Avalanche Forecast

Archived

Mar 14th, 2022–Mar 15th, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

South Coast Inland.

Snowfall amounts will vary throughout the region Tuesday. The danger rating reflects forecast snowfall for the Coquihalla. In areas that receive less than 15 cm, avalanche danger may be a step lower. Make observations and assess conditions as you travel.

Confidence

Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

Monday night: Snowfall 5-15 cm, 30-50 km/h southwest wind, alpine temperature -5 C. Freezing level 1300 m.

Tuesday: Snowfall 5-10 cm in the north, 10-20 cm in the south, 40-50 km/h southwest wind, alpine temperature -5 C. Freezing level 1500m.

Wednesday: Overnight snowfall 5-10 cm then mostly cloudy, 20-30 km/h southwest wind, treeline temperature -5 C. Freezing level 1400 m.

Thursday: Snowfall starting around 5 cm, 20-30 km/h south wind, treeline temperature -4 C. Freezing level 1500 m.

Avalanche Summary

No new avalanche observations since Wednesday when a rider triggered a persistent slab avalanche along the Duffey at 2000 m on a northeast aspect. Another suspected persistent slab avalanche was triggered by a rider on Tuesday in the north of the region. Both slabs were around 30 to 40 cm thick, resulting in small avalanches (size 1 to 1.5). It remains possible that humans could trigger this layer, where it exists.

Snowpack Summary

New snow accumulates over variable surfaces including a hard melt-freeze crust on solar aspects and low elevations, previously wind-affected snow at higher elevations and perhaps a thin layer of surface hoar or faceted snow in sheltered areas.

Around 30 to 60 cm deep, sugary faceted grains may be found around a melt-freeze crust that formed February in the north of the region (e.g., Duffey, Hurley). The layer has been most prevalent on north to northeast aspects around 1900 to 2100 m. Check out this forecaster blog for more info.

Various crusts may be found in the south of the region (e.g., Coquihalla, Manning) but reports suggest they are bonding to the snowpack and are not an avalanche concern.

There are no deeper concerns at this time.

Terrain and Travel

Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
Avoid freshly wind loaded terrain features.
Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
Dial back your terrain choices if you are seeing more than 25cm of new snow.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.