Bulletin d’avalanche

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Danger d’avalanche

Wed
Alpin
3 · Marqué
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

Strong wind blowing from the west and periods of heavy snow yesterday built new wind slabs likely to produce avalanches with a human trigger. Largest on easterly aspects receiving direct wind loading, you should find these new and unstable slabs on many aspects near and above treeline. Expect heavily wind affected and variable conditions in wind exposed terrain. You can identify and avoid these variable wind slabs as pillowy, somewhat dense, and deep drifts of new snow over much harder refrozen snow.

Problèmes avalancheux

  • Wind Slabs

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

    You are likely to trigger wind slab avalanches near and above treeline that vary from small to quite large in size. Sustained west wind around 30 mph yesterday, with gusts over 50 mph, should decrease a little though continue today. A few more inches of snow today should result in storm totals since Sunday night of 10-12”. We expect variable loading patterns from these strong and gusty winds, with thickest slabs on directly loaded slopes and many cross loaded areas. These wind speeds likely produced relatively firm and potentially stubborn, but large, wind slabs in truly above treeline terrain. Less wind hammered terrain near treeline and even a few wind affected areas below treeline should have softer and smaller slabs that are less obvious but touchy to a human trigger. Carefully evaluate all potentially wind affected terrain, looking for and avoiding these recent wind slabs in terrain 35 degrees and steeper. Wind scoured terrain avoids this avalanche problem, as does wind sheltered terrain which also holds the best powder riding conditions.

    (4/4/2022)

    Crown of intentionally triggered wind slab avalanche 3/4/22, failing on an interface 5 cm above the late March refrozen layer. Glidden Ridge, N aspect.

    Photo: Ryan Matz

Avalanche Discussion

It feels like winter again in the mountains! Yesterday’s wind event combined with nearly a foot of new snow at our highest elevations to rapidly elevate avalanche danger. We were able to easily trigger new wind slab avalanches around Noon yesterday. While maybe a little less sensitive today, we expect similar slabs have increased in size and might continue to grow with a little continued snowfall and west wind. New wind slabs failed yesterday on an interface a few inches above the late March refrozen snow. This hard, refrozen layer confines avalanche concerns to the new snow above it for today but makes a great sliding surface for avalanches and people alike. Even a small avalanche could result in a high consequence sliding fall. Continual observations and avoidance of our variable wind slabs is necessary for reasonably safe travel in, and around, steep wind affected terrain today.

Lower elevations received very little snow, though some rain, yesterday and feel much more spring-like. You’ll find the starkly more winter-like conditions as you gain elevation from trailheads. Keep your avalanche brains engaged, maintaining safe practices like moving one at a time from safe zone to safe zone. Some excellent soft snow conditions are out there in wind sheltered areas. Seek these areas to avoid our new wind slabs and to score some late season powder!

We will issue the final avalanche forecast for the 2021/2022 winter season on Friday, April 8th.

Régions couvertes