Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Mon
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3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
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In sintesi

Dangerous avalanche conditions are expected on Sunday with warming temperatures, and heavy snow changing to rain. Wet avalanches of all types could run from steep slopes, and may become large. Danger will increase as precipitation intensity picks up in the afternoon, and a cycle of natural slides could occur overnight into Monday.

Problemi valanghivi

  • Loose Wet

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

    Wet snow avalanches including wet loose, wet slab, glide slab, and cornices could begin to run naturally on Sunday. A few to several inches of new snow may accumulate before temperatures warm up in the afternoon. This is expected to create fairly widespread instability, and it should increase into the evening/night as rain falls up to 6,000ft. Heavy, wet loose slides could churn downhill from long steep slopes. These may run on a slick crust, but could begin to gouge deeper. Fresh, large debris piles are indicators that other avalanches like it could run. Storm slabs and wet slabs could run in the afternoon when the snow changes to rain. Glide cracks should begin to open more and could release naturally.

    With all of the above, the travel advice is clear- stay off of steep slopes. Stay out from underneath large steep slopes as slides could entrain and run down into trees and other strainers or terrain traps.

    Example wet loose avalanches from Snoqualmie on Friday. Photo: Patrick O'Moore

Avalanche Discussion

It'll definitley be a wet, soggy day out there on Sunday. The snow that does fall before it turns to rain should be pretty moist. At some point in the middle of the day the snow is expected to change over to rain, and instability should begin to increase rapidly. As precipitation rates and snow levels increase Sunday afternoon, we could see a natural cycle of large avalanches that lasts overnight into Monday.

Over the past couple of days, observers have reported rounds of wet loose avalanches. These were in frequent locations such as Lichtenberg Mountain. The recent slides were mainly small, but larger wet loose slides have been reported from both the East Central and Snoqualmie Passes. 

Many slopes hold a crust of sorts beneath the recent snow. You may find up to a foot of recent snow over a crusts from the 6th, and from the 31st. However, on northerly aspects above 6,000ft, you could find weaker dry snow beneath the warm, dense storm snow. Last week, observers on Jim Hill found buried surface hour about 1 foot below the surface near the 3/31 interface. This layer could be a concern in very isolated locations (N facing above 5,500ft) At lower elevations, the snowpack is well on its way to melting out for the year.

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