Avalanche Forecast
Issued: Feb 24th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
mconlan,
Avalanche Canada
Wind slabs are the primary concern, but lingering storm slabs may still exist in wind-sheltered terrain.
Summary
Confidence
Moderate
Avalanche Summary
Over the past few days we received reports of many natural, explosive, and human-triggered storm slab and wind slab avalanches. The storm slab avalanches were generally releasing within the storm snow since Tuesday or about 100 cm deep at the base of the snow that accumulated last weekend. Wind slab avalanches were occurring on all aspects in wind-exposed terrain where recent strong wind redistributed the storm snow. Avalanches were most often at treeline and alpine elevations and were mostly small to large (size 1 to 2.5).
Clear skies from the past few days allowed for observations of many deep persistent slab avalanches as well as explosive control missions, which produced large to very large (size 2 to 3.5) avalanches. They were on all aspects and between 2200 m and 2800 m in elevation. Although many of the avalanches occurred in unrideable terrain, they are evidence that the layer is still triggerable. Riders should continue to avoid thin snowpack areas, which are often found near ridgelines.
Snowpack Summary
Stormy conditions return on Saturday, bringing snow and southwest wind that could form new wind slabs in wind-exposed terrain. The snow will overly storm slabs that formed from Tuesday's 20 to 50 cm of snow and wind slabs that formed from sustained northeast wind.
Around 80 to 100 cm of snow may rest on a small layer of surface hoar crystals that was buried mid-February. This layer is most likely found around treeline elevations in areas sheltered from the wind. The remainder of the mid-pack is generally strong.
A layer of large and weak facets that formed in November is deeply buried, found near the base of the snowpack. The likelihood of human triggering this layer is currently low given its depth. However, it is still best to avoid steep, thin, rocky slopes near ridges at alpine and upper treeline elevations.
Weather Summary
Friday Night
Cloudy with snowfall, accumulation 1 to 3 cm, 20 to 40 km/h southwest wind, treeline temperature -17 °C.
Saturday
Cloudy with snowfall, accumulation 5 to 10 cm with local enhancement possible, 20 to 40 km/h south wind, treeline temperature -15 °C.
SundayCloudy with snowfall, accumulation 15 to 30 cm, 20 to 40 km/h southwest wind, treeline temperature -13 °C.
MondayCloudy with snowfall, accumulation 5 to 10 cm, 20 km/h southwest wind, treeline temperature -12 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Carefully evaluate steep lines for wind slabs.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Wind slabs are prevalent in wind-exposed terrain. They formed from northeast wind that has now switched back to southwest wind, meaning that slabs may be found on all aspects. Note that storm slabs may also linger, particularly where they overly surface hoar crystals in sheltered treeline terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's deep burial depth. Suspect terrain for human triggering includes steep, thin, shallow, and rocky terrain, which is often found near ridgelines.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 25th, 2023 4:00PM
