Avalanche Forecast

Archived

May 4th, 2024–May 5th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Regions

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

The hazard rating is for the highest danger for the day.

The deterioration could happen fast with the forecasted warm temps, sunny skies in the morning, and light winds. Be mindful that snow is on the way and could start as early as the afternoon.

Start very early and finish early.

Confidence

Moderate

Avalanche Summary

Afternoon warming has produced numerous wet loose avalanches sizes 1-2 over the last several days. While activity may be tapering, there is still a high likelyhood for avalanches when the sun is shining and temperatures warm up in the afternoon.

On Saturday, there was a size 3 avalanche that failed on the deep persistent slab. The cornice that triggered the layer is a reminder that large loads have the potential to trigger these basal facets.

Snowpack Summary

Expect isothermal snow below 2100m. Surface crusts exist to ridge top on solar aspects. Dry snow can still be found high on due north aspects above 2400m.

The mid-pack Feb 3 persistent layer (facet layer) is still lingering on high northerly aspects, above 2500m. Basal facets and depth hoar remain a weak layer at the bottom of the snowpack at all elevations and aspects.

Weather Summary

Sat Evening: Wind southeast: 10 km/h. Freezing level 1900m.

Sunday: Mix of sun and clouds in the morning with 10-15 cm of snow expected to start in the late pm. Alpine High -2 °C, with light southerly winds.

Freezing level: 2600 m

Monday: Cloudy with sunny periods and isolated flurries. Alpine low -8 °C, high -5 °C. Winds out of the west @ 15 km/h.

Freezing level: 2400 m

For more detailed weather click here.

Terrain and Travel Advice

Avoid exposure to overhead hazards when solar radiation is strong.
Cornices become weak with daytime heating or solar exposure.
Cornice failure may trigger large avalanches.

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.