Avalanche Forecast

Archived

Apr 12th, 2023–Apr 13th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

If stepping out into more serious terrain, do so with caution and backed-up with evidence. Watch-out for solar radiation affecting the new snow if the sun comes out.

Confidence

Moderate

Avalanche Summary

A road patrol on Wednesday down the Icefields Parkway saw several large avalanches up to size 3 in the alpine. These are likely from Sunday or Monday. Explosive control along Maligne Lake road produced one size 2 running onto the road. This avalanche stepped down to ground.

Don't forget to post avalanche observations to the MIN.

Snowpack Summary

Up to 20cm precipitation since Sunday sits on a melt freeze/solar crust. Snow in the alpine was accompanied by strong southwest winds creating new wind slabs in lee features. Snowpack below 1800m is in a daily melt-freeze cycle. The mid pack above this elevation consists of multiple layers of sun crusts or facets. Depth hoar and basal facets make up the base of the snowpack.

Weather Summary

Thursday

A mix of sun and cloud.

Precipitation: Nil.

Alpine temperature: High -5 °C.

Ridge wind light to 15 km/h.

Freezing level: 1700 metres.

Friday

A mix of sun and cloud.

Precipitation: Nil.

Alpine temperature: Low -12 °C, High -5 °C.

Ridge wind southwest: 10-30 km/h.

Freezing level: 1600 metres.

Terrain and Travel Advice

Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Remember that the snowpack will be significantly different at higher elevations than lower down.

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.

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.