Avalanche Forecast

Issued: Jan 13th, 2018 4:00PM

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 warmer still on Sunday potentially making triggering a bit more likely. Persistent slabs that begin to be encountered at treeline, and are more developed in the Alpine, make it tough to travel with confidence.

Summary

Weather Forecast

Warm, moist air will continue to override the cold arctic air over the Jasper region through Sunday with a chance of a few flurries in the early AM and cloud for the day. Freezing levels will climb to near 2300m and winds should back a bit and shift to the North. Monday winds should shift to the South but temps will cool a bit.

Snowpack Summary

10-15cm of recent snow has blown into thin slabs TL and above. Old slabs, 10-40cm deeper, sit on a weak layer of facets or surface hoar TL and above. In sheltered areas the new snow sits a weak,faceted upper snowpack at all elevations. A strong mid snowpack crust is providing strength but is weakening. The lower snowpack continues to lose strength.

Avalanche Summary

No new avalanche activity seen since Thursday when a sz 2 slab 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 mid-pack crust). All of this ran 70m to a cliff triggering a small slab below.

Confidence

Freezing levels are uncertain on Sunday

Problems

Persistent Slabs

New snow covers pockets of old slab found in exposed areas that sit on weak, faceted snow that lacks strength, and may fail, to mid-pack depths. Treat all wind exposed areas with care but approach larger, uniform features and thin areas 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 been redistributed into thin, spotty slabs in exposed areas. These slabs sit on freshly buried, weak facets and surface hoar in some areas. Triggering one of these slabs may provide enough load to trigger the deeper persistent slab.

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

Expected Size

1 - 2

Loose Dry

New snow covers a facetted and weak upper snowpack in sheltered areas. Be cautious in very steep terrain and in confined features where a small sluff could build mass. Consider the potential for these small sluffs to trigger slabs TL and above.

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

Expected Size

1 - 2

Valid until: Jan 14th, 2018 4:00PM