Avalanche Forecast
Issued: Jan 22nd, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
zryan,
Avalanche Canada
Reactive wind slabs may exist on leeward slopes and behind terrain features.
Be mindful of a lingering persistent slab problem. Buried surface hoar has produced some spooky human-triggered avalanches in the past few days.
Summary
Confidence
Weather Forecast
Saturday Overnight: Cloud cover increasing, snowfall in the early morning, 5-10 cm accumulation. Moderate to strong southwest winds. Freezing level around 800m.
Sunday: Mainly cloudy, light precipitation. Freezing level around 1000m. Moderate to strong northwest winds.
Monday: Partially cloudy. Freezing level rising to 2500m. Light to moderate southwest winds.
Tuesday: Mainly cloudy, light precipitation. Freezing level around 1000m. Light to moderate southwest winds.
Avalanche Summary
On Thursday, numerous natural, human-triggered, and remote-triggered storm slab avalanches up to size 2.5 were observed throughout the region. A buried layer of surface hoar, and below 1300m a thick melt-freeze crust likely contributed to the reactivity and wide propagation of these storm slabs.
On Friday, operators north of Terrace reported several skier-remote wind slab avalanches size 1.5-2.5 that failed on a surfacer hoar layer.
Snowpack Summary
Overnight, 5-10 cm of new snow adds to this week's storm totals of 30-50 cm. In the past 3 days, freezing levels have fluctuated between 500-1300m in the Terrace area with periods of rain on snow. It is likely that lower elevations and potentially steep solar aspects have some form of crust on or near the surface.
This week's storm came in with warm temperatures, building a denser slab above a weak layer of buried surface hoar and a thin melt-freeze crust below 1300 m. The presence of these weak layers means reactivity might persist for longer than usual. In wind loaded areas, associated strong southwest winds have created wind slabs in lee areas.
A layer of sugary facetted grains may be found about 80 to 130 cm deep, which formed during the cold spell in late December to early January. To date, this layer has only been problematic in the northern half of the region.
The remainder of the snowpack is strong in the south of the region. In the north of the region, the base of the snowpack consists of faceted grains around a melt-freeze crust, which is currently dormant.
Terrain and Travel
- Be alert to conditions that change with elevation and wind exposure.
- Watch for areas of hard wind slab on alpine features.
- Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
Problems
Persistent Slabs
Earlier in the week, 30 to 50 cm of new snow fell with warm temperatures, creating a denser slab above a weak layer of surface hoar which sits on a hard melt-freeze crust below 1300m. Below ~1000m, rain on snow has probably destroyed this layer of surface hoar and formed a crust on the surface. The most suspect areas would be sheltered, open areas near treeline.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Overnight snowfall will add to this week's 30-50cm of new snow. Southwest winds will have continued to build wind slabs in lee areas in the alpine and treeline.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 23rd, 2022 4:00PM
