Avalanche Forecast

Archived

Mar 15th, 2025–Mar 16th, 2025

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Continued reports of human-triggered persistent slab avalanches show buried weak layers remain sensitive

Careful snowpack evaluation and conservative decision-making are essential

Confidence

Moderate

Avalanche Summary

On Friday, a size 1.5 and a size 2 human-triggered persistent slab avalanches were reported in open alpine features at 2000 m.

Reports from earlier this week observed both natural and human-triggered wind slab and persistent slab avalanche activity to size 3 in the alpine. These avalanches were 20 to 40 cm deep and were all suspected of running on a weak layer of surface hoar buried in early March.

Snowpack Summary

Southerly winds have redistributed 20 to 40 cm of recent snow into deep pockets on lee slopes. This snow buried a widespread layer of large surface hoar crystals, which sits on a crust on solar aspects and at low elevations. This layer has been reactive in recent days where a slab has consolidated above.

A layer of facets, surface hoar and/or a crust from mid-February is buried 50 to 100 cm deep. This layer produced large natural and human-triggered avalanches last week.

The remainder of the snowpack is well consolidated with no concerns at this time.

Weather Summary

Saturday Night

Cloudy with light flurries, 1 to 5 cm of snow. 20 to 30 km/h south ridgetop wind. Treeline temperature -10 °C.

Sunday

Cloudy with light flurries, 2 to 3 cm of snow. 15 to 25 km/h southwest ridgetop wind. Treeline temperature -8 °C.

Monday

A mix of sun and clouds. 15 to 30 km/h west ridgetop wind. Treeline temperature -11 °C.

Tuesday

Cloudy with light flurries, 1 to 5 cm of snow. 20 to 30 km/h southwest ridgetop wind. Treeline temperature -6 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
Be aware of the potential for large avalanches due to buried weak layers.
Keep in mind that human triggering may persist as natural avalanches taper off.
In times of uncertainty, conservative terrain choices are our best defense.

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.