Avalanche Forecast

Issued: Mar 1st, 2019 4:37PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Wind Slabs.

swerner, Avalanche Canada

South Coast.

Persistent slab avalanche problems are tricky to manage. They tend to linger, waiting for a trigger. Check out the Forecasters' BLOG for more details.

Summary

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

Heading into March feels more like January. The strengthening ridge will bring us another fairly long stretch of cold, dry and clear weather.SATURDAY/ SUNDAY/ MONDAY: A mix of sun and cloud with treeline temperatures near -5. Light to moderate ridgetop wind from the northeast through the forecast period.

Avalanche Summary

On Thursday, no new avalanches were reported. On February 18th a fatal avalanche occurred on a steep feature at treeline elevation in the Mount Seymour backcountry (see here for incident report).

Snowpack Summary

In exposed areas the upper snowpack has been highly wind affected and stiff supportive wind slabs exist. In sheltered areas you can still find pockets of low density snow. Below the surface a crust/ graupel and in some places surface hoar layer can be found down 50 cm. These layers have not been producing conclusive test results. More concerning is the deeper interface down 80-120 cm which is a crust/ facet combination and still producing moderate sudden collapse snowpack test results. The bond of the upper snowpack on this layer is weaker on north aspects and triggering a large avalanche on this interface with the weight of a person is possible at treeline.The reactivity of this layer appears to be worse in the North Shore Mountains. The problem is not typical for the region and we expect this persistent layer to linger into the future. The lower snowpack is settled and strong.Please check out these MIN reports for more snowpack information:Diggin' Mt. Seymour AST Mt Seymour

Problems

Persistent Slabs

A weak layer of facets (sugary snow) over a crust is buried 50-100 cm deep. Triggering large avalanches on this layer remains possible in steep terrain, especially in the North Shore Mountains.

Be aware of the potential for wide propagations due to the presence of a buried weak layer.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Isolated wind slabs may be reactive especially on southwesterly aspects.

If triggered the loose dry sluffs may step down to deeper layers resulting in large avalanches.Use caution above cliffs and gullies where small avalanches may have severe consequences.

Aspects: South, South West, West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Mar 2nd, 2019 2:00PM