Avalanche Forecast

Archived

Apr 13th, 2025–Apr 14th, 2025

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Below Threshold.

Regions

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

Start and finish early. Solar radiation will increase the likelihood of all of the described avalanche problems as the day progresses on Monday.

Human triggering of the persistent weak layers is much more of a concern in these shallow snowpack areas compared to areas to the West that are described in the Little Yoho bulletin.

Confidence

Moderate

Avalanche Summary

No new avalanches were observed at the time of writing Sunday.

On Saturday, skiers in the Ferris Glacier area remote-triggered a wind slab 60 cm deep on NE alpine terrain.

On Friday, skiers remote triggered a wind slab, possibly over a recent crust, on St. Nicholas size 2.5 that stepped down to deeper layers and occurred on steep, unsupported terrain.

Snowpack Summary

10-20 cm of dry snow overlays crusts found in most locations, with up to 60 cm on north-facing alpine zones. Windslabs can be found on lee aspects in the alpine.

The lower half of the snowpack is facets and depth hoar beneath a 30-60 cm stiff midpack slab. On all but high north aspects, upper snowpack crusts overlay this midpack slab. If these crusts are thick and remain frozen, they provide some strength over the weakness. On high north slopes, this weakness remains a concern.

Weather Summary

Clearing overnight Sunday with treeline temperatures dropping to -10°C while W/NW winds diminish to light.

Monday, a mix of sun and cloud as the freezing levels rise to 2400 m. Significant solar effects are likely. West winds increase to moderate. Overnight temperatures at treeline will drop to -7°C.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.