Avalanche Forecast
Issued: Feb 16th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Wind Slabs.
jpercival,
Avalanche Canada
A thin and very tricky snowpack that harbors a deep persistent slab avalanche is prevalent in this region. Employ travel techniques that focus on conservative terrain selection and minimize exposure to steep terrain features.
Avoid shallow rocky areas where the snowpack transition from thick to thin and triggering deep persistent layers is more likely.
Summary
Confidence
Moderate
Avalanche Summary
On Tuesday, several large natural deep persistent slab avalanches were reported near South Chilcotin Mountains Provincial Park and the Birkenhead area. The avalanches were up to size 3 and were likely triggered by cornices or wind. See this MIN for photos of a few of the avalanches.
Numerous small loose dry avalanches were reported to size 1.5 on all aspects. A skier accidental size 1 wind slab avalanche was reported in northeast facing alpine terrain.
On Monday afternoon, search and rescue technicians responded to a fatal avalanche incident north of the Sea to Sky region. The avalanche is believed to have occurred on Saturday and was initiated in a shallow rocky area. See the MIN for more details.
A skier remote triggered, size 2 avalanche was reported on a cross-loaded morainal feature. The group reported the avalanche as a soft wind slab over a crust. The slope fractured 30 m above the group. See the MIN for more information.
Snowpack Summary
10-20 cm of recent storm snow is being redistributed by variable winds. This overlies wind-affected surfaces at higher elevations and a crust at lower elevations. On steep solar slopes, a new sun crust has formed on the surface.
A melt-freeze crust from late January is found down 60-80 cm. At the moment this layer appears to be gaining strength though in isolated areas small facets are still found surrounding the crust.
There is a widespread weak layer of large sugary of facets at the bottom of the snowpack. This layer has recently resulted in a handful of large destructive avalanches. These avalanches seem to be concentrated in the northern half of the region however the layer is found throughout. Snowpack depths around treeline range between 150 to 250 cm.
Weather Summary
Thursday Night
Overcast with continued light to moderate snowfall, 5 to 15 cm of accumulation. Winds southwest 30 km/h gusting 50 km/h. Treeline temperatures -9 °C and freezing levels 500 m.Â
Friday
Cloudy with sunny periods and isolated flurries, with a trace of accumulation. Winds west 25 km/h. Treeline temperature -6 °C. Freezing level rising to 1000 m mid-day.
Saturday
Cloudy with isolated flurries, trace accumulation. Winds northwest 10 km/h gusting to 40 km/h. Treeline temperature -6 °C. Freezing level rising to 1000 m mid-day.
Sunday
Cloudy with isolated flurries, trace accumulation. Winds northwest 10 km/h gusting to 40 km/h. Treeline temperature -6 °C. Freezing level rising to 1000 m mid-day.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer is most likely to be problematic in steep, unsupported, wind-loaded terrain or by first triggering a layer further up in the snowpack. Avoid shallow rocky snowpack areas where the risk of triggering these layers is higher.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Southwesterly winds are distributing available snow into fresh wind slabs on north and east slopes in the alpine and upper treeline. Wind slabs may be sitting on a crust making them especially reactive to ridder triggering.
Previously northerly winds built wind slabs in exposed alpine features. Continue to use caution around these features and watch for areas that have been reverse-loaded and cross-loaded.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 17th, 2023 4:00PM
