Avalanche forecast

East Cabinet Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Mon
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

An Avalanche Warning is in effect from Sunday 6 AM to Monday 6 AM.Very dangerous avalanche conditions have developed from wet, dense snowfall and moderate to heavy rain saturating the snowpack and will last through Monday morning. The snow line will likely rise to between 6,000 and 7,000 feet Sunday afternoon-evening. You can very easily trigger avalanches large enough to bury or kill you, and some will release spontaneously. Avoid travel in avalanche terrain during this period.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2

    Wet, heavy snowfall has built denser slabs of snow above softer, lower-density snow creating an inverted, “upside-down” layering at the surface. The significant hardness difference between the storm snow and what’s below increases your chance to trigger a dangerous avalanche on slopes steeper than about 30 degrees with around 6 inches of new snow. These more cohesive slabs also have higher potential to break wider than you expect, even in wind-sheltered areas. Avoid traveling on or below steep slopes or broad openings, and heed the warning signs of shooting cracks, audible whumpfing, or fresh avalanches.

    (1/1/2025)

    A shallow, soft slab avalanche failing in the recent storm snow. Bitterroot Mountains. January 1, 2025.

    Photo: Izzy Davis

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    Weak layers - surface hoar, faceted grains, and a faceted crust - two to three feet deep are the culprit of lingering instability in the upper snowpack. Snowpack tests on slopes near treeline down to about 5,000 feet continue to produce ongoing failures in these weak grains. Well-preserved and upright surface hoar is found on north to east-facing slopes, while southeast through south to west-facing slopes harbor a breakable crust with facets looming above and below. While deeper weak grains are showing evidence of strengthening, the ability to affect weaker snow and trigger a slide appears directly influenced by overlying slab depth.

    (2/16/2025)

    Surface hoar feathers are still 10 to 12 mm in size below a stiffening slab. While becoming harder to impact, they still produce propagating failures in tests. Selkirk Mountains. February 16, 2025.

    Photo: Chris Bilbrey

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Rain saturating cold, dry snow in the upper snowpack will make it easier to trigger a wet snow avalanche on slopes steeper than about 30 degrees. Loose snow slides that travel long distances can gouge deeper and leave a dangerous pile of snow at the bottom of a slope, or in gullies and creek bottoms. Some wet avalanches may fail as a more dangerous slab of wet snow, and those types of avalanches will be more difficult to escape. Roller balls and pinwheels as early signs the snow surface is losing cohesion. If you experience periods of moderate to heavy rainfall, calling it a day may be the best option.

    (4/4/2024) Photo: Mikey Church

Avalanche Discussion

Wild weather often breeds unusual avalanche behavior. 36-hour snowfall totals around 5,000 feet and higher range 6 to 12 inches of very wet, dense snow - 17 to 25 percent snow densities. Liquid water input so far is 1 to 2 inches over the same timeframe and most elevations around 4,000 feet and lower have received all rain. Another potent slug of warm air arrives Sunday afternoon and drives the snow line higher in the sky. An above mountain top rain event will likely pan out for the Bitterroot Mountains while the highest terrain across the Northern Mountains has the best odds of being spared the major snow wetting event. 

By Monday morning, the snowpack in some places could hit the 3 to 4 inch watermark adding an insurmountable load to persistent grains that have not disappointed us in terms of their lingering sensitivity since burial on January 31. 

Strom slab densities are a significant shift from the 5 to 7 percent storm snow that accumulated over the last 10 days or so. This inverted layering will make newly formed slabs touchy, and you may be able to provoke avalanches on lower-angled slopes than typical. As you move closer to the treeline and above, deeper and harder slabs more capable of producing large, terrain wide avalanches come into play. Triggering a slide that spans adjacent terrain features or those that fail naturally are more likely to run long distances into mature forests and cause timber damage - especially where a slide initially fails in upper snowpack layers then steps deeper into persistent grains several feet deep.

Weak layers - surface hoar, faceted grains, and a faceted crust - two to three feet deep are the culprit of lingering instability in the upper snowpack. Snowpack tests on slopes near treeline down to about 5,000 feet continue to produce ongoing failures in these weak grains. Well-preserved and upright surface hoar is found on north to east-facing slopes, while southeast through south to west-facing slopes harbor a breakable crust with facets looming above and below. If the snowpack undergoes a prolonged period of steady rain, the wetting front may advance deeper in the snowpack to the January Drought Layer (JDL). If water reaches this interface, we may be entering the Wet Slab avalanche realm of higher uncertainty around the exact moment a slope fails.

If you decide to head into the mountains today, be ready for just about anything. Keep things simple and limit the temptation to thread the snowpack-terrain needle. Avoidance is the best card in the deck for days like this.

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