Avalanche Forecast

Archived

Apr 23rd, 2025–Apr 24th, 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.

Assess for wind slabs in steep terrain. Cornice failures during daytime warming could trigger buried weak layers, particularly in northerly alpine terrain.

Confidence

Moderate

Avalanche Summary

No new avalanches were observed on Tuesday. A few small loose avalanches and cornice failures were observed on Monday.

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

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

Snowpack Summary

Around 10 cm of dry snow may be found on high elevation north aspects, with potentially deeper deposits in immediate lee terrain due to strong southwest wind. Elsewhere, a hard melt-freeze crust is likely found on the snow surface, which may soften with daytime warming.

At alpine and treeline elevations, a layer of surface hoar that formed in early March may be found around 70 to 120 cm deep. A layer of facetted grains and a crust that formed mid-February may be found 120 to 200 cm deep.

The remainder of the snowpack is consolidated.

Weather Summary

Wednesday Night

Mostly cloudy. 20 km/h southeast ridgetop wind. Treeline temperature -2 °C. Freezing level 1100 m.

Thursday

A mix of sun and cloud. 20 to 30 km/h south ridgetop wind. Treeline temperature +2 °C. Freezing level 1500 m.

Friday

Cloudy with 5 to 10 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1300 m.

Saturday

Cloudy with 5 cm of snow. 10 to 20 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1300 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.