Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Despite the calmer weather, you can still trigger wide avalanches big enough to bury people in this zone. You'll want to give the new snow time to settle out. Continue to seek out sheltered slopes out of the wind that are below 30 degrees. 

Problemas de aludes

  • Storm Slabs

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

    The new snow still needs time to settle. Slabs could break within the new snow, at the old snow interface, or even deeper on a number of weaker layers at higher elevations. The new snow recently buried a layer of facets and surface hoar on sheltered, shaded slopes above 5,000ft. If you find one of these areas, slides may fracture widely or be triggered from adjacent slopes.As you travel, look for signs of instability such as cracking in the new snow, test slopes releasing easily, or hear whumphing collapses. Default to less steep terrain if you find more than 6 inches of new snow and notice obvious signs of instability mentioned above. 

    Loose snow avalanches: 

    We have a lot of low-density, cohesionless snow. If skies are sunnier than weather models predict, we may see some surficial sun-induced loose snow avalanches. Most avalanches should be relatively small, but some could be large enough to knock you over and carry you where you don't want to go. 

    (2/16/2024)

    An example of a small storm slab in sheltered terrain. 

    Photo: Mt Hood Meadows Pro Patrol

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–2.5

    Triggering a 1-3 ft thick avalanche remains likely. Incremental snowfall and significant loading will continue to stress multiple weak layers in the upper snowpack, most notably the Early February Crust. With anywhere from 6-12 inches of new snow across the zone, the forecast team thinks we'll start seeing more activity on this weak snow. So far, forecasters and observers have found this structure to exist on most slopes above 5000 ft. This weak layer was already responsible for a close call in the Teanaway drainage where a group triggered a D2 on a W aspect @ 6200 ft ( Obs here) last week. 

    You'll generally find the largest slabs in wind-loaded terrain, but we're getting to the point that any steep slope, even in sheltered areas, should be considered suspect. Avalanches could break widely across terrain features and easily be large enough to bury or kill you. 

    If your primary goal is to not get caught in an avalanche, staying off of and out from below steep slopes is the most reliable way to reduce your risk.

    (1/6/2021) 

    An example of a persistent slab in the East Central zone from several years ago. You could trigger similar-sized avalanches, especially adjacent to ridgelines that receive wind loading. 

    Photo: Jake Larson

Avalanche Discussion

Monday was a stormy day across the east-central. Backcountry travelers and avalanche professionals reported excellent powder riding and gusty winds at higher elevations. The Mission Ridge Pro Patrol reported triggering shallow propagating soft slabs in more sheltered pockets during avalanche mitigation work. They reported these slabs failing on recently buried surface hoar. Weather stations across the zone picked up anywhere from 6-12 inches of new snow. The Wenatchee Mountains did impressively well and squeezed 8-10 inches of cold, blower snow. 

Tuesday is shaping to be the calm before another potent storm comes crashing into the region in the evening hours. This storm will feature warmer and wetter conditions, which will undoubtedly increase avalanche danger during the evening hours and into Wednesday. 

Our snowpack has become complicated throughout intermittent dry spells in February. There are multiple potential weak layers in the snowpack, all the way down to the early February Crust. This crust may be up to 2ft deep in some areas, and it'll be getting buried deeper on Sunday. There are also potential layers of surface hoar and faceted grains from the 11th, 14th, 18th, and the 24th. The upcoming storm and stormy week should begin to test all of these weak layers.

Your avalanche, snowpack, or weather observations are extremely valuable to the avalanche community. Help create a more accurate avalanche forecast by submitting your observations here.  

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