Avalanche forecast

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Significant new snow accumulation + very strong winds = increased avalanche hazard. Wind slabs have formed much further down slope than we are accustomed to seeing are likely to be large and dangerous. Recent storm snow is overlaying several potential weak layers. Careful snowpack evaluation, cautious route finding and conservative decision making are warranted.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Yesterday’s strong winds from the southwest have deposited recently fallen snow into thick reactive slabs on north and east aspects. Be aware that 20-40mph winds have built large wind slabs much further down slope than we are accustomed to seeing. Silver Ski Patrol reported initiating wind slab avalanches with 3-4’ crowns much further down slopes than where they usually see results.

    In areas sheltered from the winds recent snowfall may be cohesive enough to form storm slabs over density changes and a melt freeze crust from last week. Test for stability before committing to steep open slopes and convexities.

    Photo: Mikey Church

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    Wind and storm slabs may overlay deeper buried layers of surface hoar and crust/facet combos in isolated areas. The recent wet heavy snow has added weight and stress to the snowpack, and may be the tipping point to trigger large avalanches on these weak layers.

    A slide last week on a pocket of buried surface hoar on a northeast aspect.

Avalanche Discussion

Yesterday on our way up to Taft Summit area we encountered 6’ wind drifted snow blocking the trail and deep pockets of heavy wet snow that swallowed up the tracks of our snowmobiles.

Although the Silver/St. Regis zone has not seen the storm totals the other IPAC zones have, we still have all the necessary ingredients for avalanches: recent snow, wind and big temperature fluctuations. The most recent pulse of snow came in hot and heavy, but cooled overnight, creating layers of density changes within the upper snowpack. Underlying that are various crusts and pockets of preserved surface hoar.

Today is a day to proceed into the mountains with caution. Be on the lookout for signs of instability and avalanche red flags like shooting cracks, whoomphs, wet surface snow, etc. and be prepared to step back into low angle terrain. As you proceed be keenly aware of avalanche hazards above you and your proximity to terrain traps. Avalanche hazards today are complicated and hard to predict, so trend on the side of caution.

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