Avalanche Forecast

Archived

Feb 21st, 2023–Feb 22nd, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

Moderate to strong winds continue to redistribute the recent storm snow. Although, there has been a minimal natural avalanche activity observed following this weather change, wind slab and deep persistent slab are still of concern. Choose terrain conservatively and bear in mind the potential for a low probability high consequence avalanche occurrence.

Confidence

Moderate

Avalanche Summary

Parkway patrol on Tuesday observed minimal new natural activity. The visibility was intermittent but observations were made from all elevation bands and aspects. Significant wind drifting observed to reach to below tree line in wind prone areas.

Maligne road patrol on Tuesday saw no new natural avalanche activity.Late report from Shangrila area of a large avalanche off Mt Jeffrey reaching the creek likely on Feb 16.

Don't forget to post avalanche observations to the MIN.

Snowpack Summary

Up to 15 cm of new snow from Monday night has been redistributed by the recent moderate to strong north to easterly winds. Reverse loading present in the alpine and open tree line. In sheltered locations the upper snowpack is comprised of 25-35 cm soft snow from the past couple of weeks on top of a generally weak mid and lower snowpack with facets and depth hoar at the base. The height of snow is variable from 50 to 150cm.

Weather Summary

Wednesday will be mainly cloudy with isolated flurries and trace of precipitation. Alpine temperature high is forecast at -28 C. Thursday brings a mix of sun and cloud, but the sun may only warm your soul and not your toes as the arctic air persists over the Rockies and alpine high is expected at - 26 C. Easterly lights wind shifting to southeasterly on Thursday.

Detailed weather forecasts from Avalanche Canada: https://avalanche.ca/weather/forecast

Terrain and Travel Advice

Expect slab conditions to change drastically as you move into wind exposed terrain.
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.