Avalanche Forecast

Archived

Mar 27th, 2025–Mar 28th, 2025

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

The past few days have seen a major avalanche cycle due to a crappy snowpack and mix of weather inputs—warm temperatures, rain, high freezing levels, and new snow in the forecast.

Give avalanche terrain a miss for now. There is uncertainty about what will happen in the short term, and the snowpack will take time to adjust.

Confidence

Moderate

Avalanche Summary

A widespread avalanche cycle throughout the region occurred on Wednesday and Thursday. Avalanches to size 3.5 started at all elevations and ran mainly to the tops of runouts, with some going to valley bottom. A notable on Thursday was the ice climb Masseys in Field, running for a second time in 2 days to the valley bottom.

Snowpack Summary

Freezing levels reached ~2800m for the second day in a row, accompanied by rain and snow. Precipitation totals since March 25 are 10-20mm of rain at lower elevations and unknown amounts of snow up high! A dense slab, 50-100 cm thick, sits atop persistent weak layers of facets. In Eastern areas, facets and depth hoar extend to the ground (see profiles below), whereas, in thicker regions west of the divide, the layer is thinner with a more settled lower snowpack.

Weather Summary

Freezing levels will drop to valley bottom Friday AM and rise to 2000m in the afternoon. Expect 10-30cm over the region by Friday night with light winds. See below for details.

Terrain and Travel Advice

Uncertainty is best managed through conservative terrain choices.

Problems

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.