Bollettino valanghe

East Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

The most likely place to trigger a large avalanche is in wind-drifted snow near ridgelines. But the snowpack is complex, variable, and quite dangerous. On shady aspects, recent snow fell over old weak surfaces, and there is still a chance of triggering a large avalanche on a steep, sheltered slope. With high uncertainty, choose conservative terrain on lower-angle slopes.

Problemi valanghivi

  • Wind Slabs

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

    Wind slabs formed from the recent snow and winds may rest over weak or slick snow surfaces and could remain sensitive for longer than usual. While we don't expect avalanches in the recent wind-drifted snow to be large, small wind slabs could be sensitive, step down to deeper weak layers, and break wider than anticipated.  Avoid steep slopes below ridgelines, the base of cliffs, and cross-loaded terrain features. Textured surfaces and visible blowing snow are great visual clues to identify wind-affected terrain.

    With the variability in the old snow surfaces, this problem could be tricky to pin down, and similar slopes may not react the same. With high levels of uncertainty, the best management practice is greater safety margins between you and steep open slopes.  An avalanche on an east aspect of Snagtooth ridge that propagated into older, deeper snow layers highlights the complexity of our snowpack. (See video) This could be an isolated incident or the first sign of more insidious problems later. 

  • Storm Slabs

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

    The most dangerous areas will be shaded northern aspects. Widespread weak facets on the old snow surface could make avalanches easy to trigger. These slides could break widely across terrain features or might even be triggered from below. With an uneven distribution of old surfaces, quick handpit tests, kick turn tests, and test slopes you would typically use to assess stability might not be reliable. Adjacent slopes could have significantly different stability. Consider the high level of uncertainty, give yourself greater safety margins, and enjoy the return to winter on low-angle sheltered terrain with limited overhead exposure. 

    Fast running dry loose avalanches are also likely, so manage your terrain appropriately by stopping in safe locations, and don't sluff out your backcountry partners below. 

    (2/1/2025) This small sled triggered storm slab is a great example of how sensitive some slopes may be on Sunday. 

    Photo: Will Govus

Avalanche Discussion

Well, we probably have more questions than answers about the snowpack right now. In the last 72 hours, 8-16 inches of snow accumulated in the Washington Pass area. The precipitation tapered off on Sunday, but right after the storm, there were widespread reports of small natural and triggered wind slabs, storm slabs, and dry loose avalanches from Friday and Saturday. While most of these avalanches were small, one reported avalanche stepped down to a more deeply buried weak layer. On Sunday, an NWAC forecaster investigated this avalanche and found the crown depth widely variable from just 8in to over 3ft deep. This avalanche failed from a shallow spot in the slab and propagated along a crust into the deeper snowpack. The weak layer involved was 1-2mm faceted grains over the crust. We can't say how widespread this problem may be, but it'd be wise to consider it a possibility as you decide where to travel.

With increased uncertainty about this weak and variable snowpack, your best course of action is to keep your decision-making simple and choose conservative, simple terrain. If you choose to venture into avalanche terrain, consider the unpredictable distribution of old snow surfaces.  Snow fell on slick crusts on steep southerly terrain and weak faceted snow on northern aspects. Meanwhile, east and west aspects likely harbor a mix of both surfaces. As we gain more information, we'll likely be able to narrow the areas where we suspect avalanches are most likely. However, gaining confidence in the distribution takes patience, time, and many observations.

You can help us gather more data by submitting an observation HERE or via the Avy App. 

Regioni coperte