Avalanche Forecast

Archived

Mar 4th, 2024–Mar 5th, 2024

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

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

Dangerous avalanche conditions persist.Large avalanches continue to be remotely triggered and are propagating widely.

Confidence

High

Avalanche Summary

Numerous large and very large natural, explosive, and human-triggered avalanches have occurred across the region over the last few days. These include several large (size 2) remotely triggered slabs.

Remote triggers indicate a sensitive snowpack and the need for very conservative terrain choices.

Recent avalanches have occurred on all aspects and at various elevations, on buried weak layers up to 100 cm deep.

Click on the photos below for more details.

Snowpack Summary

Strong winds have created widespread wind effect and built reactive wind slabs at treeline and above. Wind direction has varied so you can expect these slabs on all aspects. In sheltered areas, new surface hoar is growing.

Several persistent weak layers are buried between 50 to 120 cm deep. These weak layers include hard crusts, weak facets and surface hoar.

The recent storm snow is not bonding well to these underlying persistent weak layers. These layers have been producing ongoing avalanche reactivity, including remote triggering and very large step-down avalanches.

Weather Summary

Monday Night

Clear skies. North ridgetop wind, 5 to 15 km/h. Treeline temperature -18 °C.

Tuesday

Sunny. West ridgetop wind, 10 to 20 km/h. Temperature inversion with treeline temperature -15 °C.

Wednesday

Cloudy with 2 to 8 cm new snow by next day. Southwest ridgetop wind, 25 to 50 km/h. Temperature inversion with treeline temperature -10 °C.

Thursday

Cloudy with up to 3 cm of new snow. Southwest ridegtop wind, 30 to 50 km/h. Temperature inversion with treeline temperature -7 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Caution required around non obvious avalanche terrain like road cutbanks, cutblocks and other non obvious avalanche terrain

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.