Avalanche Forecast

Issued: Dec 19th, 2016 4:29PM

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

Avalanche Canada jlammers, Avalanche Canada

Sunday's snowfall amounts varied greatly across the region. Where more snow fell, the avalanche danger may be higher than posted.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

Tuesday: 3-10cm of new snow / Strong west winds / Freezing level at 600mWednesday: 5-15cm of new snow / Extreme Southwest winds / Freezing level at 900mThursday: Light flurries with possible sunny breaks / Moderate southwest winds / Freezing level at 500m

Avalanche Summary

No recent avalanches have been reported in this region. There was likely a round of fresh wind slab activity in response to new snow and wind on Sunday night. Despite possible breaks in the weather, fresh wind slabs may remain sensitive to human triggering due to underlying weak crystals.

Snowpack Summary

Between 3 and 15 cm of new snow fell on Sunday night. Extreme winds have redistributed the new snow into fresh wind slabs in exposed terrain. The new storm snow sits over a highly variable interface resulting from over a week of clear skies, cold temperatures, and strong outflow winds. This mid-December interface consists of scoured surfaces and hard wind slabs in wind exposed terrain, widespread faceting of the upper snowpack, and surface hoar in sheltered areas. The new snow is expected to bond poorly to this interface.Snowpack observations have been very limited recently in the region. The snowpack is very shallow throughout the region and widespread faceting of the entire snowpack is expected in most areas. A thick rain crust that formed in early November is probably near the bottom of the snowpack and is expected to be developing facets. Reports from the Ningunsaw Pass area and the far north of the region suggest that depth hoar is developing in shallow snowpack areas.

Problems

Wind Slabs

An icon showing Wind Slabs
New snowfall with extreme alpine winds is expected to have developed new wind slabs throughout the region. In the deepest snowfall areas in the region, there is the potential for a more widespread wind slab problem to exist.
Use ridges or ribs to avoid pockets of wind loaded snow.The new snow buries a weak layer which may increase the reactivity of new slabs.Be aware of the potential for wide propagations due to the presence of hard windslabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Valid until: Dec 20th, 2016 2:00PM