Bollettino valanghe

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Rain and snow will weaken and stress the snowpack today, increasing the risk of avalanches as the day progresses. Expect varying conditions as you gain elevation, so adjust your awareness accordingly. Due to the uncertainty in changing conditions, the safest option is to stick to low-angle slopes today.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Upper-elevation slopes may contain weaker snow near a rain crust buried one to two feet deep. The hardness and thickness of the rain crust vary with elevation, and these weak snow grains have proven difficult to trigger in snowpack tests. The additional weight from rain and snow today will add stress to the snow above the rain crust. Rain may also enhance the cohesion of the snow above the crust, forming a stronger slab and increasing the potential for an avalanche on the rain crust.

Avalanche Discussion

The avalanche hazard and danger are likely to change with the incoming precipitation today. Expect the hazard to rise as rain and snow add weight to the upper snowpack and stress buried weak layers. This storm is hovering around 30°F, making it difficult to predict whether precipitation will fall as snow or rain. Either scenario could alter the avalanche problem or at least affect the potential danger.

Over the past week, field observations have reported various forms of faceting, ranging from large Surface Hoar grains to near-surface facets on wind-sheltered, shady aspects, and newly formed faceted sun crusts on southerly-facing slopes. Snowpack tests are requiring more force to trigger failures in these collapsible snow layers, and the overlying slab has softened enough to limit failure propagation in Extended Column Tests. The incoming rain could melt away the Surface Hoar and sun crusts.

Digging deeper, the lower snowpack benefited from mild temperatures and abundant snowfall during the first storms in November. More consistent snowfall limited the opportunity for the snow surface to facet, so the bottom of the snowpack currently lacks widespread, identifiable weak layers.

Tread lightly today. Be aware of changing conditions . Due to the uncertainty around what type of precipitation falls, the safest option is to stick to low-angle slopes today.

Regioni coperte