Avalanche Forecast

Archived

Jan 26th, 2022–Jan 27th, 2022

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Northwest Coastal.

Warming and solar radiation could weaken the snowpack, perhaps increasing the chance of triggering slab avalanches on steep open slopes.

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

WEDNESDAY NIGHT: Clear skies, moderate wind from the southwest, mild temperatures with above freezing temperatures between 1000 and 2000 m.

THURSDAY: Clear skies, moderate wind from the southwest, freezing level drops from 2000 to 1000 m throughout the day.

FRIDAY: Storm arrives with cloudy skies and 5-15 cm of snow, strong wind from the south, freezing level fluctuates between 500 m and 1000 m with treeline temperatures around -2 C.

SATURDAY: Stormy weather continues with another 15-25 cm of snow, strong wind from the south, freezing level fluctuates between 500 m and 1000 m with treeline temperatures around -2 C.

Avalanche Summary

Warm sunny weather since Monday has resulted in a few loose wet and glide slab avalanches. The most concerning avalanche activity has been a string of persistent slab avalanches over the past week. These have occurred on a 30-50 cm deep layer of surface hoar in southern parts of the region around Terrace and Stewart. This has included both natural avalanches (last report from Tuesday) and human-triggered avalanches (last report from Sunday). The photos of the avalanche in this MIN report at Clague are good examples of the type of treeline elevation terrain where this problem can be found. We are uncertain whether the persistent slab problem will remain reactive throughout the current melt-freeze cycle and into the weekend.

Snowpack Summary

The snow surface is undergoing a spring-like melt-refreeze pattern. Warm sunny weather will likely melt the surface in most places except high north-facing terrain. The snowpack is likely capped by a hard crust in most areas, which has helped create a strong settled snowpack. The exception is a 30-50 cm deep surface hoar layer that could still be reactive, especially at treeline elevations in the Terrace and Stewart areas.

Terrain and Travel

Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Back off slopes as the surface becomes moist or wet with rising temperatures.
When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

Problems

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.