Avalanche Forecast

Archived

Mar 23rd, 2023–Mar 24th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

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.

A return to more winter-like conditions is expected for Friday and Saturday with 5 to 10cm of new snow forecasted for the region. The widespread natural avalanche activity we've been seeing this past week will likely subside with the drop in temperatures, but the possibility of a human triggering the deep persistent problems still exists.

Also keep an eye out for local wind or storm slab development as this next weather system moves through, since there is a high amount of uncertainty in the forecast.

Confidence

Moderate

Avalanche Summary

Several wet loose avalanches observed in the last week occurring mid to late afternoon at all elevations southerly aspects with many stepping down to the basal weakness or triggering persistent and deep persistent slab avalanches. Large to very large deep persistent slabs have been observed throughout the region, generally triggered by a small loose wet slide, or a cornice fall.

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

Snowpack Summary

A crust has formed on solar aspects at all elevations, and on northerly aspects at low elevations. Approximately 20-30cm down is a buried sun crust at low elevations on steep southerly slopes and a surface facet layer in sheltered terrain. The mid-pack is 40 to 80cm of supportive facetted snow. Near the ground it is generally weak with large facets and depth hoar.

Weather Summary

Friday

Flurries.

Accumulation: 7 cm.

Alpine temperature: High -5 °C.

Ridge wind northwest: 10-20 km/h.

Freezing level: 1500 metres.

Saturday

Cloudy with sunny periods and isolated flurries.

Precipitation: Trace.

Alpine temperature: Low -11 °C, High -5 °C.

Ridge wind light to 15 km/h.

Freezing level: 1600 metres.

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

Terrain and Travel Advice

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

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.