Boletín de aludes

Snoqualmie Pass

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

On Monday, warm weather should finally work its way to the Pass proper and eastern parts of the zone. Expect both dry and wet avalanche problems as you manage a two-elevation band kind of day.  Look for storm slabs anywhere you find six or more inches above an underlying crust.

7:30am: Forecast updated to Considerable due to overnight snowfall and expected high snowfall rates during the day. The likelihood of triggering a Storm Slab has increased from possible to likely on slopes over 35 degrees as you ascend elevation.

Problemas de aludes

  • Storm Slabs

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

    Sunday produced multiple rounds of precipitation, and that pattern is expected to continue through Monday at mid to upper elevations. Snow should be heavy and wet, possibly creating an upside-down snowpack. This will give you multiple insterstorm layers to investigate over the 1/20 crust. That freezing rain crust could make an excellent sliding surface for potential avalanches. Use quick hand pits or small test slopes to check the reactivity of the recent storm snow. Avoid steep features over 35 degrees if you find a poor bond.

    (1/19/2024)

    A skier-triggered slab avalanche on Dungeon Peak. The crown was 12-18" deep and is suspected to have failed at the 1/16 interface.

  • Loose Wet

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

    This time, we really do expect it to rain at lower elevations. So, as we discussed in Sunday’s forecast - the highest potential for wet avalanches will be in areas where rain falls on dry snow. Fan-shaped avalanche debris, pinwheels, and rollerballs are visual clues that should have you heading for lower-angled terrain. These slides could grow large or trigger slabs as they descend, making them more than just a nuisance. 

    (1/21/2024)

    Wet avalanche activity near Chair Peak Lake. Rollerballs, pinwheels, fan-shaped avalanche debris.

    Photo: Jordan Rogers

Avalanche Discussion

We’re in the midst of a tricky forecasting period at Snoqualmie Pass as we transition from cold and dry to warmer and wetter. It seems like the east flow refuses to die, and winter is putting up a good fight. Winter enthusiasts at the Pass proper aren’t complaining, but those traveling in the western half of the zone may say otherwise. It’s been wet and soggy, and allegedly, the Pass proper and the eastern half of the zone will get into the action on Monday. We’ll see if the Pass throws us another curveball and keeps things cold [7:30am update: it did... with more snow overnight than anticipated and heavy snowfall rates expected during the day, expect more reactive slabs as you ascend in elevation. The line for this change is fuzzy, but use your tests and default to lower-angled terrain if there's a question. As (If?) temperatures warm in the early afternoon, there will be more snow available for wet avalanches.] 

In most areas of the zone, the rain and freezing rain never materialized on Sunday. Instead, we had snow showers interspersed with sunshine. Avalanche professionals and backcountry travelers reported wet loose avalanches during and shortly after the sunny spell. Alpental Pro Patrol reported isolated small slabs during their morning mitigation work. No other avalanches were reported.

We haven’t had a suspected failure on the Solstice Crust since 1/10. After several days of running the problem at unlikely, we have pulled it from the forecast. That doesn’t mean the setup is not still in place. It is. However, NWAC forecasters and avalanche professionals have seen signs of healing in recent days and less concerning test results. Combined with the lack of avalanche activity, we have decided to let this layer sleep for now. It could wake up at any point, so limit your time spent in big open terrain if you want to minimize your exposure.

Other layers in the upper snowpack are also capable of producing avalanches. The 1/8 and 1/16 crusts have shown signs of life with snowpack tests over the weekend. An avalanche in the eastern part of the zone is suspected to have failed on the 1/16 on Friday. On Saturday, an avalanche professional experienced a whumpfing collapse at lower elevations. This is also suspected to be the 1/16 interface. This layer contains faceted grains but has spotty distribution. It could be bridged by the most recent 1/20 rain and freezing rain crusts. The 1/20 varies in thickness across the landscape.

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