Avalanche Forecast

Issued: Apr 6th, 2016 4:00PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Deep Persistent Slabs, Loose Wet and Cornices.

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Expect the hazard to rise towards HIGH as skies clear and temperatures rise on Thursday. There may be an opportunity for some corn skiing if timed right. Plan to finish early over the next few days.

Summary

Weather Forecast

Skies will clear through Thursday as another warm ridge of high pressure arrives and temperatures will skyrocket for Thursday afternoon and Friday and the hazard will again rise towards HIGH with heating and as crusts break down.

Snowpack Summary

A skiff of new snow on top of surface crusts that remained intact today except at valley bottom elevations. The morning snowpack is strong when frozen, but this can rapidly break down with warming. In many places the snowpack is sitting on a deep persistent layer of facets that has been avalanching with solar heating over the previous week.

Avalanche Summary

Another day of cool day. Tuesday's trip through Surprise Pass showed a snowpack locked up from the cold temperatures. Sunshine reports isolated wind slabs in the immediate NW lees of ridgelines 20-50 cm thick. They were less reactive today, but may be more touchy in the warmer days to come. Similar conditions may exist on the Wapta.

Confidence

Problems

Deep Persistent Slabs

Deep facet layers remain weak especially in thin snowpack areas. On Thursday be cautious in large steep terrain especially when temperatures increase during the later part of the day as skies clear and temperatures rise.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Wet

Freezing levels will spike to 3300 m on Thursday as the ridge of high pressure settles in. In the afternoon any steep slopes should be avoided when the crust on top of the snowpack melts. Start early and finish early!

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Cornices

We have seen numerous cornice failures in the past week during periods of warm temperatures, some of which have triggered large slabs on the slopes below. Minimize your time under these at this time of the year.

Cornices become weak with daytime heating, so travel early on exposed slopes.Even small cornice falls may trigger larger avalanches.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 7th, 2016 4:00PM