Avalanche Forecast

Archived

Jan 23rd, 2021–Jan 25th, 2021

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Below Threshold.

Regions

Yukon.

White Pass has performed its typical transformation into a landscape of heavily wind affected surfaces and large, hard wind slabs. These slabs may have grown stubborn to trigger but they carry big consequences. Select routes that minimize your exposure to these hazards.

Confidence

High -

Weather Forecast

SATURDAY NIGHT: Cloudy with scattered flurries bringing up to 5 cm of new snow. Light southwest winds.

SUNDAY: Cloudy with lingering isolated flurries and about 5 cm of new snow, including overnight amounts. Light north winds. Alpine high temperatures around -10

MONDAY: Cloudy with isolated flurries and a trace of new snow. Light southwest winds. Alpine high temperatures around -13.

TUESDAY: Cloudy with isolated flurries and a trace of new snow. Light northeast winds. Alpine high temperatures around -17.

Avalanche Summary

A widespread natural avalanche cycle occurred during the height of last week's storm with naturally triggered storm slabs reported up to size 3.

Explosives control on Thursday in the pass south of the US-Canada border produced consistent slab releases to size 2. This gives some indication of hazards that may still exist on the Canadian side.

Snowpack Summary

About 50 cm of recent snow and strong southwest, shifting to northerly winds have created widespread, potentially still reactive wind slabs on a variety of aspects. The same conditions also created fragile new cornice growth.

Around Log Cabin, around 70 cm of snow may overlie a layer of surface hoar. This layer was the culprit of avalanche activity during the first week of January but has not been reported elsewhere in the region.

A buried crust from early December can be found 50-130 cm below the surface, but most reports suggest the snow is well-bonded to it.

The lower snowpack is strong around White Pass, but there is potential for a generally thinner and weaker snowpack structure to exist in inland areas, such as the Wheaton Valley and even more so in the south Klondike.

Terrain and Travel

Watch for areas of hard wind slab on alpine features.
Recent wind has varied in direction so watch for wind slabs on all aspects.
Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

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.