Avalanche Forecast

Archived

Apr 21st, 2025–Apr 22nd, 2025

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Coastal, Northwest Inland, Boundary, Stewart, Kispiox, Ningunsaw, Ningunsaw, Ningunsaw.

Weak layers in the snowpack continue to be a concern. A cautious approach is recommended, especially in high-elevation, north terrain where the snowpack remains most complex.

Confidence

Moderate

Avalanche Summary

On Sunday, cornice failures triggered two very large (3-5) natural persistent slab avalanches. There were multiple step-downs visible in the crowns, and these avalanches likely failed on the weak layers formed in February and March.

Cornices continue to be a prime suspect for triggering large, destructive avalanches.

Snowpack Summary

A widespread surface crust formed following last week's warming event. At upper elevations, moderate to strong southwest winds will continue to redistribute new snow in exposed terrain.

Three layers of note currently exist in the mid-snowpack and still have the potential to cause large avalanches:

A layer of surface hoar and a crust that formed in mid-March is 50 to 80 cm below the snow surface.
Another layer of surface hoar that formed in early March buried 70 to 120 cm.
A layer of facets, surface hoar, and/or a crust from mid-February is buried 120 to 200 cm deep.

The remainder of the snowpack is well consolidated.

Weather Summary

Monday night

Cloudy with up to 5 cm of new snow. 30 to 50 km/h northwest ridgetop wind. Treeline temperature -4 °C. Freezing level 700 m.

Tuesday

Cloudy with up to 5 cm of new snow. 30 to 60 km/h southwest ridgetop wind. Treeline temperature -0 °C. Freezing level rises to 1300 m.

Wednesday

Cloudy with up to 5 cm of new snow. 20 to 50 km/h southwest ridgetop wind. Treeline temperature +1 °C. Freezing level rises to 1500 m.

Thrusday

A mix of sun and cloud. 30 to 50 km/h south ridgetop wind. Treeline temperature +2 °C. Freezing level rises to 1900 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.
Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Limit exposure to steep, sun exposed slopes, especially when the solar radiation is strong.

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.

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.