Avalanche Forecast

Archived

Apr 20th, 2023–Apr 21st, 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, Akamina, Flathead, Lizard, Moyie.

Watch for freshly formed wind slab in the alpine as you transition over convex roll features or just below ridgetop.

Expect the upper snowpack to become unconsolidated during daytime warming and allow for even small avalanches to gain enough mass to become hazardous.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported in the region on Thursday.

On Wednesday a large (size 2.5) skier trigger avalanche was reported west of the town of Fernie. This avalanche initiated near 1700 m on a south aspect and ran approximately 700 m. Initially the avalanche was a slab and then began to entrain the available storm snow in the track with debris photos reminiscent of a wet loose avalanche. See this MIN report link for further information.

We expect backcountry users will see evidence of a small dry loose avalanche cycle in the alpine from convective flurries through the last few days.

If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.

Snowpack Summary

In the alpine and around treeline, 10-30 cm of recent snow covers a frozen melt freeze crust.

Below treeline, expect to find moist or refrozen surfaces, and a shrinking snowpack that is isothermal during the heat of the day.

The mid snowpack is generally settled and strong, except in areas with snow depths less than 150 cm. In these lower snow areas, the mid-pack is likely weaker and more faceted.

The lower snowpack includes a layer of weak sugary crystals near the ground. This layer has shown signs of gaining strength, and it has not produced recent avalanche activity in this area.

Weather Summary

Thursday Night

Cloudy with isolated flurries, 1-5 cm accumulation. Light southwest ridgetop winds. Freezing levels 500 m. Treeline low around -9 °C.

Friday

Mainly cloudy with isolated flurries, trace accumulations. Light to moderate northwest ridgetop wind. Freezing levels 1600 m. Treeline high around -1 °C.

Saturday

Mix of sun and cloud with isolated flurries, trace accumulations. Light to moderate west ridgetop wind. Freezing levels rise from valley bottom to 2000 m by mid-day. Treeline high 0 °C.

Sunday

Mostly cloudy with sunny periods and isolated flurries, trace accumulations. Moderate west ridgetop wind. Freezing levels rise from 700 m bottom to 2100 m by mid-day. Treeline high +2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Brief periods of sun could quickly initiate natural avalanche activity.
Be carefull around freshly wind loaded features.
Be alert to conditions that change with elevation and sun exposure.

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.

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.