Bulletin d’avalanche

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Danger d’avalanche

Sun
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Cold temperatures, snow and gusty northerly winds showed up last night. Avalanche danger will increase today as new snow and wind continues through the day, creating wind slabs and storm slabs on the surface. Uncertainty with rapidly changing conditions is best managed through conservative terrain choices today. 

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    New snow from the past 24 hours has favored the southern part of the zone because the primary winds have been coming out of the SW, but last night saw a shift to winds coming out of the N-NE.  Weather stations across the zone show anywhere from 2''- 14'' of new snow last night. Snow totals favored the Cabinet mountains. The Selkirks haven't seen as much snow, from this system, yet. Because the temperatures have cooled off and the new snow is low density,  that creates good conditions for blowing snow which means that wind loading, cornice build and slab formation will be happening at a fast rate today.  It's best to make careful terrain choice today with rapid changing conditions.

  • Persistent Slabs

    • Toutes altitudes
    Probabilité
    Unlikely
    Taille
    1–2

    Two crust layers (persistent weak layers) are pretty easy to find in the snowpack. You can find both crusts across the zone at all elevations and aspects. The upper crust, which was formed during a rain event on 1/13, is pretty close to the surface. It has weak snow above and below the crust, but hasn’t proven to be overly susceptible to failure, yet. One of the reasons we're not seeing avalanches happen because of this layer is the lack of a cohesive slab above it. 

    The second crust is about a meter (100cms) below the surface. This crust is more intact in most places but is deep enough in the snowpack that it'd be hard to trigger.  Even though this layer is lying dormant in the snowpack, we haven't completely stopped keeping an eye on it. If these PWL's see enough stress today from rapid loading, failure could happen. If it were to fail and avalanche, it would be a big, deep slab avalanche (low frequency, high consequence).  Not knowing how close the snowpack is to a tipping point, I wouldn't test it today.  Low angle slopes with good pow is the place to play today!

Avalanche Discussion

Today's a day of big change in the backcountry. Whenever winds spin 180 degrees , blow 40 mph and have snow to transport, that's a recipe for avalanche formation. It'll take some time to figure out exactly how the conditions have changed, but we know enough from field visits, observations and weather to know that we need to give the mountains some time to settle down. Cold temperatures could complicate any poor decision today, so plan for the worst and take a conservative approach to route finding and decision-making.

IPAC Forcasters' goal is to provide as much clear information about a complex problem as possible. If you do get out in the mountains today, let us know where and what you see by submitting an observation. It really helps us figure out what's going on in the backcountry! 

IPAC OBSERVATION PLATFORM- https://www.idahopanhandleavalanche.org/observations#/view

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