Avalanche Forecast

Issued: Jan 11th, 2018 5:01PM

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

Tim Haggarty, Parks Canada

Jasper.

A bit of new snow has given the wind something to push around resulting in the first first real avalanche activity in the region for several weeks. Be on your game for the weekend: watch for increasing west winds and rising temperatures.

Summary

Weather Forecast

A ridge will reach the coast Friday and bring warmer, moist air to the region through the weekend. Watch for light west winds Friday to bring clouds but rising temperatures reaching a high of -10C in the Alpine. Temperatures will reach -6C on Saturday with a chance of a few flurries however watch for West winds to increase to 20-30km/h.

Snowpack Summary

Up to 15cm of recent snow has blown into thin windslabs TL and above. Old slabs 10-20cm deeper sit on a weak layer of facets or surface hoar TL and above. In sheltered areas this new snow sits a faceted upper snowpack at all elevations. A strong mid snowpack crust is providing strength but weakening. The lower snowpack continues to lose strength.

Avalanche Summary

Numerous sz 1 loose dry sluffs were seen spilling off of alpine ridges. A sz 2 slab avalanche 20cm deep and 50m wide likely failed on the Dec 18 persistent layer. This shallow slab ran a few meters before stepping down another 40 cm (likely through weak facets to the November 27 midpack crust). This ran 70m to a cliff triggering a small slab below.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

New snow covers pockets of old windslab sitting on weak, faceted snow that lacks strength, and may fail, to midpack depths. Treat all wind exposed areas with care but approach larger, uniform features and thin areas should be treated with caution.

Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

The new snow has already formed thin, spotty slabs even with the limited amount of wind we have seen so far. These slabs sit on freshly buried, weak facets and surface hoar in some areas. Watch for these slabs to develop with more wind Saturday.

Watch for surface cracking and stiffer surface layers of snow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 1

Loose Dry

New snow covers a facetted/weak upper snowpack in sheltered areas. Be cautious in very steep terrain and in confined features where a small sluff could build mass. Even light winds were triggering these events along alpine ridges Thursday.

The shallow, weakening snowpack makes for difficult trail breaking at low elevations.Use caution above ledges and cliffs where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 12th, 2018 4:00PM