Avalanche Forecast

Archived

Feb 28th, 2024–Feb 29th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

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

As natural activity tapers off remember human triggering is still very likely.

Avalanches continue to be triggered from flat adjacent terrain and are propagating widely.

Confidence

Moderate

Avalanche Summary

Remotely triggered avalanches continue, with slabs to size 2.5 triggered from flat, non-avalanche terrain. Remote triggers indicate a sensitive snowpack and the need for very conservative terrain choices. Recent avalanches mostly occurred on north and east facing slopes at treeline and above, on both buried weak layers up to 100 cm deep.

While natural activity may have tapered off in some areas, this is not a sure sign of stability given the weak snowpack structure.

Snowpack Summary

40-70 cm of recent snow has been redistributed by strong winds at upper elevations. Soft snow can still be found in terrain sheltered from winds. This snow sits over facets, crust, and surface hoar in sheltered terrain. Reports show this is not bonding well, producing ongoing reactivity including remote avalanches.

A thick crust with weak facets on top is buried 50-100 cm deep. This layer has been problematic in the last 3 days, producing step-down avalanches.

Below, the mid and lower snowpack is generally well-bonded and strong.

Weather Summary

Wednesday Night

Partly cloudy with possible flurries. 20-40 km/h southeast ridgetop wind. Treeline temperature -10 °C.

Thursday

Mostly cloudy. Possible flurries. 30-50 km/h southeast ridgetop wind. Treeline temperature -8 °C.

Friday

A mix of sun and cloud. 30-50 km/h southeast ridgetop wind. Treeline temperature -7 °C.

Saturday

Cloudy with some sunny breaks. 20-30 km/h southeast ridgetop wind. Treeline temperature -10 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Make conservative terrain choices and avoid overhead hazard.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

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.