Avalanche forecast

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Avalanche problems today are determined by elevation: Wind slabs on ridges at upper elevations and near tree line down to around 5,500’, transitioning to wet loose at lower elevations. Triggering an avalanche on persistent weak layers in the lower half of the snowpack remains a low likelihood, high consequence possibility.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Snow has been falling incrementally at upper elevations, while the valley has seen rain. Because of this, we have very different conditions at different elevations. Along with the new snow, ridgeline wind gusts have reached moderate speeds out of the S/SW, loading snow primarily on N-NE aspects. If you venture to upper elevations to hunt for soft snow, inspect North facing aspects for signs of wind loading. These wind slabs may be identifiable by cracking underfoot, or textured snow. 

    (1/25/2024)

    Cracks shooting from skis on an eight inch thick wind slab.

    Photo: Mikey Church

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Temperatures hovering just above freezing at lower elevations will keep snow mostly saturated below tree line. Elevations above 5,000' have seen more snow than rain, but below that band precipitation has fallen in the form of rain. Wet loose activity has slowed in the zone, but still remains a possibility today. Signs of pinwheels and rollerballs fanning out from your skis or snowmobile are an indicator that this problem still exists. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–3

    Adding to the variability of the current snowpack, we are still seeing our persistent weak layers sticking around. The buried surface hoar from 1/1 can still be found intact beneath all of the snow that has accumulated this month, and even lower down the 11/24 buried surface hoar is stubbornly persisting beneath the 12/7 rain crust. It has been a few weeks since we have seen these layers prove they will propagate in stability tests; however, they should be given an appropriate amount of respect as they now have over 2+ feet of snow sitting on top of them. Triggering an avalanche of anyone of these instabilities would be a very low likelihood, and highly consequential situation and would likely produce a large avalanche. 

    (1/25/2024) Photo: Mikey Church

Avalanche Discussion

Yesterday Izzy and escaped the rain by getting elevated: We toured around East Grouse Peak, 6,279ft. Up there we found 8” of accumulation from the past several days on top of a rain crust from earlier in the week. We were able to kick off small, 6”-8”, wind slab avalanche on the lee side of a steep north aspect of a ridgeline. An avalanche of this size is not particularly dangerous in and of itself, but could sweep a rider off their feet and drag them into a terrain trap, or possibly step down to deeper buried instabilities.

This week’s snow is resting on 2.5’ of stable snow from early January. But below this are several crusts, persistent weak layers and the beginnings of depth hoar in old rotten snow from December and November. We have not seen recent avalanches or propagation potential associated with these layers in the past two weeks, but we will continue to keep an eye on them as the snowpack evolves.

At lower elevations rain and melt have saturated the entire pack. The upshot is that mild temperatures and infusion of water promote rounding of snow crystals and break down crusts and persistent weak layers. The downside is that all that water lubricates the snowpack and increases chances of loose wet avalanches. Early in the week we saw a cycle of natural loose wet avalanches, which has since subsided. We are still concerned about human triggered wet loose avalanches as the lack of overnight freeze up and continued rain have weakened the snowpack.

The take home message is that there is spatial variability in the distribution of avalanche problems today. It is prudent to look in the snowpack and perform basic stability tests before committing to consequential terrain.

Ski and ride safe!

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