Avalanche Forecast

Archived

Jan 14th, 2023–Jan 15th, 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 unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Jasper, Churchill, Cirrus-Wilson, Fryatt, Icefields, Miette Lake.

Natural cornice failure and wind slabs have been triggering large avalanches in the Deep Persistent Weak Layers. Natural activity is tapering, but the likely hood of human triggered avalanches still remains high.

Confidence

Moderate

Avalanche Summary

Friday there was evidence of a Na cycle up to Size 3. Better visibility on Saturday showed continued evidence of this cycle. The avalanches are initiating with cornice fall or in the Wind Slab and stepping down to the basal facets.

If you're out in the hills, don't forget to post to the MIN. Every bit of information helps

Snowpack Summary

5cm of new snow with strong to extreme SW winds in the alpine on Friday. Freezing levels have dropped since Friday and left a new crust below 2200m. A layer of surface hoar and facets is down 20-40cm in sheltered areas. Large facets and depth hoar comprise the bottom portion of the snowpack. Snowpack depths vary from 50-100cm.

Weather Summary

Sunday

Mainly cloudy with isolated flurries.

Precipitation: Trace.

Alpine temperature: High -4 °C.

Ridge wind light to 15 km/h.

Freezing level: 1600 metres.

Monday

Cloudy with sunny periods and isolated flurries.

Precipitation: Trace.

Alpine temperature: Low -8 °C, High -6 °C.

Ridge wind southwest: 15-25 km/h.

Freezing level at valley bottom.

Tuesday

Cloudy with sunny periods and isolated flurries.

Precipitation: Trace.

Alpine temperature: Low -12 °C, High -8 °C.

Ridge wind southwest: 15-35 km/h.

Freezing level at valley bottom.

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

Terrain and Travel Advice

Make conservative terrain choices and avoid overhead hazard.
Caution around slopes that are exposed to cornices overhead.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

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.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.