Avalanche Forecast

Archived

Jan 18th, 2023–Jan 19th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

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.

Below Treeline

Natural avalanches unlikely.

Regions

Lizard-Flathead, South Rockies, Flathead, Lizard, Moyie, Bull, Elkford East, Elkford West.

Keep an eye on recent wind loading patterns to avoid newly formed wind slabs. A weak basal snowpack structure continues to demand diligent group management. Regroup in safe locations, space out, and avoid shallow rocky start zones.

Confidence

Moderate

Avalanche Summary

On Tuesday, human-triggered wind slabs up to size 1 were reported from treeline and above.

Ski cutting in the Fernie area on Monday yielded small (size 1) wind slab releases after the area received 15 cm of new snow. Natural dry loose releases from steep alpine terrain reached size 1.5.

Snowpack Summary

Up to 15 cm of recent snow now settles on wind-affected surfaces above 2000 m and on a crust below 2000 metres.

A crust/facet layer is down 50-90 cm (and 2-15 cm thick at TL elevation). Where it's thickest, it caps a well-settled and consolidated mid-snowpack.

Another crust/facet layer is down 70-150 cm. Below this crust, the basal snowpack is weak and faceted.

Weather Summary

Wednesday Night

Mainly cloudy with isolated flurries 5-10 cm. Ridge winds moderate to strong from the southwest. Freezing level 1000 m.

Thursday

Cloudy with isolated flurries in the morning and sunny periods developing in the afternoon. Moderate southwest winds, potentially strong in the alpine, increasing over the day. Treeline high temperature near -5.

Friday

Cloudy with sunny breaks. Ridge wind light from the West. Alpine temperatures near -8 and freezing levels valley bottom.

Saturday

Mostly cloudy with scattered flurries. Ridge wind moderate from the southwest and freezing levels valley bottom.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

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.