Avalanche Forecast

Archived

Mar 26th, 2023–Mar 27th, 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, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Variable convective flurries produced 2-10cm of new snow on Sunday. Isolated pockets of deeper snow may be found in the forecast area and will likely not be bonding well to a solar crust from last week.

Large triggers such as cornice falls continue to trigger persistent slabs. Human triggering of the persistent and deep persistent slab remains possible.

Solar warming should once again factor into your trip planning - avoid exposure to southerly slopes during peak warming.

Confidence

Moderate

Avalanche Summary

Limited new activity noted on the Icefields Parkway on Sunday - a couple of dry loose size 1.5 in the alpine Mount Cirus; serac activity estimated size 2 off of Stutfield.

Maligne patrol noted a cornice triggered persistent slab size 2.5 east aspect and a size 2 persistent slab west aspect both visible just south of Medicine lake.

Cornice failures and loose wet avalanches may increase late afternoons as sunshine returns Monday and Tuesday.

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

Snowpack Summary

2-10cm of new snow/graupel sits over a breakable sun crust at all elevations on solar aspects. True north aspects are faceted with widespread wind effect in open areas at tree line and above. Approximately 20-50cm down is a persistent slab sitting over a facet layer in sheltered terrain or a weak crust at low elevations / southerly slopes. The lower snowpack is generally weak with large facets and depth hoar at the base.Snow depth varies from 60-150cm.

Weather Summary

Monday will be a mix of sun and cloud as a surface ridge of high pressure becomes established. The freezing level will remain at valley bottom with winds staying light from the north. Tuesday will be similar with the freezing level rising to 1500m. Scattered flurries are expected Wednesday afternoon as a low pressure system descends from the north. Freezing level rising to 1900m - light rain possible at lower elevations.

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.