Avalanche Forecast

Archived

Mar 5th, 2019–Mar 6th, 2019

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Cariboos.

Human triggered avalanches remain possible, especially in wind loaded areas. A persistent slab problem at lower elevations still requires careful terrain selection, as the consequences of an avalanche on this layer remain high.

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT - Clear periods / east winds 20-35 km/h / alpine low temperature near -10WEDNESDAY - Cloudy with sunny periods / southeast winds 20-40 km/h / alpine high temperature near -5THURSDAY - Flurries, 5 cm / southwest winds 10-20 km/h / alpine high temperature near -7FRIDAY - Cloudy with scattered flurries / west winds, 15-25 km/h / alpine high temperature near -10

Avalanche Summary

No new avalanches have been reported in the region over the past few days, but observations in neighbouring regions have shown regular, generally small (size 1) wind slabs reacting to skier traffic and ski cutting at higher elevations. Avalanche activity on the mid January persistent weak layer has tapered off, however test results still suggest that this layer could be triggered by humans in specific locations. When persistent weak layers stop producing regular avalanches, they can become very difficult to manage. This weak layer has become a low likelihood/high consequence avalanche problem. Check out a recent MIN report from Allen Creek here that illustrates this.

Snowpack Summary

The upper snowpack at higher elevations is a mix of wind-affected snow and wind slabs on all aspects, as well as a crust on sun exposed slopes. The wind slabs are sitting on facets (sugary snow), and may continue to be reactive.In more sheltered areas at lower elevations, a weak layer buried in mid January can be found approximately 50-60 cm deep. This layer consists of surface hoar (feathery crystals) and facets, and may be combined with a crust on south facing slopes. This layer has been most reactive at treeline and below treeline. The lower snowpack is generally considered to be strong, except for shallow, rocky areas where cold temperatures continue to facet (weaken) the snowpack.

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.