Avalanche Forecast

Archived

Feb 25th, 2023–Feb 26th, 2023

Alpine

Natural avalanches possible, human triggered probable.

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, Tutshi, Wheaton, White Pass East, White Pass West.

Snow continues to accumulate in small amounts and will be redistributed by moderate winds creating reactive wind slabs.

The persistent slab problem remains a concern. Choose terrain that has low consequences to manage this problem.

Confidence

Moderate

Avalanche Summary

No new avalanche observation since last weekend but this could be due to few to no reports coming from the backcountry.

Last Sunday, a size 1 wind slab was skier-triggered in a gully at treeline, reminding us that despite great riding in sheltered areas, reactive wind slabs still exist in more exposed areas. See the full report here.

The week previous, our field team observed debris from a previous large persistent slab avalanche. At least once a week evidence of large persistent slab avalanches is reported. Keep this in mind when traveling in the backcountry.

Thank you to all who contribute to the Mountain Information Network. If you head to the backcountry please help out your community by sharing your experiences.

Snowpack Summary

New snow has fallen on aging wind slabs on all aspects Approximately 30 to 50 cm down a decomposing crust, up to 5 cm thick, can be found. It appears to be bonding well to layers above and below and is widespread up to 1300 m and isolated as high as 1700 m.

A weak layer of surface hoar and facets may be buried about 90 to 140 cm deep on north-to-east aspects. This layer may rest on a harder melt-freeze crust. Where preserved, this layer, if triggered, is capable of producing very large avalanches.

Weather Summary

Saturday Night

Cloudy with possible late-day sunny breaks, 2 cm accumulation, winds north 20 to 30 km/h, treeline temperatures around -15 ºC.

Sunday

A mix of sun and cloud, trace accumulation, winds northeast 35 to 40 km/h, treeline temperatures around -20 ºC.

Monday

Mostly sunny, trace accumulation, winds north northeast 30 km/h, treeline temperatures -20 ºC.

Tuesday

Mostly sunny, trace accumulation, winds north northeast 30 km/h, treeline temperatures -25 ºC.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Recent wind has varied in direction so watch for wind slabs on all aspects.
The best and safest riding will be on slopes that have soft snow without any slab properties.
Avalanche hazard may have improved, but be mindful that deep instabilities are still present.

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.

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.