Avalanche Forecast

Issued: Jan 29th, 2015 8:22AM

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

Avalanche Canada pgoddard, Avalanche Canada

Cooling has improved avalanche danger, but deep avalanches remain a possibility, especially in thin snowpack areas at high elevations.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Light to moderate snow (5-15 cm) on Friday peters out on Saturday. Expect moderate SW to W winds, easing by Saturday afternoon. A second pulse of snow (5-15 cm) is due late Sunday. Freezing level is at valley floor.

Avalanche Summary

As the temperature drops I expect that avalanche activity will continue to slow down. The recent snow, rain, and wind were a great test of buried persistent weaknesses in the snowpack and resulted in a widespread avalanche cycle. The mid-January surface hoar layer was responsible for the majority of the recent avalanche activity in the region, producing numerous avalanches up to size 3.5. However, some deeper persistent layers were also triggered during this avalanche cycle. Reactive wind slabs may be lingering in the alpine and could produce large avalanches where they sit above the surface hoar.

Snowpack Summary

After a recent bout of intense warming and rain, cooler temperatures have left a supportive crust below about 2000 m. At higher elevations, recently formed wind slabs may be found lee to the south-west. Although warming and subsequent cooling have helped strengthen the snowpack, the mid-January surface hoar layer remains a concern and can be found down between 40 and 80 cm. The mid-December surface hoar layer is 80 to 140cm below the surface and appears to be slowly gaining strength.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent snow and SW winds have left wind slabs and cornices on lee slopes above treeline. A cornice fall or wind slab could step down and trigger a deeper weak layer.
Be cautious as you transition into wind affected terrain.>Travel on ridgetops to avoid wind slabs on slopes below.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
A layer of surface hoar buried in the upper snowpack remains a concern, especially above about 1900 m. An avalanche in motion or cornice fall could also trigger a second, deeper persistent weakness.
Caution around convexities or areas with a thin or variable snowpack.>Conditions are greatly improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Jan 30th, 2015 2:00PM