Boletín de aludes

South Rockies

Mar 18, 2019Avalanche Canada
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Archivado · caducó 8 years ago

Peligro de aludes

Tue
Wed
Alta montaña
4 · Fuerte
Límite del bosque
4 · Fuerte
Bajo el límite
3 · Notable

Lo esencial

Sunshine and warmth may feel good to us, but it doesn't help the snow. It's a good time to step aside, watch from afar, and let the mountains shed some of their winter coat. Riding will be better, or at least safer, when it cools off in a few days.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Very Likely
    Tamaño
    1–2.5
    Sunshine and warming temperatures will peel away layers or recent snow on sunny slopes as loose wet slides, weaken cornices, and possibly re-energize wind slabs. The key unknown is how warming and weakening upper snowpack will affect deeper layers.

Confidence

Moderate -

Weather Forecast

Significant warming in the forecast and next week looks very warm with freezing level above the summits. Don't let overnight cooling at low elevations (temperature inversion) fool you; very little cooling is expected at higher elevation.SUNDAY NIGHT:  Clear & dry. Freezing level around 2000m. Light variable wind.MONDAY: Sunny and dry. Freezing level around 2500m, no real overnight re-freeze expected at treeline elevations. Light variable wind.TUESDAY: Just like Monday but freezing level approaching 3000m.WEDNESDAY:  Just like Monday and Tuesday but freezing level exceeding 3000m.

Avalanche Summary

On Thursday, a group of riders remotely triggered a size 1.5 persistent slab from 100 metres away. See the MIN report for details. I view this as an important piece of data when considering the effect of forecast strong sunshine and warming.Saturday's reports are of significant warming but only small loose wet avalanches. Neighbouring regions (for example Kananaskis Country) where the snowpack is thinner and weaker entered a natural avalanche cycle involving most aspects, most elevations, and most snowpack layers. IMHO this foretells the story of what's soon coming to a mountain range near you!

Snowpack Summary

Upper snowpack: Getting warm and moist during the day, maybe forming ephemeral crusts overnight. On sunny aspects there may be buried crusts serving as sliding layers. On lee slopes there may be buried hard layers of wind effected snow (buried wind slabs). There might even be some good old soft snow (powder) hiding out on high elevation shady slopes. Mid pack: The mid-snowpack consists of sugary faceted grains (facets) and layers of harder wind effected snow. In isolated wind protected locations a thin surface hoar layer from mid-January is 50-80 cm deep. The surface hoar is most prominent in the Elk Valley between 1600 - 1900 m. See Avalanche Activity section below for why this is relevant!Lower pack: I have doubts about it's strength in shallower areas where the February cold weakened even the deep layers.Now add a bunch of heat and sun ... the snowpack won't be feelin' the love. Forecasting how many sunny days and warm nights it's going to take to wake up deeper layers is tough; however, I can say with confidence it's a good time to stand aside, watch from afar, let the mountains shed their coat, and come back to the game when things return to normal after the temperatures cool.

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