Avalanche Forecast

Archived

Feb 5th, 2022–Feb 6th, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Below Threshold.

Regions

Yukon.

Strong winds and rising freezing levels are keeping the danger elevated. Start simple and avoid wind-drifted areas. Continually monitor the effect of warming on the recent snow.

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Uncertainty is due to difficult to forecast freezing levels.

Weather Forecast

Saturday night: Cloudy, 5-10 cm of snow, strong south wind with extreme gusts in the alpine, alpine temperatures near -4 C, freezing level rising to 200 m.

Sunday: Cloudy, 5-15 cm of snow, strong south wind with extreme gusts in the alpine, alpine high temperature near -3 C, freezing levels vary through region from 500-1000 m.

Monday: Cloudy with sunny breaks, 5-15 cm of snow, strong southwest winds, alpine temperatures dropping from -5 C to -8 C, freezing level dropping to valley bottom m.

Tuesday: Cloudy with sunny breaks, 10-20 cm of snow, strong southwest winds, alpine high temperatures near -4 C, freezing level rising to 1000 m.

Avalanche Summary

Recent reports have been limited. Earlier in the week, there were reports of numerous small (size 1) dry loose and soft slab avalanches. These ran naturally and we easy to trigger with ski cuts. On the Alaska side, strong outflow winds made for touchy avalanche conditions, with large natural releases running to the road. We expect that similar conditions exist on White Pass as the wind has picked up.

Snowpack Summary

Strong south winds picked up on Saturday, re-distributing 50 cm of low-density snow into reactive wind slabs on lee terrain features. These wind slabs will remain likely to trigger on Sunday. These slabs formed above surface hoar on sheltered northerly aspects and hard slab in wind-affected areas. Investigate these underlying surfaces for a poor bond.

Treeline temperatures have warmed rapidly over the past 48 hours, which is likely to destabilize the new snow. Freezing levels are forecast to vary but may reach 1000 m in the eastern half of the region. Use extra caution in areas experiencing above freezing temperatures for the first time.

In shallow snowpack areas, a layer of loose facets can be found at the bottom of the snowpack.

Terrain and Travel

Avoid freshly wind loaded terrain features.
Expect slab conditions to change drastically as you move into wind exposed terrain.
Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
Extra caution for areas experiencing rapidly warming temperatures for the first time.
As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.

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.