Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Update 07:15: More snowfall will continue through the day in the Wenatchee Mountains and near Leavenworth creating deeper storm snow. This, combined with uncertainty about the recently buried crust facet layer means today is a good day to take a step back in your terrain selection. You can trigger large wind slabs in upper elevation start zones and near exposed features. Avoid likely drifted slopes that have increased consequences. Loose dry avalanches could run large and entrain all the recent storm snow, as it rests over a slick crust.

Problemi valanghivi

  • Wind Slabs

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

    Travel cautiously as you gain elevation, especially near ridgelines and other exposed terrain features. Scattered snowfall overnight into Thursday morning will likely bring another 2-5 inches of new snow to the area. Temperatures stay cold and any snow on the ground will continue to be easily transported by moderate winds.

    Expect slabs and drifts along ridgelines and in other exposed areas. These slabs will be noticeably more dense than the new snow and could be fairly sensitive to your weight. Stay alert to signs of instability in the new snow such as shooting cracks, or whumphing collapses. If you find these, dial it back to avoid slopes steep enough to slide nearby.

  • Loose Dry

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

    The low density storm snow is getting deeper, and it's sitting on a slick crust. Expect that fresh snow could entrain on steep, sustained slopes if you provoke it. You can avoid these by choosing less steep slopes. If you do venture into steeper terrain, look for shorter, less committing slopes rather than larger features while this new snow settles out.

    Example loose dry avalanche

Avalanche Discussion

On Thursday, I found soft wind slabs up to 14" deep in the near treeline zone and above at Blewett Pass. I was able to easily trigger a 12" deep by 20ft wide slab on a wind loaded north aspect near Windy Knob. It ran on weaker storm snow just above facets and a slick crust. In sheltered areas, you may find eight to fourteen inches of storm snow resting on these weak grains over a slick crust. Observers have noted that both near surface facets and surface hoar are widespread within the zone. This facet/crust interface will be the main concern moving forward, especially as snowfall begins to incrementally load these layers over the next week. 

Even though the current storm is a much needed refresh, debris piles, icy runnels, and evidence of the recent avalanche cycle can still be found in the mountains -- especially at lower elevations and along wind scoured southerly aspects. You are likely to still feel the recent crust underneath in most places.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte