Avalanche Forecast

Issued: Apr 5th, 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 Cornices.

deryl kelly, Parks Canada

Jasper.

Good skiing can be found in sheltered terrain.Persistent weak layers continue to show isolated signs of reactivity, this problem will likely persist for some time.

Summary

Weather Forecast

The timeless struggle between good (spring wx and evil (Arctic like wx) unfolds in the bulletin region. Good is forecast to come about yet, another surge of evil... er, arctic air will hold the cold front in place and, as a result, cold. The systems continue to mix through the weekend and fxs are calling for more of the same in the short term.

Snowpack Summary

Recent snow has been blown in to an isolated wind slab up to 30cm thick. This has added to the previous slab sitting on a sun-crust on solar aspects and facets on polar aspects - these are now buried as deep as 60cm. Underneath the variable slab in the upper snowpack, as well as in shallow areas, the snowpack is generally facetted and weak.

Avalanche Summary

No new avalanches observed or reported

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Problems

Persistent Slabs

Persistent slabs sit on facets on polar aspects (more reactive recently), and a hard melt-freeze crust on solar aspects. Use a cautious approach in open terrain and assess the bond at these interfaces carefully before committing to a slope.

Watch for signs of instability such as whumpfing, or cracking. Avoid shallow snowpack areas where triggering is more likely.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3

Wind Slabs

In most cases this interface presents as a manageable surface instability and is expected to go dormant pretty quickly.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution on open slopes and convex rolls

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Cornices continue to grow with fresh snow and wind. Several failures were noted in the past week, in most cases triggering a slab below.

Minimize exposure during periods of loading from new snow and wind.Give cornices a wide berth when travelling on or below ridges.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Apr 6th, 2018 4:00PM