Avalanche Forecast

Issued: Feb 28th, 2019 4:20PM

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 further details about the conditions in the South Coast region.

Summary

Confidence

Moderate - The weather pattern is stable

Weather Forecast

FRIDAY: A mix of sun and cloud. Treeline temperatures near -2 and ridgetop winds light from the northwest. Freezing levels near 700 m.SATURDAY/ SUNDAY: A mix of sun and cloud. Treeline temperatures near -4 and ridgetop winds light to moderate from the northeast. Freezing levels 600 m.

Avalanche Summary

On Wednesday 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

The new snow will likely have a poor bond to the older snow surfaces. 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 layer can be found down 50 cm and is starting to slowly bond to the upper snowpack. The deeper interface down 80-120 cm 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 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. This deeper weak layer has produced large natural and human-triggered avalanches over the past week. 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 over a crust is buried 50-100 cm deep. Triggering large avalanches on this layer remains possible in steep terrain, especially on the North Shore Mountains.

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

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Isolated wind slabs may be reactive on southwesterly aspects. Loose dry avalanches may be running on steeper slopes and terrain features.

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

Aspects: South East, South, South West, West, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Mar 1st, 2019 2:00PM