Avalanche Forecast

Issued: Feb 27th, 2019 4:14PM

The alpine rating is moderate, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Persistent Slabs and Loose Dry.

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 on the conditions in the South Coast region.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

WEDNESDAY OVERNIGHT: Light snowfall amounts 5-10 cm overnight with light southwest winds. THURSDAY: New snow 5-10 cm by the end of the day. Ridgetop winds light from the East and treeline temperatures near -3. FRIDAY: Mix of sun and cloud. Ridgetop winds light from the northeast and treeline temperatures near -3. Freezing levels 600 m.SATURDAY: Mix of sun and cloud. Ridgetop winds light from the northeast and treeline temperatures near -2. Freezing levels 700 m.

Avalanche Summary

As of Tuesday there have been no recent reports of avalanche activity. Last Monday, a fatal avalanche occurred on a steep feature at treeline elevation in the Mount Seymour backcountry (see here for incident report).

Snowpack Summary

The recent snow will likely have a poor bond to the older snow surfaces and loose dry avalanches may occur on steeper slopes and terrain features depending on accumulative amounts. Roughly 30 cm of snow from the weekend storm sits above a mix of sun crusts and possibly some weak faceted snow and surface hoar. Below this, a widespread crust layer is now buried 50-100 cm deep with weak snow above it. This deeper weak layer has produced large natural and human-triggered avalanches over the past week. The reactivity of this layer appears to be worse in the south of the region (i.e. the North Shore Mountains), since this part of the region saw more snow from recent storms and this storm snow consolidated into a stiffer slab. This problem is not typical for the region and we expect this layer to remain reactive for some time into the future. The lower snowpack is settled and strong.Please check out these MIN reports for more snowpack information:Near Mt. Seymour AST Course 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.

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

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Dry

New cold low density snow that falls on Thursday will likely have a poor bond to the older snow surfaces. Loose dry avalanches may be running on steeper slopes and terrain features.

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: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Feb 28th, 2019 2:00PM