Avalanche Forecast

Archived

Mar 21st, 2020–Mar 22nd, 2020

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

South Rockies.

Clouds may temper day-time warming. Minimize exposure to cornices and steep slopes that face the sun during the warmest part of the day. A deep weak layer remain a concern.

Confidence

High -

Weather Forecast

Saturday night: Partly cloudy with brief flurries bringing a trace. Light northwest wind. Freezing level valley bottom.

Sunday: Mix of sun and cloud. Moderate to strong southwest wind. Freezing level 1700 m.

Monday: Scattered flurries bringing trace. Moderate to strong southwest wind. Freezing level 1800 m.

Tuesday: 10-20 cm new snow. Light southwest wind. Freezing level 1000 m.

Avalanche Summary

A single snowmobile triggered size 1 wind slab was observed amid extensive slope "testing" on Friday. In neighboring Waterton National Park, solar-triggered loose dry and wind slabs up to size 1.5 were observed Thursday and Friday, having run surprisingly far on a crust. A size 2 deep persistent slab out of steep, thin, rocky alpine terrain Thursday reminds us that the basal facets still exist and can be triggered in this type of terrain.

If you decide to travel in the backcountry, consider sharing your observations with us and fellow recreationists via the Mountain Information Network (MIN) to supplement our data stream as operators are shutting down. Even just a photo of what the day looked like would be helpful.

Snowpack Summary

Sunny skies have formed a melt-freeze crust on sun-exposed slopes. The alpine consists of wind affected snow from easterly wind, so you may find small pockets of wind slabs in atypical terrain features on south to west aspects.

A layer of faceted grains overly a melt-freeze crust from early February. This layer currently sits 40 to 80 cm below the surface.

The base of the snowpack contains basal facets that are most prominent in shallow, rocky start zones.

Terrain and Travel

Carefully evaluate steep lines for wind slabs.
Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Rocks will heat up with daytime warming and may become trigger points for loose wet avalanches
Be aware of the potential for large avalanches due to the presence of a deep persistent slab.

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.

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.