Avalanche Forecast

Issued: Mar 28th, 2016 4:26PM

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

Tim Haggarty, Parks Canada

Banff Yoho Kootenay.

With a high pressure system settling into the divide over the next few days, heating will be the critical factor to monitor. Expect a steady heating trend to increase the avalanche hazard toward the weekend.

Summary

Weather Forecast

Following the upslope precip that arrived Sunday, forecasts show a large high pressure system pushing into the divide overnight. This should bring a good freeze into Tuesday but freezing levels will quickly return to around treeline with the potential for a trace of precip. A weak freeze into Wednesday, again with a bit of precip as temps rise...

Snowpack Summary

A few cm of new snow today became moist with heating at low elevations and some solar input. Crusts are buried on solar aspects and on shady aspects below 2000m in the upper snowpack. Shallow snowpack areas are weak, and we are concerned about facets in the lower snowpack overlain by a stiff slab which produces easy, sudden collapses in tests.

Avalanche Summary

No avalanches observed or reported today.

Confidence

Freezing levels are uncertain on Wednesday

Problems

Deep Persistent Slabs

Deep facet layers remain very weak, especially in thin or rocky areas. Avoid large open slopes, steep slopes (>30 degrees) and be wary that you can trigger this problem from a long distance away - the slab is stiff and it propagates far.

Avoid steep convexities or areas with a thin or variable snowpack.Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Loose Wet

As the new snow from Sunday is heated it will fail easily over the recently buried crust. As freezing levels rise through the week this problem should progress to affect more and more terrain.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Minimize exposure when the solar radiation is strong, especially if snow is moist or wet.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Cornices

Cornices are large. Give them a wide berth on ridge crests, as they can pull back a long way when they fail and may trigger avalanches below. If you need to travel under cornices, move quickly and think twice if there is significant heating.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Mar 29th, 2016 4:00PM