Avalanche Forecast

Archived

Apr 23rd, 2025–Apr 24th, 2025

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Regions

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

It's a great time to get out! Easy travel on firm surfaces (crampons helpful!) with 5 - 15 cm on high due north aspects. Travel in the early morning hours and watch for sun-triggered wet loose avalanches. Spring Conditions - The hazard is expected to be Low in the cold mornings and rise in accordance with the degree of warming.

Enjoy!

Confidence

No Rating

Avalanche Summary

Tuesday, Sunshine patrol reported observing a distant cornice failure on the Monarch in the Sunshine backcountry. They estimated it was not larger than a size 1.5, and that it was unlikely to have triggered a slab.

Otherwise, no avalanches observed or reported on Tuesday or Wednesday.

No avalanches reported on the persistent weak layer since the last warm-up on April 18th, when there were 2-3 size 2.5 avalanches off Pilot Mtn.

Snowpack Summary

Hard surface crusts exist on steep solar aspects and at treeline and below.

On north alpine aspects, 5 - 20 cm of dry snow over firmer surfaces. Off due north, some alpine slopes may have a new surface thin crust capping the 5-10 cm of snow from a few days ago.

The March 27 crust is 30-70 cm deep and extends to about 2500m and to the ridge top on solar aspects.

Below the settled mid-pack, weak facets and depth hoar at the ground remain.

Weather Summary

Progressively warmer over Thursday through Saturday with clear skies and light SW wind. Despite the warming trend for temperatures at 3000 m over the next few days, the freezing levels drop to the valley bottom for Wednesday and Thursday night. Daytime freezing levels rise to 2500 m on Thursday, 2800 m on Friday, and about 3000 m on Saturday.

See the attached weather table for more on temperatures and wind.

Terrain and Travel Advice

A moist or wet snow surface, pinwheeling, and natural avalanches are all indicators of a weakening snowpack.

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.

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.

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.