Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Tue
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

Several days of above freezing temperatures, poor overnight freezes, and continued warm weather will maintain wet avalanche concerns across the West South zone. While avalanches may not be prevalent on every slope, be suspicious of any steep terrain where you find wet punch snow.

Problemi valanghivi

  • Loose Wet

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

    The upper snowpack is generally wet and weak due to this prolonged stretch of warm and occasionally sunny weather. While you may find a thin breakable crust in the morning, it shouldn’t take long for this to soften. As a result, anticipate wet avalanche issues right off the bat. Even though you might not be able to trigger a loose wet slide on every slope, all steep terrain with wet snow deeper than your ankle should be suspect. It may be hard to tell exactly which slopes may slide and which ones won’t. So, choose lower consequence terrain away from cliffs and creeks where these slides have a greater chance to hurt you despite their relatively small size. 

    As the mountains continue to transition to spring, sometimes snow just falls down. Cornices collapse and snow sheds from rocky slopes. This has been going on around the zone for the past several days. Needless to say, you don’t want to be under these slopes if they fell. So, don’t linger under these features, especially during the heat of the day.

    (3/24/2022)

    Take a moment to step off your mode of travel to see how deeply you are plunging into the snow. If you are sinking in past your ankle, start to think about wet avalanches. 

    Photo: Dallas Glass

Avalanche Discussion

We’re well into this prolonged warm stretch of weather and some mountain locations will see their 3rd or even 4th night without a solid freeze Sunday evening. This can often be a critical threshold causing the snowpack to become more unstable. Fortunately, slightly cooler weather and some clouds should help offset the continued warm weather. However, the longer we go without a solid freeze the more our uncertainty grows. 

The main concern stems from the snow above the stout and pronounced Early March Crust. On more southerly slopes, this upper snowpack should be well transitioned to spring-like snow (melt forms). While it still may be wet and weak, fewer layers exist to cause concern. A more nuanced snowpack may still exist on shadier aspects with layers of melt-forms and dry rounded grains. These are the same slopes where we tracked the 3/8 facets over the Early March Crust. This persistent weak layer produced avalanches near White Pass, Crystal Mt, and Paradise. At this point, it would likely take a large trigger in just the right spot to trigger an avalanche. However, with cornices collapsing and rocks shedding snow, could that be all these slopes need? This gives you just one more reason not to hang out underneath looming cornices during periods of warm weather. 

At lower elevations, the snowpack has been through a lot this week and is generally transitioned to spring-like snow. In fact, it's often melting back exposing creeks and even bare ground. This substantially limits any avalanche concerns down in the forest at this time. 

 

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