Lawinenlagebericht

Bitterroot

West Central Montana Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

An avalanche warning has been issued. Very dangerous avalanche conditions are developing throughout the forecast area. Heavy snowfall and strong winds are rapidly loading the snowpack. Temperature and freezing levels will rise throughout the day with rain possible to 7000', further destabilizing the snowpack. Widespread avalanches are very likely. Avoid all avalanche terrain, and stay well away from the base of slopes capable of sliding. 

Lawinenprobleme

  • Storm Slabs

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

    Heavy snowfall and southwest winds are loading slopes above 6000' feet today. There are a variety of snow surfaces this is landing on, many of them weak and low friction, increasing the potential size of slides and the distance they will run. The likelihood of storm slab avalanches will increase throughout the day. Travel in avalanche terrain is not recommended. Avoid slopes over 30º and stay well away from the base of avalanche slopes.

  • Loose Wet

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

    Rising temperatures and freezing levels mean that rain is possible up to 7000' today. Rain on snow is never good for avalanche conditions. Wet loose slides are certain at lower elevations, and wet slab avalanches are possible if the moisture reaches buried crusts. The southern Bitterroot is at greater risk of wet problems as the temperature will rise higher and buried crusts are closer to the surface. Wet problems are hard to predict, can't be checked with standard snowpack tests, and can be very destructive. Wet slides may run in areas not easily identified as avalanche terrain. Travel in avalanche terrain is not recommended. Stay well away from the base of slopes capable of sliding. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–3

    A crust/facet combo in the Central Bitterroot could become more reactive today with rapid loading and warming. This layer is up to three feet deep, is getting buried deeper, and could produce very large destructive avalanches. While most reactive in the Gash and Bear Creek area, warming temperatures may reawaken dormant persistent layers outside of this. These slabs are not something to temp; slides on them would be unsurvivable. Travel in avalanche terrain is not recommended. Stick to slopes under 30º and stay well away from the base of avalanche slopes. Slides on this layer could run very long distances.

Avalanche Discussion

The snowpack does not like rapid change, but that is what it is getting right now. Heavy snowfall and rising temperatures are rapidly destabilizing the snowpack. Up to 8" of new snow could fall today, adding to 6" from last night and over 1" of snow water equivalent (SWE). Strong southwest winds are further loading upper elevation slopes. The past week of cold temperatures and wind has created widespread faceting in the upper portion of the snowpack and scoured upper elevation slopes back down to slick crusts. The new snow is landing on this, increasing the potential touchiness, size, and distances avalanches will run. Rain is possible to 7000', and all snow that falls will be dense and heavy, creating slabs on top of low-density snow. Rain on snow is never good and rapidly destabilizes the snowpack. Throughout the forecast area, it may rain to 6000'. The southern Bitterroot may see rain to 7000' today. The mid -February crust is closer to the surface in this area and could provide a sliding plane for wet slab avalanches if the snow gets wet enough. Travel in avalanche terrain is not recommended today. Keep slope angles below 30º and stay well away from the base of potential avalanche slopes. 

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