Boletín de aludes

Coquihalla

Feb 25 – 26, 2023Avalanche Canada
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Archivado · caducó 4 years ago

Peligro de aludes

Mon
Tue
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil

Lo esencial

Watch for changing conditions. As new snow and wind arrive on Saturday afternoon, fresh reactive wind slabs may form in exposed areas.

Sheltered terrain will offer the best and safest riding.

Problemas de aludes

  • Wind Slabs

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

    Snowfall and increasing southwesterly winds on Saturday afternoon may form small but reactive wind slabs by the end of the day. Stiffer and less reactive slabs may linger in lee and cross-loaded areas from previous strong northeasterly winds.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    1–3

    A crust formed in mid-January can be found down 80 to 120 cm. In areas around the Coquihalla facets can be found sitting on the crust. This layer is of greatest concern with large triggers, such as a cornice fall, or by first triggering a smaller avalanche that could step down to this interface.

Confidence

Moderate

Avalanche Summary

Early in the week, a natural avalanche cycle occurred with heavy snowfall on Monday night and Tuesday. Avalanches were reported as size 2-3 wind slabs, storm slabs and persistent slabs on northwest, northeast and southeast aspects in the alpine and treeline elevation bands. The persistent slab avalanches were suspected to have run on the facet/crust layer buried in mid-January (outlined in the avalanche problem section).

Looking forward to Saturday, snowfall and increasing southwesterly winds may form small but reactive wind slabs by the end of the day. Riders should be aware that stiffer and less reactive slabs may linger in lee and cross-loaded areas from previous strong northeasterly winds.

Please continue to post your reports and photos to the Mountain Information Network.

Snowpack Summary

Previous northeasterly winds have redistributed 20-40 cm of recent storm snow and formed stiff wind slabs in exposed areas. In sheltered areas, surface faceting due to cold temperatures and/or soft surface snow remains.

A melt-freeze crust formed in mid-January is buried up to 90-140 cm deep. In some areas, small faceted crystals can be found above the crust. This layer has been reactive during the storm Tuesday night and Wednesday this week. The snow below this layer is well consolidated.

Snowpack depths are just below seasonal averages. Total amounts range from 150 to 300 cm at treeline, but decreases significantly below 1500 m.

Weather Summary

Friday night

Clear with cloudy periods. Alpine temperatures around -14 °C. Ridge wind southwest 10-20 km/h. Freezing level at valley bottom.

Saturday

Cloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -6 °C. Mostly light ridge wind occasionally gusting to 40 km/h from the southwest. Freezing level at valley bottom.

Sunday

Cloudy with snowfall, 5-15 cm of accumulation. Alpine temperatures reach a high of -3 °C. Ridge wind 20km/h gusting to 65 km/h from the southwest. Freezing level 700 meters.

Monday

A mix of sun and cloud. Alpine temperatures reach a high of -1 °C. Mostly light ridge wind occasionally gusting to 50 km/h from the southeast. Freezing level 800 meters.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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