Avalanche Forecast

Issued: Feb 7th, 2017 3:41PM

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

Avalanche Canada cgarritty, Avalanche Canada

Wind slabs have been either resupplied or thinly covered, depending on local winds. Especially touchy conditions have been reported in the south of the region where more new snow has accumulated.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

Wednesday: A mix of sun and cloud. Winds light from the south. Alpine temperatures of -13 with a possible alpine temperature inversion.Thursday: Flurries bringing 10-20 cm of new snow. Winds moderate from the southeast. Alpine temperatures of -5.Friday: Flurries delivering another 5-10 cm of new snow. Winds strong from the southwest. Alpine temperatures of -5

Avalanche Summary

No new avalanches were reported on Monday, but a Size 1.5 slab was triggered by a ski touring party in the central part of the region on Sunday. The slide initiated in a wind loaded pocket on a southwest aspect at 2100 metres and featured a 100cm deep crown fracture. While it is not believed to have involved persistent weak layers, it does reveal the scale of recent wind slab growth as well as their remaining sensitive to light triggers in specific terrain. Another relatively recent report includes details of a remotely triggered Size 2.5 avalanche that occurred in the south of the region on Thursday. The slide took place on a roughly 30 degree south-facing slope at 2100 m in elevation. The remote trigger, a depth of 80 cm, and a failure plane attributed to our January 15 surface hoar all reinforce enduring concerns for persistent slab problems in the region.

Snowpack Summary

Up to 10 cm of new snow over the past few days has given a thin cover to wind slabs that currently exist on a variety of aspects in wind-exposed terrain. While these wind slabs are suspected to be growing stubborn, our supply of new snow can be expected to have fed into the wind slab problem in wind exposed areas. In more sheltered areas, the new snow has buried faceted surface snow as well as surface hoar existing on sheltered open slopes. The persistent weakness buried mid-January is now down 50-100 cm and consists of buried surface hoar in sheltered areas, and/or widespread faceted old snow. It has generally stabilized but may remain reactive in isolated areas where buried surface hoar is preserved. Another surface hoar/facet weakness buried mid-December can now be found down about 70 cm in shallow snowpack areas. While reactivity at this layer has declined, professionals in the region are still treating it with a great deal of caution.It should be noted that areas in the far south of the region saw as much as 25 cm of new snow over the course of the recent storm, coupled with strong winds. In these areas, the wind slab problem should be treated with considerably more caution.

Problems

Wind Slabs

An icon showing Wind Slabs
Variable winds formed touchy wind slabs on a wide range of aspects last week. Light snowfall and strong winds over the past couple of days have contributed to the problem, especially in the south of the region where more new snow accumulated.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 8th, 2017 2:00PM