Bollettino valanghe

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Several days of snow and wind continue to point towards a heightened avalanche danger across the Selkirks and Cabinets. Reactive wind slabs can be expected in specific areas above treeline. Wind slabs may not be obvious due to the blanket of snow from the past couple days, but they're likely to be a problem on steep NE-N-NW slopes, above treeline.  The best way to avoid reactive wind slabs is to stay away from the base of cliffs, steep convex rolls or textured drifts of snow on slopes steeper than 35 degrees.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Fresh snow and strong southwest winds have created new wind slabs, primarily at upper elevations. New wind slabs have built above old wind slabs that formed last week and might be hard to identify as the new snow blankets the mountains. These older wind slabs may be stubborn, but they likely exist on all aspects. Yesterday, we found a sandwich of soft wind slabs. In the top 12'' of the snowpack we found firm wind packed snow over soft snow which sat on another layer of firm snow. Extended column and compresson tests failed easily in the new wind slabs (CT 2  20cm down, ECTP 1 @ 30cm down). You can avoid this problem by avoiding steep and wind loaded slopes above treeline. The best riding can be found in timber where the snow is sheltered from the southwest winds. Yesterday, we found the snowmobiling was deep below treeline.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–2

    Facets above the January 13th rain crust are still showing signs of weakness at upper elevations on aspects with a thinner snowpack. Last week were seeing propagation in this layer on south and west aspects near treeline. On north and easterly aspects this layer can be found, but is not showing much potential for failure.  In most locations, it is buried approximately 2-3 feet below the surface and will have enough volume to kill or injure a person if triggered. Our neighbors in British Columbia are seeing Persistant weak layer's (PWL) come to life, which are resulting in big avalanches. Even though the snowpack in BC is different, it's a good reminder to keep a close eye on our PWL problem. Triggering this layer in the Selkirks/Cabinets is a low-likelihood, but high consequence scenario. Avoid large open slopes that have a thin snowpack to minimize your exposure to this problem.  

Avalanche Discussion

The saying seems to be true this year, March- "In like a lion..."! This time of year I always pay attention to when the snowpack tops out and begins the decent into summer. So far this transition to spring looks like it'll be on the later side, which is fine with me! Right now, most of the snotel sites are showing the snowfall totals below average, with the exception of the low elevation sites. A couple weeks ago, it looked like we were starting to melt out at lower elevations, but recent cold temperatures and snow have kept snow cover across lower elevations.  Looking at long term weather projections, I don't see a shift towards above freezing temperatures or any reasons to think spring conditions are on the horizon, but conditions can change quickly. I'm happy with another month of winter, but we'll see! Either way, keep your avalanche brains on, as we transition into spring and enjoy the longer days! Remember we have a new observation platform on the IPAC website. We'd love to see what your seeing. I look at the observation page every day that I forecast to get good beta from the public. Have a great day out there!

https://www.idahopanhandleavalanche.org/observations#/view

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