Avalanche Forecast

Archived

Feb 25th, 2024–Feb 26th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Purcells, Dogtooth, East Purcell.

UPDATED 7:10

Avoid avalanche terrain.

Don't let storm day fever lure you into big terrain features.

Confidence

Moderate

Avalanche Summary

On Saturday small but reactive storm slabs were observed in lee features near ridgetops in the Dogtooth Range

On Friday a few size 1 to 2 naturally triggered wind slabs were observed near Invermere on north and east-facing alpine slopes.

The likelihood of human-triggered avalanches is primed to increase throughout the stormy period and may remain elevated for several days.

Snowpack Summary

Approximately 5 to 15 cm of new snow is expected to fall by the end of the day Monday. This new snow will add to previous storm snow totals of up to 35 cm in the Dogtooth Range, and around 5 to 15 cm in the rest of the region.

Combined, this snow will cover a variety of old surfaces, including surface hoar, old wind-affected snow, and a crust.

In isolated, sheltered areas, an additional layer of surface hoar may be found buried 30 to 50 cm.

A widespread crust formed in early February is buried roughly 30 to 60 cm. This crust may be less prominent or not exist at high alpine elevations.

The mid and lower snowpack is largely faceted with depth hoar and a crust found at the bottom of the snowpack in many areas.

Weather Summary

Sunday Night

Cloudy with 1 to 7 cm of new snow. 25 to 40 km/h southwest ridgetop wind. Treeline temperature dropping to -10 °C.

Monday

A mix of sun and cloud with 1 to 2 cm of new snow. 15 km/h northwest ridgetop wind. Treeline temperature -8 °C.

Tuesday

A mix of sun and cloud with 1 cm of new snow. 5 to 10 km/h variable ridgetop wind. Treeline temperature -15 °C.

Wednesday

Cloudy with 1 to 4 cm of snow. 15 to 30 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1700 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.