Bulletin d’avalanche

Coquihalla

Mar 9 – 10, 2024Avalanche Canada
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Archivé · expiré 3 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré

Points saillants

Increasing wind and snow are maintaining the wind slab problem and elevating the risk of triggering underlying weak layers. Choose simple avalanche terrain that avoids overhead hazard.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2

    Recent storm snow may still react as a slab in wind affected features at higher elevations. Watch for deeper and more reactive slabs near ridgelines.

    Expect new wind slabs to form as the southwest winds begin to increase.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1.5–2.5

    Buried weak layers are most concerning at treeline elevations. Small avalanches may step down to this layer resulting in very large, destructive avalanches.

    Use low-angle, simple terrain to help manage this problem.

Confidence

Moderate

Avalanche Summary

No new avalanches have been reported since Tuesday's report that included a few skier and machine-triggered size 2 (large) persistent slabs in the Coquihalla corridor. An observation flight also confirmed a widespread natural avalanche cycle took place at the end of last week with avalanches reaching size 3 (very large).

Snowpack Summary

Light new snow amounts of up to 5 cm and a new melt-freeze crust (on steep solar aspects) make up the surface conditions. 60-100 cm of old storm snow continues to settle above a problematic facet/surface hoar/crust layer buried beneath it. This layer has acted as the failure plane in many recent avalanches in this region and adjacent regions and it continues to produce whumpfs and concerning snowpack test results at treeline.

In some areas a second, thicker crust with weak facets above either replaces or is buried just below the layer described above. It similarly continues to produce concerning snowpack test results and may also have been involved in some of the region's recent avalanche activity.

Weather Summary

Friday night

Mainly cloudy. 80-90 km/h southwest alpine winds. Freezing level rising to near 2000 m.

Saturday

Cloudy with 5-10 mm of precipitation. 60-70 km/h southwest alpine winds. Treeline temperature 1 °C with freezing level 2000 m falling to 1500 m.

Sunday

Mainly cloudy with isolated flurries 1-5 cm of new snow. 40-50 km/h southwest alpine winds. Treeline temperature -2 °C with freezing levels around 1200 m.

Monday

Cloudy with flurries bringing 1-5 cm of new snow. 40-50 km/h south alpine winds. Treeline temperature -2 with freezing level around 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

Régions couvertes