Boletín de aludes

Stevens Pass

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The warmest temperatures so far this winter and lack of a re-freeze will create dangerous conditions for wet avalanches on slopes steeper than 35 degrees. Time your travel to be off of and out from underneath steep slopes if the snow becomes wet and punchy. Avoid traveling under slopes with cornices or glide cracks looming overhead. 

Problemas de aludes

  • Loose Wet

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

    The lack of an overnight re-freeze may cause snow surfaces to quickly become wet and weak. Wet avalanches will first be active on northeast aspects and later on south, and then west aspects. Take note of what the snow surfaces are like. Do you punch through easily, or stay on top? You may find dramatically different conditions at different aspects or elevations and as the day progresses. If the snow is unsupportive and punchy, it is probably weak enough to entrain an avalanche.

    Start early and plan to give yourself options for travel that include a variety of aspects and elevations. Be ready to end your day early if conditions become dangerous. Wet avalanches will first be active on northeast aspects and later on south and west aspects. Conditions may change dramatically from one slope to the next and from morning to afternoon.

    (4/15/2021) Wet loose avalanches ran sometime on April 14th or 15th in lower Moonlight on northeast facing slopes.

  • Glide Cracks

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2

    Look out for glide cracks, or crevasse-like cracks on steep slopes. These could release spontaneously, creating large and destructive avalanches. Similarly, cornices loom over some ridgelines and may fall during the warm temperatures this week. Use extra caution to avoid being on or under slopes with glide cracks and cornices.

    On Wednesday, a large glide avalanche on a known indicator path on the southeast face of Lichtenberg Mountain. Water has also begun to run through the lower elevation snowpack. With both of these red flags in mind, along with continued soaring temperatures, many more glide avalanches could release. This season there are seemingly more glide cracks and snow-covered rock slabs than is typical, so we expect more may occur in the coming days. The mid-January layer is about 6-8 feet below the surface and has yet to see melt-water on most slopes. This layer could produce very large avalanches as warming temperatures continue.

    (4/14/2021) A large glide avalanche occurred on the 14th. The bare rock slab bed surface is visible in the top, right corner. Lichtenberg Mtn, SE, 5,200ft. Photo: WSDOT

Avalanche Discussion

Each day continues to be warmer than the last, and the warmest day so far this winter is on tap for Friday. With these very warm temperatures, meltwater is beginning to filter deeper into the snowpack. This is quickly changing our snowpack from a dry winter-like pack to a wet and mushy one. Observers continued to report numerous wet loose avalanches on Thursday. These were from sun-exposed slopes with some on northwest and northeast aspects. Some of these were big enough to bury or kill a person. A large glide avalanche ran on Lichtenberg Mountain on Wednesday. 

Earlier in the week, strong east winds transported previously dry snow in the alpine zone. Observers in neighboring zones have found weak facets on high elevation northerly aspects under recently formed slabs.On Tuesday in upper Nason Creek, Josh Hirshberg found that surface conditions varied significantly by aspect and elevation. All but the most shaded slopes above 5,000ft were capped with crusts. The top two feet of the snowpack varied from mostly dry recent snow to all melt forms (from very hard to soft and weak) and everything in between. A total of 1.5-3 feet of snow fell in two different storms on the 7th and 9th.  Many northerly slopes still hold a mostly dry snowpack. On east through south through west aspects, the upper snowpack consists of mostly melt forms in various states of being melted or frozen. 

Daily avalanche forecasts will end on Sunday, April 18th.

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.

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