Avalanche Forecast

Archived

Feb 13th, 2023–Feb 14th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Regions

Cirrus-Wilson, Icefields.

10cm new snow fell overnight Sunday. This will make for good quality riding but will also hide previous wind slab in exposed tree line and alpine features. Natural avalanche activity may be tapering off but human triggering of large avalanches remains possible.

Confidence

Moderate

Avalanche Summary

One size 2 wind slab that stepped down to the basal facets was observed in the alpine on Monday in the Icefields area.

Natural avalanches up to size 2.5 were observed in the Icefields region, initiating in alpine and exposed tree line features on Saturday.

Avalanche control with explosives last Wednesday resulted in numerous large avalanches both wind slab and deep persistent slab running to the bottom of the avalanche paths.

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

Snowpack Summary

Up to 10cm overnight on Sunday added to the 30cm since February 7 in the Icefields area. Previous and present southwest winds had stripped exposed terrain in the alpine and continue to add to wind slab development in exposed tree line and alpine features. Generally the mid and bottom of the snowpack is weak facets with depth hoar at the base. Height of snow is variable from 50 to 150cm.

Weather Summary

A surface ridge is establishing Tuesday and Wednesday. Expect a mix of sun and cloud with light northerly winds on Tuesday. Similar on Wednesday with wind increasing to moderate values from the west. A low pressure system is expected to bring light precipitation late Thursday into Friday with winds increasing to strong values from the west. Freezing level will remain at valley bottom in the Icefields area.

Detailed weather forecasts from Avalanche Canada: https://avalanche.ca/weather/forecast

Terrain and Travel Advice

Expect slab conditions to change drastically as you move into wind exposed terrain.
Keep in mind that human triggering potential persists as natural avalanching tapers off.

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.

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.