Avalanche Forecast

Archived

Mar 6th, 2025–Mar 7th, 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 unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Kitimat, Nass, Rupert, Seven Sisters, Shames, Howson.

New snow builds fresh, reactive storm slabs over weak surfaces and adds load to deeper buried weak layers. If you see more than 25 cm, treat avalanche danger as HIGH.

Confidence

Moderate

Avalanche Summary

Persistent slabs were reactive on the February weak layer early this week, with naturals up to size 3. Activity tapered dramatically by Tuesday when several natural cornice failures did not trigger slabs on slopes below, and on Wednesday explosive control work near Shames produced minimal results.

Looking forward, new snow means an increase in likelihood of both surface avalanches as well as renewed possibility of large persistent slab avalanche activity.

Snowpack Summary

New snow accumulates over a widespread layer of large surface hoar crystals, which sit over a crust on solar aspects and low elevations.

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

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

Weather Summary

Forecast snowfall amounts are highest on the immediate coast, near Kitimat and Prince Rupert, tapering sharply as you travel inland.

Thursday night

Cloudy with 5 to 10 cm of snow. 50 to 70 km/h southwest ridgetop wind. Treeline temperatures -3 °C. Freezing level 800 m.

Friday

Cloudy with 5 to 15 cm of snow above 1000 m, rain below. 80 to 100 km/h southwest ridgetop wind. Treeline temperatures -1 °C. Freezing level 1300 m.

Saturday

Mostly cloudy with 5 to 10 cm of snow above 800 m, light rain below. 30 to 50 km/h southwest ridgetop wind. Treeline temperatures -1 °C. Freezing level 1000 m.

Sunday

A mix of sun and cloud. 10 to 20 km/h northwest ridgetop wind. Treeline temperatures -4 °C. Freezing level 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be aware of the potential for larger than expected storm slabs due to buried surface hoar.
Dial back your terrain choices if you are seeing more than 25 cm of new snow.
Be mindful that deep instabilities are still present in the snowpack.
Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.