Avalanche Forecast

Archived

May 8th, 2024–May 12th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Widespread avalanches certain.

Treeline

Widespread avalanches certain.

Below Treeline

Natural and human triggered avalanches likely.

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

The first major warm-up for the season is upon us!!!

As freezing levels spike over the weekend so will the avalanche hazard as we enter a period of All Melt, No Freeze.

Large avalanches may run into below treeline terrain.

Time to break out the bikes and avoid all avalanche terrain.

Confidence

No Rating

Avalanche Summary

Several loose wet avalanches on Thursday on West aspects up to size 2. We expect this activity will increase over the coming days, with larger avalanches involving the entire snowpack.

Snowpack Summary

Expect a crust on all aspects except high due North aspects. Warm temperatures and lots of solar radiation forecasted for Thursday through Sunday will progressively weaken the snowpack resulting in widespread loose wet avalanches.

The mid-pack persistent layer and basal depth hoar layer are expected to become active with the warm temperatures, resulting in deeper and full-depth slab avalanches that may run into below treeline terrain.

Weather Summary

A ridge of high pressure dominates the region for the next few days. Wednesday is the last night of a slight freeze as freezing levels dip to 1900 m. Freezing levels are expected to progressively climb through the weekend, reaching up to 3600 m with no overnight freeze. Valley bottom temperatures will be in the +18C range.

For more detailed weather click here.

Terrain and Travel Advice

The likelihood of deep persistent slab avalanches will increase with each day of warm weather.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.