Boletín de aludes

South Rockies

Mar 13 – 14, 2023Avalanche Canada
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Archivado · caducó 4 years ago

Peligro de aludes

Wed
Thu
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Lo esencial

Storm snow blankets the region and has created reactive storm slabs. If triggered storm slab avalanches could step down to weak layers deep in the snowpack creating large destructive avalanches. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential for a safe day out in the mountains.

Problemas de aludes

  • Storm Slabs

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

    20-40 cm of storm snow has settled with warm temperatures into a reactive storm slab over a variety of surfaces. Storm slabs will be particularly reactive on solar slopes where they may be poorly bonded to the underlying crust. Be extra cautious on north and east slopes where southwest winds have built deeper pockets of storm slabs.

    If triggered, storm slab avalanches may step down to deeper weak layers resulting in large avalanches.

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    2–4

    The base of the snowpack remains very weak. Very large human triggered avalanches are possible at treeline and above. Avoid shallow and rocky areas, where the snowpack depth is highly variable. This is a very concerning avalanche problem and should stay in your mind when traveling in the backcountry.

Confidence

Moderate

Avalanche Summary

On Saturday, a few cornice failures were observed in the alpine during a brief period of direct sun. Observed failures did not trigger the slope beneath them. Check out the MIN report for more details.

If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.

Snowpack Summary

By Tuesday morning 20-40 cm of storm snow overlies a variety of surfaces including small pockets of wind slab on exposed south and west slopes, hard wind-affected surfaces in open areas, a sun crust on steep solar aspects, and facetted snow in sheltered areas.

In the Purcells, several weak layers from Jan and Feb can be found down 50 to 120 cm however they are showing signs of strengthening. The mid-snowpack is generally well-settled.

The lower snowpack is made up of a widespread layer of large, weak basal facets and depth hoar in some areas. this weakness has been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.

Weather Summary

Monday Night

Cloudy with mixed precipitation, 10-16 cm new snow at higher elevations. Alpine temperatures reach a low of -5 °C. Ridge wind 20 km/h gusting to 50 km/h from the southwest. Freezing levels lower slowly from 1800 m to 1000 m.

Tuesday

Mainly cloudy with isolated flurries, trace accumulation. Alpine temperatures reach a high of -7 °C. Ridge wind 15 to 30 km/h from the southwest. Freezing levels 1100 meters.

Wednesday

A mix of sun and cloud with isolated flurries, trace accumulation. Alpine temperatures reach a high of -5 °C. Ridge wind 15 km/h gusting to 30 km/h from the northwest. Freezing levels rise to 1200 meters.

Thursday

Mainly sunny. Alpine temperatures reach a high of -2 °C. Ridge wind southwest 20 km/h. Freezing levels rise to 1500 meters.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Be especially cautious as you transition into wind affected terrain.
  • Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.

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