Bollettino valanghe

Purcells

Apr 19 – 20, 2023Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 3 years ago

Pericolo valanghe

Fri
Sat
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Apri la mappa completa

In sintesi

Dangerous avalanche conditions exist in the alpine where new snow continues to incrementally add load to buried weak layers. Carefully evaluate terrain as you move through the backcountry and when in doubt choose conservative terrain.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    15-40 cm of dry snow in the alpine overlies a variety of crust complexes that have been reactive in adjacent regions.

    A bit of new snow every day is incrementally adding load to these weak layers bringing them closer to threshold. Use extra caution around ridgecrest, small rolls, and on convex slopes. Retreat to mellower terrain if you find signs of instability like shooting cracks, whumpfs, or recent avalanches.

  • Loose Wet

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

    Be alert to changing conditions when daytime heating and direct sun are impacting slopes. Steep, rocky terrain facing the sun is likely to see thin loose wet avalanches release during the heat of the day.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2.5–4

    The base of the snowpack remains very weak. Avoid thin, rocky start zones and shallow areas with variable snowpack depths.

    Deep persistent slab avalanches continue to be reported in this forecast area.

    This is a low-probability/high-consequence avalanche problem, and managing it is very tricky.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported in the region on Tuesday. Adjacent regions continue to see a few natural and several human triggered avalanches, up to size 2, on burried weak layers each day.

A fatal avalanche occurred on April 15 in the Thunderwater Lake riding area, just west of this region. The avalanche was triggered near a rocky area and was very large (size 3). Two riders were caught, one was buried approximately 2 meters deep. Despite an immediate extrication rescue response, the rider did not survive. Any additional information we have on this accident can be found in this MIN.

If you are getting out in the backcountry, consider making a post on the MIN (Mountain Information Network).

Snowpack Summary

At treeline and above, 15 - 40 cm of recent snow is being redistributed by variable winds into soft slabs in lees. This overlies a variety of crust, surface hoar and/or facet layers buried in mid March through early April. These interfaces have been the culprit in recent avalanche activity in adjacent regions. Most professional operations in the forecast area are tracking their own local layer of concern to see if they become active with increasing temperatures, or more load from new rain or snow.

Below treeline, expect to find moist or refrozen surfaces, and shrinking snowpack depths.

The mid snowpack is generally settled and strong.

The lower snowpack includes a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for several very large and destructive avalanches throughout the season.

Weather Summary

Wednesday Night

Cloudy with scattered flurries, 2-5 accumulation. Light northeast ridgetop wind. Freezing levels 1200 m. Treeline high around -6 °C.

Thursday

Mix of sun and cloud with isolated flurries, 1-2 cm accumulation. Light west ridgetop wind. Freezing levels rise from valley bottom to 2100 m by mid-day. Treeline high around 0 °C.

Friday

Mix of sun and cloud. Light southeast ridgetop wind. Freezing levels rise from valley bottom to 2000 m by mid-day. Treeline high around 0 °C.

Saturday

Mix of sun and cloud with isolated flurries, trace accumulation. Light west ridgetop wind. Freezing levels rise from valley bottom to 2200 m by mid-day. Treeline high around +1 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Brief periods of sun could quickly initiate natural avalanche activity.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Regioni coperte