Avalanche Forecast

Archived

Mar 11th, 2024–Mar 12th, 2024

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 unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Lizard-Flathead, South Rockies, Akamina, Flathead, Lizard, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

It's not time to step out yet, resist the temptation of large, open terrain

Wind slabs are reactive to human triggers and buried weak layers remain capable of producing very large avalanches

Confidence

Moderate

Avalanche Summary

Small slabs were reactive to rider traffic on Sunday within the storm snow.

Over the weekend large persistent slab avalanches continued, triggered by riders and naturally by cornice falls onto the slope below. A fatal avalanche occurred in nearby Kananaskis Country on Sunday, where a similar snowpack structure exists.

Snowpack Summary

Around 20 cm of recent storm snow has fallen and been redistributed into deeper deposits on north and east facing slopes by winds. These slabs sit over a crust on sun affected slopes, surface hoar in sheltered terrain, and wind affected snow in exposed areas and currently do not appear to be bonding well.

A widespread crust with weak facets above remains a concerning layer for human triggering. Buried 80-150 cm deep, this layer has produced very large avalanche activity this week.

The snowpack below the crust is generally strong.

Weather Summary

Monday Night

Cloudy with another 5 cm possible. 40-60 km/h southwest ridgetop wind. Freezing level remains above 1000 m.

Tuesday

Cloudy with up to 10 cm of snow. 30-40 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1500 m.

Wednesday

A mix of sun and cloud with isolated flurries delivering 5 cm in most areas or higher amounts in localised areas. 10-20 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level 1600 m.

Thursday

Mostly clear skies. 30-40 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Remote triggering is a concern, watch out for adjacent and overhead slopes.
Cornice failures could trigger very large and destructive avalanches.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

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.

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.