Avalanche Forecast

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Unsettled conditions are expected on Monday as a weather system off the north coast moves southward resulting in a shifting wind direction and lower freezing levels for the region. The system is expected to reach the region Monday evening bringing light snowfall for Tuesday. 

Sunday Night: Mainly clear, moderate NW wind, freezing levels around 2000 m.

Monday: Increasing cloud cover, light to moderate NW wind, freezing levels around 1500 m.

Monday night and Tuesday: Light snowfall up to 5 cm, moderate NW wind, freezing levels around 800 m.

Wednesday: Sunny, moderate to strong NE wind, freezing levels around 500 m.

On Saturday, a natural size 2 persistent slab avalanche was reported in the Duffey area on a north aspect at 1900-2000 m elevation. This appears like it might have been triggered by a loose avalanche from a steep rocky slope above, or a cornice falling. The reported depth was 40 cm and the failure plane was assumed to be the February crust/facet layer. 

Also on Saturday, a ski cut triggered a size 1 wind slab at 2100 m elevation near a ridge crest and a few natural wind slabs up to size 2 were observed on steep, unsupported slopes. A variety of loose wet avalanches up to size 2 were also observed. In the Coquihalla, a few glide slab avalanches were observed. In the north of the region, some natural cornice failures were also reported which had occurred sometime in the past three days and had triggered slabs on the slopes below.

A surface melt-freeze crust is now expected on all aspects to at least 1700 m and on sun-exposed slopes into the alpine. Dry surface snow is still expected on shaded aspects at higher elevations, and recent periods of moderate northerly wind may be redistributing this old storm snow and forming wind slabs in exposed high elevation terrain.

Two weak interfaces from February are present in the snowpack. In the north of the region, these layers are down 40-60 cm and are expected to be very close together or may be acting as a single weak layer like in the neighbouring Sea to Sky region. In the south of the region, the late-February crust is down around 30 cm and the mid-February crust is down around 80 cm. These layers don't seem to be creating a problem for the south of the region but remain reactive in the north. While the exact distribution of the problem is uncertain, it is expected to be most reactive on shaded aspects at 1600-2000 m elevation. 

Cornices had been reported to have grown large during last week's storm, primarily on north and east aspects, and there were a few cornice failures over the weekend. Cornices are expected to be less of a concern on Monday as freezing levels drop and there is less sun in the forecast.

• Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.