Boletín de aludes

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Peligro de aludes

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

Lo esencial

Another day of unseasonably mild weather will maintain the possibility of loose wet avalanche activity, especially at middle elevations. While it may be difficult to trigger a slab avalanche today, the snowpack at higher elevations, near ridges, and rock formations, is sitting on a weak rain crust and continues to be the biggest concern. The best way to describe the current conditions is "low frequency, high consequence." To minimize risk, the safest strategy is to stay on slopes around 30 degrees. If you choose to enter steeper terrain, be especially aware for signs of instability, such as cracking or audible collapses. It’s also wise to select slopes with a clear, safe runout that won’t lead you over cliffs, into trees, or into a terrain trap.

Problemas de aludes

  • Persistent Slabs

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

    The precipitation mix from earlier in the week has added stress to  a rain crust in the upper snowpack. The 12/7 rain crust is located approximately 12-24 inches beneath the snow surface. Its hardness and thickness vary across our forecast zones, but it has been observed between 3,500 and 6,500 feet in elevation. Where the crust is around 2 inches thick or more, the weak grains below are more resistant to failure in snowpack tests. However, where the crust is thinner and more breakable, these same faceted grains have failed with less force in tests. Avoid shallow areas near exposed rocks or below cliffs, as triggering a shallow slide in these zones may provoke a deeper, more dangerous slide. Travel through avalanche terrain one at a time and be mindful of how deeply your snowmobile trenches on slopes steeper than 30 degrees. Shallow, thin, hollow areas are the most likely places to trigger an avalanche on the 12/7 rain crust.

    Photo: Izzy Davis

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Look for temperatures to stay mild again today. Surface crusts that were previously supportable began to break down yesterday and will continue to do so today. Pinwheels, snow bombs falling from trees, and snow clinging to skis and skins are all classic signs that the surface snow is wet and has lost cohesion. A loose wet avalanche could step down, triggering a larger avalanche on the persistent weak layer. Areas below 4,500 feet will have a higher chance of wet loose avalanche activity.

    Photo: Izzy Davis

Avalanche Discussion

Unseasonably mild temperatures have brought a mixed bag of weather to the forecast zones. December 18th was a significant weather event, with upper elevation snow and lower elevation rain, which triggered a short-lived but active avalanche cycle. By the 19th, conditions in the backcountry had calmed down, and firm snow dominated the surface. Yesterday, forecasters in the field observed a warm-up—enough to start breaking down the firm crust on the surface but not enough to cause melting. Today is expected to be similar. Expect continued melting, especially at lower elevations, and be prepared for the crust underfoot to become more breakable as the day progresses. Another round of rain and snow will move in this afternoon.

Avalanche classes are filling up fast! IPAC has some openings left in a few of our classes. With the snowpack becoming more complex, it's the perfect time to give your loved one a Christmas gift that shows how much you care! Learn more here.

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