Avalanche Forecast

Archived

Apr 4th, 2025–Apr 5th, 2025

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 possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

Solar warming will increase and freezing levels will rise over the weekend, leading to an increase in natural avalanche activity.

Avoid overhead exposure, especially to solar slopes and cornices.

Confidence

Moderate

Avalanche Summary

Throughout the week, large avalanches up to size 3 have been failing on a persistent weak layer in the snowpack. These avalanches have the potential to be triggered by cornice or loose wet failures caused by solar warming or sympathetically from nearby avalanches. Loose dry avalanches have also occurred out of steep terrain.

Snowpack Summary

There is 10-35 cm of recent storm snow in the icefields area. This new snow sits on a crust on all but due north aspects. 1-5mm Surface hoar sits on top of this crust in many areas. A 50-100 cm settled mid-pack rests on top of weak facets. The lower snowpack consists of depth hoar and breaking down crusts. Tree line snow depth is 110-170 cm.

Weather Summary

Saturday

A mix of sun and cloud. Precipitation: Nil. Alpine temperature: High -1 °C. Ridge wind west: 10 km/h. Freezing level: 2200 metres.

Sunday

A mix of sun and cloud. Precipitation: Nil. Alpine temperature: Low -4 °C, High 1 °C. Ridge wind southwest: 10 km/h. Freezing level: 2400 metres.

Monday

Mainly cloudy with isolated flurries. Precipitation: Trace. Alpine temperature: Low -1 °C, High 2 °C. Ridge wind southwest: 10-30 km/h. Freezing level: 2200 metres.

Terrain and Travel Advice

Make conservative terrain choices and avoid overhead hazard.
Even brief periods of direct sun could produce natural avalanches.
Be mindful that deep instabilities are still present in the snowpack.
Loose avalanches may step down to deeper layers, resulting in larger avalanches.
A moist or wet snow surface, pinwheeling, and natural avalanches are all indicators of a weakening snowpack.

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.

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.

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.