Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The recent storm snow continues to take longer to heal than we typically see here in the Northwest. As a result, you may still trigger avalanches on steep open slopes. Some of these slides could fail above you and catch you by surprise.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    Unstable snow from our recent storm continues to persist this week. Snowpack tests routinely fail suddenly at the base of the new snow. While this layer seems to be gaining strength (and we’re gaining confidence), we aren’t quite ready to put it to bed. NWAC forecasters and avalanche professionals reported buried surface hoar and large preserved stellars (snowflakes) at this interface in many of their snow profiles. At this point, it will be tricky to tell exactly where this layer may or may not linger. Any steep open slope could be suspect. If you find the right trigger point, you may release a large and deadly slide. Consider avoiding large steep open slopes, especially near treeline.

Avalanche Discussion

Not all moderate danger days are the same. In this case, we aren’t talking about our typical Northwest snow patterns. Instead, we’re dealing with persistent slabs. This is a particularly challenging avalanche problem. They can be hard to forecast, manage, and evaluate. An old adage, “when uncertainty goes up, terrain goes down,” seems to fit well with the current setup. You may want to choose a much more conservative approach to your day’s plan and stay off of steep opens slopes you’d frequently travel in more typical northwest conditions. (see video above)

A layer of surface hoar and large preserved stellars may be found about 1ft (30cm) below the surface on most aspects near and, possibly, above treeline. Snowpack tests can help you identify this 12/8 interface and its weak grains. Remember, snow profiles can help us confirm persistent weak layers, but they can not prove their absence. At lower elevations, warmer temperatures seem to form much heavier wetter snow at the tail end of the recent storm and destroy this problem layer. 

Periods of sunny weather, especially above the low clouds, formed a thin sun crust on steep southerly aspects. While thin and breakable, it may make travel less pleasant on some of these slopes. Meanwhile, mid and upper elevations continue to hold soft cold dry snow.

Regioni coperte