Avalanche Forecast

Archived

Jan 8th, 2024–Jan 9th, 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 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

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

Dangerous avalanche conditions exist at higher elevations where new snow and strong winds are building fresh, reactive storm slabs and adding additional load to buried weak layers.

Confidence

Moderate

Avalanche Summary

On Sunday, a few natural, size 2, wind slab avalanches were reported. Wind slab activity was observed in cross-loaded terrain on west aspects in the alpine.

On Saturday, a very large (size 4) avalanche was reported on Joffre shoulder. It was observed from a distance so it is hard to determine what layer this avalanche failed on however we suspect it to be the weak layer of facets or surface hoar overlying a crust at the base of the snowpack.

Snowpack Summary

By Monday morning 10 to 20 cm of snow and strong winds will have built fresh slabs at higher elevations. New snow overlies 30 to 60 cm of settling snow and wind affected surfaces.

A prominent crust varying in thickness is found at treeline and below, 40 to 80 cm down. In some areas, a layer of preserved surface hoar is found just above the crust.

Another weak layer of facets or surface hoar overlying a crust is found at the base of the snowpack down 80 to 120 cm. This is the suspected failure plane for a few large avalanches in the region that occurred on January 6.

Snowpack depths are 100 to 140 cm at treeline and decrease rapidly below.

Weather Summary

Monday Night

Cloudy with flurries, 10 to 20 cm of snow. Southwest ridgetop winds 30 to 70 km/h. Treeline temperature -8 °C.

Tuesday

Cloudy with flurries, 5 to 10 cm of snow. West ridgetop winds 20 to 40 km/h. Treeline temperature -9 °C.

Wednesday

A mix of sun and cloud with isolated flurries, trace amounts of snow. Northwest ridgetop winds 10 to 30 km/h. Treeline temperature -12 °C.

Thursday

Partly cloudy with isolated flurries, up to 3 cm of snow. Southwest ridgetop winds 20 km/h. Treeline temperatures drop through the day to -18 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Dial back your terrain choices if you are seeing more than 25cm of new snow.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Avoid exposure to overhead avalanche terrain during periods of heavy loading from new snow, wind or rain.

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.