Lawinenlagebericht

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Heavy new snow or rain, strong winds, and shallowly buried weak snow layers is the perfect recipe to trigger a dangerous avalanche. Complex weather conditions will vary depending on elevation, so keep things simple – avoid traveling on or below slopes over 30 degrees. Make conservative terrain choices to account for the uncertainty of which flavor of avalanche hazard is helping tip the snowpack scale.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Snowfall since Saturday ranges 12 to 18 inches above 5,000 feet. Additional wet, heavy snow and maybe light rain at upper elevations will make recent storm snow more reactive than in recent days. Slabs will be stiffer and deeper on leeward-facing slopes and avalanches on those slopes can break wider and travel farther down the slope than you expect. Assess new snow depths as you move through the mountains and heed the warning signs of cracking in the snow surface or audible collapses.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Above freezing temperatures and rain wetting drier surface snow increases the Loose Wet avalanche hazard at mid and lower elevations. The higher the rain line climbs, the more likely it is for weaker facets above a crust to get wet and potentially produce a more dangerous Wet Slab avalanche. Rollerballs and pinwheels are clue’s the snow surface is losing cohesion, and a natural wet slide may be imminent. If you find more than about 6 inches of wet snow, retreat to lower-angled slopes or move up in elevation. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2

    Incremental snowfall is slowly adding more stress to weak, faceted grains surrounding a rain crust in the upper snowpack. The hardness and thickness of the early December rain crust varies across our forecast zones and has been found above 6,500 feet. Where the crust is around 2 inches thick or more, weak grains below have been more stubborn to fail in snowpack tests. Where the crust is thinner and more breakable, those same faceted grains have failed with less force in tests. Avoid shallow areas near exposed rocks or below cliffs where triggering a shallow slide may provoke a deeper, more dangerous slide.

Avalanche Discussion

Snow, rain, more snow, then wind oh my! If venturing into the mountains today, be prepared for just about anything. Snowfall kicked into gear Tuesday afternoon, and before the warm air tongue arrived early Wednesday morning, the Selkirk and Cabinet Mountains received 6 to 10 inches of new snow and 3 to 5 inches in the Bitterroots – Silver Valley. This has added an additional 0.75 to 1 inch of SWE on top of similar amounts that accumulated the three days prior. Lastly, all of this is sitting on top of a layer of weak faceted snow above the widespread December 7 rain crust.

Avalanche conditions have the potential to be as complex as we’ve seen so far this season. The added complexity or biggest unknown is how much rain falls and how high it reaches. While rain-on-snow amounts look to remain relatively light, there is plenty of dry snow getting wet to be a hazard in and of itself. Every little bit of water weight further stresses shallowly buried weak snow layers making them more susceptible to fail from the extra nudge of a rider or machine. The fact the slab, weak layer combination sits above a widespread planar interface also increases the odds for avalanches to break wider across adjacent terrain features.

Multiple field teams on Tuesday found increasing sensitivity in near-surface facets above the December 7 crust. Extended column Tests produced easy-moderate propagating failures in multiple forecast zones with varying slab depths above. In some instances, the facets below the crust failed where the crust was slightly thinner and more breakable. Be mindful of how close you get to steeper slopes above you regardless of which direction the slope faces. Monitor how conditions change as you move through the mountains and recognize that potential avalanche size increases alongside increasing new snow amounts, or depth of wet snow.

FIRST AVALANCHE FATALITY 2024-25:

We are saddened to report that the first avalanche fatality of 2024-25 occurred in the mountains northwest of Cascade, ID near Lookout Peak. A group of two snow bikers triggered an avalanche, and one was caught and fully buried. The slide was reported to be relatively small, but the rider was carried into a terrain trap and buried deeply. He was found with an avalanche beacon and extricated, but did not survive. The accident occurred just south of the Payette Avalanche Center forecast area. Our sincere condolences go out to those impacted by this incident.

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