Avalanche Forecast

Issued: Apr 6th, 2018 4:00PM

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

deryl kelly, Parks Canada

Jasper.

New snow available for transport may be enough to overload existing and lingering instabilities. Read, and share conditions in the region. Write a trip report about your day on Avalanche Canada's Mountain Information Network

Summary

Weather Forecast

Arctic air remained entrenched over the Prairies for Friday. Light winds shifting to the SW have brought a warmer, moist air mass into the bulletin region. Saturday morning is forecasted for some light flurries with total snowfall of 6cm for the day. Freezing level rising to 2300m and seasonally warm temps; alpine temp 1c.

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

Read, and share conditions in the region. Write a trip report on your day on Avalanche Canada's Mountain Information NetworkActive cornice failures reported earlier in the week have triggered persistent slabs below ridge-tops. Good travel and riding conditions through the bulletin region.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Problems

Wind Slabs

New moist snow available for transport with incoming flurries. This will build on surface layers and may be enough to overload existing and lingering instabilities.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

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.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3

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.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 7th, 2018 4:00PM