily trigger avalanches in steep terrain and might see some natural avalanches as well. Stick to lower-angle, sheltered terrain while the storm plays out.

Avalanche danger could reach High in some areas. Avoid travel on or under all steep slopes if you observe natural avalanches, widespread signs of instability, or find more than 2' of new snow combined with very strong winds.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    It won’t be a day to tip-toe around big slopes or even get near them. You can assess the instability of new snow layers on small test slopes, but stormy conditions will likely keep you out of most avalanche terrain no matter what you find. Heavy snowfall and strong winds are forecast to last the entire day.

    Don’t ignore obvious signs of instability like whumping, shooting cracks, or recent natural or human-triggered avalanches. You may find strong winds transporting snow and building slabs down at low elevations. Expect deep new snow to sluff easily where less of a slab has formed. Limit your travel plan to simple, low-angled terrain with little exposure to big slopes overhead.

    Convex slopes like this one are where you are more likely to trigger an avalanche in sheltered terrain 

    Photo: Dallas Glass

Avalanche Discussion

The new snow will fall on a variety of surfaces including wind slab, crust, and weak facets depending on aspect, elevation, and exposure to wind and sun. The big question for the weekend is regarding layers of faceted snow at or just below the surface. Will they create bigger, more surprising avalanches?

The coming storm will also bring precipitation with a very strong southerly “flow”. The result is snowfall could vary widely across the zone. South flow favored locations like the Mt. Baker NRA and the Baker Backcountry/ski area could see precipitation amounts higher than forecast, while the Glacier and Canyon Creek areas might see less snow and wind.

The answer to both of these uncertainties is to start with a simple plan for the day, make good, relevant observations, and err on the side of caution until the storm passes.

A few observations that trickled in Friday afternoon. Most reported moderate winds were drifting snow and creating fresh slabs up to 12” deep that were easy to trigger on test slopes. At least one was reported as failing at a softer layer above the rain crust. A few inches of new snow were noted by the end of the day

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