Boletín de aludes

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
Ver en el mapa

Peligro de aludes

Sun
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
Open full map
Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Loose wet avalanches will be likely today on slopes exposed to direct sunlight, while slab avalanches are still possible in the upper snowpack. You can avoid avalanches today by paying attention to the surface conditions of the snowpack. Move away from steep slopes exposed to direct sun and seek shaded terrain in the afternoon. 

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Temperatures are forecast to climb up to 40 degrees in the mountains today. The warm ambient air and solar radiation will weaken the upper snowpack with an injection of moisture that lubricates weak layers and the spaces between crystals. Small, wet loose avalanches will become likely on steep aspects exposed to the sun. Snow bombs falling out of trees, pinwheels, roller balls, and snow that sticks to your skis are all signs that the surface snow is moistening and losing strength. As the snowpack surface warms and softens up during the day, you will want to avoid steep slopes that are being cooked by the sun and relocate to more north facing terrain.

    Small point release loose slides. Photo submitted on Obs page, thank you!

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5

    Snow from earlier in the week formed slabs that are still reactive on north to east slopes beneath ridgelines. There are also several crusts and facet layers buried in the upper meter of the snowpack, below last Monday’s dense storm slab.

    Even small avalanches can be dangerous as they can drag a rider through trees and rocks, or step down into deeper weak layers. Before stepping into steep and consequential terrain, take the time to dig into the snow and assess the stability of the upper snowpack.

    Small wind slab release on NE aspect.

Avalanche Discussion

Break out a Hawaiian shirt  today, spring skiing is upon us! Looks like the mild weather and partly sunny skies will hold through the weekend.

Thursday was one of those glorious March days when you start to recoup some of your depleted vitamin D reserves. While Kyla and I toured up Rabbit Gulch from the Burke Sub-station we marveled at how not cold our fingers and toes were when we stopped to dig pits. Throughout the tour, we found variable ski conditions ranging from dust on crust to ample soft snow. Solar aspects tended to have a mostly supportable sun-crust under 2 inches of low-density snow, while shaded slopes held the softer snow and better riding conditions.

We have reached the time of year when the diurnal cycle begins to dominate the avalanche discussion. The diurnal cycle is the day-time warming and night-time cooling of the upper snowpack. As the days get longer and the sun’s trajectory becomes more overhead, more solar radiation is absorbed into the surface of the snow, which results in liquid water infusing and lubricating the upper snowpack. Each night when the temperature drops below freezing, the liquid refreezes and locks the snowpack up again. The key to managing this is planning your tour to avoid steep solar aspects from mid-day onward when wet snow hazards are elevated, and recognizing the signs that indicate surface snow has lost cohesion. Snow bombs falling out of trees, pinwheels, roller balls, and snow that sticks to your skis are all signs that the surface snow is moistening and losing strength. Wet loose avalanches on steep slopes are sure to follow. When you notice these signs occurring, it’s time to head to shaded north aspects.

Even though the sun is out, it’s not time to switch off your avalanche brain yet. There are still many distinct facet and crust layers in the upper meter of the snowpack. Even though we have not been finding propagation in our pit tests, I do not trust them completely yet. I am continuing to look carefully before venturing into steep and consequential terrain. Yesterday, I kicked off a small wind slab on a northeast aspect at 6600’ while assessing stability. I would hate for that to step down into deeper instabilities.

Thank you for posting observations. Enjoy the good weather and variable riding and stay safe.

Regiones cubiertas