Avalanche Forecast

Archived

Jan 27th, 2024–Jan 28th, 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 and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

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.

Regions

Blue River, McBride, Premier, Clemina, Esplanade, North Monashee, North Selkirk, Dogtooth, West Purcell.

Rising freezing levels will further destabilize a complex snowpack with several avalanche problems. Conservative terrain selection is critical.

Confidence

High

Avalanche Summary

On Friday in the Dogtooth range, a group of skiers accidentally triggered a size 4 (!!!) (absolutely enormous) avalanche from a ridgetop and were thankfully (physically) unharmed.

This adds to a lonnng list of large to very large avalanches on various weak layers throughout the east Cariboos, northern Selkirks, and west Purcells in recent days, including natural, rider and remote triggered size 2-3.5.

Snowpack Summary

Light snowfall accumulates in the alpine while wet flurries moisten surfaces below as freezing levels creep up the mountain.

Beneath lies a complex snowpack containing several layers of concern that continue to produce avalanche activity:

Facets formed during the mid January cold snap sit 15-30 cm deep.
A surface hoar/facet/crust layer formed in early January sits 60-80 cm deep.
Another surface hoar layer that was buried in early December is now 130+ cm deep and remains a concern above 2000 m where it is not capped by a crust.

The lower snowpack is characterized by weak basal facets in many areas. Avalanches on this layer have been large and destructive.

Weather Summary

Saturday night

Up to 10 cm of new snow. Southwest alpine wind 10-20 km/h. Treeline temperature -1 °C. Freezing level 1500 m.

Sunday

Mostly cloudy with wet flurries brining 5-10 mm of mixed precipitation. Southwest alpine wind 10-20 km/h. Treeline temperature 0 °C. Freezing level 2000 m.

Monday

A mix of sun and cloud. Southwest alpine wind 20-30 km/h. Treeline temperature +2 °C. Freezing level 2500 m.

Tuesday

Mostly cloudy with scattered flurries. Southwest alpine wind 10-20 km/h. Treeline temperature 0 °C. Freezing level dropping to 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Make conservative terrain choices and avoid overhead hazard.
Extra caution for areas experiencing rapidly warming temperatures for the first time.
Be aware of the potential for large, destructive avalanches due to the presence of deeply buried weak layers.
Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.

Problems

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.